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Volume 102-B, Issue SUPP_8 August 2020 The Canadian Orthopaedic Association (COA) and The International Combined Orthopaedic Research Societies (ICORS) Meeting, Montreal, Canada, June 2019. Part 3.

General Orthopaedics
Full Access
K. Culliton A. Speirs P. Beaulé

The avascular nature of articular cartilage relies on diffusion pathways to obtain essential nutrients and molecules for cellular activity. Understanding these transport pathways is essential to maintaining and improving the health of articular cartilage and ultimately synovial joints. Several studies have shown that joint articulation is associated with fluid and solute uptake although it remains unclear what role sliding motion independently plays. This study investigates the role of sliding with a non-stationary contact area on the uptake of small molecular weight tracers into articular cartilage.

Ten-millimeter diameter cartilage-bone plugs were obtained from porcine knee joints and sealed into purpose made diffusion chambers. The chambers were designed to eliminate diffusion from the radial edge and only allow diffusion through the articular surface. The bone side of the chamber was filled with PBS to maintain tissue hydration while the cartilage side was filled with 0.01mg/ml fluorescein sodium salt (FNa) prepared using PBS. Sliding loads with a non-stationary contact area were applied across the articular surface by a custom apparatus using a 4.5 mm diameter spherical indenter. A moving contact area was chosen to represent physiological joint motions. Reciprocal sliding was maintained at a rate of 5 mm/s for 2 and 4 hours. Control samples were subject to passive diffusion for 0, 4, and 88 hours. After diffusion tests, samples were snap frozen and 20 µm cross-sectional cuts were taken perpendicular to the sliding direction. Samples were imaged using a Zeiss AxioImager M2 epifluorescent microscope under 5× magnification with a filter for FNa. Intensity profiles were mapped from the articular surface to the subchondral bone.

Unloaded control samples demonstrated minimal solute uptake at 4 hours penetrating less than 5% of the total cartilage depth. By 88 hours solute penetration had reached the subchondral bone although there was minimal accumulation within the cartilage matrix indicated by the relatively low intensity profile values. Samples that had been subjected to reciprocal sliding demonstrated accelerated penetration and solute accumulation compared to unloaded samples. After 1 hour of reciprocal sliding, the solute had reached 40% of the cartilage depth, this increased to approximately 80% at 4 hours, with much higher intensities compared to unloaded controls.

Sliding motion plays an important role in the uptake of solutes into the cartilage matrix. Maintaining joint motion both post injury and in the arthritic process is a critical component of cartilage nutrition. Samples that had been subject to reciprocal sliding demonstrated accelerated solute penetration and accumulation in the cartilage matrix, exceeding steady state concentrations achieved by passive diffusion.

B. Matache G. J.W. King A. C. Watts P. Robinson A. Mandaleson

Total elbow arthroplasty (TEA) usage is increasing owing to expanded surgical indications, better implant designs, and improved long-term survival. Correct humeral implant positioning has been shown to diminish stem loading in vitro, and radiographic loosening in in the long-term. Replication of the native elbow centre of rotation is thought to restore normal muscle moment arms and has been suggested to improve elbow strength and function. While much of the focus has been on humeral component positioning, little is known about the effect of positioning of the ulnar stem on post-operative range of motion and clinical outcomes. The purpose of this study is to determine the effect of the sagittal alignment and positioning of the humeral and ulnar components on the functional outcomes after TEA.

Between 2003 and 2016, 173 semi-constrained TEAs (Wright-Tornier Latitude/Latitude EV, Memphis, TN, USA) were performed at our institution, and our preliminary analysis includes 46 elbows in 41 patients (39 female, 7 male). Patients were excluded if they had severe elbow deformity precluding reliable measurement, experienced a major complication related to an ipsilateral upper limb procedure, or underwent revision TEA. For each elbow, saggital alignment was compared pre- and post-operatively. A best fit circle of the trochlea and capitellum was drawn, with its centre representing the rotation axis. Ninety degree tangent lines from the intramedullary axes of the ulna and humerus, and from the olecranon tip to the centre of rotation were drawn and measured relative to the rotation axis, representing the ulna posterior offset, humerus offset, and ulna proximal offset, respectively. In addition, we measured the ulna stem angle (angle subtended by the implant and the intramedullary axis of the ulna), as well as radial neck offset (the length of a 90o tangent line from the intramedullary axis of the radial neck and the centre of rotation) in patients with retained or replaced radial heads. Our primary outcome measure was the quickDASH score recorded at the latest follow-up for each patient. Our secondary outcome measures were postoperative flexion, extension, pronation and supination measured at the same timepoints. Each variable was tested for linear correlation with the primary and secondary outcome measures using the Pearson two-tailed test.

At an average follow-up of 6.8 years (range 2–14 years), there was a strong positive correlation between anterior radial neck offset and the quickDASH (r=0.60, p=0.001). There was also a weak negative correlation between the posterior offset of the ulnar component and the qDASH (r=0.39, p=0.031), and a moderate positive correlation between the change in humeral offset and elbow supination (r=0.41, p=0.044). The ulna proximal offset and ulna stem angle were not correlated with either the primary, or secondary outcome measures.

When performing primary TEA with radial head retention, or replacement, care should be taken to ensure that the ulnar component is correctly positioned such that intramedullary axis of the radial neck lines up with the centre of elbow rotation, as this strongly correlates with better function and less pain after surgery.

S. Seddigh M. J. Dunbar J. Douglas L. Lethbridge P. Theriault

Currently 180 days is the target maximum wait time set by all Canadian provinces for elective joint replacement surgery. In Nova Scotia however, only 34% of Total Knee Arthroplasties (TKA) and 51% of Total Hip Arthroplasties (THA) met this benchmark in 2017. Surgery performed later in the natural history of disease is shown to have significant impact on pain, function and Health related Quality of Life at the time of surgery and potentially affect post-operative outcomes. The aim of this study is to describe the association between wait time and acute hospital Length of Stay (LOS) during elective hip and knee arthroplasty in province of Nova Scotia. Secondarily we aim to describe risk factors associated with variations in LOS.

Data from Patient Access Registry Nova Scotia (PAR-NS) was linked to the hospital Discharge Access Database (DAD) for primary hip and knee arthroplasty spanning 2009 to 2017. There were 23,727 DAD observations and 21,329 PARNS observations identified. Observations were excluded based on missing variables, missing linkages, revision status and emergency cases. Percentage difference in LOS, risk factors and outcomes were analyzed using Poisson regression for those waiting more than 180 days compared to those waiting equal or less than 180 days.

For primary TKA, 11,833 observations were identified with mean age of 66 years, mean wait time of 348 days and mean LOS of 3.6 days. After adjusting for controls, patients waiting more than 180 days for elective TKA have a 2.5% longer acute care LOS (p < 0.028). Risk factors identified for prolonged LOS are advanced age, female gender, higher surgical priority indicator, required blood transfusion, dementia, peptic ulcer disease, cerebrovascular disease, heart failure, chronic kidney disease, malignancy, ischemic heart disease and diabetes. Factors associated with decreased LOS are surgical year, use of local anesthetic, peripheral location of hospital and admission to hospital from home.

For primary THA, 6626 observations were identified with mean age of 66 years, mean wait time of 267 days and mean LOS of 4 days. Patients waiting more than 180 days for THA did not show a statistically significant association with LOS. Risk factors and protective factors are the same with exception of CVD and use of local anesthetic.

Our findings suggest a positive and statistically significant association for patients waiting more than 180 days for TKA and longer acute care LOS. Longer LOS may be due to deteriorating health status while placed on a surgical waitlist and may represent a delayed and indirect cost to the patient and the healthcare system. Ultimately with projected increase in demand for elective joint replacement surgeries, our findings are aimed to inform physicians and policy makers in management of surgical waitlist efficiency and cost effectiveness.

For any reader inquiries, please contact shahriar-s@hotmail.com

G. Basile I. Alshaygy J. Mattei A. Griffin P. Ferguson J. S. Wunder

Lymph node metastasis are a rare occurrence in soft tissue sarcomas of the extremity, arising in less than 5% of patients. Few studies have evaluated the prognosis and survival of patients with a lymph node metastasis. Early reports compared lymph node involvement to lung metastasis, while others suggested a slightly better outcome. The purpose of this study was to evaluate the impact of lymph node metastasis on patient survival and to investigate the histologic and clinical features associated with lymph node involvement.

A retrospective review was done of the prospectively collected soft tissue sarcoma database at our institution. Two thousand forty-five patients had surgery for soft tissue sarcoma of an extremity between January 1986 and August 2017. Included patients either presented with a synchronous lymph node metastasis or were diagnosed with a lymph node metastasis after their initial treatment. Demographic, treatment, and outcome data for patients with lymph node involvement were obtained from the clinical and radiographic records.

Lymph node metastases were identified as palpable adenopathy by physical examination and were further characterized on cross-sectional imaging by computed tomography (CT) or magnetic resonance imaging (MRI) scans. All cases were confirmed by pathologic examination of biopsy specimens. A pathologist with expertise in sarcoma determined the histologic type and graded tumors as 1, 2, or 3.

One hundred eighteen patients with a mean age of 55.7 (SD=18.9) were included in our study. Seventy-two (61.3%) out of 119 patients were male. Thirty six patients (57.1%) had lymph node involvement at diagnosis. The mean follow-up from the date of the first surgery was 56.3 months. The most common histological diagnoses were Malignant fibrous histiocytoma (35) and liposarcoma (12). Ninety eight patients (89%) underwent surgical treatment of the lymph node metastasis while 21 (17.6%) were treated with chemotherapy and/or radiation therapy. The mean survival was 52.6 months (range 1–307).

Our results suggest that patients with a lymph node metastasis have a better prognosis than previously described. Their overall survival is superior to patients diagnosed with lung metastasis. A signifant proportion of patients may expect long term survival after surgical excision of lymph node metastasis. Furthermore, our study also indicates that different histological subtypes such as liposarcoma or malignant peripheral nerve sheath tumor (MPNST) may also be responsible for lymph node metastasis. Additional studies to further improve the treatment of soft tissue sarcoma nodal metastasis are warranted.

I. Alshaygy J. Mattei G. Basile A. Griffin P. Ferguson J. S. Wunder

Dermatofibrosarcoma protuberans (DFSP) is a rare, monoclonal dermal neoplasm. DFSP is known to be locally aggressive and infiltrative, but with a very low systemic recurrence risk. It is reported to be associated with high local recurrence rates following surgical excision. Positive or marginal resection margins can lead to a high risk of local recurrence. The objective was to determine the oncologic outcome for DFSP treated at our institution.

We reviewed our prospectively collected database for all DFSP treated at our unit between 1990 and 2016. Patients were included whether or not they had excision prior to referral (“whoops” procedure). Those with fibrosarcomatous degeneration at presentation to our unit or less than 1 year of follow-up were excluded. The goal of surgery was a negative margin with a minimum margin of 2 cm where possible. Patients were followed up after surgery to monitor complications, recurrence, transformation and/or metastasis.

139 patients with a mean age of 42.7 (SD=14.1) were included. Mean follow-up was 56 months.101 patients had prior “whoops” surgery before referral. 14 patients were also treated with radiotherapy (13 preoperatively, 1 postoperatively). Following surgery, 6 patients had positive margins, 4 underwent radiation treatment while the other 2 had no further treatment. One patient who presented to our unit with a local recurrence developed a further local recurrence, which demonstrated fibrosarcomatous degeneration at the time of resection (1/139, 0.7%). 1 other patient developed a lesion at another site.

The recurrence rate in our DFSP cohort is significantly lower than previous reports. Wide margin resection following oncologic principles can result in a very low recurrence rate. After the initial recovery phase, these patients do not require ongoing, frequent follow-up. Future studies should look at if closer margins can also produce similar treatment outcome.

I. Wilson T. Gascoyne T. Turgeon C. Burnell

Total hip arthroplasty (THA) is one of the most successful and commonly performed surgical interventions worldwide. Based on registry data, at one-year post THA, implant survivorship is nearly 100% and patient satisfaction is 90%. A novel, porous coated acetabular implant was introduced in Europe and Australia in 2007. Several years after its introduction, warnings were issued for the system when used with metal-on-metal bearings due to adverse local tissue reaction, with one study reporting a 24% failure rate (Dramis et al. 2014). A subsequent 2018 study by Teoh et al. showed that the acetabular system had a survival rate of 98.9% at five years when used with conventional polyethylene or ceramic bearing surfaces. The current study was conducted to determine the safety and effectiveness of the acetabular system using standard highly-crosslinked polyethylene (XLPE) and ceramic liners at five-year follow-up. Our hypothesis was that the acetabular system would exhibit survivorship comparable to other acetabular components on the market at five-year follow-up.

A prospective, non-randomized study was conducted from February 2009 to June 2017 at eight sites in Canada and the USA. One hundred fifty-five hips were enrolled and 148 hips analyzed after THA indicated for degenerative arthritis. At five-year follow-up, 103 subjects remained for final analysis. All patients received a zero, three, or multi-hole R3 acetabular shell with Stiktite porous coating (Smith & Nephew, Inc., Memphis, TN, USA). Standard THA surgical techniques were employed, with surgical approach and either of a XLPE or ceramic bearing surface chosen at the discretion of the surgeon. The primary outcome was revision at five-years post-op with secondary outcomes including the Harris Hip Score (HHS), Hip Disability and Osteoarthritis Outcome Score (HOOS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), radiographic analysis, and post-operative adverse events. Data and outcomes were analyzed using summary statistics with 95% confidence intervals, t-tests, and Wilcoxon Rank tests.

At five-year follow-up the overall success rate was 97.14% (95% CI: 91.88–100). When analyzed by liner type, the success rate was 96.81% (95% CI: 90.96–99.34) for polyethylene (n=94) and 100% (95% CI: 71.51–100) for ceramic (n=11), with no significant difference between either liner type (p=1). There were three revisions during the study (1.9%), two for femoral stem revision post fracture, and one for deep infection. The HHS (51.36 pre-op, 94.50 five-year), all 5 HOOS sub-scales, and WOMAC (40.9 pre-op, 89.13 five-year) scores all significantly improved (p < 0 .001) over baseline scores at all follow-up points. One (0.7%) subject met the criteria for radiographic failure at one-year post-op but did not require revision. Six (1.8%) of the reported adverse events were considered related to the study device, including four cases of squeaking, one bursitis, and one femur fracture.

Results from this five-year, multicenter, prospective study indicate good survivorship for this novel, porous coated acetabular system. The overall survivorship of 97.14% at five-year follow-up is comparable to that reported for similar acetabular components and aligns with previous analyses (Teoh et al. 2018).

L. Melo A. Sharma A. Stavrakis M. Zywiel S. Ward A. Atrey A. Khoshbin S. White L. Nowak

Total knee arthroplasty (TKA) is the most commonly performed elective orthopaedic procedure. With an increasingly aging population, the number of TKAs performed is expected to be ∼2,900 per 100,000 by 2050. Surgical Site Infections (SSI) after TKA can have significant morbidity and mortality. The purpose of this study was to construct a risk prediction model for acute SSI (classified as either superficial, deep and overall) within 30 days of a TKA based on commonly ordered pre-operative blood markers and using audited administrative data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database.

All adult patients undergoing an elective unilateral TKA for osteoarthritis from 2011–2016 were identified from the NSQIP database using Current Procedural Terminology (CPT) codes. Patients with active or chronic, local or systemic infection/sepsis or disseminated cancer were excluded. Multivariate logistic regression was conducted to estimate coefficients, with manual stepwise reduction to construct models. Bootstrap estimation was administered to measure internal validity. The SSI prediction model included the following co-variates: body mass index (BMI) and sex, comorbidities such as congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), smoking, current/previous steroid use, as well as pre-operative blood markers, albumin, alkaline phosphatase, blood urea nitrogen (BUN), creatinine, hematocrit, international normalized ratio (INR), platelets, prothrombin time (PT), sodium and white blood cell (WBC) levels. To compare clinical models, areas under the receiver operating characteristic (ROC) curves and McFadden's R-squared values were reported.

The total number of patients undergoing TKA were 210,524 with a median age of 67 years (mean age of 66.6 + 9.6 years) and the majority being females (61.9%, N=130,314). A total of 1,674 patients (0.8%) had a SSI within 30 days of the index TKA, of which N=546 patients (33.2%) had a deep SSI and N=1,128 patients (67.4%) had a superficial SSI. The annual incidence rate of overall SSI decreased from 1.60% in 2011 to 0.68% in 2016. The final risk prediction model for SSI contained, smoking (OR=1.69, 95% CI: 1.31 – 2.18), previous/current steroid use (OR=1.66, 95% CI: 1.23 – 2.23), as well as the pre-operative lab markers, albumin (OR=0.46, 95% CI: 0.37 – 0.56), blood urea nitrogen (BUN, OR=1.01, 95% CI: 1 – 1.02), international normalized ratio (INR, OR=1.22, 95% CI:1.05 – 1.41), and sodium levels (OR=0.94, 95% CI: 0.91 – 0.98;). Area under the ROC curve for the final model of overall SSI was 0.64. Models for deep and superficial SSI had ROC areas of 0.68 and 0.63, respectively. Albumin (OR=0.46, 95% CI: 0.37 – 0.56, OR=0.33, 95% CI: 0.27 – 0.40, OR=0.75, 95% CI: 0.59 – 0.95) and sodium levels (OR=0.94, 95% CI: 0.91 – 0.98, OR=0.96, 95% CI: 0.93 – 0.99, OR=0.97, 95% CI: 0.96 – 0.99) levels were consistently significant in all prediction models for superficial, deep and overall SSI, respectively. Overall, hypoalbuminemia and hyponatremia are both significant risk factors for superficial, deep and overall SSI.

To our knowledge, this is the first prediction model for acute SSI post TKA whereby hyponatremia (and hypoalbuminemia) are predictive of SSI. This prediction model can help fill an important gap for predicting risk factors for SSI after TKA and can help physicians better optimize patients prior to TKA.

P. Qi Wang R. Grewal N. Suh B. Matache

Numerous surgical techniques have been proposed and described in the treatment of Kienbock's disease. The objective of this systematic review was to assess the current evidence and trends in the management of Lichtman Stages IIIA and IIIB.

We performed a literature search using the Medline, Embase, and Cochrane databases to identify studies evaluating treatment outcomes in Stages IIIA and IIIB of Lichtman's Classification. We included studies between 2008 and 2018, and studies with Sackett levels one to four inclusively. We excluded studies that included skeletally immature patients, non-English papers, other hand diseases, and those without evidence of significance testing. We evaluated the quality of each included study using the Structured Effectiveness Quality Evaluation Scale (SEQES) and our outcomes of interest included Pain, ROM, Grip Strength, and Functionality.

We identified 1489 titles from the various databases. 83 papers remained after the subtraction of duplicates and abstract review. Following full-text review of the remaining 83 papers, 43 more studies were excluded and 40 papers met the criteria for SEQES assessment. There were six low-quality papers and 34 moderate-quality papers. Meta-analysis was not possible due to the variability in how outcomes were reported. A variety of surgical options were presented including decompressions, joint-levelling procedures, revascularization techniques, fusions, arthroplasty and novel combinations of these techniques. These were mainly retrospective and/or cohort studies. Most of these papers had small sample sizes and required further studies. Nonetheless, all of these treatment modalities were shown to offer pain relief and some degree of return of function ranging from minimal improvement to return to normal daily functions.

This systematic review has revealed a significant weakness in the literature and a lack of strong evidence in the treatment of Stages IIIA and IIIB of Kienbock's disease. The unknown etiology of this disease and its rarity make it very difficult to produce randomized controlled trials and appropriately-sized studies. As such, there is currently insufficient data to determine a superior treatment modality from another. Furthermore, the fact that most, if not all, surgical interventions produced positive results may also be a consequence of publication bias.

S. Papp S. Thomas N. Harris A. Salimian K. Gartke

The clinical guidelines for hip fracture management indicate that indwelling foley catheterization should be avoided when possible. Alternatives to indwelling catheters such as intermittent or condom catheters are recommended. Appropriate catheterization usage is important in hip fracture patients to avoid complications such as urinary tract infections (UTIs) (7–24% of patients) or post-operative urinary retention (POUR) (20–56% of patients). In this study, we aim to, (1) evaluate catheter usage in hip fracture patients at a large tertiary care centre, (2) compare current practices in catheter usage to clinical guidelines, (3) determine the incidence of POUR in hip fracture patients (4) determine the factors that increase one's risk of developing POUR.

We analyzed 584 hip fracture patients between the ages of 18 and 102 admitted between November 2015 and October 2017 at a tertiary Care Hospital. Data collected included patient demographics, fracture pattern, surgical procedure, length of stay, co-morbidities and catheter use. We compared actual catheter usage to suggested guidelines to determine whether recommendations were being followed. We also investigated the incidence of POUR and risk factors associated with developing POUR. Independent samples t-test were used to compare continuous dependent variables in bivariate analyses and a logistic regression was used to determine predictors of developing POUR, catheter usage, and length of stay in multivariate analyses. T

Over three quarters (76.9%) of patients with hip fractures were treated with a catheter during their admission, 63.5% of which were inserted pre-operatively and 36.5% of which were inserted post-operatively. Indwelling catheters accounted for 92.2% of catheters used, while intermittent and catheter condoms accounted for 7.8%. POUR occurred in 98 of 584 cases (16.7%). Age (p = 0.004), gender (p=0.001), and presence of kidney disease (p=0.033) were statistically significant predictors of POUR. Fracture pattern (p=0.825), surgical procedure (p=0.298), diabetes mellitus (p=0.309) and UTI in the past 60 days (p=0.848) or on admission (p=0.999) were not statistically significant predictors of developing POUR. The development of POUR did not significantly increase length of stay (p=0.558). There was no statistically significant correlation between developing POUR and extended post-operative catheter use over 24 hours (p=0.844) or 48 hours (p=0.862). Patients who received a catheter pre-operatively or post-operatively for longer than 24 hours were not significantly more likely to develop POUR (p=0.057).

Catheter use was common for all hip fracture patients and indwelling catheters were used in the overwhelming majority of cases. The high frequency of catheter usage, and specifically indwelling catheter usage, suggests that there is low compliance with the clinical guidelines for hip fracture patients. The incidence of POUR was 17%. Older, male patients were more likely to develop POUR. Although not statistically significant, more appropriate catheter use may decrease urinary complications such as POUR.

Y. Zhang N. White T. Clark G. Dhaliwal T. Samuel R. Saini T. J. Goetz

Ulnar shortening osteotomy (USO) is a procedure performed to alleviate ulnar sided wrist pain caused by ulnar impaction syndrome (UIS) and/or triangular fibrocartilage complex (TFCC) injury. Presently, non-union rates for ulnar shortening osteotomy is quoted to be 0–18% in the literature. However, there is a dearth of literature on the effect of site of osteotomy and plate placement on the rate of complications like a delayed union, symptomatic hardware and need for second surgery for hardware removal. In this study, we performed a multi-centered institutional review of ulnar shortening osteotomies performed, focusing on plate placement (volar vs. dorsal) and osteotomy site (distal vs. proximal) and determining if it plays a role in reducing complications.

This study was a multi-centered retrospective chart review. All radiographs and charts for patients that have received USO for UIS or TFCC injury between 2013 and 2017 from hand and wrist fellowship-trained surgeons in Calgary, Alberta and Winnipeg, Manitoba were examined. Basic patient demographics including age, sex, past medical history, and smoking history were recorded. Postoperative complications such as delayed union, non-union, infection, chronic regional pain syndrome, hardware irritation requiring removal were evaluated with a two-year follow-up period. Osteotomy sites were analyzed based on the location in relation to the entire length of the ulna on forearm radiographs. Surgical techniques including volar vs. dorsal plating, oblique vs. transverse osteotomy cuts, and plate type were documented.

Continuous variables of interest were summarized as mean or medians with standard deviation or inter-quartile range as appropriate. Differences in baseline characteristics were determined by t-test or one-way ANOVA for continuous variables and chi-square or Fischer exact test for dichotomous variables. All analyses were conducted using SPSS V24.0 (Chicago, IL, USA). All statistical tests were considered significant if p < 0.05.

Between 2013–2017 there were 117 ulnar shortening osteotomies performed. The average age of patients was 46.2 ± 16.2, with 62.4% being female. The mean pre-operative ulnar variance was +3.89 ± 2.17 mm and post-operative ulnar variance was −1.90 ± 1.80 mm. 84.6% of the plates were placed on the volar aspect of the ulna and 14.5% were placed on the dorsal aspect. An oblique osteotomy was made 99.1% of the time. In measuring osteotomy placement, the average placement was made in the distal 1/3 of the ulna. Overall, there was a 40% complication rate. Hardware irritation requiring removal encompassed 23%, non-union 14%, and wound infection covered 0.8%. When comparing dorsal vs volar plating, there was no statistically significant difference for non-union or hardware removal. Similarly, in evaluating osteotomy level, there was no statistical difference between proximal vs distal osteotomy for non-union and hardware removal.

In this multi-centered retrospective review of ulnar shortening osteotomies, we found that there was an overall complication rate of 40%. There was no statistically significant difference in complication rates between dorsal vs volar plate placement or proximal vs distal osteotomy sites. Further studies examining other potential risk factors in lowering the complication rate would be beneficial.

R. Selley B. Butler M. Hartwell D. Johnson M. Terry V. Tjong

Orthopaedic surgeons frequently use opioids for peri-operative pain management and there is considerable variability in the amount prescribed between surgeons. As such, the appropriate number of opioids to prescribe for specific procedures is often unknown. Leftover prescription opioids are at risk for diversion to family and friends for nonmedical use. The aim of this study was to determine the optimal amount of narcotics to prescribe postoperatively for patients undergoing hip arthroscopy.

23 consecutive patients were enrolled. All patients were prescribed 60 tablets of hydrocodone/acetaminophen 10/325 postoperatively as part of a multimodal pain management strategy. Patients were called at 14 and 21 days post-operatively to tabulate the number of pills used and knowledge of how to properly dispose of pills.

The median number of narcotic pain pills required was 6 (IQR: 3,15). Over half of patients (56.5%) required ≤10 narcotic pain pills postoperatively. A large number of narcotic tablets (1071/1380, 77.6%) were unused and a small percentage of patients (8/23, 34.8%) were aware of proper disposal techniques. Knowledge of how to properly dispose of unused narcotics was protective against a prolonged duration of narcotic use postoperatively (Parameter estimate −5.7, 95% CI: −11.3, −0.1, p = 0.045).

Reducing the number of prescribed narcotic tablets to 25 would meet the post-operative pain demands of over 85% of hip arthroscopy patients. More judicious post-operative prescribing patterns and patient education regarding disposal may help minimize physician contribution to opioid misuse, overuse and diversion.

