The study of spinopelvic anatomy and movement has received great interest as these characteristics influence the biomechanical behavior (and outcome) following hip arthroplasty. However, to-date there is little knowledge of what “normal” is and how this varies with age. This study aims to determine how dynamic spino-pelvic characteristics change with age, with well-functioning hips and assess how these changes are influenced by the presence of hip arthritis.

This is an IRB-approved, cross-sectional, cohort study; 100 volunteers (asymptomatic hips, Oxford-Hip-sore>45) [age:53 ± 17 (24-87) years-old; 51% female; BMI: 28 ± 5] and 200 patients with end-stage hip arthritis [age:56 ± 19 (16-89) years-old; 55% female; BMI:28 ± 5] were studied. All participants underwent lateral spino-pelvic radiographs in the standing and deep-seated positions to determine maximum hip and spine flexion. Parameters measured included lumbar-lordosis (LL), pelvic incidence, pelvic-tilt (PT), pelvic-femoral angles (PFA). Lumbar flexion (ΔLL), hip flexion (ΔPFA) and pelvic movement (ΔPT) were calculated. The prevalence of spinopelvic imbalance (PI–LL>10?) was determined.

There were no differences in any of the spino-pelvic characteristics or movements between sexes. With advancing age, standing LL reduced and standing PT increased (no differences between groups). With advancing age, both hip (4%/decade) and lumbar (8%/decade) flexion reduced (p<0.001) (no difference between groups). ΔLL did not correlate with ΔPFA (rho=0.1). Hip arthritis was associated with a significantly reduced hip flexion (82 ±;22? vs. 90 ± 17?; p=0.003) and pelvic movements (1 ± 16? vs. 8 ± 16?; p=0.002) at all ages and increased prevalence of spinopelvic imbalance (OR:2.6; 95%CI: 1.2-5.7).

With aging, the lumbar spine loses its lumbar lordosis and flexion to a greater extent that then the hip and resultantly, the hip's relative contribution to the overall sagittal movement increases. With hip arthritis, the reduced hip flexion and the necessary compensatory increased pelvic movement is a likely contributor to the development of hip-spine syndrome and of spino-pelvic imbalance.

In 2007, the National Hip Fracture Database (NHFD) was conceived in the United Kingdom (UK) as a national audit aiming to improve hip fracture care across the country. It now represents the world's largest hip fracture registry. The purpose of the NHFD is to evaluate aspects of best practice for hip fracture care, at an institutional level, that reflect the evidence-based clinical guidelines and quality standards developed by the National Institute for Health and Care Excellence. No national program currently exists, equivalent to the NHFD, in Canada despite evidence suggesting that national audit programs can significantly improve patient outcomes. The purpose of this study was to evaluate aspects of best practice for hip fractures at our Canadian academic tertiary referral center using the Key Performance Indicators (KPI) and benchmarks used by the NHFD. In doing so, we aimed to compare our performance to other hospitals contributing to the NHFD database.

A retrospective cohort study was conducted on consecutive patients who presented to our Canadian center for surgical management of a hip fracture between August 2019 to September 2020. Fracture types included intertrochanteric, subtrochanteric, and femoral neck fractures treated with either surgical fixation or arthroplasty. Cases were identified from the affiliate institute's Operatively Repaired Fractures Database (ORFD). The ORFD prospectively collects patient-level data extracted from electronic medical records, operating room information systems, and from patients’ discharge summaries. All applicable data from our database were compared to the established KPI and benchmarks published by the NHFD that apply to the Canadian healthcare system.

Six hundred and seven patients’ data (64.5% female) were extracted from the ORFD, mean age 80.4 ± 13.3 years. The NHFD contains data from 63,284 patients across the entire UK. The affiliate institute performed inferiorly compared to the NHFD for two KPIs: prompt surgery (surgery by the day following presentation with hip fracture, 52.8% vs. 69%) and prompt mobilization after surgery (mobilized out of bed by the day after operation, 43.0% vs. 81.0%). However, more patients at the affiliate institute were not delirious when tested postoperatively (89.6% vs. 68.4%). There was no significant difference in the average length of stay (12.23 days versus 13.5 days) or in 30-day mortality rate (8.4% versus 8.3%).