L. Melo S. White H. Chaudhry A. Stavrakis J. Wolfstadt S. Ward A. Atrey A. Khoshbin L. Nowak

Over 300,000 total hip arthroplasties (THA) are performed annually in the USA. Surgical Site Infections (SSI) are one of the most common complications and are associated with increased morbidity, mortality and cost. Risk factors for SSI include obesity, diabetes and smoking, but few studies have reported on the predictive value of pre-operative blood markers for SSI. The purpose of this study was to create a clinical prediction model for acute SSI (classified as either superficial, deep and overall) within 30 days of THA based on commonly ordered pre-operative lab markers and using data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database.

All adult patients undergoing an elective unilateral THA for osteoarthritis from 2011–2016 were identified from the NSQIP database using Current Procedural Terminology (CPT) codes. Patients with active or chronic, local or systemic infection/sepsis or disseminated cancer were excluded. Multivariate logistic regression was used to determine coefficients, with manual stepwise reduction. Receiver Operating Characteristic (ROC) curves were also graphed. The SSI prediction model included the following covariates: body mass index (BMI) and sex, comorbidities such as congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), smoking, current/previous steroid use, as well as pre-operative blood markers, albumin, alkaline phosphate, blood urea nitrogen (BUN), creatinine, hematocrit, international normalized ratio (INR), platelets, prothrombin time (PT), sodium and white blood cell (WBC) levels. Since the data met logistic assumption requirements, bootstrap estimation was used to measure internal validity. The area under the ROC curve for final derivations along with McFadden's R-squared were utilized to compare prediction models.

A total of 130,619 patients were included with the median age of patients at time of THA was 67 years (mean=66.6+11.6 years) with 44.8% (n=58,757) being male. A total of 1,561 (1.20%) patients had a superficial or deep SSI (overall SSI). Of all SSI, 45.1% (n=704) had a deep SSI and 55.4% (n=865) had a superficial SSI. The incidence of SSI occurring annually decreased from 1.44% in 2011 to 1.16% in 2016. Area under the ROC curve for the SSI prediction model was 0.79 and 0.78 for deep and superficial SSI, respectively and 0.71 for overall SSI. CHF had the largest effect size (Odds Ratio(OR)=2.88, 95% Confidence Interval (95%CI): 1.56 – 5.32) for overall SSI risk. Albumin (OR=0.44, 95% CI: 0.37 – 0.52, OR=0.31, 95% CI: 0.25 – 0.39, OR=0.48, 95% CI: 0.41 – 0.58) and sodium (OR=0.95, 95% CI: 0.93 – 0.97, OR=0.94, 95% CI: 0.91 – 0.97, OR=0.95, 95% CI: 0.93 – 0.98) levels were consistently significant in all clinical prediction models for superficial, deep and overall SSI, respectively. In terms of pre-operative blood markers, hypoalbuminemia and hyponatremia are both significant risk factors for superficial, deep and overall SSI.

In this large NSQIP database study, we were able to create an SSI prediction model and identify risk factors for predicting acute superficial, deep and overall SSI after THA. To our knowledge, this is the first clinical model whereby pre-operative hyponatremia (in addition to hypoalbuminemia) levels have been predictive of SSI after THA. Although the model remains without external validation, it is a vital starting point for developing a risk prediction model for SSI and can help physicians mitigate risk factors for acute SSI post THA.

A. Atrey J. Wu J. P. Waddell E. H. Schemitsch A. Khoshbin S. Ward E. R. Bogoch

The purpose of this investigation is to assess the rate of wear the effect once the “bedding in period”/ poly creep had been eliminated. Creep is the visco-elastic deformation that polyethylene exhibits in the first 6–12 weeks. We also assessed the wear pattern of four different bearing couples in total hip arthroplasty (THA): cobalt-chrome (CoCr) versus oxidized zirconium (OxZir) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) versus highly-crosslinked polyethylene (XLPE) acetabular liners.

This was a randomized control study involving 92 patients undergoing THA. They were randomized to one of four bearing couples: (1) CoCr/UHMWPE (n= 23), (2) OxZir/UHMWPE (n=21), (3) CoCr/XLPE (n=24), (4) OxZir/XLPE (n=24). Patients underwent a posterior approach from one of three surgeons involved in the study. All patients received a porous-coated cementless acetabular shell and a cylindrical proximally coated stem with 28 mm femoral heads. Each patient was reviewed clinically and radiographically at six weeks, three and 12 months, two, five and 10 years after surgery. Standardized anteroposterior and lateral radiographs were taken. All polyethylene wear was measured by an independent blinded reviewer. Linear and volumetric wear rates were measured on radiographs using a validated computer software (Polyware Rev. 5). Creep was defined as the wear at 6 or 12 weeks, depending on if there was a more than 10% difference between both measurements. If a greater than 10% difference occurred than the later period's wear would be defined as creep.

72 hips were included in analysis after exclusion of seven revisions, three deaths and 10 losses to follow-up. The annual linear wear rates (in mm/y) at 10 years were (1) 0.249, (2) 0.250, (3) 0.074 and (4) 0.050. After adjusting for creep these rates become were (1) 0.181, (2) 0.142, (3) 0.040 and (4) 0.023. There is statistical differences between raw and adjusted linear wear rates for all bearing couples. The percentage of the radiographically measured wear at 10 years due to creep is (1) 30% (2) 44%, (3) 58.5% and (4) 51.5% with significant differences in couples with XLPE versus those with UHMWPE. There was no significant correlation between age, gender, cup size, tilt, planar anteversion and the linear or volumetric wear rates.

The linear wear rate of both UHMWPE and XLPE are even lower thxdsxzan previously described when creep is factored out. XLPE has again demonstrated far superior linear wear rates at 10 years than UHMWPE. There were no significant differences in wear rate at 10 years between CoCr and OxZir, this may be due to an underpowered study. XLPE exhibits proportionally more creep than UHMWPE within the first 6–12 weeks and accounts for more of the total wear at 10 years as measured radiographically at the end period.

T. Baxter A. W. Howard M. Camp

Ten RCTs published between 2000 and 2013 support treating distal radius buckle fractures and other low-risk distal radius fractures with a removable splint and with no orthopaedic follow-up. Application of this evidence has been shown to be variable and suboptimal resulting in unnecessary costs to a strained healthcare system. The Canadian evidence on this topic has been generated by subspecialist physicians working in paediatric hospitals. It is unclear what factors affect the dissemination of this information. We investigated the association of hospital type and physician type with the application of best-evidence treatment for low-risk distal radius fractures in children with the goal of improving our understanding of evidence diffusion in Ontario for this common injury.

We performed a retrospective population-based cohort study using linked health care administrative data. We identified all children aged 2–14 treated in Ontario emergency departments from 2003–2015 with distal radius fractures with no reduction and no operation within a six week period. We excluded refractures and children with comorbidities. We evaluated the followup received – orthopaedic, general practitioner, or none. We examined the data for trends over time. Multivariable log binomial regression was used to quantify associations between hospital and physician type and best-evidence treatment. We adjusted for patient-related variables including age, sex, rural or urban location, and socioeconomic status.

70,801 fractures were analyzed. Best-evidence treatment was more likely to occur in a small (RR 1.86, 95%CI 1.72–2.01), paediatric (RR 1.16, 95%CI 1.07–1.26), or community (RR 1.13, 95%CI 1.06–1.20) hospital compared with treatment in a teaching hospital. Best-evidence treatment was more likely if initial management was by a paediatrician with additional emergency medicine training (RR 1.73, 95%CI 1.56–1.92) or paediatrician (RR 1.22, 95%CI 1.11–1.34). Paediatric and teaching hospitals have improved their use of best-evidence over time while other hospital types have stagnated or deteriorated. Paediatricians, paediatricians with additional emergency medicine training, and emergency medicine residency trained physicians have improved their use of best-evidence over time, while other physician types have stagnated or deteriorated. Overall, only 20% of patients received best-evidence treatment and 70% had orthopaedic follow-up.

Significant over-utilization of resources for low-risk distal radius fractures continues decades after the first randomized trials showed it to be unnecessary. Physician type and hospital rurality are most strongly associated with best-evidence treatment. Physician types involved in generating, presenting, and publishing best-evidence for this fracture type are successfully implementing it, while others have failed to change their practices. Rural hospitals are excellent resource stewards by necessity, but are deteriorating over time. Our results strongly indicate the need for targeted implementation strategies to explicitly apply clinical evidence in clinical practice Canada-wide, with the goal of providing more cost-effective care for common children's fractures.

J. Ehrlich T. Bryant M. Rainbow R. Bicknell

The purpose of this study is to quantify the distribution of bone density in the scapulae of patients undergoing reverse shoulder arthroplasty (RSA) to guide optimal screw placement. To achieve this aim, we compared bone density in regions around the glenoid that are targeted for screw placement, as well as bone density variations medial to lateral within the glenoid.

Specimen included twelve scapula in 12 patients with a mean age of 74 years (standard deviation = 9.2 years). Each scapula underwent a computed tomography (CT) scan with a Lightspeed+ XCR 16-Slice CT scanner (General Electric, Milwaukee, USA). Three-dimensional (three-D) surface mesh models and masks of the scapulae containing three-D voxel locations along with the relative Hounsfield Units (HU) were created. Regions of interest (ROI) were selected based on their potential glenoid baseplate screw positioning in RSA surgery. These included the base of coracoid inferior and lateral to the suprascapular notch, an anterior and posterior portion of the scapular spine, and an anterosuperior and inferior portion of the lateral border. Five additional regions resembling a clock face, on the glenoid articular surface were then selected to analyze medial to lateral variations in bone density including twelve, three, six, and nine-o'clock positions as well as a central region. Analysis of Variance (ANOVA) tests were used to examine statistical differences in bone density between each region of interest (p < 0 .05).

For the regional evaluation, the coracoid lateral to the suprascapular notch was significantly less dense than the inferior portion of the lateral border (mean difference = 85.6 HU, p=0.03), anterosuperior portion of the lateral border (mean difference = 82.7 HU, p=0.04), posterior spine (mean difference = 97.6 HU, p=0.007), and anterior spine (mean difference = 99.3 HU, p=0.006).

For the medial to lateral evaluation, preliminary findings indicate a “U” pattern with the densest regions of bone in the glenoid most medially and most laterally with a region of less dense bone in-between.

The results from this study utilizing clinical patient CT scans, showed similar results to those found in our previous cadaveric study where the coracoid region was significantly less dense than regions around the lateral scapular border and scapular spine. We also have found for medial to lateral bone density, a “U” distribution with the densest regions of bone most medially and most laterally in the glenoid, with a region of less dense bone between most medial and most lateral. Clinical applications for our results include a carefully planned trajectory when placing screws in the scapula, potentially avoiding the base of coracoid. Additionally, surgeons may choose variable screw lengths depending on the region of bone and its variation of density medial to lateral, and that screws that pass beyond the most lateral (subchondral) bone, will only achieve further purchase if they enter the denser bone more medially. We suspect that if surgeons strategically aim screw placement for the regions of higher bone density, they may be able to decrease micromotion in baseplate fixation and increase the longevity of RSA.

E. Villemaire-Cote B. H. Perey

Trapeziometacarpal arthritis is a common condition, causing symptoms in up to ten percent of women and one percent of men¹. LRTI is the most commonly used surgical technique for this condition however, long-term studies have shown persistent weakness of pinch strength² after surgery. The Ascension® PyroDisk is a pyrocarbon disk shaped implant designed to articulate against the trapezium and metacarpal, preserving the height of the articulation. The objective of this study was to determine whether treatment with a pyrocarbon implant resulted in comparable pain relief and range of motion, whilst providing superior gains in pinch strength when compared to LRTI.

This is a prospective randomized control trial comparing pyrocarbon implant to LRTI. Surgeries were accomplished by a single surgeon in a standardized fashion. Patients were evaluated at six weeks, three, six and 12 months following surgery. Data on pain (VAS), function (Patient Rated Wrist Evaluation (PRWE)), mobility and strength (grip, key and lateral pinch) were obtained as well as radiographic assessment of the height of the arthroplasty space.

A total of 80 patients had surgery between July 2008 and November 2016. Forty patients were allocated to the PyroDisk group and 40 to the LRTI group. Seventy-four patients (92,5%) completed the one year follow-up. Mean age was slightly older in the PyroDisk group (64 vs 60,8 y.o., p=0,03). Surgical and tourniquet times were longer in the PyroDisk group. There was no difference between the groups in strength, pain or functional outcome at one year. However, VAS was significantly higher in the PyroDisk group at three and six months (4,5 vs 2,4, p < 0,001, 2,6 vs 1,7, p=0,02) and PRWE was also significantly better at three months in the LRTI group (53,7 vs 71,2, p=0,02). The overall complication rate was three times higher in the PyroDisk group (10% vs 30%).

Treatment of trapeziometacarpal arthritis with PyroDisk does not provide superior functional gains when compared to LRTI. On the contrary, it seems to result in more pain in the first few months following surgery. This difference in pain is not seen at 1 year after surgery. This may suggest that there is a period of adaptation to the Pyrodisk after its insertion. We also found a higher risk of complications with the use of the PyroDisk.

M. Hupin T. J. Goetz N. Robertson D. Murphy M. Cresswell K. Murphy

Postero-lateral rotator instability (PLRI) is the most common pattern of recurrent elbow instability. Unfortunately, current imaging to aid PLRI diagnosis is limited. We have developed an ultrasound (US) technique to measure ulnohumeral joint gap with and without stress of the lateral ulnocollateral ligament. We sought to define lateral ulnohumeral joint gap measurements in the resting and stressed state to provide insight into how US may aid diagnosis of PLRI.

Sixteen elbows were evaluated in eight healthy volunteers. Lateral ulnohumeral gap was measured on US in the resting position and with posterolateral drawer stress test maneuver applied. Joint laxity was calculated as the difference between stress and rest conditions. Measurements were performed by two independent readers with comparison performed between stress and rest positions.

A highly significant difference in ulnohumeral gap was seen between stress and rest conditions (Reader 1: p < 0 .0001 and Reader 2: p=0.0002) with median values of 2.93 mm and 2.50 mm at rest and 3.92 mm and 3.40 mm at stress for Reader 1 and 2 respectively. Median joint laxity was 1.02 mm and 0.74 mm respectively for each reader. Correlation and agreement between readers was good.

This study provides key new insight into use of US for diagnosis as PLRI as it defines normal ulnohumeral distances and demonstrates widening when applying the posterolateral drawer stress maneuver. Further evaluation of this technique is required in patients with PLRI.

T. J. Goetz T. Mwaturura A. Li

Previous studies describing drill trajectory for single incision distal biceps tendon repair suggest aiming ulnar and distal (Lo et al). This suggests that the starting point of the drill would be anterior and radial to the anatomic insertion of the distal biceps tendon. Restoration of the anatomic footprint may be important for restoration of normal strength, especially as full supination is approached.

To determine the safest drill trajectory for preventing injury to the posterior interosseous nerve (PIN) when repairing the distal biceps tendon to the ANATOMIC footprint through a single-incision anterior approach utilising cortical button fixation.

Through an anterior approach in ten cadaveric specimens, three drill holes were made in the radial tuberosity from the centre of the anatomic footprint with the forearm fully supinated. Holes were made in a 30º distal, transverse and 30º proximal direction. Each hole was made by angling the trajectory from an anterior to posterior and ulnar to radial direction leaving adequate bone on the ulnar side to accommodate an eight-millimetre tunnel. Proximity of each drill trajectory to the PIN was determined by making a second incision on the dorsum of the proximal forearm. A K-wire was passed through each hole and the distance between the PIN and K-wire measured for each trajectory.

The PIN was closest to the trajectory K-wires drilled 30° distally (mean distance 5.4 mm), contacting the K-wire in three cases. The transverse drill trajectory resulted in contact with the PIN in one case (mean distance 7.6 mm). The proximal drill trajectory appeared safest with no PIN contact (mean distance 13.3 mm). This was statistically significant with a Friedman statistic of 15.05 (p value of 0.00054).

When drilling from the anatomic footprint of the distal biceps tendon the PIN is furthest from a drill trajectory aimed proximally. The drill is aimed radially to minimise blowing out the ulnar cortex of the radius.

For any reader inquiries, please contact vansurgdoc@gmail.com

K. Morash L. Gauthier B. Orlik R. El-Hawary K. Logan

Slipped capital femoral epiphysis (SCFE) is traditionally treated with in situ fixation using a threaded screw, leading to physeal arrest while stabilizing the femoral head. Recently, there has been interest in alternative methods of fixation for SCFE, aiming to allow growth and remodelling of the femoral neck postoperatively. One such option is the Free Gliding SCFE Screw (Pega Medical), which employs a telescopic design intended to avoid physeal compression. The objective of this study is to evaluate radiographic changes of the proximal femur following in situ fixation using the Free Gliding SCFE Screw.

This study retrospectively evaluated 28 hips in 14 consecutive patients who underwent in situ hip fixation using the Free Gliding SCFE Screw between 2014 and 2018. Initial postoperative radiographs were compared to last available follow-up imaging. Radiographic assessment included screw length, articulotrochanteric distance (ATD), posterior sloping angle (PSA), alpha angle, head-neck offset (HNO) and head-shaft angle (HSA).

Of the 28 hips reviewed, 17 were treated for SCFE and an additional 11 treated prophylactically. Average age at surgery was 11.7 years, with an average follow-up of 1.44 years. Screw length increased by 2.3 mm (p < 0.001). ATD decreased from 25.4 to 22.2 mm (p < 0.001). Alpha angle decreased from 68.7 to 59.8 degrees (p = 0.004). There was a trend towards an increase in HNO (p = 0.07). There was no significant change in PSA or HAS. There were three complications (two patients with retained broken guide wires, and one patient requiring screw removal for hip pain).

With use of the Free Gliding SCFE Screw, there was evidence of screw expansion and femoral neck remodelling with short-term follow-up. More research is required to determine the long-term impact of these changes on hip function, and to aid in patient selection for this technology.

A. Maher P. Phan M. Hoda

Degenerative lumbar spondylolisthesis (DLS) is a common condition with many available treatment options. The Degenerative Spondylolisthesis Instability Classification (DSIC) scheme, based on a systematic review of best available evidence, was proposed by Simmonds et al. in 2015. This classification scheme proposes that the stability of the patient's pathology be determined by a surgeon based on quantitative and qualitative clinical and radiographic parameters. The purpose of the study is to utilise machine learning to classify DLS patients according to the DSIC scheme, offering a novel approach in which an objectively consistent system is employed.

The patient data was collected by CSORN between 2015 and 2018 and included 224 DLS surgery cases. The data was cleaned by two methods, firstly, by deleting all patient entries with missing data, and secondly, by imputing the missing data using a maximum likelihood function. Five machine learning algorithms were used: logistic regression, boosted trees, random forests, support vector machines, and decision trees. The models were built using Python-based libraries and trained and tested using sklearn and pandas librairies. The algorithms were trained and tested using the two data sets (deletion and imputation cleaning methods). The matplotlib library was used to graph the ROC curves, including the area under the curve.

The machine learning models were all able to predict the DSIC grade. Of all the models, the support vector machine model performed best, achieving an area under the curve score of 0.82. This model achieved an accuracy of 63% and an F1 score of 0.58. Between the two data cleaning methods, the imputation method was better, achieving higher areas under the curve than the deletion method. The accuracy, recall, precision, and F1 scores were similar for both data cleaning methods.

The machine learning models were able to effectively predict physician decision making and score patients based on the DSIC scheme. The support vector machine model was able to achieve an area under the curve of 0.82 in comparison to physician classification. Since the data set was relatively small, the results could be improved with training on a larger data set. The use of machine learning models in DLS classification could prove to be an efficient approach to reduce human bias and error. Further efforts are necessary to test the inter- and intra-observer reliability of the DSIC scheme, as well as to determine if the surgeons using the scheme are following DLS treatment recommendations.

L. Somerville B. Zomar E. Vasarhelyi B. Lanting J. Howard J. Marsh

Total knee arthroplasty is a successful procedure that reduces knee pain and improves function in most patients with knee osteoarthritis. Patient dissatisfaction however remains high, and along with implant longevity, may be affected by component positioning. Surgery in obese patients is more technically challenging with difficulty identifying appropriate landmarks for alignment and more difficult exposure of the joint. Patient specific instrumentation (PSI) has been introduced with the goal to increase accuracy of component positioning by custom fitting cutting guides to the patient using advanced imaging. A strong criticism of this new technology however, is the cost associated. The purpose of this study was to determine, using a prospective, randomized-controlled trial, the cost-effectiveness of PSI compared to standard instrumentation for total knee arthroplasty in an obese patient population.

Patients with a body mass index greater than 30 with osteoarthritis and undergoing a primary total knee arthroplasty were included in this study. We randomized patients to have their procedure with either standard instrumentation (SOC) or PSI. At 12-weeks post-surgery patients completed a self-reported cost questionnaire and the Western Ontario and McMaster Osteoarthritis Index (WOMAC). We performed a cost-effectiveness analyses from a public health payer and societal perspective. As we do not know the true cost of the PSI instrumentation, we estimated a value of $100 for our base case analysis and used one-way sensitivity analyses to determine the effect of different values (ranging from $0 to $500) would have on our conclusions.

A total of 173 patients were enrolled in the study with 86 patients randomized to the PSI group and 87 to the SOC group. We found the PSI group to be both less effective and more costly than SOC when using a public payer perspective, regardless of the cost of the PSI. From a societal perspective, PSI was both less costly, but also less effective, regardless of the cost of the PSI. The mean difference in effect between the two groups was −1.61 (95% CI −3.48, 026, p=0.091). The incremental cost-effectiveness ratio was $485.71 per point increase in the WOMAC, or $7285.58 per clinically meaningful difference (15 points) in the WOMAC.

Overall, our results suggest that PSI is not cost-effective compared to standard of care from a public payer perspective. From a societal perspective, there is some question as to whether the decreased effect found with the PSI group is worth the reduced cost. The main driver of the cost difference appears to be time off of volunteer work, which will need to be investigated further. In future, we will continue to follow these patients out to one year to collect cost and effectiveness data to investigate whether these results remain past 12 weeks post-surgery.

C. Sandoval J. Di Bella A. Dragan N. de Guia G. Webster M. J. Dunbar E. Bohm C. Yu

Revision is a key negative outcome of joint replacements. The purpose of this abstract is to present revision risk curves for hip and knee replacements based on the most recently available national data sources. Having a better understanding of determinants of revision risk can help inform clinical and health care system improvements.

We explored revision risk of primary joint replacement stratified by key clinical, prosthesis, and surgeon-level factors using data from three databases managed by CIHI: the Canadian Joint Replacement Registry (CJRR), the Discharge Abstract Database, and the National Ambulatory Care Reporting System. To investigate early revisions, we used Kaplan-Meier analysis stratified by demographic factors to determine the risk of revision within up to five years of primary surgery. This analysis identified the primary cohort from the CJRR from April 1, 2012 to March 31, 2017 and was limited to mandatory reporting provinces (British Columbia, Manitoba and Ontario) to ensure maximal coverage of prosthesis information. Bearing surface was obtained from the International Prosthesis Library maintained by the International Consortium of Orthopaedic Registries (ICOR) and the International Society of Arthroplasty Registers (ISAR).

The total revision risk cohort contained 283,620 primary surgeries, of which 5,765 (2%) had at least one revision. For total hip arthroplasties, revision risk at the end of the follow-up period did not differ by age, by sex or across bearing surface (metal on cross-linked polyethylene [XLPE], ceramic on XLPE, ceramic on ceramic, metal on non-cross-linked polyethylene). For hemiarthroplasties in hip fracture patients, cement fixation was significantly associated with decreased revision risk. Surgeon volume had a positive effect on survivorship with cementless fixation (2.7% at one year [95% CI 2.3%, 3.1%] for high-volume vs 3.2% [2.7%, 3.7%] for low-volume). However, surgeon volume did not have an effect on survivorship with cemented fixation (2% at one year [95% CI 1.3%, 2.6%] for high-volume vs. 2% [1.4%, 2.6%] for low-volume). For total knee replacements, revision risk increased with decreasing age and male sex. For patients aged 75 and older, four-year revision risks were 1.5% (95% CI 1.3%, 1.7%) for women and 2.0% (1.7%, 2.3%) for men, but for patients under 55 years old, they were 4.3% (3.7%, 5%) for women and 5.9% (4.9%, 6.9%) for men. Additional results from the upcoming 2019 CJRR annual report, including data up to March 31, 2018, will be presented.

Revisions represent a key failure of the primary replacement, they are costly to the health care system and negatively affect patients' quality of life. CJRR's coverage is currently 72%, increased coverage and follow-up time will allow increasingly comprehensive reporting on hip and knee prostheses in Canada. Future work in this area involves exploring additional prosthesis attributes for stratification of revision risk curves and calculation of hazards ratios adjusted by age and sex.

E. Schaeffer R. Yamini L. Bajno W. Krishnaswamy M. Randhawa K. Mulpuri

Developmental dysplasia of the hip (DDH) is the most common paediatric hip condition and is a major cause of hip replacement or osteoarthritis in young adults. Due to potential impact on quality of life, every child is checked at birth for unstable hips. Should instability be detected, or the infant has other DDH risk factors, they are referred for an ultrasound exam and orthopaedic surgeon consultation.

Since the implementation of a DDH screening program at our institution, the Radiology Department has seen a dramatic increase in hip ultrasounds performed. While helping prevent the complications of missed DDH diagnoses, this program has placed strain on radiology resources, and often families must attend multiple appointments before receiving a diagnosis and beginning treatment. To mitigate this, we have implemented a pilot point-of-care DDH clinic, where an ultrasound technician performs hip ultrasound exams using a portable ultrasound in the orthopaedic clinic in conjunction with surgeon consultation. The aim of this clinic is to enable diagnosis and treatment in one appointment, reduce referral-to-treatment delays, wait times, and decrease costs and travel time for families while also alleviating strain on radiology resources.

A point-of-care DDH test clinic was implemented in the Orthopaedic Department at our institution. Patients referred with suspected/confirmed DDH attended a single orthopaedic clinic appointment. An ultrasound technician was present to perform scans in conjunction with the orthopaedic surgeon's clinical assessment. Surveys were distributed at the end of the appointment to collect feedback on the family's satisfaction with the program, as well as other pertinent demographic information (i.e. occupation, geographic location, travel time to hospital).

To date, 40 patients have attended the pilot clinic. Families spent an average 61.3 minutes (range 15–420 minutes) traveling to the hospital for an appointment (122.6 minutes round-trip). This program reduced the number of hospital visits for DDH screening from three (initial consultation, radiology, follow-up) to one per patient, saving an average 245.2 minutes of travel time to/from the hospital per family. Appointment time averaged 35.9 minutes and families rated their satisfaction with appointment length an average of 9.6/10 (35/40 families rated satisfaction 10/10, 1 = very unsatisfied, 10 = very satisfied). Additionally, 33/40 families were also asked to rate their satisfaction with check-in/check-out processes (average 9.4/10), ultrasound screening (average 9.9/10), and time with specialist (average 9.9/10). Satisfaction scores did not differ based on variables such as survey taker's gender, occupation, or geographic location.

The pilot point-of-care ultrasound DDH clinic has considerably reduced the number of clinic visits and travel time for families, reduced aggregate clinic wait times, and has resulted in high family satisfaction. This specialized clinic may have potential to free up hospital staff time and resources, possibly decreasing wait times in other clinical areas, ultimately improving quality of care for patients and families across our institution.

A. Salimian P. Slullitel G. Grammatopoulos C. Kreviazuk P. Beaulé J. M. Wilkinson

The use of cementless acetabular components is currently the gold standard for treatment in total hip arthroplasty (THA). Porous coated cups have a low modulus of elasticity that enhances press-fit and a surface that promotes osseointegration. Monoblock acetabular cups represent a subtype of uncemented cup with the liner moulded into the metal shell, minimizing potential backside wear and eliminating the chance of mal-seating. The aim of this study was to compare the short-term clinical and radiographic performances of a modular cup with that of a monoblock cup, with particular interest in the advent of lucent lines and their correlation with clinical outcomes.

In this multi-surgeon, prospective, randomized, controlled trial, 86 patients undergoing unilateral THA were recruited. Participants were randomized to either a porous-coated, modular metal-on-polyethylene (MoP) acetabular component (n=46) or a hydroxyapatite (HA)- and titanium-coated monoblock shell with ceramic-on-ceramic (CoC) bearing (n=42). The porous-coated cup had an average pore size of 250 microns with an average volume porosity of 45%, whereas the monoblock shell had an average pore size of 300 microns with an average volume porosity of 48% and a HA coating thickness of 80 nm. There were no baseline demographic differences between both groups regarding sex, age, body mass index (BMI), or American Society of Anaesthesia (ASA) class (p>0.05). All of the sockets were under-reamed by 1 mm. Radiographs and patient-reported outcome measures (PROMs), including modified Harris Hip Score (mHHS), Western Ontario and McMaster Universities Arthritis Index (WOMAC) and University of California at Los Angeles (UCLA) Hip Score, were available for evaluation at a minimum of 2 years of follow-up. A radiolucent distance between the cup and acetabulum of ≥0.5 mm was defined as gap if it was diagnosed from outset or as radiolucency if it had sclerotic edges and was found on progressive x-ray analyses.

Thirty-two gaps (69%) were found in the modular cup group and 28 (6%) in the monoblock one (p=0.001). Of the former, 17 filled the gaps whereas 15 turned into a radiolucency at final assessment. Of the latter, only 1 of the gaps turned into a radiolucency at final follow-up (p 0.05) in both groups. Only the porous-coated cup was an independent predictor of lucent lines (OR:0.052, p=0.007). No case underwent revision surgery due to acetabular loosening during the study period. Only 2 cases of squeaking were reported in the CoC monoblock shell.

Both porous-coated modular and hydroxyapatite-coated monoblock cups showed successful clinical results at short-term follow-up, however, the former evidenced a significantly higher rate of radiolucent line occurrence, without any association with PROMs. Since these lines indicate the possibility of future cup loosening, longer follow-up and assessment are necessary.

A. Salimian J. Howatt G. Dervin P. Kim

The Oxford mobile bearing knee prosthesis (Zimmer Biomet Inc, Warsaw, Ind) is considered a good treatment option for isolated medial compartment knee arthrosis. From February 2001 until August 2016, 1719 primary Oxford medial unicompartmental knee replacement procedures were completed at our center by a group of seven surgeons. We undertook this study to examine the long-term survivorship of the Oxford unicompartmental knee replacement looking at survivorship and reasons for failure.

A retrospective consecutive case series review was completed, and all revisions and re-operations were identified. Conversion to total knee replacement (TKA) was considered a failure. Kaplan-Meier survival analysis was used to calculate the 15-year survivorship of the group overall. We specifically looked at age, gender, BMI and surgeon caseload in addition to the reasons for failure. A statistical analysis was performed and differences in survivorship were compared for the variables listed. A logistic cox regression was performed to explore predictors of revision.

Overall 15-year survivorship was 89.9%. Female survivorship of 88.1% was statistically worse than the male group at 91.8% (p=0.018). Younger patients (75yrs of age (p= 0.036). There was a large range in surgical case load by individual surgeons (range 17–570 knees). There were no statistically significant differences in age, BMI, or gender when comparing the individual surgeon groups. There was a large range in 15-year survivorship between individual surgeons (range 78.3% – 95%). Overall the most common reason for revision was due to wear of the unreplaced portion of the knee (lateral and/or patella-femoral joint) followed by aseptic loosening, polyethylene dislocation, infection or persistent pain.

The 15-year survivorship results of the Oxford medial unicompartmental knee replacement at our center compares favourably to other published series and large registry data series. We found a reduction in survivorship in female patients and younger patients (< 5 5yrs). There were also significant differences in survivorship based on the individual surgeon. A more selective patient approach yielded the best long-term survivorship and equivalent to that of total knee replacement. We therefore suggest using a more selective approach when choosing patients for a medial unicompartmental knee replacement with the Oxford mobile bearing prosthesis in order to enhance long-term survivorship.

I. Wong A. P. T. Ravipati

To determine the effect that preoperative use of 3D printed models has on the outcomes for femoroacetabular impingement (FAI) surgery.

Ninety patients that underwent FAI surgeries by the same surgeon were retrospectively analyzed. Patients were age- and sex-matched for two groups - those who had pre-operative 3D printed hip models (n=45) and those with conventional planning using X-rays and/or CT scan (n=45) were identified. Radiographic parameters on pre- and post-operative radiographs that include the alpha angle (45 Dunn view), center edge angle (CEA) (weight bearing AP pelvis), and head-neck offset ratio (cross-table lateral) were obtained. Clinical outcomes were assessed by analyzing iHOT and HOS scores pre- and post-operatively.

Ninety patients (3D printed group 45, Conventional group 45) with a mean age of 36 years were evaluated. Mean follow-up time was 28 months. For all of the radiological variables (CEA and alpha angle), there was a significant improvement seen for both groups (p=0.001). However, the 3D printed group showed significantly better resection of bone to a normal alpha angle (< 5 5) than did the Conventional group. Additionally, head-neck offset was significantly better in the 3D printed group (p=0.001). Statistically significant improvements were seen in both groups on the HOS and iHOT-33 (p=0.001).

Planning FAI surgery using 3D hip models helps in achieving better resection, especially in CAM-type FAI.

S. Abdic G. Athwal T. Wittman G. Walch P. Raiss

The use of shorter humeral stems in reverse shoulder arthroplasty has been reported as safe and effective. Shorter stems are purported to be bone preserving, easy to revise, and have reduced surgical time. However, a frequent radiographic finding with the use of uncemented short stems is stress shielding. Smaller stem diameters reduce stress shielding, however, carry the risk of varus or valgus malalignment in the metadiaphyseal region of the proximal humerus. The aim of this retrospective radiographic study was to measure the true post-operative neck-shaft (N-S) angle of a curved short stem with a recommended implantation angle of 145°.

True anteroposterior radiographs of patients who received RTSA using an Ascend Flex short stem at three specialized shoulder centres (London, ON, Canada, Lyon, France, Munich, Germany) were reviewed. Radiographs that showed the uncemented stem and humeral tray in orthogonal view without rotation were included. Sixteen patients with proximal humeral fractures or revision surgeries were excluded. This yielded a cohort of 124 implant cases for analysis (122 patients, 42 male, 80 female) at a mean age of 74 years (range, 48 – 91 years). The indications for RTSA were rotator cuff deficient shoulders (cuff tear arthropathy, massive cuff tears, osteoarthritis with cuff insufficiency) in 78 patients (63%), primary osteoarthritis in 41 (33%), and rheumatoid arthritis in 5 (4%).

The humeral component longitudinal axis was measured in degrees and defined as neutral if the value fell within ±5° of the humeral axis. Angle values >5° and < 5 ° were defined as valgus and varus, respectively. The filling-ratio of the implant within the humeral shaft was measured at the level of the metaphysis (FRmet) and diaphysis (FRdia). Measurements were conducted by two independent examiners (SA and TW). To test for conformity of observers, the intraclass correlation coefficient (ICC) was calculated.

The inter- and intra-observer reliability was excellent (ICC = 0.965, 95% confidence interval [CI], 0.911– 0.986). The average difference between the humeral shaft axis and the humeral component longitudinal axis was 3.8° ± 2.8° (range, 0.2° – 13.2°) corresponding to a true mean N-S angle of 149° ± 3° in valgus. Stem axis was neutral in 70% (n=90) of implants. Of the 34 malaligned implants, 82% (n=28) were in valgus (mean N-S angle 153° ± 2°) and 18% (n=6) in varus position (mean N-S angle 139° ± 1°). The average FRmet and FRdiawere 0.68 ± 0.11 and 0.72 ± 0.11, respectively. No association was found between stem diameter and filling ratios (FRmet, FRdia) or cortical contact with the stem (r = 0.39).

Operative technique and implant design affect the ultimate positioning of the implant in the proximal humerus. This study has shown, that in uncemented short stem implants, neutral axial alignment was achieved in 70% of cases, while the majority of malaligned humeral components (86%) were implanted in valgus, corresponding to a greater than 145° neck shaft angle of the implant. It is important for surgeons to understand that axial malalignment of a short stem implant does influence the true neck shaft angle.

I. Wong R. John

To evaluate the short-term clinical outcomes of patients treated arthroscopically with chitin-based scaffolding for acetabular chondral defects in conjunction with microfracture compared to microfracture alone.

This study is a retrospective analysis of prospectively collected data. A review of charts was performed (2014–2016) on all patients who underwent hip arthroscopy and had microfracture +/− scaffolding for acetabular chondral defects, intraoperative details (lesion size, grade, labral repair/reconstruction) and postoperative complications were recorded with a minimum follow-up of 2 years. Clinical outcomes were assessed by analysing iHOT and HOS scores which were obtained pre-operatively, at six months, one year and two years post-surgery. Plain radiographs were assessed for hip osteoarthritis by Kellgren & Lawrence grading.

A total of 60 patients (microfracture=25, scaffolding=35) were included. Patients had a mean age of 36.2 years at the time of the index operation. There were no major adverse events of deep vein 36.2 years at the time of the index operation. There were no major adverse events of deep vein thrombosis, blood vessel or nerve damage, hemarthrosis or device related adverse events in both groups. Two patients were readmitted due to pain as a result of an inflammatory reaction in the scaffolding group. Both treatments of microfracture and scaffolding showed significant improvement in outcome score (iHOT) (p < 0 .001) when compared postoperative to preoperative.

Both the arthroscopic treatment of chondral acetabular defects with chitin based scaffolding and microfracture demonstrated significant improvement from their pre-operative outcomes.

I. Wong M. Oldfield

The primary objective of this study was to establish a safety profile for an all-arthroscopic anatomic glenoid reconstruction via iliac crest autograft augmentation for the treatment of shoulder instability with glenoid bone loss. Short-term clinical and radiological outcomes were also evaluated.

This study involved a retrospective analysis of prospectively collected data for 14 patients (male 8, female 6) who were treated for shoulder instability with bone loss using autologous iliac crest bone graft between 2014 and 2018. Of 14 patients, 11 were available for follow-up. The safety profile was established by examining intra-operative and post-operative complications such as neurovascular injuries, infections, major bleeding, and subluxations. Assessment of pre-operative and post-operative Western Ontario Shoulder Instability (WOSI) index, radiographs, and CT scans comprised the evaluation of clinical and radiological outcomes.

A good safety profile was observed. There was no occurrence of intraoperative complications, neurovascular injuries, adverse events, or major bleeding. One patient did develop an infection in the neurovascular injuries, adverse events, or major bleeding. One patient did develop an infection in the treated shoulder post-surgery. There were no subluxations or positive apprehension tests on clinical examination post-operatively. Short-term clinical outcomes were seen to be favorable WOSI scores at the most recent follow-up were significantly higher than pre-operative scores, with a mean increase of 39.6 ± 10.60 (p = 0.00055). The average follow-up for CT scan was 4.66 (SD± 2.33) months, where all patients showed bone graft union.

Arthroscopic treatment of shoulder instability with bone loss via autologous iliac crest bone graft is shown to be a safe operative procedure that results in favorable short-term clinical and radiological outcomes. Further investigations must be done to evaluate the longevity of these positive health outcomes.

B. Ristevski M. Gjorgjievski B. Petrisor D. Williams M. Denkers K. Rajaratnam H. Johal J. Al-Asiri H. Chaudhry A. Nauth J. Hall D. B. Whelan S. Ward A. Atrey A. Khoshbin R. Leighton P. Duffy P. Schneider R. Korley R. Martin L. Beals C. Elgie L. Ginsberg Y. Mehdian P. McKay N. Simunovic J. Ratcliffe S. Sprague M. Vicente T. Scott J. Hidy P. Suthar T. Harrison K. Dillabough S. Yee A. Garibaldi M. Bhandari

Distracted driving is now the number one cause of death among teenagers in the United States of America according to the National Highway Traffic Safety Administration. However, the risks and consequences of driving while distracted spans all ages, gender, and ethnicity. The Distractions on the Road: Injury eValuation in Surgery And FracturE Clinics (DRIVSAFE) Study aimed to examine the prevalence of distracted driving among patients attending hospital-based orthopaedic surgery fracture clinics. We further aimed to explore factors associated with distracted driving.

In a large, multi-center prospective observational study, we recruited 1378 adult patients with injuries treated across four clinics (Hamilton, Ontario, Toronto, Ontario, Calgary, Alberta, Halifax, Nova Scotia) across Canada. Eligible patients included those who held a valid driver's license and were able to communicate and understand written english. Patients were administered questions about distracted driving. Data were analyzed with descriptive statistics.

Patients average age was 45.8 years old (range 16 – 87), 54.3% male, and 44.6% female (1.1% not disclosed). Of 1361 patients, 1358 self-reported distracted driving (99.8%). Common sources of distractions included talking to passengers (98.7%), outer-vehicle distractions (95.5%), eating/drinking (90.4%), music listening/adjusting the radio (97.6%/93.8%), singing (83.2%), accepting phone calls (65.6%) and daydreaming (61.2%). Seventy-nine patients (6.3%), reported having been stopped by police for using a handheld device in the past. Among 113 drivers who disclosed the cause of their injury as a motor vehicle crash (MVC), 20 of them (17%) acknowledged being distracted at the time of the crash. Of the participants surveyed, 729 reported that during their lifetime they had been the driver in a MVC, with 226 (31.1%) acknowledging they were distracted at the time of the crash.

Approximately, 1 in 6 participants in this study had a MVC where they reported to be distracted. Despite the overwhelming knowledge that distracted driving is dangerous and the recognition by participants that it can be dangerous, a staggering amount of drivers engage in distracted driving on a fairly routine basis. This study demonstrates an ongoing need for research and driver education to reduce distracted driving and its devastating consequences.

L. Nowak R. DiGiovanni R. Walker D. W. Sanders A. Lawendy M. MacNevin M. D. McKee E. H. Schemitsch

Delayed management of high energy femoral shaft fractures is associated with increased complication rates. It has been suggested that there is less urgency to stabilize lower energy femoral shaft fractures. The purpose of this study was to evaluate the effect of surgical delay on 30-day complications following fixation of lower energy femoral shaft fractures.

Patients ≥ 18 years who underwent either plate or nail fixation of low energy (falls from standing or up to three steps' height) femoral shaft fractures from 2005 – 2016 were identified from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) via procedural codes. Patients with pathologic fractures, fractures of the distal femur or femoral neck were excluded. Patients were categorized into early (< 2 4 hours) or delayed surgery (2–30 days) groups. Bivariate analyses were used to compare demographics and unadjusted rates of complications between groups. A multivariable logistic regression was used to compare the rate of major and minor complications between groups, while adjusting for relevant covariables. Head injury patients and polytrauma patients are not included in the NSQIP database.

Of 2,716 lower energy femoral shaft fracture patients identified, 2,412 (89%) were treated within 1 day of hospital admission, while 304 (11.2%) were treated between 2 and 30 days post hospital admission. Patient age, American Society of Anesthesiologists (ASA) classification score, presence of diabetes, functional status, smoking status, and surgery type (nail vs. plate) were significantly different between groups (p After adjusting for all relevant covariables, delayed surgery significantly increased the odds of 30-day minor complications (p=0.02, OR = 1.48 95%CI 1.01–2.16), and 30-day mortality (p < 0 .001), OR = 1.31 (95%CI 1.03–2.14).

The delay of surgical fixation of femoral shaft fractures appears to significantly increase patients' risk of minor adverse events as well as increase mortality. With only 89% of patients being treated in the 24 hour timeframe that constitutes best practice for treatment of femoral shaft fractures, there remains room for improvement. These results suggest that early treatment of all femoral shaft fractures, even those with a lower energy mechanism of injury, leads to improved outcomes.

L. Nowak E. H. Schemitsch

Increased operative time has been previously identified as a risk factor for complications following total joint arthroplasty. The purpose of this study was to evaluate the influence of surgical time on 30-day complications following Total Knee Arthroplasty (TKA) and to determine if there were specific time intervals associated with worse outcomes.

The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was utilized to identify patients ≥18 years who underwent TKA between 2005 and 2016 using procedural codes. Patients with surgical durations >240 minutes were excluded. Patient demographics, operation length, and 30-day major and minor complication rates were captured. Multivariable logistic regression was used to determine if the rate of complications differed depending on length of operation, while adjusting for age, sex, American Society of Anaesthesiologists (ASA) class, functional status, smoking status, comorbidities, anesthesia type, and Body Mass Index (BMI). Multivariable linear regression was used to identify independent predictors of duration of surgery.

A total of 213,921 TKA patients (average age 67 ± 10 years) were identified from the database. Within 30-days of the index procedure, 3,321 (1.55%) experienced a major complication, and 6,144 (2.86%) experienced a minor complication. Mean surgical duration was 92 minutes (range 20 – 240). Underweight, or overweight/obese BMI, male sex, hypertension, cancer, dependent functional status, epidural anaesthesia, and ASA class III and IV were determined to be independent predictors of prolonged operation length, while COPD, current smoking, spinal anesthesia, and older age predicted lower operation times.

Operation lengths ≥ 90 minutes significantly increased the risk of both major and minor complications (P>0.01). Specifically, the rates of deep vein thrombosis (DVT), unplanned reintubation, surgical site infection (SSI), sepsis, and wound disruption were higher for patients whose operations lasted ≥ 90 minutes (p 0.05). With respect to specific complications, following covariate adjustment, operation lengths ≥ 90 minutes increased the risk of DVT, deep and superficial incisional SSI, and wound disruption, while operation lengths ≥ 120 minutes increased the risk of deep, non-incisional SSI, and sepsis (P < 0 .01).

Surgical times of ≥90 minutes independently increase the 30-day risk of DVT, infection, and wound disruption following TKA after controlling for other variables that influence operation length. This study confirms the importance of surgical duration on early outcomes following TKA.

A. Karir K. Cheung S. Carsen K. Smit M. N. Q. Huynh

The diagnosis of a clinical scaphoid fracture is made when a scaphoid fracture is suspected, but radiographs are normal. Standard treatment in this scenario involves immobilization and repeat x-rays in 10–14 days. When repeat x-rays are also normal but a scaphoid fracture is still suspected clinically, the optimal management in children is unknown. Our objective was to characterize these patients and evaluate their management and outcomes.

A retrospective study was performed of all patients presenting to a tertiary paediatric center over a two year period with a diagnosis of wrist or hand pain. Charts were identified by ICD-10 diagnostic codes and reviewed for inclusion and exclusion criteria. Patients were included if they had clinical suspicion of a scaphoid fracture but two sets of x-rays negative for fracture within 14 days of injury.

Ninety-one children (mean age 13.2 years, SD: 2.2) were identified with a clinical scaphoid fracture. Mean follow-up was 7.1 weeks. Most patients (60%) were injured either from a fall while ambulating or from sports. Sixteen (18%) patients received CT or MRI at an average of 8.4 weeks post-injury (95%CI:5–15.3). All patients were immobilized for a mean of 5.4 weeks. No patients underwent surgery. Five patients (5.5%) were found to have a scaphoid fracture diagnosed by X-ray or CT at a mean of 5.7 weeks post-injury (range 4.3–6.6). Other carpal fractures or ligamentous injuries were identified in three patients (3%) by MRI or CT. Seventy percent of patients healed within 6 weeks of injury.

The majority of children presenting with clinical suspicion of a scaphoid fracture but 2 sets of X-rays negative for fracture healed with immobilization. While the incidence of true scaphoid fracture may be low in children, MRI or CT may be warranted for patients where clinical suspicion persists.

L. Nowak M. MacNevin M. D. McKee D. W. Sanders A. Lawendy E. H. Schemitsch

Distal radius fractures are the most common adult fractures, yet there remains some uncertainty surrounding optimal treatment modalities. Recently, the rate of operative treatment of these injuries has been increasing, however, predictors of outcomes in patients treated surgically remain poorly understood. The purpose of this study was to evaluate independent predictors of 30-day readmission and complications following internal fixation of distal radius fractures.

Patients ≥18 years who underwent surgical intervention for distal radius fractures between 2005 and 2016 were identified from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) using procedural codes. Patient demographics, as well as 30-day readmission, complication, and mortality rates were ascertained. Multivariable logistic regression was used to determine independent predictors of 30-day outcomes while adjusting for patient age, sex, American Society of Anaesthesiologists (ASA) class, functional status, smoking status, comorbidities, and Body Mass Index (BMI).

A total of 10,051 patients were identified (average age 58 ±16). All patients received open reduction and internal fixation with no cases of external fixation identified in the data set. Included fractures were 37% extraarticular and 63% intraarticular. Within 30-days of initial fixation 143 (1.42%) patients were readmitted to the hospital, 71 patients experienced a complication, and 18 (0.18%) patients died. After adjusting for relevant covariables, current smoking increased the odds of readmission by 1.73 (95%Confidence interval [95%CI] 1.15 – 2.50), ASA class III/IV vs. I/II increased the odds of readmission by 2.74 (95%CI 1.85 – 4.06), and inpatient surgery vs. outpatient surgery increased the odds of readmission by 2.10 (95%CI 1.46 – 3.03). Current smoking also increased the odds of complications by 2.26 (95%CI 1.32 – 3.87), while ASA class III/IV increased it by 2.78 (95%CI 1.60 – 4.85), inpatient surgery increased it by 2.26 (95%CI 1.37 – 3.74), and dependent functional status increased it by 2.55 (1.16 – 5.64).

In conclusion, patients with severe systemic disease, current smokers and patients undergoing inpatient surgery are at risk for 30-day readmissions and complications following operative treatment of distal radius fractures. In addition, patients with dependent functional statuses are more likely to experience a complication within 30-days.

J. Kendal A. Singla A. Al-Ani A. Affan K. Hildebrand D. Itani M. Ungrin M. Monument

Impaired bone healing biology secondary to soft tissue deficits and chemotherapy contribute to non-union, fracture and infection following limb salvage surgery in Osteosarcoma patients. Approved bone healing augments such as recombinant human bone morphogenetic protein-2 (rhBMP-2) have great potential to mitigate these complications. rhBMP-2 use in sarcoma surgery is limited, however, due to concerns of pro-oncogenic signalling within the tumour resection bed. To the contrary, recent pre-clinical studies demonstrate that BMP-2 may induce Osteosarcoma differentiation and limit tumour growth. Further pre-clinical studies evaluating the oncologic influences of BMP-2 in Osteosarcoma are needed. The purpose of this study is to evaluate how BMP-2 signalling affects Osteosarcoma cell proliferation and metastasis in an active tumour bed.

Two Osteosarcoma cell lines (143b and SaOS-2) were assessed for proliferative capacity and invasion. 143b and SaOS-2 cells were engineered to upregulate BMP-2. In vitro proliferation was assessed using a cell viability assay, motility was assessed with a scratch wound healing assay, and degree of osteoblastic differentiation was assessed using qRT-PCR of Osteoblastic markers (CTGF, ALP, Runx-2 and Osx). For in vivo evaluation, Osteosarcoma cells were injected into the intramedullary proximal tibia of immunocompromised (NOD-SCID) mice and local tumour growth and metastases were assessed using weekly bioluminescence imaging (BLI) and tumour volume measurements for 4–6 weeks. At the experimental end point we assessed radiographic tumour burden using ex-vivo micro-CT, as well as tibial and pulmonary gross and histologic pathology.

SaOS-2 was more differentiated than 143b, with increased expression of Runx-2 (p = 0.009), Osx (p = 0.004) and ALP (p = 0.035). BMP-2 upregulation did not stimulate an osteoblast differentiation response in 143b, but stimulated an increase in Osx expression in SaOS-2 (p = 0.002). BMP-2 upregulation in 143b cells resulted in increased proliferation in vitro (p = 0.014), faster in vitro wound healing (p = 0.03), significantly increased tumour volume (p = 0.001) with enhanced osteolysis detected on micro-CT, but did not affect rates of lung metastasis (67% vs. 71%, BMP-2 vs. Control). BMP-2 over-expression in SaOS-2 cells reduced in vitro proliferation when grown in partial osteogenic-differentiation media (p < 0.001), had no effect on in vitro wound healing (p = 0.28), reduced in vivo SaOS-2 tumour burden at 6 weeks (photon counts, p < 0.0001), decreased tumour-associated matrix deposition as assessed by trabecular thickness (p = 0.02), and did not affect rates of lung metastasis (0% vs. 0%).

Our results indicate BMP-2 signalling incites a proliferative effect on a poorly differentiated Osteosarcoma cell line (143b), but conditionally reduces proliferative capacity and induces a partial differentiation response in a moderately-differentiated Osteosarcoma cell line (SaOS-2). This dichotomous effect may be due to the inherent ability for Osteosarcoma cells to undergo BMP-2 mediated terminal differentiation. Importantly, these results do not support the clinical application of BMP-2 in Osteosarcoma limb salvage surgery due to the potential for stimulating growth of poorly differentiated Osteosarcoma cells within the tumour bed. Additional studies assessing the effects of BMP-2 in an immune-competent mouse model are ongoing.

Z. Glaris T. J. Goetz A. Li P. Daneshvar

Four-Corner Fusions (4CF) and Proximal Row Carpectomies (PRC) are common procedures utilized to treat carpal pathologies and radial sided wrist pain. Usually, the range of motion (ROM) and grip strength (GS) is affected by such conditions. Literature quotes significant reduction in ROM (50–60%) and grip strength (GS) (80% of normal) with PRC and 4CF. This study aims to determine the correlation between pre-operative ROM and GS and post-operative ROM and GS for patients with wrist pain undergoing PRC or 4CF. We hypothesize that ROM between pre-operative and post-operative patients does not change, but GS improves.