More than half of all KPI's and benchmarks for patients receiving a hip fracture surgery at our tertiary referral center in Canada ranked significantly lower than patients receiving a hip fracture surgery in the UK. These findings indicate that perhaps a national audit program should be implemented in Canada to improve aspects of hip fracture care, at an institutional level. Following evidence-based clinical guidelines and using standardized benchmarks would encourage change and foster improvement across Canadian centres when necessary.

With an ageing population and an increasing number of primary arthroplasties performed, the revision burden is predicted to increase. The aims of this study were to 1. Determine the revision burden in an academic hospital over a 11-year period; 2. identify the direct hospital cost associated with the delivery of revision service and 3. ascertain factors associated with increased cost.

This is an IRB-approved, retrospective, single tertiary referral center, consecutive case series. Using the hospital data warehouse, all patients that underwent revision hip or knee arthroplasty surgery between 2008-2018 were identified. 1632 revisions were identified (1304 patients), consisting of 1061 hip and 571 knee revisions. The majority of revisions were performed for mechanical-related problems and aseptic loosening (n=903; 55.3%); followed by periprosthetic joint infection (n=553; 33.9%) and periprosthetic fractures (176; 10.8%). Cost and length of stay was determined for all patient. The direct in-hospital costs were converted to 2020 inflation-adjusted Canadian dollars. Several patients- (age; gender; HOMR- and ASA-scores; Hemoglobin level) and surgical- (indication for surgery; surgical site) factors were tested for possible associations.

The number of revisions increased by 210% in the study period (2008 vs. 2018: 83 vs. 174). Revision indications changed over study period; with prevalence of fracture increasing by 460% (5 in 2008 vs. 23 in 2018) with an accompanying reduction in mechanical-related reasons, whilst revisions for infection remained constant. The mean annual cost over the entire study period was 3.9 MMCAD (range:2.4–5.1 MMCAD). The cost raised 150% over the study period from 2.4 MMCAD in 2008 to 3.6 MMCAD. Revisions for fractured had the greatest length of stay, the highest mean age, HOMR-score, ASA and cost associated with treatment compared to other revision indications (p < 0 .001). Patient factors associated with cost and length of stay included ASA- and HOMR-scores, Charlson-Comorbidity score and age.

The revision burden increased 1.5-fold over the years and so has the direct cost of care delivery. The increased cost is primarily related to the prolonged hospital stay and increased surgical cost. For tertiary care units, these findings indicate a need to identify strategies on improving efficiencies whilst improving the quality of patient care (e.g. efficient ways of reducing acute hospital stay) and reducing the raise of the economic burden on a publicly funded health system.

Adverse spinopelvic characteristics (ASC) have been associated with increased dislocation risk following primary total hip arthroplasty (THA). A stiff lumbar spine, a large posterior standing tilt when standing and severe sagittal spinal deformity have been identified as key risk factors for instability. It has been reported that the rate of dislocation in patients with such ASC may be increased and some authors have recommended the use of dual mobility bearings or robotics to reduce instability to within acceptable rates (<2%).

The aims of the prospective study were to 1: Describe the true incidence of ASC in patients presenting for a THA 2. Assess whether such characteristics are associated with greater symptoms pre-THA due to the concomitant dual pathology of hip and spine and 3. Describe the early term dislocation rate with the use of ≤36mm bearings.

This is an IRB-approved, two-center, multi-surgeon, prospective, consecutive, cohort study of 220 patients undergoing THA through anterolateral- (n=103; 46.8%), direct anterior- (n=104; 27.3%) or posterior- approaches (n=13; 5.9%). The mean age was 63.8±12.0 years (range: 27.7-89.0 years) and the mean BMI 28.0±5.0 kg/m² (range: 19.4-44.4 kg/m²). There were 44 males (47.8%) and 48 females (52.2%). The mean follow-up was 1.6±0.5 years. Overall, 54% of femoral heads was 32 mm, and 46% was 36mm.

All participants underwent lateral spinopelvic radiographs in the standing and deep-flexed seated positions were taken to determine lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic-femoral angle (PFA) and pelvic incidence (PI) in both positions. Spinal stiffness was defined as lumbar flexion <20° when transitioning between the standing and deep-seated position; adverse standing PT was defined as >19° and adverse sagittal lumbar balance was defined as mismatch between standing PI and LL >10°.