Data from a prospective database of patients with wrist pain was searched to identify patients who have undergone PRC or 4CF with one year follow-up completed in the past two years. 17 such participants were identified. The diagnosis, pre-operative ROM in flexion, extension, radial deviation, ulnar deviation, pronation and supination, as well as GS at time of surgery and at six months and one year follow up were identified and assessed. The data was analysed to determine correlation between pre-and postoperative ROM and GS. The analysis was subdivided to compare patients treated with PRC versus patients with 4CF.

No significant difference between pre- and post-operative ROM was detected, except in flexion at 6 months post-operatively. The average flexion was significantly lower at 6 months (p=0.0251) compared to pre-operative levels. Average flexion pre-operatively and at 6 and 12 months was found to be 46.6 (SD=15), 34.3 (SD=13.3), 51.2 (SD=21.5) respectively. Extension was at 41.4 (SD=15.3) pre-operatively and at 33.4 (SD=12.8) and 42.1 (SD=15.5) at 6 and 12 months post-operatively. Similarly, radial and ulnar deviation averages pre-operatively and at 6 and 12 months post-operatively were found to be 11.33 (SD=5.9), 11.9 (SD=4.5), 16 (SD=8.2) [radial deviation] and 24.1 (SD=8.3), 21.4 (SD=7.3), 26 (SD=12.8) [ulnar deviation].

No significant difference was found in GS at 6 months post-operative. However, significant difference at 12 months post-operatively was observed with an average GS of 28.4 kg (SD=12.8) [p=0.0385]. Average GS pre-operatively and at 6 months was 15.8 kg (SD=9.7) and 17.3 kg (SD=8.9) respectively.

This study provides an insight on ROM and GS after PRC and 4CF. It shows that patients do not gain or lose ROM after surgery. As expected, GS improves with treatment as the pain diminishes. It is interesting to note that flexion gets worse at 6 months post-operatively before it bounces back to pre-operative levels.

D. Milad K. Smit S. Carsen K. Cheung A. Karir

True scaphoid fractures of the wrist are difficult to diagnose in children. In 5–40% of cases, a scaphoid fracture may not be detectable on initial X-ray, some fractures may take up to six weeks to become evident. Since missing a scaphoid fracture may have serious implications, many children with a suspected or “clinical” scaphoid fracture, but normal radiographs, may be over-treated. The purpose of this study was to identify predictors of true scaphoid fractures in children.

A retrospective cohort study was performed using electronic medical records for all patients over a two-year period presenting to a tertiary paediatric hospital with hand or wrist injury. Charts were identified by ICD-10 diagnostic codes and reviewed for pre-specified inclusion and exclusion criteria. Patients with either a clinical or true scaphoid fracture were included. When a scaphoid fracture was suspected, but imaging was negative for fracture, the diagnosis of a clinical scaphoid fracture was made. True scaphoid fractures were diagnosed when a fracture was evident on any modality of medical imaging (X-ray, CT, MRI) at any time post-injury.

Over the two-year study period, 148 patients (60 scaphoid fractures, 88 non-fractures) met inclusion and exclusion criteria for review. Mean (±SD) age was 13±2 years and 52% were male. The left wrist was injured in 61% of cases. Of the 60 true scaphoid fractures, mean age was 14±2 years, and 69% were male. Fracture location was primarily at the waist (48%) or distal pole (45%) of the scaphoid. Sports were the prevailing mechanism of injury. Six (11%) underwent surgery. Multivariate logistic regression demonstrated that older age, male gender, and right-sided injury were predictors of scaphoid fracture with odds ratios of 1.3 (95% CI: 1.1–1.6, p=0.005), 2.8 (95% CI: 1.3–6, p=0.007), and 2.4 (95% CI: 1.1–5.2, p=0.025).

Older age, male gender, and right-sided injury may be predictors of scaphoid fractures in children. Further evidence to support this may enable the formulation of clinical guidelines or rules to reduce the overtreatment of children presenting with a clinical scaphoid fracture.

J. Mattei I. Alshaygy G. Basile A. Griffin J. S. Wunder P. Ferguson

Sarcomas generally metastasize to the lung, while extra-pulmonary metastases are rare. However, they may occur more frequently in certain histological sub-types. Bone metastases from bone and soft tissue sarcomas account for a significant number of extra-pulmonary disease. Resection of lung metastases is widely accepted as therapeutic option to improve the survival of oligometastatic patients but there is currently no literature supporting curative surgical management of sarcoma bone metastases. Most are treated on a case-by-case basis, following multidisciplinary tumour boards recommendations. One study reported some success in controlling bone metastases using radiofrequency ablation. Our goal was to assess the impact of curative resection of bone metastases from soft tissue and bone sarcomas on oncologic outcomes.

Extensive review of literature was done to evaluate epidemiological and outcomes of bone metastases in sarcoma. We examined our prospective database for all cases of bone metastases from sarcoma treated with surgical resection between 1990 and 2016. Epidemiology, pathology, metastatic status upon diagnosis, type of secondary relapses and their treatments were recorded.

Overall survival and disease-free survival were calculated and compared to literature.

Thirty-five patients were included (18 men, 17 women) with a mean age of 46 years. Fifteen were soft tissue (STS) and 20 were bone (BS) sarcomas. Most STS were fibrosarcomas, leiomyosarcomas or UPS while chondrosarcomas and osteosarcomas were the most frequent BS. Nine (60%) STS were grade 3, 4 (27%) grade 2 and one grade 1 (3%). Eight (23%) were metastatic upon diagnosis (6 lungs, 3 bone). Treatment of the primary tumour included wide excision with reconstruction and (neo)-adjuvant therapies as required. Margins were negative in 32 cases and micro-positive in 3 cases. Amputation occurred in 6 (17%) cases. Primary lung metastases were treated by thoracotomy and primary bone metastases by wide excision. First relapse occurred in bone in 19 cases (54%), lungs and bone in 7 cases, 5 in lungs and 4 in soft-tissues. Lung metastases were treated by thoracotomy and chemotherapy in 3 cases, chemotherapy alone in the remaining cases. Bone metastases were treated by wide resection-reconstruction in 24 cases, extensive curettage in 4. Soft tissue relapses were re-excised in 4 patients. Two amputations were required. All margins were negative except for the 4 treated by curettage. Fourteen second relapses occurred in bone, 7 were radically-excised and 2 curetted.

At last follow-up, 6 patients were alive (overall survival of 17%), with a mean survival of 57 months, a median overall survival of 42.5 months and a median disease-free survival (DFS) of 17 months. Overall survival was 17%, compared to an 11% 10-year survival previously reported in metastatic sarcomas. Median disease-free survival was better in this study, compared to 10 months in literature, so as median OS (42.5 months vs 15). Three patients were alive with no evidence of disease. DFS, OS and median survival seemed to be improved by bone metastases wide excision and even if several recurrences occur, curative surgery with adjuvant therapies should be considered.

C. Ma C. Li Y. Jin W. W. Lu

To explore a novel machine learning model to evaluate the vertebral fracture risk using Decision Tree model and train the model by Bone Mineral Density (BMD) of different compartments of vertebral body.

We collected a Computed Tomography image dataset, including 10 patients with osteoporotic fracture and 10 patients without osteoporotic fracture. 40 non-fracture Vertebral bodies from T11 to L5 were segmented from 10 patients with osteoporotic fracture in the CT database and 53 non-fracture Vertebral bodies from T11 to L5 were segmented from 10 patients without osteoporotic fracture in the CT database. Based on the biomechanical properties, 93 vertebral bodies were further segmented into 11 compartments: eight trabecular bone, cortical shell, top and bottom endplate. BMD of these 11 compartments was calculated based on the HU value in CT images.

Decision tree model was used to build fracture prediction model, and Support Vector Machine was built as a compared model. All BMD data was shuffled to a random order. 70% of data was used as training data, and 30% left was used as test data. Then, training prediction accuracy and testing prediction accuracy were calculated separately in the two models.

The training accuracy of Decision Tree model is 100% and testing accuracy is 92.14% after trained by BMD data of 11 compartments of the vertebral body. The type I error is 7.14% and type II error is 0%. The training accuracy of Support Vector Machine model is 100% and the testing accuracy is 78.57%. The type I error is 17.86% and type II error is 3.57%.

The performance of vertebral body fracture prediction using Decision Tree is significantly higher than using Support Vector Machine. The Decision Tree model is a potential risk assessment method for clinical application. The pilot evidence showed that Decision Tree prediction model overcomes the overfitting drawback of Support Vector Machine Model. However, larger dataset and cohort study should be conducted for further evidence.

A. Li Z. Glaris T. J. Goetz

Physical examination is critical to formation of a differential diagnosis in patients with ulnar-sided wrist pain. Although the specificity and sensitivity of some of those tests have been reported in the literature, the prevalence of positive findings of those provocative maneuvers has not been reported. The aim of the study is to find the prevalence of positive findings of the most commonly performed tests for ulnar sided wrist pain in a population presenting to UE surgeon clinics, and to correlate those findings with wrist arthroscopy findings.

Patients with ulnar sided wrist pain were identified from a prospective database of patients presented with wrist pain from September 2014. Prevalence of positive findings for the following tests were gathered: ECU synergy test, ECU instability test (Ice cream and Fly Swatter), Lunotriquetral ballottement, Kleinman shear, triquetrum tenderness, triquetrum compression test, triquetral-hamate tenderness, pisotriquetral shuck test, ulnar fovea test, ulnocarpal impaction (UCI) maneuver, UCI maneuver with fovea pressure (ulnar carpal plus test), piano key sign. A subgroup was then created for those who underwent wrist arthroscopy, and analysis of the sensitivities, the specificities and the predictive values of these provocative tests was carried out with correlation to arthroscopic finding.

Prevalence of ECU instability tests was t 1.13% (ice cream scoop) and 1.5% (fly swatter). Lunotriquetral ballottement test's positive findings range from 4.91% (excessive laxity) to 14.34% (pain reproducing symptoms. The Kleinman shear test yielded pain in 13.58% of patients, and instability in only 2.26%. Triquetrum compression test reproduces pain in 32.83% of patients, and triquetral-hamate tenderness reproduced pain in 13.21%. Pisotriquetral grind test yields 15.85% positive findings for pain, and 10.57% for crepitus with radioulnar translation. The ulnar fovea test revealed pain in 69.05% of cases. The UCI maneuver yielded pain in 70.19%. The UCI maneuver plus ulnar fovea test reproduced pain in 80.38% of cases. Finally, the piano key sign yields positive finding in 2.64% of cases.

For patients who underwent surgery, sensitivities, specificities and predictive values were calculated based on arthroscopic findings. The lunotriquetral ballottement test has 59.6% sensitivity, 39.6% specificity, 20.3% positive predictive value and 85.4% negative predictive value. The sensitivity of Kleinman test was 62.4%, the specificity was 41.3%, the positive predictive value was 23.5%, and the negative predictive value was 83.2%. The sensitivity of fovea test was 94.3%, the specificity was 82.5%, the positive predictive value was 89.5% and the negative predictive value was 92.3%. The UCI maneuver plus ulnar fovea test has 96.5% sensitivity, 80.7% specificity 86.4% positive predictive value, and 95.3% negative predictive value.

Among the provocative tests, the prevalence of positive findings is low in the majority of those maneuvers. The exceptions are the fovea test, the UCI maneuver, and the UCI plus maneuver. With regard to the sensitivity and the specificity of those tests, the current study reproduces the numbers reported in the literature. Of those patients who underwent wrist arthroscopy, the tests are better at predicting at the absence of injury rather than at predicting its presence

X. Zhang J. Liu J. Li X. Chen Z. Qiao J. Xu F. Xiao P. Cui

Osteosarcoma (OS) is the most prevalent bone tumor in children and young adults. Most tumors arise from the metaphysis of the long bones and easily metastasize to the lungs. Current therapeutic strategies of osteosarcoma are routinely surgical resection and chemotherapy, which are limited to the patients suffering from metastatic recurrence. Therefore, to investigate molecular mechanisms that contribute to osteosarcoma progression is very important and may shed light on targeted therapeutic approach to improve the survival of patients with this disease. Several miRNAs have been found expressed differentially in osteosarcoma (OS), In this study, we found that miR-144 significantly suppresses osteosarcoma cell proliferation, migration andinvasion ability in vitro, and inhibited tumor growth and metastasisin vivo. The function and molecular mechanism of miR-144 in Osteosarcoma was further investigated.

Tissue samples from fifty-one osteosarcoma patients were obtained from Shanghai Ninth People's Hospital. The in vitro function of miR-144 in Osteosarcoma was investigated by cell viability assay, wound healing assay, invasion assay, the molecular mechanism was identified by Biotin-coupled miRNA capture, Dual-luciferase reporter assays, etc. the in vivo function of miR-144 in osteosarcoma was confirmed by osteosarcoma animal model and miR-144−/− zebrafish model.

Mechanically, we demonstrated that Ras homolog family member A (RhoA) and its pivotal downstream effector Rho-associated, coiled-coil containing protein kinase 1 (ROCK1) were both identified as direct targets of miR-144. Moreover, the negative co-relation between downregulated miR-144 and upregulated ROCK1/RhoA was verified both in the osteosarcoma cell lines and clinical patients' specimens. Functionally, RhoA with or without ROCK1 co-overexpression resulted a rescue phenotype on the miR-144 inhibited cell growth, migration and invasion abilities, while individual overexpression of ROCK1 had no statistical significance compared with control in miR-144 transfected SAOS2 and U2-OS cells.

This study demonstrates that miR-144 inhibited tumor growth and metastasis in osteosarcoma via dual-suppressing of RhoA and ROCK1, which could be a new therapeutic approach for the treatment ofosteosarcoma.

J. Powell P. Railton A. Parkar H. Khong F. Moradi C. Smith

There has been growing interest in the literature regarding evaluation of functional outcomes in patients undergoing total knee arthroplasty (TKA) and total hip arthroplasty (THA) while suffering from depression and using selective serotonin reuptake inhibitors (SSRI). Previous literature has shown that these patients have lower post-operative functional scores compared to those without SSRI use and with multiple musculoskeletal co-morbidities. This might be the result of potentially suboptimal motivation and participation in the post-operative rehabilitation programs. One recent study from a single center has suggested a reduction in adverse events in patients undergoing arthroplasty while on SSRI. The purpose of this study is to evaluate the post operative functional scores of patients on SSRI and compare them with the patients not prescribed SSRIs.

A retrospective data analysis was performed on patients who had primary TKA and primary THA between 1st June 2014 and 31st May 2017. The patients into two groups. In the first, patients received SSRI for at least one year before the surgery while in group two, patients did not receive SSRI. Outcome measures included Western Ontario and McMaster university osteoarthritis index (WOMAC) and EQ5D5L scores at pre surgery, three months and 12 months post surgery.

Chi-square and t test was used to compare categorical variables and continuous variables respectively. Multivariate linear regression was conducted to compare the change of scores between the two groups and was adjusted for age, gender, and comorbidities. These outcome scores were analyzed separately for TKA and THA.

In the TKA group, there were 1,452 patients using SSRI and 15,981 not using SSR. In the THA group there were 851 patients using SSRIs and 10,102 patients without SSRIs. The baseline WOMAC for TKA patients was 45.6 for the controls and 41.8 for those patients on SSRIs (p < 0 .001). The baseline EQ5DL was 0.53 and 0.46 in the same groups (p < 0 .001). The baseline WOMAC for THA patients was 39.1 for the controls and 36.2 for patients using SSRIs (p < 0 .001). The baseline EQ5DL scores were 0.43 and 0.37respectively, again indicating patients on SSRI therapy had lower baseline scores (p < 0 .001).

There was improvement in WOMAC and EQ5DL scores in all patient groups at 3 months and 12 months. After adjusting for gender, age, comorbidities and baseline score, THA patients not using SSRI showed a greater improvement in their WOMAC and EQ5DL scores than those prescribed SSRIs, WOMAC (p=0.008), EQ5DL (p=0.001). TKA patients showed a similar outcome but only the EQ5DL was statistically significant, WOMAC (p=0.12), EQ5DL (p=0.036).

Our results show that patients on SSRI have lower preoperative WOMAC and EQ5DL scores at baseline when compared to patients not undergoing treatment for depression or anxiety with SSRIs. After arthroplasty, patients using SSRIs show significant improvement at 12 months but the improvement is smaller than the group not using SSRIs.

E. Laende M. J. Dunbar G. Richardson

The dual mobility design concept for acetabular components is intended to reduce the risk of dislocation and increase range of motion, but the wear pattern of this design is unclear and may have implications in implant fixation. Additionally, the solid back cups do not have the option for supplementary screw fixation, providing an additional smooth articulating surface for the liner to move against. The objective of this study was to assess cup fixation by measuring implant migration as well as proximal femoral head penetration to evaluate wear performance.

Thirty subjects were recruited in a consecutive series prospective study and received dual mobility uncemented acetabular components with mobile bearing polyethylene liners through a direct lateral approach. Femoral stems were cemented or uncemented. All subjects had 28 mm femoral heads. The femur, acetabulum, and non-articulating surface of the mobile polyethylene liner were marked with tantalum beads. Radiostereometric analysis (RSA) exams were performed post-operatively and at 6 weeks, 3 months, 6 months, 1 year, 2 years, and 3 years. Oxford 12 Hip and Satisfaction questionnaire responses were recorded. Mobile bearing motion was assessed under fluoroscopy for a single case under loaded and unloaded conditions.

Twenty-nine subjects (17 female) proceeded to surgery. Subjects were 63±11 years of age with BMIs of 28±4.7 kg/m2. Cup migration reached 0.16 ± 0.31 mm of proximal translation and 0.29±1.03 degrees of sagittal rotation at three years. A single individual had more than 3 degrees of cup rotation, occurring by 6 months and not substantially increasing after this time. Proximal translation was low for this subject. Wear of the highly cross-linked mobile bearings was 0.18 ± 0.30 mm of proximal femoral head penetration from 0 to 3 years. The mean wear rate from 1 to 3 years was 0.02 mm/year. One subject was an outlier for wear, with more than 1 mm of femoral head penetration at 1 year. However, wear did not increase after 1 year for this subject and cup migrations were below average for this individual. Similarly, the outlier for cup rotation had below average wear. Satisfaction (out of 100%) improved from 25±27% to 96±7% pre-operatively to 3 years post-operatively. Oxford 12 scores (best possible score of 48) improved from 21±7 to 43±7 over the same period. The fluoroscopic case study demonstrated visible motion of the mobile bearing during hip rotation tasks.

The overall migration of the cup was low and demonstrated favorable patterns suggesting low risk of aseptic loosening. Wear rates are also within the expected range of 0 to 0.06 mm/year for highly cross-linked polyethylene. The combination of low subsidence and low sagittal rotations of the cup, and low wear of the polyethylene are favorable predictors of good long-term performance.

Z. Li Z. Geng Z. Cui S. Wu S. Zhu Y. Liang X. Yang

Surgical failure, mainly caused by loosening implants, causes great mental and physical trauma to patients. Improving the physicochemical properties of implants to achieve favourable osseointegration will continue to be the focus of future research. Strontium (Sr), a trace element, is often incorporated into hydroxyapatite (HA) to improve its osteogenic activity. Our previous studies have shown that miR-21 can promote the osteogenic differentiation of mesenchymal stem cells by the PI3K/β-catenin pathway. The aim of this study is to fabricate a SrHA and miR-21 composite coating and it is expected to have a favorable bone healing capability.

Ti discs (20 mm diameter and one mm thickness for the in vitro section) and rods (four mm diameter and seven mm length for the in vivo section) were prepared by machining pure Ti. The Ti cylinders were placed in a Teflon-lined stainless-steel autoclave for treating at 150°C for 24 h to form SrHA layer. The miR-21 was encapsulated in nanocapsules. The miR-21 nanocapsules were mixed with CMCS powder to form a gel-like sample and uniformly coated on the SrHA modifed Ti. Osteoblast-like MG63 cells were cultured on SrHA and miR-21 modified Ti, Cell proliferation activity and osteogenesis-related gene expression were evaluated. A bone defect model was established with mature New Zealand to evaluate the osseointegration. Cylindrical holes (four mm in diameter) were created at the distal femur and tibial plateau. Each rabbit was implanted with four of the aforementioned rods (distal femur and tibial plateau of the hind legs). After implantation for one, two and three months, the rabbits were observed by X-ray and scanned using u-CT. Histological and Immunohistochemical analysis were performed to examine the osteogenic markers. A biomechanical push-in test was used to assess the bone-implant bonding strength.

Both SrHA nanoparticles with good superhydrophilicity and miR-21 nanocapsules with uniform sizes were distributed evenly on the surface of the Ti. In vitro experiments revealed that the composite coating was beneficial to osteoblast proliferation, differentiation and mineralization. In vivo evaluations demonstrated that this coating could not only promote the expression of angiogenic factor CD31 but also enhance the expression of osteoblastic genes to facilitate angio-osteogenesis. In addition, the composite coating also showed a decreased RANKL expression compared with the miR-21 coating. As a result, the SrHA/miR-21 composite coating promoted new bone formation and mineralization and thus enhanced osseointegration and bone-implant bonding strength.

A homogeneous SrHA and miR-21 composite coating was fabricated by generating pure Ti through a hydrothermal process, followed by adhering miR-21 nanocapsules. This coating combined the favorable physicochemical properties of SrHA and miR-21 that synergistically promoted angiogenesis, osteogenesis, osseointegration, bone mineralization and thus bone-implant bonding strength. This study provided a new strategy for surface modification of biomedical implants.

S. Kelley M. Feeney C. Maddock L. Murnaghan C. Bradley

Developmental Dysplasia of the Hip (DDH) is the most common orthopaedic disorder in newborns. Whilst the Pavlik harness is one of the most frequently used treatments for DDH, there is immense variability in treatment parameters reported in the literature and in clinical practice, leading to difficulties in standardising teaching and comparing outcomes. In the absence of definitive quantitative evidence for the optimal Pavlik harness management strategy in DDH, we addressed this problem by scientifically obtaining international expert-based consensus on the same.

An initial list of items relevant to Pavlik harness treatment was derived by systematic review of the literature according to PRISMA criteria and reviewed by two expert clinicians in DDH management. Delphi methodology was used to guide serial rounds of surveying and feedback to content matter experts from the International Hip Dysplasia Institute (IHDI), a collaborative group of paediatric orthopaedic surgeons with expertise in the management of DDH. Rounds of surveying continued in the same manner until consensus was reached.

Importance ratings were derived from each round of surveying by calculating median score responses on the 5-point Likert scale for each item. Items requiring clarification or those with a median score of below 4 (“agree”) were modified as needed prior to each subsequent round. Consensus was considered reached when 90% or more of the items had an interquartile range (IQR) of ≤ 1. This value indicates low sample deviation and is accepted as having achieved consensus. This was followed by a corroboration of face validity to derive the final set of management principles.

The literature search and expert review identified an initial list of 66 items in 8 categories relevant to Pavlik harness management. Four rounds of structured surveying were required to reach consensus. Following a final round of face validity, a definitive list of 33 items in 8 categories met consensus by the experts. These items were tabulated and presented as “General Principles of Pavlik Harness Treatment for DDH” and “Pavlik Harness Treatment by Severity of Hip Dysplasia”. Furthermore, highly contentious items were identified as important future areas of study and will be discussed.

We have developed a comprehensive set of principles derived by expert consensus to assist clinicians, and for use as a teaching resource, in the non-operative management of DDH using the Pavlik harness. We have gained consensus on both the general principles of Pavlik harness treatment as well as the detailed treatment of hip subtypes seen across the spectrum of pathology of DDH. Furthermore, this study has also served to generate a list of the most controversial areas in the non-operative management of DDH which should be considered high priority for future study to further refine and optimise the outcomes of children with developmental hip dysplasia.

B. Charbonnier A. Baradaran E. Harvey M. Gilardino N. Makhoul J. Barralet

The treatment of critical-sized bone defects still remains today a challenge, especially when the surrounding soft, vascularized and innervated tissues have been damaged - a lack of revascularization within the injured site leading to physiological disorders, from delayed healing to osteonecrosis. The axial insertion of a vascular bundle (e.g. arterio-venous loop, AVL) within a synthetic bone filler to initiate and promote its revascularization has been foreseen as a promising alternative to the current strategies (e.g., vascularized free flaps) for the regeneration of large bone defects. In a previous work, we showed that the insertion of a vein in a 3D-printed monetite scaffold induced its higher revascularization than AVL, thus a possible simplification of the surgical procedures (no microsurgery required). Going further, we investigate in this study whether or not the presence of a vein could stimulate the formation of mineralized tissue insides a synthetic scaffold filled with bone marrow and implanted in ectopic site.

Monetite scaffolds were produced by additive manufacturing according to a reactive 3D-printing technique co-developed by the authors then thoroughly characterized. Animal study was performed on 14 male Wistar rats. After anesthesia and analgesia, a skin medial incision in rat thigh allowed the site on implantation to be exposed. Bone marrow was collected on the opposite femur through a minimally invasive procedure and the implant was soaked with it. For the control group (N=7), the implant was inserted in the incision and the wound was closed whereas the femoral bundle was dissected and the vein inserted in the implant for the experimental group (N=7). After 8 weeks animals were sacrificed, the implant collected and fixed in a 4% paraformaldehyde solution. Explants were characterized by µCT then embedded in poly-methyl methacrylate prior SEM, histology and immunohistochemistry. Images were analyzed with CT-Analyzer (Bruker) and ImageJ (NIH) and statistical analyses were carried out using SPSS (IBM).

Implants were successfully 3D-printed with a +150 µm deviation from the initial CAD. As expected, implants were composed of 63%wt monetite and 37%wt unreacted TCP, with a total porosity of 44%. Data suggested that scaffold biodegradation was significantly higher when perfused by a vein. Moreover, the latter allowed for the development of a dense vascular network within the implant, which is far more advanced than for the control group. Finally, although mineralized tissues were observed both inside and outside the implant for both groups, bone formation appeared to be much more important in the experimental one.

The ectopic formation of a new mineralized tissue within a monetite implant soaked with bone marrow seems to be highly stimulated by the simple presence of a vein alone. Although AVL have been studied extensively, little is known about the couple angiogenesis/osteogenesis which appears to be a key factor for the regeneration of critical-sized bone defects. Even less is known about the mechanisms that lead to the formation of a new bone tissue, induced by the presence of a vein only. With this in mind, this study could be considered as a proof of concept for further investigations.

T. Niedermair R. Straub S. Grässel

Previously, we reported impaired biomechanical bone properties and inferior bone matrix quality in tachykinin1 (Tac1)-deficient mice lacking the sensory neuropeptide substance P (SP). Additionally, fracture callus development is affected by the absence of SP indicating a critical effect of sensory nerve fibers on bone health and regeneration. For α-calcitonin gene-related peptide (α-CGRP)-deficient mice, a profound distortion of bone microarchitecture has also been described. We hypothesize that SP and α-CGRP modulate inflammatory as well as pain-related processes and positively affect bone regeneration during impaired fracture healing under osteoporotic conditions. Therefore, this study investigates the effects of SP and α-CGRP on fracture healing and fracture-related pain processes under conditions of experimental osteoporosis using SP- and α-CGRP-deficient mice and WT controls.

We ovariectomized female WT, Tac1−/− and α-CGRP−/− mice (age 10 weeks, all strains on C57Bl/6J background) and set intramedullary fixed femoral fractures in the left femora 28 days later. We analyzed pain threshold (Dynamic Plantar Aesthesiometer Test) and locomotion (recorded at day and night, each for 1 hour, EthoVision®XT, Noldus) at 5, 9, 13, 16 and 21 days after fracture. At each time point, fractured femora were prepared for histochemical analysis of callus tissue composition (alcian blue/sirius red staining).

Pain threshold is significantly higher in Tac1−/− mice 13 days after fracture and tends to be higher after 21 days compared to WT controls. In contrast, touch sensibility was similar in α-CGRP−/− mice and WT controls but compared to Tac1−/− mice pain threshold was significantly lower in α-CGRP−/− mice 13 and 16 days and tends to be lower 21 days after fracture. Locomotion of Tac1−/− mice during daylight was by trend higher 9 days after fracture and significantly higher 16 days after fracture whereas nightly locomotion is reduced compared to WT mice. Analysis of locomotion during daylight or night revealed no differences between α-CGRP−/− and WT mice. During early fracture healing phase, 5 and 9 days after fracture, transition of mesenchymal to cartilaginous callus tissue tends to be faster in Tac1−/− mice compared to WT controls whereas no difference was observed during late stage of fracture healing, 13, 16 and 21 days after fracture. In contrast, callus tissue maturation seems to be similar in α-CGRP−/− and WT mice.

Our data indicate different effects of SP and α-CGRP on fracture healing under conditions of experimental osteoporosis as a model for impaired bone tissue. Lack of α-CGRP seems to have no effects, but loss of SP affects locomotion throughout osteoporotic fracture healing and fracture-related pain processes during late phases of osteoporotic fracture healing. This indicates a modified role of SP during fracture healing under impaired versus healthy conditions, where SP changed early fracture-related pain processes and had no influence on callus tissue composition.

D. Burns

Participation in a physical therapy program is considered one of the greatest predictors for successful conservative management of common shoulder disorders, however, adherence to standard exercise protocols is often poor (around 50%) and typically worse for unsupervised home exercise programs. Currently, there are limited tools available for objective measurement of adherence and performance of shoulder rehabilitation in the home setting. The goal of this study was to develop and evaluate the potential for performing home shoulder physiotherapy monitoring using a commercial smartwatch. We hypothesize that shoulder physiotherapy exercises can be classified by analyzing the temporal sequence of inertial sensor outputs from a smartwatch worn on the extremity performing the exercise.

Twenty healthy adult subjects with no prior shoulder disorders performed seven exercises from a standard evidence-based rotator cuff physiotherapy protocol: pendulum, abduction, forward elevation, internal/external rotation and trapezius extension with a resistance band, and a weighted bent-over row. Each participant performed 20 repetitions of each exercise bilaterally under the supervision of an orthopaedic surgeon, while 6-axis inertial sensor data was collected at 50 Hz from an Apple Watch. Using the scikit-learn and keras platforms, four supervised learning algorithms were trained to classify the exercises: k-nearest neighbour (k-NN), random forest (RF), support vector machine classifier (SVC), and a deep convolutional recurrent neural network (CRNN). Algorithm performance was evaluated using 5-fold cross-validation stratified first temporally and then by subject.

Categorical classification accuracy was above 94% for all algorithms on the temporally stratified cross validation, with the best performance achieved by the CRNN algorithm (99.4± 0.2%). The subject stratified cross validation, which evaluated classifier performance on unseen subjects, yielded lower accuracies scores again with CRNN performing best (88.9 ± 1.6%).

This proof-of concept study demonstrates the feasibility of a smartwatch device and machine learning approach to more easily monitor and assess the at-home adherence of shoulder physiotherapy exercise protocols. Future work will focus on translation of this technology to the clinical setting and evaluating exercise classification in shoulder disorder populations.

D. Sheyn A. Papalamprou J. Chahla V. Chan O. Limpisvasti B. Mandelboum M. Metzger

The meniscus is at the cornerstone of knee joint function, imparting stability and ensuring shock absorption, load transmission, and stress distribution within the knee joint. However, it is very vulnerable to injury and age-related degeneration. Meniscal tears are reported as the most common pathology of the knee with a mean annual incidence of 66 per 100,000. Knee osteoarthritis progresses more rapidly in the absence of a functional meniscus. Historically, tears extending to the avascular inner portion of the meniscus (white-white zone, “WW”), such as radial tears were considered as untreatable and were often resected, due to the lack of vascularity in the WW zone. Perfusion-based anatomical studies performed on cadaveric menisci in the 1980s shaped the current dogma that human meniscus has poor regenerative capacity, partly due to limited blood supply that only reaches 10 to 25% of the meniscus, commonly referred to as red-red zone (“RR”). Previous studies, including those utilizing animal models have shown mobilization of Mesenchymal Stem Cells (MSCs) upon injury into the WW zone, and successful MSC recruitment when administered externally to the injury site. We and others have recently reported positive outcomes of repaired tears in the inner zone of patients. We hypothesized that the “avascular” white-white zone of the meniscus possesses regenerative capacity due to a resident stem/progenitor cell population. Further, we sought to redefine the presence of microvessels in all meniscal zones using advanced stereology and imaging modalities.

Fifteen menisci from fresh human cadaveric knees (mean age: 21.53±6.53 years) without evidence of previous injury were obtained from two tissue banks (JRF, Centennial, CO) and Biosource Medical (Lakeland, FL) and utilized for this study. The use of cadaveric specimens for research purposes was approved by the institutional review board. Tibial plateaus were dissected to harvest medial and lateral menisci along their entire length. The RR, red-white (RW) and WW zones were dissected and separated into three thirds from the inner aspect to the marginal border of the meniscus and their wet weights recorded (Fig.1A). Meniscus tissue cellular content in each zone was obtained from dissociation of meniscus tissue using 0.02% w/v pronase (Millipore) for 1h at 37oC, followed by 18h 0.02% w/v collagenase II (Worthington) at 37oC with shaking. Isolated cells were characterized immediately after harvest using flow cytometry with antibodies against MSCs surface markers (CD105, CD90, CD44 and CD29) as well as respective isotype controls. Further, meniscal cells were cultured and split twice when confluence was reached, characterized at P2 and compared to bone marrow-derived MSCs (BM-MSCs) using the same markers. Self-renewal of cells was assessed using colony forming unit (CFU) assay. Differentiation assays were performed to assess whether colony-forming cells retained multilineage potential. For morphological examination of bigger vessels, samples were fixed in 10% formalin for 1 week, paraffin embedded, sectioned (4 μm thick) and stained with H&E and Masson's trichrome. Presence of microvessels was assessed by CD31 immunofluorescence staining. Further, menisci were cleared using the uDisco protocol labeled with the TO-PRO®-3 stain, a fluorescent dye that stains cell nuclei and imaged using light-sheet microscopy. All continuous data are presented as mean ±standard deviation. Non-repeated measures analysis of variance (ANOVA) and Tukey-Kramer HSD post hoc analysis were performed on sample means for continuous variables. Statistical significance was set at p < 0 .05.

Menisci were successfully cleared using a modified uDISCO procedure, imaged and analyzed for total cell density. As expected, bigger vessels were observed in RR but not in WW. However, immunofluorescent staining for CD31 showed a subset of CD31+endothelial cells present in the WW zone, indicating the presence of small vessels, most likely capillaries. In order to assess whether enzymatic digestion had a differential result depending on meniscus zone due to cellular content, we analyzed yields per meniscus per zone. The wet weight of different zones (WW:RW:RR) was at a ratio of ∼1:3:5 respectively, however, the ratio of cells isolated from each zone was at ∼1:4:20, indicating that RR has a denser population of mononuclear cells. However, the difference between all zones in cell yields was not significant. The clonogenic potential of isolated cells was shown to be non-significantly different between the three zones. Differentiation of isolated cells to osteogenic lineage using osteogenic media in vitroshowed no difference between the three zones. Flow cytometry analysis of cells from the three meniscal zones displayed presence of two distinct subpopulations of cells immediately after isolation. One subpopulation was positive to MSC surface markers and the other negative. Additionally, flow cytometry of cultured meniscal cells at P2 displayed that the entire cell population was CD44+CD105+CD29+CD90+, suggesting that culturing meniscal cells results in selection of stem/progenitor cells (plastic adherence). Surface marker expression analysis showed differential expression patterns between markers depending on zone. Similar fraction of cells was detected to express both MSC markers CD90 and CD105 (7–10%) and similar fraction of cells expressed both MSC markers CD29 and CD44 (1–2%) in all three zones, indicating similar density of resident stem/progenitor cells in each zone. Importantly, WW showed significantly higher expression for all four MSC markers compared to the RR zone, indicating higher relative density of stem/progenitor resident cells in the WW zone.

Our results determine that CD31-expressing microvessels were present in all zones, including the WW zone, which was previously considered completely avascular. Additionally, stem/progenitor cells were shown to be present in all three zones of the menisci, including the WW zone, showcasing its regenerative potential.

For any figures or tables, please contact the authors directly.

A. Woloszyk K. Tuong K. Tetsworth V. Glatt

Treatment of segmental bone defects remains a major clinical problem, and innovative strategies are often necessary to successfully reconstruct large volumes of bone. When fractures occur, the resulting hematoma serves as a reservoir for growth factors and a space for cell infiltration, both crucial to the initiation of bone healing. Our previous studies have demonstrated very clear ultrastructural differences between fracture hematomas formed in normally healing fractures and those formed in segmental bone defects. However, there is little information available regarding potential differences in the underlying gene expression between hematomas formed in normal fractures, which usually heal by themselves, and segmental bone defects, which do not. Therefore, the aim of this study was to identify differences in gene expression within hematomas collected from 0.5 mm (normal fracture) and 5 mm (segmental bone defect) fracture sites during the earliest stages of bone healing.

Osteotomies of 0.5 and 5 mm in the femur of Fisher 344 rats were stabilized with external fixators (RISystem AG). After 3 days the rats were sacrificed, and the fracture hematomas were collected for RNA-sequencing. Ingenuity pathway analysis (IPA) was used to identify upstream regulators and biological functions that were significantly enriched with differentially expressed genes from the RNA-sequencing analysis. Animal procedures were conducted following the IACUC protocol of the UT Health Science Center San Antonio.

Key upstream regulators of bone formation were less active (e.g. TGFB1, FGF2, SMAD3) or even inhibited (e.g. WNT3A, RUNX2, BMP2) in non-healing defects when compared to normally healing fractures. Many upstream regulators that were uniquely enriched in healing defects were molecules recently discovered to have osteogenic effects during fracture healing (e.g. GLI1, EZH2). Upstream regulators uniquely enriched in non-healing defects were mainly involved in an abnormal modulation of hematopoiesis, revealing evidence of impaired maturation of functional macrophages and cytokines (e.g. IL3, CEBPE), both essential for successful bone healing. In addition, the enrichment pattern suggested a dysregulation of megakaryopoiesis (e.g. MRTFA, MRTFB, GATA2), which directly affects platelet production, and therefore fracture hematoma formation. Remarkably, the organization of the ECM was the most significantly enriched biological function in the normally healing fractures, and implies that the defect size directly affected the structural properties within the fracture hematoma. Conversely, genes encoding important ECM components (e.g. BGN, various collagens, IBSP, TNC), cell adhesion molecules, MMPs (MMP2), and TIMPs were all significantly downregulated in non-healing defects.

Our most recent findings reveal new important key molecules that regulate defect size-dependent fracture healing. Combined with our previous results, which identified structural differences in fracture hematomas from both types of defects, current findings indicate that differential expression of genes is dictated by the structural properties of the hematomas formed during early fracture healing. Consequently, creating a bioscaffold that mimics the structure of normal fracture hematomas could be the first step towards developing new orthoregenerative treatment strategies that potentiate healing of large bone defects and non-healing fractures.

T. Nau A. Teuschl H. Redl

Due to unsatisfactory results and reported drawbacks of anterior cruciate ligament (ACL) reconstruction new regenerative approaches based on tissue-engineering strategies are currently under investigation. It was the purpose of this study to determine if a novel silk fiber-based ACL scaffold is able to initiate osteointegration in the femoral and tibial bone tunnels under in vivo conditions. Furthermore we tested if the osteointegration process will be improved by intraoperatively seeding the scaffolds with the autologous stromal vascular fraction, an adipose-derived, stem cell-rich isolate from knee fat pads.

In this controlled laboratory study, 33 sheep underwent ACL resection and were then randomly assigned to 2 experimental groups: ACL reconstruction with a scaffold alone and ACL reconstruction with a cell-seeded scaffold. Half of the sheep in each group were randomly chosen and euthanized 6 months after surgery and the other half at 12 months. To analyze the integration of the silk-based scaffold in the femoral and tibial bone tunnels, hard tissue histology and micro-computed tomography measurements were performed.

The histological workup showed that in all treatment groups, with or without the application of the autologous stromal vascular fraction, an interzone of collagen fibers had formed between bone and silk-based graft. This collagen-fiber continuity partly consisted of Sharpey fibers, comparable with tendon-bone healing known for autografts and allografts. Insertion sites were more broad based at 6 months and more concentrated on the slightly protruding, bony knoblike structures at 12 months. Histologically, no differences between the treatment groups were detectable. Analysis of micro-computed tomography measurements revealed a significantly higher tissue density for the cell-seeded scaffold group as compared with the scaffold-alone group in the tibial but not femoral bone tunnel after 12 months of implantation.

The novel silk fiber-based scaffold for ACL regeneration demonstrated integration into the bone tunnels via the formation of a fibrous interzone similar to allografts and autografts. Histologically, additional cell seeding did not enhance osteointegration. No significant differences between 6 and 12 months could be detected. After 12 months, there was still a considerable amount of silk present, and a longer observation period is necessary to see if a true ligament-bone enthesis will be formed.

M. Abuhantash F. Rauch J. Rak R. C. Hamdy H. Al-Jallad

Osteogenesis Imperfecta (OI) is a heritable bone disorder characterized by bone fragility and often caused by mutations in the Type I collagen-encoding genes COL1A1 and COL1A2. The pathophysiology of OI, particularly at the cellular level, is still not well understood. This contributes to the lack of a cure for this disorder as well as an effective preventive or management options of its complications. In the bone environment, mesenchymal stem cells (MSCs) and osteoblasts (Ob) exert their function, at least partially, through the secretion of extracellular vesicles (EV). EV is a heterogeneous group of nanosized membrane-enclosed vesicles that carry/transfer a cargo of proteins, lipid and nucleic acids from the secreting cell to its target cells. Our objective is to characterize EVs secreted by human control (HC)- and OI-MSCs and their derived Obs, with focus on their protein content. We hypothesize that there will be differences in the protein content of EVs secreted by OI-Obs compared to HC-Ob, which may indicate a deviation from healthy Ob behavior and, thus, a role in OI pathophysiology.

MSCs were harvested from the adipose tissue of four COL1A1-OI and two HC patients. They were proliferated in an EV-depleted media, then induced to differentiate to extracellular matrix (ECM)-producing osteoblasts, which then gets mineralized. EVs secreted by MSCs (MSC-EV) and Obs (Ob-EV) were then purified and concentrated.

Using liquid chromatography- tandem mass spectrometry, proteomic analysis of the EV groups was done. A total of 384 unique proteins were identified in all EVs, 373 were found in Vesiclepedia indicating a good enrichment of our samples with EV proteins. 67 proteins of the total 384 were exclusively or significantly upregulated (p-value < 0 .05) in OI-Ob-EV and 28 proteins in the HC-Ob-EVs, relative to each other. These two groups of differentially expressed proteins were compared by Gene Ontology (GO) analysis of their cellular compartment, molecular functions and biological processes. We observed that there were differences in the cellular origin of EV-proteins, which may indicate heterogeneity of the isolated EVs. Molecular function and biological process analyses of the HC-Ob-EV proteins showed, as expected, predominantly calcium-related activities such as extracellular matrix (ECM) mineralization. OI-Ob-EV proteins were still predominantly exhibiting ECM organization and formation functions. Annexins A1,2,4,5 and 6 were differentially and significantly upregulated by the HC-Ob-EVs. Fibronectin (FN), Fibulin-1 and −2, and Laminins (α4 & γ1), which are amongst the early non-collagenous proteins to form the ECM, were differentially and significantly upregulated in the OI-Ob-EVs.

We concluded that the persistent expression of Fibronectin (FN), Fibulin-1 and −2, and Laminins in OI-Ob-EVs might indicate the presence of an immature ECM that the OI-Obs are trying to organize. ECM mineralization is largely dependent on the presence of an organized mature ECM, and this being compromised in OI bone environment, may be a contributor to the bone fragility seen in these patients. Annexins, which are calcium-binders that are vital for ECM mineralization, were significantly downregulated in the OI-Ob-EVs and this may be a further contributor to ECM mineralization impairment and bone fragility.

H. Cherif D. Bisson S. Kocabas L. Haglund

Intervertebral discs (IVDs) degeneration is one of the major causes of back pain. Upon degeneration, the IVDs tissue become inflamed, and this inflammatory microenvironment may cause discogenic pain. Cellular senescence is a state of stable cell cycle arrest in response to a variety of cellular stresses including oxidative stress and adverse load. The accumulation of senescent IVDs cells in the tissue suggest a crucial role in the initiation and development of painful IVD degeneration. Senescent cells secrete an array of cytokines, chemokines, growth factors, and proteases known as the senescence-associated secretory phenotype (SASP). The SASP promote matrix catabolism and inflammation in IVDs thereby accelerating the process of degeneration. In this study, we quantified the level of senescence in degenerate and non-degenerate IVDs and we evaluated the potential of two natural compounds to remove senescent cells and promote overall matrix production of the remaining cells.

Human IVDs were obtained from organ donors. Pellet or monolayer cultures were prepared from freshly isolated cells and cultured in the presence or absence of two natural compounds: Curcumin and its metabolite vanillin. Monolayer cultures were analyzed after four days and pellets after 21 days for the effect of senolysis. A cytotoxicity study was performed using Alamar blue assay. Following treatment, RNA was extracted, and gene expression of senescence and inflammatory markers was evaluated by real-time q-PCR using the comparative ΔΔCt method. Also, protein expression of p16, Ki-67 and Caspase-3 were evaluated in fixed pellets or monolayer cultures and total number of cells was counted on consecutive sections using DAPI and Hematoxylin. Proteoglycan content was evaluated using SafraninO staining or DMMB assay to measure sulfated glycosaminoglycan (sGAG) and antibodies were used to stain for collagen type II expression.

We observed 40% higher level of senescent cells in degenerate compare to the non-degenerate discs form unrelated individuals and a 10% increase when we compare degenerate compare to the non-degenerate discs of the same individual. Using the optimal effective and safe doses, curcumin and vanillin cleared 15% of the senescent cells in monolayer and up to 80% in pellet cultures. Also, they increased the number of proliferating and apoptotic cells in both monolayer and pellets cultures. The increase in apoptotic cell number and caspase-3/7 activity was specific to degenerate cells. Following treatment, mRNA expression levels of SASP factors were decreased by four to 32-fold compared to the untreated groups. Senescent cell clearance decreased, protein expression of MMP-3 and −13 by 15 and 50% and proinflammatory cytokines levels of IL-1, IL-6 and IL-8 by 42, 63 and 58 %. Overall matrix content was increased following treatment as validated by an increase in proteoglycan content in pellet cultures and surrounding culture media.

This work identifies novel senolytic drugs for the treatment of IVD degeneration. Senolytic drugs could provide therapeutic interventions that ultimately, decrease pain and provide a better quality of life of patients living with IVDs degeneration and low back pain.

D. Bisson L. Haglund S. Kocabas J. Ouellet N. Saran

Adolescent idiopathic scoliosis (AIS) is a poorly understood progressive curvature of the spine. The 3-dimmensionnal spinal deformation brings abnormal biomechanical stresses on the load-bearing organs. We have recently reported for the first time the presence of facet joint cartilage degeneration comparable to age-related osteoarthritis in scoliotic adolescents. To better understand the degenerative mechanisms and explore new therapeutic possibilities, we focused on Toll-like receptors (TLRs) which are germline-encoded pattern recognition receptors that recognize pathogens and endogenous proteins such as fragmented extracellular matrix components (alarmins) present in intervertebral discs (IVD) and articular cartilage. Once activated, they regulate the production pro-inflammatory cytokines, proteases and neurotrophins which can lead to matrix catabolism, inflammation and potentially pain. These mechanisms have however not been studied in the context of AIS or facet joints.

Facet joints of AIS patients undergoing corrective surgery and of cadaveric donors (non-scoliotic) were collected from consenting patients or organ donors with ethical approval. Cartilage biopsies and chondrocytes were isolated using 3mm biopsy punches and collagenase type 2 digestion respectively. qPCR was used to assess gene expression of the degenerative factors (MMP3, MMP13, IL-1ß, IL-6, IL-8) The biopsies were cut into two equal halves, one was treated for 4 days with a TLR2 agonist (Pam2CSK4, Invivogen) in serum-free chondrocyte media while the other one was cultured in media alone. MMP3, MMP13, IL-6 and IL-8 ELISAs and DMMB assays were performed on the biopsy cultured media. The ex vivo cartilage was then fixed, cryosectionned and also stained with SafraninO-Fast Green dyes.

Baseline gene expression levels of TLR1,−2,−4,−6 were all upregulated in scoliotic chondodryctes compared to non-scoliotic. Pearson correlation analysis revealed that all TLR1,−2,−4,−6 gene expression correlated strongly and significantly with degenerative markers (MMP3, MMP13, IL-6, IL-8) in scoliotic chondrocytes but not in non-scoliotic. (Figure 1) When monolayer facet joint chondrocytes were activated with Pam2CSk4, there was a significant upregulation in previously described degenerative markers, TLR2 and NGF, a potent neurotrophin. These findings were strengthened by protein secretion analysis of select markers such as MMP-3, −13, IL-6 and IL-8 which were all upregulated after TLR2 activation. The scoliotic biopsies which were treated with Pam2CSK4 had a significant loss of proteoglycan content as shown by histology, was reflected in the proteoglycan content found in the media by DMMB.

TLR gene expression levels were upregulated and correlated with proteases and pro-inflammatory cytokines in degenerating scoliotic cartilage, suggesting they promote cartilage degradation, especially considering the lack of correlations in non-scoliotic healthy cartilage. Furthermore, when TLRs are activated by Pam2CSK4 it triggers the release of the same proteases and pro-inflammatory cytokines in our ex vivo experiment. All this exacerbates the loss of proteoglycan in the cartilage ex vivo model after four days of insult with a TLR2 specific agonist. These results suggest that TLRs are an important pathway partaking in the cartilage degeneration of scoliotic facet joints and potentially all cartilage beyond our scope. Future studies aim at blocking TLRs to alleviate proteolysis and inflammation.

For any figures or tables, please contact the authors directly.

C. Goplen L. Beaupre D. Voaklander S. H. Hyun Kang C. A. Jones

Up to 40% of patients are using opioids at the time of joint replacement surgery in the USA despite emerging evidence suggesting opioids are ineffective for chronic non-cancer pain. Our primary objective was to determine if preoperative opioid use among patient awaiting total knee arthroplasty (TKA) was associated with worse patient-reported outcomes (PRO) measures at one-year follow-up when compared to non-opioid users, after adjusting for age, gender, and comorbidities.

The study linked Alberta's Pharmacy Information Network (PIN) data with prospectively collected Alberta Bone and Joint Health Repository administrative data (medical and PRO data) for patients who underwent primary TKA in Alberta from 2013–2015. The PIN contains prescribing information from physician offices and pharmacies across Alberta. Preoperative ‘opioid users’ were defined as having 90-days of consistent opioid use in the 180-days prior TKA, and ‘opioid-exposed’ subjects had recorded opioid prescriptions in the 180-days prior to TKA, but did not meet the definition of an opioid user. Those with no opioid-exposure in the 180-days pre-TKA were deemed a ‘non-opioid user’. We used multiple linear regression to examine how preoperative opioid use (opioid user, opioid-exposed, non-opioid user) impacted Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and function scores at one year after TKA after adjusting for confounding variables. These included age, sex, preoperative WOMAC scores, comorbidities including depression, diabetes, obesity, stroke, pulmonary disease, renal disease, cardiac disease, liver disease, and overall comorbid burden.

Of the 2182 unique cases identified, 151 (7%) were opioid users, 527 (24%) opioid-exposed and 1504 (69%) non-opioid user. Opioid users were more likely to be prescribed strong opioids (e.g., hydromorphone, oxycodone) compared to with opioid-exposed subjects (p < 0 .001) and had a median morphine equivalent dose of 30.7 mg/day compared with the opioid-exposed group (2.2 mg/day, p < 0 .001) in the 180-days prior to TKA. Opioid users, in the 180-days prior to TKA had an active opioid prescription for a mean duration of 153 days (95CI 149, 157) within the 180-days prior to TKA, compared to 34 days (95CI 32, 37) for opioid-exposed (p < 0 .001). In the parsimonious pain and function models, opioid use, lower preoperative WOMAC score, depression, and obesity were associated with worse one-year pain and function. Patients prescribed preoperative opioids had worse WOMAC scores one-year after TKA respectively when compared to non-opioid users, after adjusting for other factors (opioid user pain score: −9.5, function score: −9.4, opioid exposed pain score: −2.6, function score: −3.6, p < 0 .001 for all). Further, opioid users with a concomitant diagnosis of depression had significantly worse one-year postoperative WOMAC scores when compared to non-depressed non-opioid users (scores −14, p < 0 .001 for both pain and function).

In Alberta, 31% of patients were prescribed opioids within 180-days before TKA, preoperative opioid use was associated with worse one-year postoperative WOMAC pain and function scores relative to non-opioid users. Our results suggest that strategies to reduce preoperative opioid use could improve patient outcomes after TKA, and support the most recent Canadian opioid prescribing guidelines that attempt to minimize opioid use for chronic conditions such as arthritis.