Pre-operative patient reported outcomes was measured using the Oxford Hip Score (OHS) and EuroQol Five-Dimension questionnaire (EQ-5D). Dislocation rates were prospectively recorded. Non-parametric tests were used, significance was set at p<0.05.

The prevalence of PI-LL mismatch was 22.1% (43/195) and 30.4% had increased standing PT (59/194). The prevalence of lumbar stiffness was 3.5% (5/142) and these patients had all three adverse spinopelvic characteristics (5/142; 3.5%).

There was no significant difference in the pre-operative OHS between patients with (20.7±7.6) and patients without adverse spinopelvic characteristics (21.6±8.7; p=0.721), nor was there for pre-operative EQ5D (0.651±0.081 vs. 0.563±0.190; p=0.295).

Two patients sustained a dislocation (0.9%): One in the lateral (no ASC) and one in the posterior approaches, who also exhibited ASC pre-operatively.

Sagittal lumbar imbalance, increased standing spinal tilt and spinal stiffness are not uncommon among patients undergoing THA. The presence of such characteristics is not associated with inferior pre-operative PROMs. However, when all characteristics are present, the risk of instability is increased. Patients with ASC treated with posterior approach THA may benefit from the use of advanced technology due to a high risk of dislocation. The use of such technology with the anterior or lateral approach to improve instability is to date unjustified as the rate of instability is low even amongst patients with ASCs.

In patients admitted to hospital with a hip fracture, urinary issues are common. Despite guidelines that recommend avoiding foley catheter usage when possible, it remains a common part of perioperative care. To date, there is no prospective data on the safety and satisfaction associated with catheter use in such cohort. The aim of this study was to evaluate the satisfaction of patients when using a foley catheter while they await surgery for their fractured hip and the safety associated with catheter use.

In our prospectively collected database, 587 patients were admitted to our tertiary care center over a 1 year period. Most patients (328) were catheterized within the first 24h of admission, primarily inserted in ED. Of these patients, 119 patients (61 catheterized and 58 noncatheterized) completed a questionnaire about their perioperative management with foley catheter usage administered on day 1 of admission. This was used to determine satisfaction of catheter use (if catheterized) and pain levels (associated with catheterized or associated with transferring/voiding if not catheterized). Adverse effects related with catheter use included urinary tract infection (UTI) and post-operative urinary retention (POUR).

Ninety-five percent of patients found the catheter to be convenient. Only 5% of patients reported any pain with catheter use. On the contrary, 47.5% of non-catheterized patients found it difficult to move to the bathroom and 30.4% found it difficult to urinate. Catheterized patients had significative less pain than uncatheterized patients (0.62/10 vs 2.45/10 respectively, p < 0 .001). The use of nerve block reduced pain levels amongst catheterized patients but was not associated with reduced pain levels or satisfaction amongst non-catheterized patients. The use of catheter was not associated with increased risk of UTI(17.5% in the catheterized vs 13.3% in the non-catheterized, p = 0.541) or POUR (6.8% in the catheterized vs 11.1% in the non-catheterized, p = 0.406).

This study illustrates the benefits and safety associated with the use of urinary catheters in the pre-operative period amongst hip fractures. The use of catheters was associated with reduced pain and satisfaction without increasing post-operative UTI or POUR. These findings suggest that pre-operative catheter use is associated with less pain and more satisfaction for patients awaiting hip surgery and whom other measures, such as nerve blocks, are unlikely to reduce the discomfort associated with the mobility required to void. A prospective randomized control study could lead to a more evidence based approach for perioperative foley catheter usage in hip fracture patients.

The presence of hip osteoarthritis is associated with abnormal spinopelvic characteristics. This study aims to determine whether the pre-operative, pathological spinopelvic characteristics “normalize” at 1-year post-THA.

This is a prospective, longitudinal, case-control matched cohort study. Forty-seven patients underwent pre- and post- (at one-year) THA assessments. This group was matched (age, sex, BMI) with 47 controls/volunteers with well-functioning hips. All participants underwent clinical and radiographic assessments including lateral radiographs in standing, upright-seated and deep-flexed-seated positions. Spinopelvic characteristics included change in lumbar lordosis (ΔLL), pelvic tilt (ΔPT) and hip flexion (pelvic-femoral angle, ΔPFA) when moving from the standing to each of the seated positions. Spinopelvic hypermobility was defined as ΔPT>30° between standing and upright-seated positions.