D. J. Stockton G. Tobias J. Pike P. Daneshvar T. J. Goetz

Compared to single-incision distal biceps repair (SI), double-incision repair (DI) theoretically allows for reattachment of the tendon to a more anatomically favorable position. We hypothesized that DI repair would result in greater terminal supination torque compared to SI repair for acute distal biceps ruptures.

In this retrospective cohort study, patients were included if they sustained an isolated, acute (° supinated position. Secondary outcomes included supination torque in 45° supinated, neutral, and 45° pronated positions, ASES elbow score, DASH, SF-12, and VAS. Power analysis revealed that at least 32 patients were needed to detect a minimum 15% difference in the primary outcome (β = 0.20). Statistical analysis was performed with significance level α = 0.05 using R version 3.4.1 (R Core Team 2017, Vienna, Austria).

Of 53 eligible patients, 37 consented to participate. Fifteen were repaired using DI technique and 22 using SI technique. Mean age was 47.3yrs and median follow-up time was 28.1months. The groups did not differ with respect to age, time-to-follow-up, dominance of arm affected, Workers Compensation or smoking status. Mean supination torque, measured as the percentage of the unaffected side, was 60.9% (95%CI 45.1–76.7) for DI repair versus 80.4% (95%CI 69.1–91.7) for SI repair at the 60°supinated position (p=0.036). There were no statistically significant differences in mean supination torque at the 45°supinated position: 67.1% (95%CI 49.4–84.7) for DI versus 81.8% (95%CI 72.2–91.4) for SI (p=0.102), at the neutral position: 88.8% (95%CI 75.2–102.4) for DI versus 97.6% (95%CI 91.6–103.7) for SI (p=0.0.170), and at the 45°pronated position: 104.5% (95%CI 91.1–117.9) for DI versus 103.4 (95%CI 97.2–109.6) for SI (p=0.0.862). No statistically significant differences were detected in the secondary outcomes ASES Pain, ASES Function, DASH scores, SF-12 PCS or MCS, or VAS Pain. A small difference was detected in VAS Function (median 1.3 for DI repair versus 0.5 for SI repair, p=0.023). In a multivariate linear regression model controlling for arm dominance, age, and follow-up time, SI repair was associated with a greater mean supination torque than DI repair by 19.6% at the 60°supinated position (p=0.011).

Contrary to our hypothesis, we found approximately a 20% mean improvement in terminal supination torque for acute distal biceps ruptures repaired with the single-incision technique compared to the double-incision technique. Patients uniformly did well with either technique, though we contend that this finding may have clinical significance for the more discerning, high-demand patient.

K. Almaazmi L. Beaupre M. R. G. Menon B. Tsui

We performed a randomized feasibility trial to examine the impact of preoperative femoral nerve block (FNB) on elderly patients with hip fractures, including those with mild to moderate cognitive impairment. We evaluated the impact of preoperative FNB on the following outcomes within 5 days of surgical fixation: 1. Pain levels, 2. Total narcotic consumption, 3. Postoperative mobilization.

Randomized allocation of 73 patients in a 2:1 intervention:control ratio. To allow comparison between the 2 groups as well as sub- analysis of the intervention group to examine treatment fidelity (i.e. the ability to deliver the intervention as planned).

Inclusion criteria: Patient age≥ 65 years admitted with a low energy hip fracture, ambulatory preinjury, Mini Mental State Exam MMSE score≥13 (moderate dementia), Able to provide direct or proxy consent. Exclusion criteria: Admission ≥ 30 hours after injury, prior regular use of opiates. Potential participants were identified and either participants or proxy respondents provided signed informed consent. Participants allocated to the intervention group received a FNB administered by the UAH acute pain service (APS) within 20 hours of admission to hospital in addition to the usual care. Participants in the control group received usual care. Participants were followed for 5 days postoperatively with daily assessment of pain, narcotic consumption, delirium and mobility.

Main outcome measure: (1) Pain at rest and activity (2) Preoperative and postoperative opioid consumption, (3) Mobilization in POD#1.

Overall, 73 participants were enrolled (23 Control: 50 FNB). The FNB group was slightly older (mean [SD] 80.1 [8.7] vs. 76.2 [9.2], p=0.09) and had more males (21 [42%] vs. 5 [22%], p=0.09) than the Control group. The mean MMSE score for both groups was >24 (p=0.35 for group comparison), suggesting minimal cognitive impairment of participants. The FNB group reported significantly less pain at rest and activity than the control group over time (p < 0 .001 for both). Opioid consumption were non-significantly higher and more variable in the control group preoperatively (Median [25, 75 quartile] 10.6 [0, 398] vs 7.5 [0, 125], p=0.26) and postoperatively (13.1 [0, 950] vs 10 [0, 260], p=0.31). 41 (85%) of FNB participants mobilized on day 1 vs. 16 (73%) of control participants (p=0.21).

Preoperative FNB significantly reduced pain. Opioid consumption was not significantly different, but more variable in the control group. Although not significant, more FNB patients successfully mobilized on day 1 postoperatively. Participants with cognitive impairment were not enrolled due to difficulty in obtaining proxy consent. A definitive randomized trial would be feasible and add valuable information about pain management following hip fracture.

B. Burgesson M. Glazebrook T. Daniels A.S.E. Younger

Ankle arthrodesis and replacement are the widely accepted options in managing end-stage ankle arthritis. Ankle replacement as an alternate treatment option for ankle arthritis is relatively new and this is in large part to the successes observed with hip and knee arthroplasty for arthritis. Relative benefits of ankle replacement and arthrodesis remains a contentious topic. We conducted a multicenter pilot randomized controlled trial, first of its kind, comparing the clinical outcomes of ankle arthrodesis and ankle replacement in managing ankle arthritis. We hypothesized that clinical outcomes would be similar for both.

Patients recruited for this study were part of Canadian Orthopaedic Foot and Ankle Society (COFAS) Database. Canadian orthopaedic surgeons with fellowship training in foot and ankle surgery or extensive experience in the surgical treatment of end stage ankle arthritis determined whether the patient met the criteria for randomization, skeletal maturity, symptomatic ankle arthritis no longer amenable to non-operative management, and ability to give informed consent. Data was collected on patient demographics, follow-up time period, complication rates, and Ankle Osteoarthritis Scale (AOS) and Short Form-36 (SF-36) scores. Our analysis of clinical outcomes was divided into two parts: (1) comparison of pre and postoperative data for each cohort separately, and (2) comparison of outcome scores, and revision rates between both cohorts. We employed the Student's t-test and calculated effect sizes in assessing improvements in AOS and SF-36 scores from baseline to latest follow-up within and between the two groups. We also examined postoperative complication and reoperation rates in the study population using the standardized coding system for reoperations following ankle replacement and arthrodesis.

Thirty-nine ankles were enrolled in the study with a mean follow-up of 5.1 ± 2.8 years. Ankle osteoarthritis scale scores improved significantly from baseline and last follow-up in both groups. The average baseline AOS total score for ankle replacement improved from 59.4 ±15.9 to 38 ±20 at last follow-up (p-value 19.7 to 31.8 ±16.5 at last follow-up (p-value 25.4 compared to ankle replacement's 20.3 ±23. Two major complications (10.5%) were observed in the ankle replacement cohort while the ankle arthrodesis cohort saw four major complications (20%).

Clinical outcomes of ankle replacement and arthrodesis were comparable. The ankle arthrodesis cohort held a slight advantage over ankle replacement in improvement of AOS scores, though not statistically significant. Rates of major complications and reoperations were higher with ankle arthrodesis.

M. Alaqeel P. A. Martineau I. Tamimi A. Crapser J. Tat J. Schupbach

Several studies have highlighted the relationship between anterior cruciate (ACL) injury and knee geometry particularly tibial slope (TS). However, clinical data are inconsistent, whether the lateral or medial or slopes have a different influence on ACL injury. Our goal was to assess whether the medial, lateral slopes are associated with ACL injury and whether meniscus geometry is associated with ACL injury. In addition, we sought to determine if lateral meniscal height could serve as a simple surrogate measurement for ACL injury risk.

A case-controlled study compared 68 patients with an ACL injury and 68 matched nested controls. Radiological analysis of MRI measured the anterior-posterior distance of the medial and lateral plateaus, the tibial slope of both plateaus and meniscus geometry. Groups were compared using a Mann-Whitney test and α < 0 .05.

The lateral tibial plateau slope was significantly higher in the ACL injured group (6.92 degrees ±5.8) versus the control group 2.68 ±5.26 (p 0.0001). In addition, the lateral meniscal slope was significantly steeper with (ACL injuries: −1 ±4.7 versus −4.73 ±4.4 (p 0.0001) in the control group. The ACL Injured group had a significantly lower lateral meniscal height 0.76 cm ±0.09, compared to the control group that has 0.88 cm ±0.12 (p 0.0001). The Lateral meniscal height had a sensitivity of 76.47% and specificity 75% for predicting ACL injury using a cut off of

Patients with ACL-injury had significantly higher lateral tibial plateau slope. Lateral meniscus height was found to be an easy measurement to make on MRI with a high specificity for predicting ACL injury. Lateral tibial slope and meniscal Geometry can be used to identify patients with high risk of an ACL injury, that might benefit from further surgery to optimize rotational stability in high-risk patients.

H. Al Farii L. Farahdel A. Salimi

The aim was to analyze whether non-steroidal anti-inflammatory drugs (NSAIDs) have an adverse effect on bone healing by evaluating all available human randomized controlled trials (RCTs) on this subject.

A systematic search of electronic databases (PubMed, MEDLINE, and Cross-References) was performed to identify RCTs comparing the occurrence of nonunion in patients who received NSAIDs to the control group. Risk of bias of the studies was assessed. Nonunion was the main outcome evaluated, however, regression analysis was used to estimate the relative risk comparing duration and type of NSAIDs.

Six RCTs (609 patients) were included. The risk of nonunion was higher in the patients given NSAIDs after the fracture (P-value= 0.0009, relative risk [RR] = 2.9, 95% confidence interval [CI] = 1.6 to 6.3). However, once the studies have been categorized to the duration of NSAIDs, those who received short period of NSAIDs (4 weeks) (P-value = 0.0002, RR = 4.1, CI = 2.1 to 8). Also, indomethacin agent has associated with high nonunion (P-value = 0.0001, RR = 3.9, CI = 2.3 to 13.9) compared to other NSAIDs which did not show a nonunion risk (P-value = 0.24, RR = 2.3, CI = 0.6 to 8.9).

Using NSAIDs for long period (> 4 weeks) after fracture is significantly associated with nonunion especially with indomethacin agent. However, short period of NSAIDs (< 2 weeks) did not show the adverse effects of nonunion. Overall, further studies are required to support our conclusion.

P. Jean E. Belzile S. Pelet J. Caron

Over the last decade, the number of total knee arthroplasty (TKA) has risen over 125%. Numerous studies have established a relationship between obesity and complications in primary TKA. Interestingly, few studies have investigated medical and orthopaedic complications in obese patients undergoing revision TKA (RTKA). With the increasing number of RTKA and with the prevalence of obesity still on the rise, the study of obesity on complications following RTKA is indicated.

We retrospectively reviewed 180 RTKA performed by a single surgeon done between August 2008 and June 2017. All patients who underwent RTKA were included, but revisions done with simultaneous extensor mechanism reconstruction and/or distal femur replacement were excluded since these procedures are technically more demanding. 154 revisions met our inclusion/exclusion criteriaes and were included in the final analysis. 81 patients were included in the non-obese group (BMI .

The total number of orthopaedic complications in the obese group (46.6%) was significantly higher than in the non-obese group (27.2%) (OR=1.71) (p = 0.01). The number of infection was higher in the obese group (11%) than in the non-obese (6.2%) but this was not statistically significant (OR=1.77) (p = 0.28). Reoperation rate was also higher in the obese group (23.3%) than in the non-obese group (16%) but this did not reach statistical significance (OR=1.46) (p = 0.26) (Table 3). Medical complications were higher in the obese group (31.5% vs 19.8%) (OR=1.59) (p=0.09). According to the Dindo-Clavien classification, the obese group demonstrated a significantly higher rate of grade 3 or higher complications (p = 0.01).

Obesity significantly increases the occurrence of orthopaedic complications following RTKA. Obesity also seems to increase the number of medical complications following RTKA. The obese patient should be informed prior to revision TKA that there is an increased risk of complications when compared with the non-obese patient. Further research with higher power would seem advisable to confirm this trend.

For any figures or tables, please contact the authors directly.

S. Kooner J. Kubik S. Mahdavi H. Khong E. Batuyong R. Sharma

Given the high prevalence of psychiatric illness in the total joint arthroplasty (TJA) population, relatively little is known about how these two conditions affect each other. Therefore, the purpose of this study is to evaluate the role of major psychiatric illness on patient specific outcomes after TJA. We hypothesize that patients with major psychiatric illnesses will report inferior outcomes and have more complications after TJA compared to those without any psychiatric illness.

We matched and compared two cohorts of patients undergoing TJA from a prospectively collected database registry, which included those with and without a major psychiatric disorder. Major psychiatric disorder was identified in the registry database by determining if patients had been formally diagnosed with any of the following conditions: bipolar disorder, major personality disorder, chronic mental health diagnoses, depression, or schizophrenia. Primary outcomes of interest included patient specific outcomes measured using the WOMAC or EQ5D. Secondary outcomes included complications, infections, hospital length of stay, 30-day readmission rates and final discharge destination.

In total we included 1828 TJAs (1000 THAs, 828 TKAs). In terms of the primary outcome, both the THA experimental group (37.80 ± 17.91 vs. 40.74 ± 19.3, p=0.023) and TKA experimental group (43.38 ± 18.41 vs 45.45 ± 20.07, p=0.050) had significantly lower preoperative WOMAC scores compared to their respective control groups. At the 3-month period both the THA experimental group (76.74 ± 16.94 vs. 79.16 ± 16.19, p=0.036) and TKA experimental group (71.09 ± 18.64 vs. 75.92 ± 16.22, p=0) again had significantly lower 3-month postoperative WOMAC score. Clinical outcomes at the 1-year mark were similar for both groups in terms of WOMAC and EQ5D. Patients with psychiatric illness were more likely to have increased LOS and non-routine discharge from hospital. In the THA subset, the experimental group had an increased LOS by 1.43 days (p=0.0028), in the TKA subset, the experimental group had an increased LOS by 0.77 days (p= 0.050). In terms of non-routine discharge, the THA experimental group was discharged home 86.9% of the time compared to the control group at 91.8% (p=0.024). In the TKA subset, the experimental group was discharged home 87.6% of the time compared to the control group at 92% (p=0.022). There were no other differences between the two subsets in regards to transfusions, 30-day readmissions, infections, mechanical adverse events, and medical complications.

In conclusion, our results demonstrate that psychiatric illness can result in worse outcomes in the early perioperative period after TJA, although outcomes are equivalent 1 year postoperatively. Patients with psychiatric illness can be expected to gain significant improvements in outcome after surgery that are comparable to a baseline population without psychiatric illness. Nonetheless, patients with psychiatric illness are at increased risk of delayed discharge and non-routine discharge. As such, they may require personalized care post-operatively, and should be counseled accordingly. Based on our results, psychiatric illness should not be an impediment to proceeding with TJA.

A. Hoffer D. Banaszek J. Potter H. Broekhuyse

Distal radius fractures are among the most common fractures seen in the emergency department. Closed reduction can provide definitive management when acceptable radiographic parameters are met. Repeated attempts of closed reduction are often performed to improve the alignment and avoid operative management. However, multiple reduction attempts may worsen dorsal comminution and lead to eventual loss of reduction, resulting in no demonstrable benefit. We hypothesize that compared to one closed reduction attempt, repeated closed reduction of extra-articular, dorsally angulated, displaced distal radius fractures has a low success rate in the prevention of operative fixation and improvement of radiographic parameters.

Initial and post reduction radiographs for all distal radius fractures managed at Vancouver General Hospital between 2015 and 2018 were reviewed. Inclusion criteria were based on the AO fracture classification and included types 23-A2.1, 23-A2.2 and 23-A3. Exclusion criteria included age less than 18, intra-articular involvement with more than two millimeters of displacement, volar or dorsal Barton fractures, fracture-dislocations, open fractures and volar angulation of the distal segment. Distal radius fractures that met study criteria and underwent two or more attempts of closed reduction were matched by age and gender with fractures that underwent one closed reduction. Radiographic parameters including radial height and inclination, ulnar variance and volar tilt were compared between groups.

Sixty-eight distal radius fractures that met study criteria and underwent multiple closed reduction attempts were identified. A repeated closed reduction initially improved the radial height (p = 0.03) and volar tilt (p < 0.001). However, by six to eight weeks the improvement in radial height had been lost (p = 0.001). Comparison of radiographic parameters between the single reduction and multiple reduction groups revealed no difference in any of the radiographic parameters at one week of follow up. By six to eight weeks, the single reduction group had greater radial height (p = 0.01) ulnar variance (p = 0.05) and volar tilt (p = 0.02) compared to the multiple reduction group. With respect to definitive management, 38% of patients who underwent a repeated closed reduction subsequently received surgery, compared to 13% in the single reduction group (p = 0.001).

Repeated closed reduction of extra-articular, dorsally angulated, displaced distal radius fractures did not improve alignment compared to a single closed reduction and was associated with increased frequency of surgical fixation. The benefit of repeating a closed reduction should be carefully considered when managing distal radius fractures of this nature.

A. Nooh R. Marc-antoine R. Turcotte A. Alaseem K. Goulding

The use of endoprosthesis implants is frequent for tumours involving the proximal third of the femur and not amenable to primary arthroplasty or internal fixation. In this population, these implants are preferentially cemented given poor bone quality associated with systemic diseases and treatments. Loosening is a common complication of these implants that have been linked to poor bone quality, type of implants and importantly cementing technique. Thus, these techniques vary between different surgeons and based mainly on previous experience. One of the most successful cementing techniques in the arthroplasty literature is the French paradox. This technique involves removing the cancellous bone of the proximal femoral metaphysis and selects the largest stem to tightly fit the created cavity delineated by cortical bone. Cementing the implant results in a very thin cement layer that fills the inconsistent gaps between the metal and the bone. To our knowledge, no previous report exists in the literature assessing loosening in proximal femur replacement using the French paradox cementing technique. In this study, we sought to examine (1) rates of loosening in proximal femur replacement, and (2) the oncological outcomes including tumour recurrence and implant related complications.

A retrospective study of 42 patients underwent proximal femur replacement between 1990 and 2018 at our institution. Of these, 30 patients met our inclusion criteria. Two independent reviewers have evaluated the preoperative and the most recent postoperative radiographs using the International Society of Limb Salvage (ISOLS) radiographic scoring system and Gruen classification for femoral stem loosening. Additionally, the acetabulum was evaluated for erosion according to the criteria of Baker et al. The mean age of this cohort was 60.5 (19–80), with 60% being males. The primary origin was metastatic in 17 (56.7%) patients, bone sarcoma in 10 (33.3%) patients and soft tissue sarcoma in 3 (10%) patients. Pathological fractures were present in 11 (36.7%) patients. Seven (23.3%) patients had prior intramedullary nailing. Preoperative radiotherapy was used in 8 (26.7%) and postoperative radiotherapy in 17 (56.7%) patients. The mean clinical follow-up was 25.2±26.3 months and the mean radiographical follow-up was 24.8±26 months.

The mean ISOLS score for both reviewers was found to be 89±6.5% and 86.5±6.1%, respectively. Additionally, the first reviewer found two patients to be possibly loos (6.7%) compared to one (3.3%) patient for the second reviewer. No components scored as probably or definitely loose and non-required revision for either loosening or metal failure. Furthermore, both reviewers showed no acetabular erosion in 25 (83.3%) and 24 (80%) patients, respectively. On the other hand, the overall rate of complications was 36.6% with 11 complications reported in 30 patients. Local recurrence occurred in five (16.6%) patients. Prosthetic Dislocation was the most frequent complications with eight dislocations in four patients.

Despite complications, our results showed no radiographic evidence of stem loosening. Cementing proximal femur prosthesis with a tight canal fit and with a thin cement mantle appears to be a viable option at short and medium term.

S. Ekhtiari A. Shah J. Levesque D. Williams J. Yan P. Thornley

Three-dimensional (3D) printing has become more frequently used in surgical specialties in recent years. Orthopaedic surgery is particularly well-suited to 3D printing applications, and thus has seen a variety of uses for this technology. These uses include pre-operative planning, patient-specific instrumentation (PSI), and patient-specific implant production. As with any new technology, it is important to assess the clinical impact, if any, of three-dimensional printing.

The purpose of this review was to answer the following questions:

What are the current clinical uses of 3D printing in orthopaedic surgery?

Does the use of 3D printing have an effect on peri-operative outcomes?

Four electronic databases (Embase, MEDLINE, PubMed, Web of Science) were searched for Articles discussing clinical applications of 3D printing in orthopaedics up to November 13, 2018. Titles, abstracts, and full texts were screened in duplicate and data was abstracted. Descriptive analysis was performed for all studies. A meta-analysis was performed among eligible studies to compare estimated blood loss (EBL), operative time, and fluoroscopy use between 3D printing cases and controls. Study quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS) criteria for non-randomized studies and the Cochrane Risk of Bias Tool for randomized controlled trials (RCTs). This review was prospectively registered on PROSPERO (Registration ID: CRD42018099144).

One-hundred and eight studies were included, published between 2012 and 2018. A total of 2328 patients were included in these studies, and 1558 patients were treated using 3D printing technology. The mean age of patients, where reported, was 47 years old (range 3 to 90). Three-dimensional printing was most commonly reported in trauma (N = 41) and oncology (N = 22). Pre-operative planning was the most common use of 3D printing (N = 63), followed by final implants (N = 32) and PSI (N = 22). Titanium was the most commonly used 3D printing material (16 studies, 27.1%). A wide range of costs were reported for 3D printing applications, ranging from “less than $10” to $20,000. The mean MINORS score for non-randomized studies was 8.3/16 for non-comparative studies (N = 78), and 17.7/24 for non-randomized comparative studies (N = 19). Among RCTs, the most commonly identified sources of bias were for performance and detection biases. Three-dimensional printing resulted in a statistically significant decrease in mean operative time (−15.6 mins, p < .00001), mean EBL (−35.9 mL, p<.00001), and mean fluoroscopy shots (−3.5 shots, p < .00001) in 3D printing patients compared to controls.

The uses of 3D printing in orthopaedic surgery are growing rapidly, with its use being most common in trauma and oncology. Pre-operative planning is the most common use of 3D printing in orthopaedics. The use of 3D printing significantly reduces EBL, operative time, and fluoroscopy use compared to controls. Future research is needed to confirm and clarify the magnitude of these effects.

D. You R. Korley R. Buckley P. Duffy T. Harrison P. Schneider A. Soo R. Martin

Venous thromboembolism (VTE) is the second most common complication and pulmonary embolism (PE) is the fourth most common cause of death after a hip fracture. Despite thromboprophylaxis, deep vein thrombosis (DVT) is detected in up to 45% of hip fracture patients. Thrombelastography (TEG) is a whole-blood, point of care test capable of providing clinicians with a global assessment of the clotting process, from fibrin formation to clot lysis. Maximal amplitude (mA) from TEG analysis is a measure of clot strength. Elevated admission mA values of >65mm and >72mm have been determined to be independent predictors of in-hospital PE. The coagulation index (CI) is calculated based on TEG parameters and defines hypercoagulable state as CI >3. This study aimed to use serial TEG analysis to determine the duration of hypercoagulable state after hip fracture.

A prospective cohort of hip fracture patients >50 years of age amenable to surgical treatment (AO 31A1–A3 & 31B1–B3) were enrolled at a Level I trauma centre. Serial TEG analysis (TEG 6S) was performed every 24-hours from admission until 5-days post-operatively and at 2- and 6-week follow-up visits. All patients received a minimum of 28 days of thromboprophylaxis. Descriptive statistics and single sample t-tests were used for comparison of mA to the 65mm threshold.

Thirty-five patients (26 female) with a median age of 83 (range = 71–86) years were included. On admission, 31.4% and 82.9% of patients were hypercoagulable based on mA >65mm and CI, respectively. At 2 weeks, all patients remained hypercoagulable, however, mA >72mm showed that 16 patients (47.1%) were at even higher risk for VTE. At 6-weeks, 65.7% and 97.1% of patients were hypercoagulable based on mA >65mm and CI, respectively. When compared with the mA >65mm threshold, patients were hypocoagulable at the time of admission (mA = 62.2 (±6.3), p = 0.011), but became significantly more hypercoagulable at 2-weeks (mA = 71.6 (±2.6), p < 0 .001), followed by continued hypercoagulability at 6-weeks, however not significantly elevated above the 65mm threshold (mA = 66.2 (±3.8), p = 0.058). One patient developed a symptomatic DVT at 2-weeks and had a mA = 72.9 and a CI of 5.9.

This is the first study to demonstrate that >50% of hip fracture patients remain hypercoagulable 6 weeks post fracture despite thromboprophylaxis, and there are individual hypercoagulable responses. This is critical, as guidelines only recommend 28 to 35 days of thromboprophylaxis in this high-risk population. Previously determined mA thresholds may be a more sensitive test for risk-stratifying patients' VTE risk than the CI threshold. Additionally, assessing ΔmA using serial TEG may better predict VTE risk.

J. Chang R. Jenkinson D. Wasserstein H. Kreder B. Ravi D. Pincus

Echocardiography is commonly used in hip fracture patients to evaluate perioperative cardiac risk and identify cardiac abnormalities. However, echocardiography that delays surgical repair may be harmful. The objective of this study was to compare mortality, surgical wait times, length of stay (LOS), and health care costs for similar hip fracture patients managed with and without preoperative echocardiograms.

A population based, retrospective cohort study of all hip fracture patients (>age 45) in Ontario, Canada was conducted. The primary exposure was pre-operative echocardiography (between hospital admission and surgery). Patients receiving preoperative echocardiograms were matched to those without using a propensity score incorporating patient demographic information, comorbidity status, and provider information. Mortality rates, surgical wait times, post-operative length of stay (LOS), and medical costs (expressed as 2013$ CAN) up to 1-year post-operatively were assessed after matching.