Pre-THA, patients illustrated less hip flexion (ΔPFA −54.8°±17.1° vs. −68.5°± 9.5°, p<0.001), greater pelvic tilt (ΔPT 22.0°±13.5° vs. 12.7°±8.1°, p<0.001) and greater lumbar movements (ΔLL −22.7°±15.5° vs. −15.4°±10.9°, p=0.015) transitioning from standing to upright-seated. Post-THA, these differences were no longer present (ΔPFApost −65.8°±12.5°, p=0.256; ΔPTpost 14.3°±9.5°, p=0.429; ΔLLpost −15.3°±10.6°, p=0.966). The higher prevalence of pre-operative spinopelvic hypermobility in patients compared to controls (21.3% vs. 0.0%; p=0.009), was not longer present post-THA (6.4% vs. 0.0%; p=0.194). Similar results were found moving from standing to deep-seated position post-THA.

Pre-operative, spinopelvic characteristics that contribute to abnormal mechanics can normalize post-THA following improvement in hip flexion. This leads to patients having the expected hip-, pelvic- and spinal flexion as per demographically-matched controls, thus potentially eliminating abnormal mechanics that contribute to the development/exacerbation of hip-spine syndrome.

A stiff spine leads to increased demand on the hip, creating an increased risk of total hip arthroplasty (THA) dislocation. Several authors propose that a change in sacral slope of ≤10° between the standing and relaxed-seated positions (ΔSSstanding→relaxed-seated) identifies a patient with a stiff lumbar spine and have suggested use of dual-mobility bearings for such patients. However, such assessment may not adequately test the lumbar spine to draw such conclusions. The aim of this study was to assess how accurately ΔSSstanding→relaxed-seated can identify patients with a stiff spine.

This is a prospective, multi-centre, consecutive cohort series. Two-hundred and twenty-four patients, pre-THA, had standing, relaxed-seated and flexed-seated lateral radiographs. Sacral slope and lumbar lordosis were measured on each functional X-ray. ΔSSstanding→relaxed-seated seated was determined by the change in sacral slope between the standing and relaxed-seated positions. Lumbar flexion (LF) was defined as the difference in lumbar lordotic angle between standing and flexed-seated. LF≤20° was considered a stiff spine. The predictive value of ΔSSstanding→relaxed-seated for characterising a stiff spine was assessed.

A weak correlation between ΔSSstanding→relaxed-seated and LF was identified (r2= 0.15). Fifty-four patients (24%) had ΔSSstanding→relaxed-seated ≤10° and 16 patients (7%) had a stiff spine. Of the 54 patients with ΔSSstanding→relaxed-seated ≤10°, 9 had a stiff spine. The positive predictive value of ΔSSstanding→relaxed-seated ≤10° for identifying a stiff spine was 17%.

ΔSSstanding→relaxed-seated ≤10° was not correlated with a stiff spine in this cohort. Utilising this simplified approach could lead to a six-fold overprediction of patients with a stiff lumbar spine. This, in turn, could lead to an overprediction of patients with abnormal spinopelvic mobility, unnecessary use of dual mobility bearings and incorrect targets for component alignment. Referring to patients ΔSSstanding→relaxed-seated ≤10° as being stiff can be misleading; we thus recommend use of the flexed-seated position to effectively assess pre-operative spinopelvic mobility.

Short cementless femoral stems are increasingly popular as they allow for less dissection for insertion. Use of such stems with the anterior approach (AA) may be associated with considerable per-operative fracture risk. This study's primary aim was to evaluate whether patient-specific femoral- and pelvic- morphology and surgical technique, influence per-operative fracture risk. In doing so, we aimed to describe important anatomical thresholds alerting surgeons.

This is a single-center, multi-surgeon retrospective, case-control matched study. Of 1145 primary THAs with a short, cementless stem inserted via the AA, 39 periprosthetic fractures (3.4%) were identified. These were matched for factors known to increase fracture risk (age, gender, BMI, side, Dorr classification, stem offset and indication for surgery) with 78 THAs that did not sustain a fracture. Radiographic analysis was performed using validated software to measure femoral- (canal flare index [CFI], morphological cortical index [MCI], calcar-calcar ratio [CCR]) and pelvic- (Ilium-ischial ratio [IIR], ilium overhang, and ASIS to greater trochanter distance) morphologies and surgical technique (% canal fill). Multivariate and Receiver-Operator Curve (ROC) analysis was performed to identify predictors of fracture.