There were 2354 (∼5.6%) of 42,230 eligible hip fracture patients that received a preoperative echocardiogram during the study period. After successfully matching 2298 (∼97.6%) patients, echocardiography was associated with significant increases in mortality at 90 days (20.1% vs. 16.8%, p=0.004) and 1 year (32.9% vs. 27.8%, p < 0 .001), but not 30-days (11.4% vs. 9.8%, p=0.084). Patients with echocardiography also had an increased (mean ± SD) delay (in hours) from presentation to surgery (68.80 ± 44.23 hours vs. 39.69 ± 27.09 hours, p < 0 .001) and only 38.1% of patients had surgery within 48 hours. Total LOS (in days) (mean 19.49 ± 25.39 days vs. 15.94 ± 22.48 days, p < 0 .001) and total healthcare costs at 1 year (mean: $51,714.69 ± 54,675.28 vs. $41,861.47 ± 50,854.12, p < 0 .001) were also increased. There was wide variability in echocardiography ordering practice in Ontario, with a range of 0% to 22.97% of hip fracture patients undergoing preoperative echocardiography at different hospital sites.

Preoperative echocardiography for hip fracture patients is associated with increased postoperative mortality. It is also associated with increased surgical delay, post-operative LOS, and total health care costs at 1 year. Echocardiography should be considered an urgent test when ordered to prevent additional surgical delay, and further research is necessary to clarify indications for this common preoperative investigation.

Y. Atwan S. Sprague S. Bzovsky K. Jeray B. Petrisor M. Bhandari E. H. Schemitsch

Negative pressure wound therapy (NPWT) is commonly used to manage severe open fracture wounds. The recently completed X randomized controlled trial (RCT) evaluated the effect of NPWT versus standard wound management on 12-month disability and rate of deep infection among patients with severe open fractures of the lower limb and reported no differences. Using data from the Y trial of open fracture patients, we aimed to evaluate the impact of NPWT on the odds of having deep infections and health-related quality of life (HRQL).

Our analyses included participants from the Y trial who had Gustilo II and III lower extremity fractures. To adjust for the influence of injury characteristics on type of dressing received, a propensity score was developed from the dataset. A one-to-one matching algorithm was then used to pair patients with a similar propensity for NPWT.

Mixed effects logistic regression was used to evaluate the association between type of wound dressing and development of a deep infection requiring operative management (dependent variable) in the matched cohort. Gustilo type, irrigation solution, fracture location, mechanism of injury, and degree of contamination were included as adjustment variables. To determine any differences in HRQL between the NPWT and standard wound dressing groups, we conducted two multi-level models with three levels (centre, patient, and time) and included Short Form-12 (SF-12) Physical Health Component (PCS) and SF-12 Mental Health Component (MCS) as dependent variables. Gustilo type, irrigation solution, fracture location, mechanism of injury, degree of contamination, and pre-injury SF-12 scores were included as adjustment variables. All tests were 2-tailed with alpha=0.05.

After applying propensity score-matching to adjust for the influence of injury characteristics on type of dressing used, there were 270 matched pairs of patients available for comparison. The odds of developing a deep infection requiring operative management within 12 months of initial surgery was 4.22 times higher in patients who received NPWT compared to those who did not receive NPWT (Odds Ratio (OR) 4.22, 95% Confidence Interval (CI) 2.26–7.87.

1,329 participants were included in our HRQL analysis and those treated with NPWT had significantly lower SF-12 PCS at all follow-up visits (6w, 3m, 6m, 12m) post fracture (p=0.01). Participants treated with NPWT had significantly lower SF-12 MCS at 6-weeks post-fracture (p=0.03).

Unlike the X trial, our analysis found that patients treated with NPWT had higher odds of developing a deep infection requiring operative management and that being treated with NPWT was associated with lower physical quality of life in the 12 months post-fracture. While there may have been other potential adjustment variables not controlled for in this analysis, our results suggest that the use of this treatment should be re-evaluated.

T. Boettcher S. H. Hyun Kang L. Beaupre R. McLeod C. A. Jones

Total joint arthroplasty (TJA) is often utilized to improve pain and dysfunction associated with end-stage osteoarthritis. Previous research has suggested that depression may negatively impact patient reported pain and function. The purpose of this study was to determine the effect of pre-operative depressive symptoms, using the Center for Epidemiologic Scale for Depression (CES-D) scale, on patient reported function and pain at one, three and six months following TJA, after controlling for the impact of age, sex, pain, joint replaced, and other comorbidities.

This was a secondary analysis of a prospective cohort of 710 patients aged 40 years and older who underwent elective primary TJA in the Edmonton zone. Participants were recruited pre-operatively and reported socio-demographics, comorbid conditions and medications (including depression medications where appropriate), each participant also completed the Western Ontario McMaster (WOMAC) Osteoarthritis Index and the CES-D scale preoperatively. Participants then completed the WOMAC and CES-D scale again at one, three, and six months postoperatively. Risk-adjusted longitudinal data analysis using a linear mixed regression model was performed, controlling for age, sex, joint replaced, chronic pain, comorbidity, social support and employment status.

THA participants had a mean age of 65.9±10.1 years and included 175 (57%) female while TKA participants had a mean age of 67.9±10.1 years and included 249 (61%) females. ‘Possible’ depressive symptoms (CES-D score 16–19) were identified in 58 (8.1%) participants while ‘probable’ depressive symptoms (CES-D score ≥20) were identified in 68 (9.6%) participants. The mean WOMAC pain and function scores, when analyzed using the linear mixed regression model, demonstrated improvement from baseline at one, three, and six months (p < 0 .001 for both pain and function models as well as over time). However, in the patients with possible and probable depressive symptoms, WOMAC pain scores were 7.6±1.5 and 11.7±1.3 worse respectively than those without depressive symptoms after controlling for age, sex, joint replaced, chronic pain, comorbidities and social support. Similarly, WOMAC function scores in the patients with possible and probable depressive symptoms were 8.8±1.4 and 14.2±1.2 worse respectively than those without depressive symptoms after controlling for age, sex, joint replaced, comorbidities and employment status.

Depressive symptoms negatively affect postoperative pain and function measured using WOMAC scales even after risk adjustment up to six-months post TJA. Screening for depressive symptomology both pre- and postoperatively may provide an opportunity to identify and manage depressive symptoms to improve postoperative pain and function.

J. Montreuil F. Lavoie F. Thibeault T. Cresson J. de Guise

Evaluate precisely and reproducibly tridimensional positioning of bone tunnels in anterior cruciate ligament reconstructions (ACL). To propose biplanar stereoradiographic imaging as a new reference in tridimensional evaluation of ACL reconstruction (ACLR). Comparing knee 3D models issued from EOStm low-irradiation biplanar X-Ray with those issued from computed tomography (CT-Scan) high definition images will allow a bone morphological description of a previously unseen precision.

We carried out the transfer of 3D models from EOStm X-Ray images obtained from 10 patients in the same reference frame with models issued from CT-Scan. Two evaluators reconstructed both pre-operative and post-operative knees, using two different stereoradiographic projections, for a total of 144 knee 3D models from EOStm. A surface analysis by distance mapping allowed us to know the differences or errors between the homologous points of the EOStm and CT reconstructions, the latter being our “bronze-standard”.

At the femur, we obtained a mean (95% confidence level) error of 1.5 mm (1.3–1.6) between the EOStm models compared to the Arthro-CT segmentations when using AP-LAT incidences, compared to 1 mm (1.0 – 1.1) with oblique projections. For the tunnels placement analysis, the total radius difference between EOStm and Arthro-CT's femoral tunnel apertures was 0.8 mm (0.4–1.2) in AP-LAT and 0.6 mm (0.0–1.2) in oblique views. These femoral apertures positioning on EOStm models were within 4.3 mm (3.0–5.7) of their homologues on CT-Scan models, 4.6 mm (3.5–5.6) with the oblique views. Furthermore, 9.3o (7.2–11.4) of difference in direction between femoral tunnels from EOStm models and CT reconstructions is obtained with AP-LAT projections, 8.3o (6.6–10) with obliques views. Measures of these parameters were also performed at the tibia.

According to the intra and inter-reproducibility analysis of our knee 3D models, EOStm biplanar X-Ray images prove to be fast, efficient and precise in the design of ACLR 3D models with respect to CT-Scan. Our results also propose the recourse of oblique stereoradiographic projections for the realization of knee 3D models. These models will be subjects of further analysis and will allow us eventually to propose a new frame of reference guiding the positioning of the tunnels in the ACLR.

A. Meldrum P. Schneider T. Harrison C. Kwong K. Archibold

Olecranon Osteotomy is a common approach used in the management of intraarticular distal humerus fractures. Significant complication rates have been associated with this procedure, including non-union rates of 0–13% and implant removal rates between 12–86%. This study is a multicentre retrospective study involving the largest cohort of olecranon osteotomies in the literature, examining implant fixation types, removal rates and associated complications.

Patients were identified between 2007 and 2017 (minimum one year follow-up) via Canadian Classification of Health Interventions (CCI) coding and ICD9/10 codes by our health region's data information service. CCI intervention codes were used to identify patients who underwent surgery for their fracture with an olecranon osteotomy. Reasons for implant removal were identified from a chart review. Our primary outcome was implant removal rates. Categorical data was assessed using Chi square test and Fischer's Exact test.

Ninety-nine patients were identified to have undergone an olecranon osteotomy for treatment of a distal humerus fracture. Twenty patients had their osteotomy fixed with a plate and screws and 67 patients were fixed with a tension band wire. Eleven patients underwent “screw fixation”, consisting of a single screw with or without the addition of a wire. One patient had placement of a cable-pin system. Of patients who underwent olecranon osteotomy fixation, 34.3% required implant removal. Removal rates were: 28/67 for TBW (41.8%), 6/20 plates (30%), 0/1 cable-pin and 0/11 for osteotomies fixed with screw fixation. Screw fixation was removed less frequently than TBW p<.006. TBW were more commonly removed than all other fixation types p<.043. Screws were less commonly removed than all other fixation types p<.015. TBW were more likely to be removed for implant irritation than plates, p<.007, and all other implants p<.007. The average time to removal was 361 days (80–1503 days). A second surgeon was the surgeon responsible for the removal in 10/34 cases (29%). TBWs requiring removal were further off the olecranon tip than those not removed p=.006. TBWs were associated with an OR of 3.29 (CI 1.10–9.84) for implant removal if implanted further than 1mm off bone. Nonunion of the osteotomy occurred in three out of 99 patients (3%). K-wires through the anterior ulnar cortex did not result in decreased need for TBW removal. There was no relation between plate prominence and the need for implant removal. There was no association between age and implant removal.

The implant removal rate was 34% overall. Single screw fixation was the best option for osteotomy fixation, as 0/11 required hardware removal, which was statistically less frequent than TBW at 28/67. Screw fixation was removed less frequently than TBW and screw fixation was less commonly removed than all other fixation types. Only 6/20 (30%) plates required removal, which is lower than previously published rates. Overall, TBW were more commonly removed than all other fixation types and this was also the case if hardware irritation was used as the indication for removal. Nonunion rates of olecranon osteotomy were 3%.

O. Gagne M. Symes K. Z. Abbas M. Penner K. Wing A.S.E. Younger K. Syed J.T.C. Lau A. Veljkovic L. Anderson

Patients' perspective and experience is heavily modulated by their understanding of their pre-operative disability along with their overall coping strategy and life philosophy. Given that evidence-based practice is relying on patient-reported outcomes more and more, the orthopaedic community must be diligent in differentiating patients that may have the same objective outcome but vary widely on a patient-reported subjective basis. In clinical practice, patient selection is often a sensitive, experience-based decision process that screens for catastrophization, recognizing that certain patients will not benefit from a simple surgery. It is well appreciated that patient's catastrophization can affect their subjective outcome but there is little reported literature on this abstract concept. The study set out to determine if post-operative outcomes correlated with pre-operative catastrophization scales.

This current study set out to look at a cohort of complex consecutive foot and ankle cases and describe the relationship between Patient Catastrophizing Score (PCS) and multiple functional outcomes that are used commonly in foot and ankle specifically (SF-12 & FAOS). The PCS has three subcategory rumination, helplessness and magnification. A single institution undertook recruitment in consecutive patients within three surgeon's practice. In the end, 46 patients were found to be eligible in the study with an average age of 54.72 ± 14.41 years-old, a majority female 30 / 46 (65.22%), a minority employed at the pre-operative visit 19/46 (41%) and with an average BMI of 26.2 ± 5.56.

We found that the mental component of the SF12 had a statistically significant negative effect with the rumination score (r=−1.03) (p = 0.01) and the helplessness score (r=−1.05) (0.001). There was no statistically significant effect for the physical component of the SF-12. Looking at the FAOS Pain component, it correlated was significantly with the PCS rumination (Multivariate : r= −7.6 (p=0.002) Univariate: r=−2 (0.03)) and helplessness (Multivariate : r=−6.73 (p=0.01) Univariate: r=−1.5 (p=0.03)). Otherwise the FAOS ADL component showed correlation as well with the PCS rumination (Multivariate: r=−4.67 (p=0.02) Univariate : r=−1.85 (p=0.01)), helplessness (Multivariate r=−5.89 (p = 0.01) Univariate r=−1.81 (p = 0.001)) and total score (Multivariate : r=3.74 (p=0.02) Univariate r=−0.75 (p=0.01)). The FAOS Quality of life component was statistically significant for the rumination score (Univariate r=−11.59) (p < 0.05) and the helplessness score (Univariate r=−9.65) (p = 0.002) also the PCS total (Univariate r=8.54) (p = 0.0003).

As layed out in our hypothesis, this study did show an association between an increase patient catastrophizing score pre-operatively and a worse outcome in the following scores: Mental component of SF12, FAOS Pain, FAOS ADL and FAOS Quality of life components. This is an association and no causality can be proven within the limits of this current pilot study, but remains alarming. In elective surgeries, catastrophization should be screened for using the PCS form and potentially modulated pre-operatively with the help of allied health therapist while a patient is on the waitlist.

P. Dust J. Antoniou O. L. Huk D. J. Zukor J. Kruijt S. Bergeron N. Stavropoulos

Osteoarthritis (OA) is one of the most common causes of knee pain in the aging population and presents with higher odds with increased BMI. Total knee arthroplasty (TKA) has become the standard of care for the treatment of OA. Over “719,000 TKA's were performed in 2010 in the USA alone, with dramatic economic burden- costing 16,000 USD per TKA” (CDC 2012). Over the past two decades, this cost was compounded by the unknown increasing rate of primary TKA and cannot be explained by the expanding population or worldwide obesity epidemic. These facts raise two key questions: are patients' quality of life expectations higher and driving the TKA rate up, or have surgeons changed their indications and started to operate on less disabled people? Our study aimed to determine the average functional profile for patients undergoing TKA using patient reported Outcome Measure (SF-36), to document if preoperative SF-36 scores have changed over the past two decades, and lastly to asses if patient pre-operative SF-36 scores are lower in in the USA vs the rest of the world.

A literature search of Medline, Embase and Cochrane databases was performed extracting data from publishing year 1966 to 2016 with a search date of Dec 12, 2016. Two independent reviewers revised the abstracts and excluded articles with: no TKA, revision TKA, no pre-op SF-36, no SF-36 reported, incomplete scores to calculate SF-36, duplicates, review article, meta-analysis, letter to the editor, conference proceeding or abstract, disagreements were resolved with a third reviewer. All languages were included to maximize the catchment of data. All remaining articles were independently read and excluded if they did not provide data required for our study. Included articles were analyzed for data including: for year of patient enrollment, location (USA vs. non-USA), pre-operative SF-36 mental (MCS) and physical (PCS) component summary, level of evidence. Recorded data was compared post completion to assess inter-observer accuracy as per PRISMA guidelines for meta-analysis.

After applying all the exclusion criteria on 923 selected abstracts, a total of 136 articles of which 30 were randomized control trials, were completely reviewed and included in our study. A total of 56,713 patients' physical component scores were analyzed and revealed an overall pre-operative SF-36 physical component score 31.93. When stratifying the data, it was revealed that patients operated in the USA had an average score of 32.3 whereas Non-US countries were 31.7, with no statistical significance. No statistical difference between SF36 scores was seen over time amongst studies of all nations.

Based on the results of this study, we have shown that orthopaedic surgeons are performing TKA universally at the same pre-operative scores, independent of country of origin or year of surgery. The indications thus have remained consistent for two decades regardless of the advances in technology. Functional profiles of patients appear similar among US and Non-US countries. Further, we infer that based on pre-operative SF-36 PCS scores, the optimal time to undergo a TKA is when PCS is 31.9 +/−3.

M. Mistry R. Feibel A. Salimian J. C. Malcolm

Dysglycemia in the post-operative period has been associated with increased rates of infection following total joint arthroplasty. Additionally, patients without clinical diagnosis of diabetes with hemoglobin A1c% values between 5.7% and 6.4% have been shown to be dysglycemic in the peri-operative period. This study examines the influence of post-operative blood glucose management on rates of re-operation for infection in patients undergoing total joint arthroplasty in diabetic, and clinically non-diabetic patients.

We performed a retrospective review of prospectively collected data, for all primary, elective total hip and total knee arthroplasties performed at The Ottawa Hospital between April 2010 and October 2017. Kaplan-Meier survivorship, and mutivarient regression analysis were used to determine predictors of infection based on pre-operative diabetes status, HbA1c%, and post-operative insulin management.

4159 joints met inclusion criteria. Patients with HbA1c 5.7–6.4% had lower rate of revision for infection if they received post-operative blood glucose management (0.80%), vs without glucose management (1.20%). Kaplan-Meier survivorship analysis showed this difference to be insignificant (p=0.23). Patients with DM1 had statistically worse survivorship when compared to other groups (p=0.010).

Patients with undiagnosed perioperative dysglycemia may be at a greater predisposition for developing infection, requiring re-operation, following total joint arthroplasty. This study may be underpowered due to overall low rates of revision. More rigorous peri-operative glucose management strategies may be required for patients, who otherwise receive no glycemic management outside of hospital. This is more pertinent with trends towards decreasing post-operative lengths-of-stay.

D. Axelrod J. Al-Asiri H. Johal M. Sarraj

The purpose of this project was to evaluate North American trauma surgeon preferences regarding patient positioning for antegrade fixation of mid shaft femoral shaft fractures.

This project was a cross sectional survey taken of orthopaedic fellows and staff surgeons, belonging to three organizations across North America. An estimated sample size was calculated a priori, while various online techniques were utilized to reduce non responder and fatigue bias. The survey was distributed multiple times to optimize yield.

Two hundred twelve (212) participants responded in full, 134 (56%) of whom practiced in Canada. The majority of surgeons worked in level one trauma centres (74%), while 72% treated more than one femoral shaft fracture per week. The most common patient position for mid shaft fixation amongst all surgeons was lateral positioning with manual traction (68%), however community surgeons were significantly more likely to use a fracture table. The most common difficulties faced with using a fracture table were inability to achieve fracture reduction and peroneal nerve palsies. The majority (64%) of surgeons quoted a complication rate with fracture tables of greater than 1 per 100 cases.

Lateral position with use of manual traction is the preferred set up for antegrade fixation of femoral shaft fracture in this large North American cohort of trauma surgeons. However, a large subset of community and non academic surgeons still prefer use of the fracture table. Amongst all respondents, a high rate of fracture table complications, including malreduction, were quoted. To date, there is no prospective data comparing these two options for patient positioning, and a randomized controlled trial may be an appropriate next step.

A. Habis R. Bicknell X. Mei

Reverse shoulder arthroplasty (RSA) has an increasing effective use in the treatment of patients with a variety of diagnoses, including rotator cuff deficiency, inflammatory arthritis, or failed shoulder prostheses. Glenoid bone loss is not uncommonly encountered in these cases due to the significant wear. Severe bone loss can compromise glenoid baseplate positioning and fixation, consequently increasing the risk for early component loosening, instability, and scapular notching. To manage severe glenoid bone deficiencies, bone grafts are commonly used. Although, many studies report outcome of bone grafting in revision RSA, the literature on humeral head autograft for glenoid bone loss in primary RSA is less robust. The purpose of this study is to evaluate the clinical and radiographic outcomes of primary RSA with humeral head autograft for glenoid bone loss at our institution.

Institutional review board approval was obtained to retrospectively review the records of 22 consecutive primary RTSA surgeries in 21 patients with humeral head autograft for glenoid bone loss between January 2008 and December 2016. Five patients died during follow-up, three were unable to be contacted and one refused to participate, leaving a final study cohort of 12 patients with 13 shoulders that underwent RSA. All patients had a clinical evaluation including detailed ROM and clinical evaluation using the American Shoulder and Elbow Surgeons (ASES) Score, Constant Score, Western Ontario Osteoarthritis of the Shoulder Index (WOOS), and Short Form-12 (SF-12) questionnaires. Preoperative and postoperative plain radiographs and CT scans were assessed for component position, loosening, scapular notching, as well as graft incorporation, resorption, or collapse.

There were 6 males and 6 females, with an average age of 74 ± 6.8 years. The average BMI was 31.7 ± 5.3, and the median ASA score was 3. Average follow-up was 3.4 ± 1.1 years. The average postoperative range of motion measurements for the operative arm are: flexion = 120 ± 37, abduction = 106 ± 23, external rotation = 14 ± 12, internal rotation at 90 degrees of abduction = 49 ± 7, external rotation at 90 degrees of abduction = 50 ± 28. Average functional scores are: ASES: 76.9 ± 19.2, WOOS: 456 ± 347, SF12 physical: 34.2 ± 8.2, SF12 mental: 54.1 ± 10.2, Constant Score: 64.6 ± 14. No evidence of hardware loosening or evidence of bone graft resorption were encountered. On CT, the average of pre operative B-angle was 79.3 ± 9.3 while the pre operative reverse shoulder angle was 101.4 ± 28. Glenoid retroversion average on CT was 13.3 ± 16.6. Post operative baseplate inclination average was 82 ± 7.4 while the baseplate version 7.8 ±10. The operative technique was able to achieve up to 30 degrees of inclination correction and up to 50 degrees of version correction.

In conclusion, primary reverse shoulder arthroplasty with humeral head autograft for glenoid bone loss provides excellent ROM and functional outcomes at mid-term follow-up. This technique has a high rate of bone incorporation and small risk of bone resorption at mid term follow up.

M. Wong J. Bourget-Murray N. Desy

Surgical fixation of tibial plateau fractures in elderly patients with open reduction and internal fixation (ORIF) provides inferior outcomes compared to younger patients. Primary total knee arthroplasty (TKA) may be of benefit in patients with pre-existing arthritis, marked osteopenia, or severe fracture comminution. Rationale for primary TKA includes allowing early mobility in hopes of reducing associated complications such as deconditioning, postoperative pneumonia, or venous thromboembolism, and reducing post-traumatic arthritis which occurs in 25% to 45% of patients and requires revision TKA in up to 15%. Subsequent revision TKA has been shown to have significantly worse outcomes than TKA for primary osteoarthritis. This systematic review sought to elicit the clinical outcomes and peri-operative complication rates following primary TKA for tibial plateau fractures.

A comprehensive search of MEDLINE, Embase, and PubMed databases from inception through March 2018 was performed in accordance with PRISMA guidelines. Two reviewers independently screened papers for inclusion and identified studies featuring perioperative complications and clinical outcomes following primary TKA for tibial plateau fractures. Studies were included for final data analysis if they met the following criteria: (1) studies investigating TKA as the initial treatment for tibial plateau fractures, (2) patients must be ≥ 18 years old, (3) have a minimum ≥ 24-month follow-up, and (4) must be published in the English language. Case series, cohort, case-control, and randomized-control trials were included. Weighted means and standard deviations are presented for each outcome.

Seven articles (105 patients) were eligible for inclusion. The mean age was 73 years and average follow-up was 39 months. All-cause mortality was 4.75% ± 4.85. The total complication rate was 15.2% ± 17.3% and a total of eight patients required revision surgery. Regarding functional outcomes, the Knee Society score was most commonly reported. The average score on the knee subsection was 85.6 ± 5.5 while the average function subscore was 64.6 ± 13.7. Average range of motion at final follow-up was 107.5° ± 10°.

Total knee arthroplasty for the treatment of acute tibial plateau fractures is enticing to allow early mobility and weightbearing. However, complication rates remain high. Functional outcomes are similar to patients treated with ORIF or delayed arthroplasty. Given these findings, surgeons should be highly selective in performing TKA for the immediate treatment of tibial plateau fractures.

Y. Marwan P. A. Martineau S. Kulkarni A. Addar N. Algarni I. Tamimi M. Boily

The anterolateral ligament (ALL) is considered as an important stabilizer of the knee joint. This ligament prevents anterolateral subluxation of the proximal tibia on the femur when the knee is flexed and internally rotated. Injury of the ALL was not investigated in patients with knee dislocation. The aim of the current research is to study the prevalence and characteristics of ALL injury in dislocated knees.

A retrospective review of charts and radiological images was done for patients who underwent multiligamentous knee reconstruction surgery for knee dislocation in our institution from May 2008 to December 2016. Magnetic resonance imaging (MRI) was used to describe the ALL injury. The association of ALL injury with other variables related to the injury and the patient's background features was examined.

Forty-eight patients (49 knees) were included. The mean age of the patients was 32.3 ± 10.6 years. High energy trauma was the mechanism of dislocation in 28 (57.1%) knees. Thirty-one knees (63.3%) were classified as knee dislocation (KD) type IV. Forty-five (91.8%) knees had a complete ALL injury and three (6.1%) knees had incomplete ALL injury. Forty (81.6%) knees had a complete ALL injury at the proximal fibres of the ALL, while 23 (46.9%) knees had complete distal ALL injury. None of the 46 (93.9%) knees with lateral collateral ligament (LCL) injury had normal proximal ALL fibres (p = 0.012). Injury to the distal fibres of the ALL, as well as overall ALL injury, were not associated with any other variables (p >0.05). Moreover, all patients with associated tibial plateau fractures (9, 18.4%) had abnormality of the proximal fibres of the ALL (p = 0.033).

High grade ALL injury is highly prevalent among dislocated knees. The outcomes of reconstructing the ALL in multiligamentous knee reconstruction surgery should be investigated in future studies.

A. Bozzo M. Ghert J. Reilly

Advances in cancer therapy have prolonged patient survival even in the presence of disseminated disease and an increasing number of cancer patients are living with metastatic bone disease (MBD). The proximal femur is the most common long bone involved in MBD and pathologic fractures of the femur are associated with significant morbidity, mortality and loss of quality of life (QoL).

Successful prophylactic surgery for an impending fracture of the proximal femur has been shown in multiple cohort studies to result in longer survival, preserved mobility, lower transfusion rates and shorter post-operative hospital stays. However, there is currently no optimal method to predict a pathologic fracture. The most well-known tool is Mirel's criteria, established in 1989 and is limited from guiding clinical practice due to poor specificity and sensitivity. The ideal clinical decision support tool will be of the highest sensitivity and specificity, non-invasive, generalizable to all patients, and not a burden on hospital resources or the patient's time. Our research uses novel machine learning techniques to develop a model to fill this considerable gap in the treatment pathway of MBD of the femur. The goal of our study is to train a convolutional neural network (CNN) to predict fracture risk when metastatic bone disease is present in the proximal femur.

Our fracture risk prediction tool was developed by analysis of prospectively collected data of consecutive MBD patients presenting from 2009–2016. Patients with primary bone tumors, pathologic fractures at initial presentation, and hematologic malignancies were excluded. A total of 546 patients comprising 114 pathologic fractures were included. Every patient had at least one Anterior-Posterior X-ray and clinical data including patient demographics, Mirel's criteria, tumor biology, all previous radiation and chemotherapy received, multiple pain and function scores, medications and time to fracture or time to death.

We have trained a convolutional neural network (CNN) with AP X-ray images of 546 patients with metastatic bone disease of the proximal femur. The digital X-ray data is converted into a matrix representing the color information at each pixel. Our CNN contains five convolutional layers, a fully connected layers of 512 units and a final output layer. As the information passes through successive levels of the network, higher level features are abstracted from the data. The model converges on two fully connected deep neural network layers that output the risk of fracture. This prediction is compared to the true outcome, and any errors are back-propagated through the network to accordingly adjust the weights between connections, until overall prediction accuracy is optimized. Methods to improve learning included using stochastic gradient descent with a learning rate of 0.01 and a momentum rate of 0.9.

We used average classification accuracy and the average F1 score across five test sets to measure model performance. We compute F1 = 2 x (precision x recall)/(precision + recall). F1 is a measure of a model's accuracy in binary classification, in our case, whether a lesion would result in pathologic fracture or not. Our model achieved 88.2% accuracy in predicting fracture risk across five-fold cross validation testing. The F1 statistic is 0.87.

This is the first reported application of convolutional neural networks, a machine learning algorithm, to this important Orthopaedic problem. Our neural network model was able to achieve reasonable accuracy in classifying fracture risk of metastatic proximal femur lesions from analysis of X-rays and clinical information. Our future work will aim to externally validate this algorithm on an international cohort.

S. Montgomery P. Schneider S. Kooner

Three dimensional printing is an emerging new technology in medicine and the current educational value of 3D printed fracture models is unknown. The delayed surgery and need for CT imaging make calcaneal fractures an ideal scenario for preoperative 3D printed (3Dp) fracture models. The goal of this study is to assess if improvements in fracture understanding and surgical planning can be realized by trainees when they are given standard CT imaging and a 3Dp model compared to standard CT imaging and a virtual 3D rendering (3D CT).

Ethics approval was granted for a selection of calcaneal fracture imaging studies to be collected through a practice audit of a senior orthopaedic trauma surgeon. 3Dp models were created in house. Digital Imaging and Communications in Medicine (DICOM) files of patient CT scans were obtained from local servers in an anonymized fashion. DICOM files were then converted to .STL models using the Mimics inPrint 2.0 (Materialise NV, Leuven, Belgium) software. Models were converted into a .gcode file through a slicer program (Simplify3D, Blue Ash, OH USA). The .gcode files were printed on a TEVO Little Monster Delta FDM printer (TEVO USA, CO USA) using 1.75mm polylactic acid (PLA) filament.

Study participants rotated through 10 workstations viewing CT images and either a digital 3D volume rendering or 3Dp model of the fractured calcaneus. A questionnaire at each workstation assessed fracture classification, proposed method of treatment, confidence with fracture understanding and satisfaction with the accuracy of the 3Dp model or 3D volume rendering. Participants included current orthopaedic surgery trainees and staff surgeons.

A total of 16 residents and five staff completed the study. Ten fracture cases were included in the analysis for time, confidence of fracture understanding, perceived model accuracy and treatment method. Eight fracture cases were included for assessment of diagnosis. There were no cases that obtained universal agreement on either Sanders classification or treatment method from staff participants. Residents in their final year of studies had the quickest mean time of assessment (60 +/− 24 sec.) and highest percentage of correct diagnoses (83%) although these did not reach significance compared to the other residency years. There was a significant increase in confidence of fracture understanding with increasing residency year. Also, confidence was improved in cases where a 3Dp model was available compared to conventional CT alone although this improvement diminished with increasing residency year. Perceived accuracy of the cases with 3Dp models was significantly higher than cases without models (7 vs 5.5 p < 0.0001).

This is the first study to our knowledge to assess trainee confidence as a primary outcome in the assessment of the educational value of 3Dp models. This study was able to show that a 3Dp model aides in the perceived accuracy of fracture assessment and showed an improvement in trainee confidence, although the effect on confidence seems to diminish with increasing residency year. We propose that 3D printed calcaneal fracture models are a beneficial educational tool for junior level trainees and the role of 3Dp models for other complex orthopaedic presentations should be explored.

M. Nitikman P. Daneshvar T. Mwaturura B. Kilb

In the setting of traumatic elbow injuries involving coronoid fractures, the relative size of the coronoid fragment has been shown to relate to the stability of the joint. Currently, the challenge lies in accurately classifying the amount of bone loss in coronoid fractures. In comminuted fractures, bone loss is difficult to measure with plain radiographs or computed tomography. The purpose of this study is to describe a novel radiographic measure, the Coronoid Opening Angle (COA), on lateral elbow radiographs. We demonstrate the relationship of the COA to coronoid height and describe how this measure can be used to estimate bone loss and potentially predict elbow instability following coronoid fracture.

Radiographs were drawn from a regional database in a consecutive fashion. Candidate radiographs were excluded on the basis of radiographic evidence of degenerative changes, previous surgery or injury, bony deformity, and inadequate lateral view of the elbow. The COA was measured as the angle between the long axis of the ulna at the level of the trochlear notch, and the tip of coronoid, from a common origin at the posterior cortex of the olecranon. Images were reviewed by a fellowship trained upper extremity surgeon, an upper extremity fellow, and a junior resident. Normal COA, coronoid height, and calculated COA at varying amounts of bone loss were calculated by three reviewers. A sensitivity analysis was performed to determine how the COA can most effectively predict bone loss at varying coronoid heights. Intraclass correlation coefficient (ICC) was calculated for 39 subjects.

Seventy-two subjects were included for analysis (M=40, F=32). The normal coronoid opening angle is 33.19 degrees [32.2 – 34.2]. Coronoid height is 18.8 mm [18.1 – 19.6]. Extrapolating this baseline data, the COA at 20%, 33%, and 50% of coronoid bone loss was calculated to be 27.5, 23.5, and 18 degrees, respectively. ICC was found to be 0.90 or higher. Cutoff values were determined to maximize the sensitivity of the COA. A cutoff value of 21 degrees has a 92% sensitivity in detecting a minimum of 50% bone loss. The COA with similar sensitivity in predicting 20% and 33% bone loss are 32 and 27 degrees.

The coronoid opening angle is a novel technique that can be used on a lateral elbow radiograph to predict the minimum coronoid bone loss. This can be used to guide clinical decision making and potentially predict instability. Future research will aim to validate this tool in the clinical setting in predicting instability.

A. Addar R. C. Hamdy F. Fassier F. Jiang Y. Marwan N. Algarni K. Montpetit

The use of intramedullary implants in Osteogenesis Imperfecta (OI) patients to treat and prevent fractures, non-unions and limb deformities has been well established. To serve this purpose different implants are available from non-telescoping rods such as Rush rods and Kirschner wires, to telescoping rods such as the Dubow-Bailey rod, the Sheffield rod and the Fassier-Duval (FD) rod (Pega Medical, Laval, Quebec, Canada). The purpose of this study is to report on the long-term results of the femoral Fassier-Duval rod.

A retrospective chart review of all patients with OI who underwent a femoral intramedullary Fassier-Duval rodding between 2002 and 2017 and followed for an average of 12 years at the Shriner's Hospital, Montreal, Quebec, Canada was performed.

A total of 81 patients underwent femoral FD rodding between 2002 and 2017. Twenty-seven children undergoing 83 procedures had completed a minimum 10-year follow up with complete charts and these were included here. The average follow up time was 12 years (10–15 years). Fifty procedures were initial rodding surgeries and 30 (36.1%) were revision surgeries. A total of 69 complications were reported in the medical record and confirmed on x-ray. The 3 most common complications were a bent rod 24 (34.8%), femur fracture 16 (23.2%) and loss of telescoping in 12 (17.4%) of patients. The 3 most common cause of revision were femur fracture 16 (53.3%), broken rod 5 (16.7%) and coxa vara in 3 (10%) of patients. The average time from initial surgery to the first revision was 5.9 years.

Long term performance of femoral FD rodding shows that despite improved functioning with these rods, certain complications are to be expected, most commonly a risk of femoral fracture requiring revision surgery.

A. Behman J. G. Wright J. M. Lee B. Feldman A. Doria C. Fusco

The primary goal of this study was to understand the subjective impact of a diagnosis of Simple Bone Cyst on children with regards to activity participation and psychosocial development. We aimed to explore the concepts of labeling, embodiment and activity participation to understand the impact of SBC.

This was a qualitative study. Ten children between the ages of 4 and 17 years with SBC and their families participated in semi-structured interviews related to activity participation, social interactions and psychological impact of SBC. Interview questions were derived from psychology, sociology and philosophy literatures pertaining to illness and activity, sense of embodiment, self-concept and interactions with the social environment. Interviews were transcribed and analyzed using thematic analysis.

First, children and families view SBC as an injury more than an illness and did not experience labeling or significant changes in embodiment. Second, SBCs cause anxiety in children related fear of fracture or pain, however normal function and activity participation were maintained. Third, there were significant shortcomings identified in the communication and the decision-making process between families and physicians regarding SBC management.

SBC as a benign disease does not neatly fit into the category of illness or injury based on children's experiences. Children who previously perceived themselves as normal feel different and not normal following diagnosis with SBC. The experience of parents is largely one of anxiety, and much of that anxiety is derived from the uncertainty over the treatment plans for their child.

The proposed framework of normality allows for the more temporary and fluid changes in perception experienced by the children in our study. The results of this study suggest that the current decision-making process in SBC is unsatisfactory leading to anxiety and worry. Parents felt pressure to make decisions regarding surgery without feeling that they sufficient information. Though understanding how children experience SBCs and how parents experience the treatment course of their child with SBC, we can shared decision-making as a potential way to reduce parents' anxiety and limit negative experience in children.

J. Kubik H. Johal S. Kooner

The optimal management of rotationally-unstable ankle fractures involving the posterior malleolus remains controversial. Standard practice involves trans-syndesmotic fixation (TSF), however, recent attention has been paid to the indirect reduction of the syndesmosis by repairing small posterior malleolar fracture avulsion fragments, if present, using open reduction internal fixation. Posterior malleolus fixation (PMF) may obviate the need for TSF. Given the limited evidence and diversity in surgical treatment options for rotationally-unstable ankle fractures with ankle syndesmosis and posterior malleolar involvement, we sought to assess the research landscape and identify knowledge gaps to address with future clinical trials.

We performed a scoping review to investigate rotational ankle fractures with posterior malleolar involvement, utilizing the framework originally described by Arksey and O'Malley. We searched the English language literature using the Ovid Medline and Embase databases. All study types investigating rotationally-unstable ankle fractures with posterior malleolus involvement were categorized into defined themes and descriptive statistics were used to summarize methods and results of each study.

A total of 279 articles published from 1988 to 2018 were reviewed, and 70 articles were included in the final analysis. The literature consists of studies examining the surgical treatment strategies for PMF (n=21 studies, 30%), prognosis of rotational ankle fractures with posterior malleolar involvement (n=16 studies, 23%), biomechanics and fracture pattern of these injuries (n=13 studies, 19%), surgical approach and pertinent anatomy for fixation of posterior malleolus fractures (n=12 studies, 17%), and lastly surgical treatment of syndesmotic injuries with PMF compared to TSF (n=4 studies, 6%). Uncontrolled case series of single treatment made up the majority of all clinical studies (n=44 studies, 63%), whereas controlled study designs were the next most common (n=16 studies, 23%). Majority of research in this field has been conducted in the past eight years (n=52 studies, 74%).

Despite increasing concern and debate among the global orthopaedic community regarding rotationally-unstable ankle fractures with syndesmosis and posterior malleolar involvement, and an increasing trend towards PMF, optimal treatment remains unclear when comparing TSF to PMF. Current research priorities are to (1) define the specific injury pattern for which PMF adequately stabilizes the syndesmosis, and (2) conduct a randomized clinical trial comparing PMF to TSF with the assistance of the orthopaedic community at large with well-defined clinical outcomes.

Y. Li L. Beaupre C. Stiegelmar E. Pedersen D. Dillane M. Funabashi

Chronic postsurgical pain (CPSP) can occur after elective mid/hindfoot and ankle surgery. Effective treatment approaches for CPSP in this population have not been extensively investigated. The impact of multimodal strategies on CPSP following elective mid/hindfoot surgery is unknown due to both the heterogeneity of acute pain management and the lack of a recognized definition specific to this type of surgery. This study aimed to identify and evaluate current pain management strategies after elective mid/hindfoot and ankle surgery.

We conducted a systematic review under Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Three databases (MEDLINE, Embase and Cochrane Library) were electronically searched for English studies published between 1990 and July 2017. Reference lists of relevant systematic reviews were also manually searched. Comparative studies of adults undergoing elective mid/hindfoot and ankle surgery were included. Two reviewers independently reviewed studies and assessed their methodological quality.

Of 1,159 studies, seven high-quality randomized controlled trials met our inclusion criteria. Though all studies examined regional anesthesia techniques, intervention heterogeneity precluded meta-analysis. Participants were typically followed up to 48 hours post-operatively. Interventions effective at reducing postoperative pain and/or opioid consumption included inserting popliteal catheters under ultrasound instead of nerve stimulation guidance, infusing perineural dexamethasone, bupivacaine, or ropivacaine perioperatively, and adding a femoral catheter infusion to a popliteal catheter infusion. Only one study assessed pain six months following elective mid/hindfoot and ankle surgery, demonstrating significant pain reduction with activity with the addition of a femoral to popliteal catheter infusion.

There is an overwhelming lack of evidence regarding CPSP and its management for patients undergoing elective mid/hindfoot and ankle surgery. Although specific regional anesthesia techniques and adjuncts may be effective at reducing in-hospital pain and opioid consumption after elective mid/hindfoot and ankle surgery, our systematic review identified only seven studies addressing multimodal pain management in this population. Further comparative studies with longer-term follow-up are required.

J. Purnell A. Bois J. Bourget-Murray A. Kwapisz J. LeBlanc

This review compares the outcomes and complication rates of three surgical strategies used for the management of symptomatic os acromiale. The purpose of this study was to help guide best practice recommendations.

A systematic review of nine prospective studies, seven retrospective studies, and three case studies published across ten countries between 1993 and 2018 was performed. Adult patients (i.e., ≥ 18 years of age) with a symptomatic os acromiale that failed nonoperative management were included in this review. Surgical techniques utilized within the included studies include excision, acromioplasty, and open reduction and internal fixation (ORIF). The primary outcomes of interest included patient satisfaction and return to activity. Range of motion and several standardized outcome measurement tools were also included in the final analysis.

Patient satisfaction was highest in the excision and ORIF groups, with 92% and 82% of patients reporting good to excellent postoperative results, respectively, compared to 63% in the acromioplasty group. All three patient groups experienced improved postoperative objective scores (i.e., patient-reported outcome scores and active range of motion). The excision group experienced a complication rate of 1%, while the acromioplasty group experienced a complication rate of 11% and the ORIF group a rate of 67%.

This study reports on the largest sample of patients who have undergone surgical treatment for a symptomatic os acromiale. We have demonstrated that excision of the os with repair of the deltoid resulted in the best clinical outcomes with the least complications. In healthy adult patients with a large os fragment and a normal rotator cuff, surgical fixation may provide increased preservation of deltoid function while offering good patient satisfaction. Such patients should be aware that they are at increased risk of requiring a second procedure due to symptomatic hardware following ORIF.

E. Gusnowski P. Schneider

Distal radius fractures (DRF) are the most common fracture type in all age groups combined. Unstable DRF may be surgically managed with volar or dorsal plate fixation. Dorsal plating has traditionally been associated with decreased range of motion (ROM). However, this assumption has not been recently assessed to determine whether functional ROM is achievable (approximately 54 degrees of flexion and 60 degrees of extension) with recent advances in lower profile dorsal plate design. The aim of this study was therefore to compare ROM and patient reported outcome measures between volar and dorsal plating methods for DRF.

A meta-analysis was performed to directly compare ROM and Disabilities of Arm, Shoulder and Hand (DASH) scores between dorsal and volar plate fixation for DRF. Separate literature searches for each plating method were performed using MedLine and EMBase on January 28, 2018. Exclusion criteria consisted of non-English articles, basic science articles, animal/cadaver studies, case studies/series, combined operative approaches, papers published more than 20 years ago and paediatric studies. Only articles with at least one year patient follow-up and a) ROM and AO-OTA distal radius fracture classification, or b) DASH scores were included. Raw data was extracted from all articles that met inclusion criteria to compile a comprehensive dataset for analysis. Descriptive statistics with z-score comparison for AO-OTA classification or a two-tailed independent samples t-tests for ROM and DASH scores for dorsal versus volar plating were performed. Significance was defined as p < 0 .05.

After rigorous screening, six dorsal plating and 43 volar plating articles met inclusion criteria for ROM/AO-OTA classification versus six dorsal plating and 44 volar plating articles for DASH scores. The weighted means of flexion (dorsal 54.9 degrees, SD 9.3, n=257, volar 61.3 degrees, SD 11.5, n=1906) and extension (dorsal 60 degrees, SD 12, n=257, volar 62.8 degrees, SD 11.4, n=1906) were significantly different (both p < 0 .001) between the two plating methods. The volar plating group had a significantly higher proportion of type C fractures (dorsal 0.5, n =169, volar 0.6, n=1246, p < 0 .001). The weighted means of reported DASH scores were not significantly different between dorsal (14, SD 14.8) versus volar (13.6, SD 12.8) plating (p=0.54).

Though mean wrist flexion and extension were statistically different between the dorsal versus volar plating methods, the difference between group means was less than 5-degrees, which is unlikely to be clinically significant. Additionally, there was no significant difference in DASH scores between the two plating methods. Taken together, these findings imply that the statistical difference in ROM outcomes are likely not clinically significant and should therefore not dictate choice of plating method for fixation of DRF.

E. Karam S. Pelet

Complex proximal humerus fractures account for 10% of fractures in patients over 65 years of age. With the emergence of new implants, there is growing trend towards surgical management of these types of fractures, despite the lack of clinical evidence of its superiority over a conservative option. Orthopaedic surgeons' perception plays a large role in the surgical decision making for complex proximal humerus fractures in the elderly. No studies have been conducted to date to examine factors that influence the surgical decision-making in orthopaedic surgeons in regards to these types of fractures.

A self-administered questionnaire was sent to orthopaedic surgeons. It included demographic questions as well as clinical vignettes assessing the risk / benefit perception of orthopaedic surgeons in different situations. Orthopaedic surgeons self-reported the proportion of proximal humerus fractures that were treated surgically in patients during the last year. Univariate analyzes were conducted to identify the factors that influenced the operation rates.

A total of 127 orthopaedic surgeons completed the questionnaire. The response rate was 37%. The risk / benefit perception of surgical management varied according to the type of practice, year of training, operation rate as well as the ease of the surgeon in performing shoulder procedures (p < 0.05). According to the queried surgeons, the most important factors affecting their decision-making were patient's age, the type of fracture, co-morbidities, level of independence and potential for rehabilitation. The type of surgery proposed varied depending on the training and familiarity of the surgeon with the procedure.

The risk / benefit perception of orthopaedic surgeons regarding surgical treatment of proximal humerus fractures in elderly patients appears to vary widely. The decision to opt for surgical management is influenced by the surgeon's familiarity with the procedure, their year of training and their subspecialty. This study demonstrates the need to establish a decision-making tool to assist orthopaedic surgeons and patients with this clinical decision.

J. Bourget-Murray J. Kendal P. Schneider S. Montgomery S. Kooner J. Kubik A. Meldrum C. Kwong E. Gusnowski K. Thomas L. Fruson M. Litowski S. Sridharan D. You J. Purnell M. James M. Wong T. Ludwig A. Abbott J. Lukenchuk B. Benavides L. Morrison

Advances in orthopaedic surgery have led to minimally invasive techniques to decrease patient morbidity by minimizing surgical exposure, but also limits direct visualization. This has led to the increased use of intraoperative fluoroscopy for fracture management. Unfortunately, these procedures require the operating surgeon to stay in close proximity to the patient, thus being exposed to radiation scatter. The current National Council on Radiation Protection recommends no more than 50 mSv of radiation exposure to avoid ill-effects. Risks associated with radiation exposure include cataracts, skin, breast and thyroid cancer, and leukemia. Despite radiation protection measures, there is overwhelming evidence of radiation-related diseases in orthopaedic surgeons. The risk of developing cancer (e.g. thyroid carcinoma and breast cancer) is approximately eight times higher than in unexposed workers. Despite this knowledge, there is a paucity of evidence on radiation exposure in orthopaedic surgery residents, therefore the goal of this study is to quantify radiation exposure in orthopaedic surgery residents.

We hypothesize that orthopaedic surgery residents are exposed to a significant amount of radiation throughout their training. We specifically aim to: 1) quantify the amount of radiation exposure throughout a Canadian orthopaedic residency training program and 2) determine the variability in resident radiation exposure by rotation assignment and year of training.

This ongoing prospective cohort study includes all local orthopaedic surgery residents who meet eligibility criteria. Inclusion criteria: 1) adult residents in an orthopaedic surgery residency program. Exclusion criteria: 1) female residents who are pregnant, and 2) residents in a non-surgical year (i.e. leave of absence, research, Masters/PhD). After completion of informed consent, each eligible resident will wear a dosimeter to measure radiation exposure in a standardized fashion. Dosimeters will be worn on standardized lanyards underneath lead protection in their left chest pocket during all surgeries that require radiation protection. Control dosimeters will be worn on the outside of each resident's scrub cap for comparison. Dosimeter readings will then be reported on a monthly and rotational basis. All data will be collected on a pre-developed case report form. All data will be de-identified and stored on a secure electronic database (REDCap). In addition to monthly and rotational dosimeter readings, residents will also report sex, height, level of training, parental status, and age for secondary subgroup analyses. Residents will also report if they have personalized lead or other protective equipment, including lead glasses. Resident compliance with dosimeter use will be measured by self report of >80% use on operative days. Interim analysis will be performed at the 6-month time point and data collection will conclude at the 1 year time point.

Data collection began in July 2018 and interim 6-month results will be available for presentation at the CORA annual meeting in June 2019.

This is the first prospective study quantifying radiation exposure in Canadian orthopaedic residents and the results will provide valuable information for all Canadian orthopaedic training programs.

R. Kelc

Injured skeletal muscle repairs spontaneously via regeneration, however, this process is often incomplete because of fibrotic tissue formation. In our study we wanted to show improved efficiency of regeneration process induced by antifibrotic agent decorin in a combination with Platelet Rich Plasma (PRP)-derived growth factors. A novel human myoblast cell (hMC) culture, defined as CD56 (NCAM)+ developed in our laboratory, was used for evaluation of potential bioactivity of PRP and decorin. To determine the their effect on the viability of hMC we performed a MTT assay. To perform the cell proliferation assay, hMCs were separately seeded on plates at a concentration of 30 viable cells per well. Cell growth medium prepared with different concentrations of PRP exudates (5%, 10%, and 20%) and decorin (10 ng/mL, 25 ng/mL, and 50 ng/mL) were added and incubated for 7 days. After incubation we stained the cells with crystal-violet and measured the absorbance.

To study the expression of Transforming Growth Factor Beta (TGF-β) and myostatin (MSTN), two main fibrotic factors in the process of muscle regeneration we performed several ELISA assays in groups treated with all therapeutic agents (PRP, decorin and their combination). Further, we have studied the ability of these agents to influence the differential cascade of dormant myoblasts towards fully differentiated myotubes by monitoring step wise activation of single nuclear factors like MyoD and Myogenin via multicolor flow cytometry. We stained the cells simultaneously with antibodies against CD56, MyoD and myogenin. We acquired cell images of 5,000 events per sample at 40 x magnification using 488 nm and 658 nm lasers and fluorescence was collected using three spectral detection channels. We analysed the cells populations according to expression of single or multiple markers and their ratios.

Finally, we examined the treated cell populations using a multicolour laser microscope after staining for desmin (a key marker of myogenic differentiation of hMC), α-tubulin, and nuclei. Optical images were acquired at the center of chamber slides where the cell density is at its highest using a Leica TCS SP5 II confocal microscope and analysed using Photoshop CS6, where a “Color Range” tool was used in combination with a histogram palette to count the pixels that correspond to desmin-positive areas in an image.

The mitochondrial activity of cells, as determined by the MTT assay, was significantly increased (p < 0 .001) after exposure to tested concentrations of PRP exudate. Similarly, viability was elevated in all tested concentrations of decorin. PRP exudate enhanced the viability of cells to more than 400% when compared to the control (p < 0 .001). The viability of cells treated with PRP exudates was also significantly higher when compared to decorin (p < 0 .001). Decorin did not show a significant effect on cell proliferation compared to the control, however, cultivation with PRP exudate leads to a 5-fold increase in cell proliferation (p < 0 .001). Decorin was shown to down-regulate the expression of TGF-β when compared to the control by more than 15% (p < 0 .001) but significantly less than PRP exudate p < 0 .005). PRP significantly down-regulated TGF-β expression by more than 30% (p < 0 .001). Similarly, the MSTN expression levels were significantly down-regulated by decorin and PRP. MSTN levels of cells treated with decorin were decreased by 28.4% (p < 0 .001) and 23.1% by PRP (p < 0 .001) when compared to the control group.

Using flow cytometry we detected a 39.1% increase in count of myogenin positive cells in the PRP-treated group compared to the control. Moreover, there was a 3.09% increase in cells positive only for myogenin, whereas no such cells were found in the control cell population. The population of cells positive only for myogenin is considered as fully differentiated and capable of fusion into myotubes as well as future mucle fibers and is thus of great importance for muscle regeneration. At the same time 20.6% fewer cells remained quiescent (positive only for CD56). Cells positive for both MyoD and myogenin represent the population that shifted significantly towards mature myocites during myogenesis but are not yet fully committed.

Finally, a statistically significant up-regulation of desmin expression (p < 0 .01 for the PRP treated group, p < 0 .005 for the decorin and PRP + decorin treated groups) was present in all therapeutic groups when compared to the control. While no significant difference was found between the PRP and decorin-treated groups, their combination led to a more than 3-fold increase (p < 0 .005) of desmin expression when compared to single bioactives.

PRP can be a highly potential therapeutic agent for skeletal muscle regeneration and repair, especially if in combination with a TGF-β antagonis decorin. Achieving better healing could likely result in faster return to play and lower reinjury rate.