Femoral factors that differed included CFI (3.7±0.6 vs 2.9±0.4, p3.17 and II ratio>3 (OR:29.2 95%CI: 9.5–89.9, p<0.001).

Patient-specific anatomical parameters are important predictors of fracture-risk. When considering the use of short stems via the AA, careful radiographic analysis would help identify those at risk in order to consider alternative stem options.

Surgical treatment options for Femoroacetabular impingement (FAI) includes both surgical dislocation and hip arthroscopy techniques. The primary aim of this study was to evaluate and compare the survivorship of arthroscopies (scope) and surgical dislocations (SD) at minimum 5-year follow-up. The secondary aim was to describe differences in functional outcomes between the 2 groups.

This was a retrospective, single surgeon, consecutive, case-series from a large tertiary care centre. We evaluated all surgeries that were performed between 2005 and 2011. Our institutional database was queried for any patient undergoing surgery for FAI (pincer (n=23), cam (n=306), or mixed (n=103) types). Patients with childhood pathologies i.e. Legg Calve Perthes and slipped capital femoral epiphysis were excluded. This resulted in 221 hips (169 males, 52 females) who underwent either SD (94, 42.5%) or scope (127, 57.5%). A manual chart review was completed to identify patients who sustained a complication, underwent revision surgery or progressed to a total hip arthroplasty (THA). In addition, we reviewed prospectively collected patient reported outcome measure (PROMs) using (SF12, HOOS, and UCLA). Survivorship outcome was described for the whole cohort and compared between the 2 surgical groups. PROMs between groups were compared using The Mann-Whitney U test and the survival between groups was assessed using the Kaplan-Meier Analysis and the Log-Rank Mantel Cox test. All analyses were performed in SPSS (IBM, v. 26.0).

The cohort included 110 SDs and 320 arthroscopies. The mean age of the whole cohort was 34±10; patients in the SD group (32±9) were younger compared to the arthroscopy group (39±10) (p<0.0001). There were 16 post-operative complications (similar between groups) and 77 re-operations (more common in the SD group (n=49) due to symptomatic metal work (n=34)). The overall 10-year survival was 91±3%. Survivorship was superior in the arthroscopy group at both 5- (96% (95%CI: 93 – 100)) and 8- years 94% (95%CI: 90 – 99%) compared to the SD Group (5-yr: 90% (95%CI: 83 – 98); 8-yr: 84% (95%CI:75 – 93)) (p=0.003) (Figure 1). On average HOOS improved from 54±19 to 68±22 and WOMAC from 65±22 to 75±22. The improvement in PROMs were similar between the 2 groups.

We report very good long-term joint preservation for the treatment of FAI, which is similar to those reported in hip dysplasia. In addition, we report satisfactory improvement in function following such treatment. The differences reported in joint survival likely reflect selection biases from the treating surgeon; more complex cases and those associated with more complex anatomy were more likely to have been offered a SD in order to address the pathology with greater ease and hence the inferior joint preservation identified in this group.

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

Management of acetabular fractures in the elderly population remains somewhat controversial in regards to when to consider is open reduction internal fixation (ORIF) versus acute primary total hip. study aims to (1) describe outcome of this complex problem and investigate predictors of successful outcome.

This retrospective study analyzes all acetabular fractures in patients over the age of 60, managed by ORIF at a tertiary trauma care centre between 2007 and 2018 with a minimum follow up of one year. Of the 117 patients reviewed, 85 patients undergoing ORIF for treatment of their acetabular fracture were included in the analysis. The remainder were excluded based management option including acute ORIF with THA (n=10), two-stage ORIF (n=2), external fixator only (n=1), acute THA (n=1), and conservative management (n=1). The remainder were excluded based on inaccessible medical records (n=6), mislabelled diagnosis (n=6), associated femoral injuries (n=4), acetabular fracture following hemiarthroplasty (n=1). The mean age of the cohort is 70±7 years old with 74% (n=62) of patients being male. Data collected included: demographics, mechanism of injury, Charlson Comorbidity Index (CCI), ASA Grade, smoking status and reoperations. Pre-Operative Radiographs were analyzed to determine the Judet and Letournel fracture pattern, presence of comminution and posterior wall marginal impaction. Postoperative radiographs were used to determine Matta Grade of Reduction. Outcome measures included morbidity-, mortality- rates, joint survival, radiographic evidence of osteoarthritis and patient reported outcome measures (PROMs) using the Oxford Hip Score (OHS) at follow-up. A poor outcome in ORIF was defined as one of the following: 1) conversion to THA or 2) the presence of radiographic OA, combined with an OHS less than 34 (findings consistent with a hip that would benefit from a hip replacement). The data was analyzed step-wise to create a regression model predictive of outcome following ORIF.

Following ORIF, 31% (n=26) of the cohort had anatomic reduction, while 64% (n=54) had imperfect or poor reduction. 4 patients did not have adequate postoperative radiographs to assess the reduction. 31 of 84 patients undergoing ORIF had a complication of which 22.6% (n=19) required reoperation. The most common reason being conversion to THA (n=14), which occurred an average of 1.6±1.9 years post-ORIF. The remainder required reoperation for infection (n=5). Including those converted to THA, 43% (n=36) developed radiographic OA following acetabular fracture management. The mean OHS in patients undergoing ORIF was 36 ± 10; 13(16%) had an OHS less than 34. The results of the logistic regression demonstrate that Matta grade of reduction (p=0.017), to be predictive of a poor outcome in acetabular fracture management. With non-anatomic alignment following fixation, patients had a 3 times greater risk of a poor outcome. No other variables were found to be predictive of ORIF outcome.

The ability to achieve anatomic reduction of fracture fragments as determined by the Matta grade, is predictive of the ability to retain the native hip with acceptable outcome following acetabular fracture in the elderly. Further research must be conducted to determine predictors of adequate reduction in order to identify candidates for ORIF.

Introduction

Interactions between hip, pelvis and spine, as abnormal spinopelvic movements, have been associated with inferior outcomes following total hip arthroplasty (THA). Changes in pelvis position lead to a mutual change in functional cup orientation, with both pelvic tilt and rotation having a significant effect on version. Hip osteoarthritis (OA) patients have shown reduced hip kinematics which may place increased demands on the pelvis and the spine.

Sagittal and coronal planes assessments are commonly done as these can be adequately studied with anteroposterior and lateral radiographs. However, abnormal pelvis rotation is likely to compromise the outcome as they have a detrimental effect on cup orientation and increased impingement risk. This study aims to determine the association between dynamic motion and radiographic sagittal assessments; and examine the association between axial and sagittal spinal and pelvic kinematics between hip OA patients and healthy controls (CTRL).

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.

Spinopelvic mobility describes the change in lumbar lordosis and pelvic tilt from standing to sitting position. For 1° of posterior pelvic tilt, functional cup anteversion increases by 0.75° after total hip arthroplasty (THA). Thus, spinopelvic mobility is of high clinical relevance regarding the risk of implant impingement and dislocation.

Our study aimed to 1) determine the proportion of OA-patients with stiff, normal or hypermobile spino-pelvic mobility and 2) to identify clinical or static standing radiographic parameters predicting spinopelvic mobility.

This prospective diagnostic cohort study followed 122 consecutive patients with end-stage osteoarthritis awaiting THA. Preoperatively, the Oxford Hip Score, Oswestry Disability Index and Schober's test were assessed in a standardized clinical examination. Lateral view radiographs were taken of the lumbar spine, pelvis and proximal femur using EOS© in standing position and with femurs parallel to the floor in order to achieve a 90°-seated position. Radiographic measurements were performed for the lumbar lordosis angle (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI) and pelvic-femoral-angle (PFA). The difference in PT between standing and seated allowed for patient classification based on spino-pelvic mobility into stiff (±30°).

From the standing to the sitting position, the pelvis tilted backwards by a mean of 19.6° (SD 11.6) and the hip was flexed by a mean of 57° (SD 17). Change in pelvic tilt correlated inversely with change in hip flexion.

Spinopelvic mobility is highly variable in patients awaiting THA and we could not identify any clinical or static standing radiographic parameter predicting the change in pelvic tilt from standing to sitting position. In order to identify patients with stiff or hypermobile spinopelvic mobility, we recommend performing lateral view radiographs of the lumbar spine, pelvis and proximal femur in all patients awaiting THA. Thereafter, implants and combined cup inclination/anteversion can be individually chosen to minimize the risk of dislocation.

No predictors could be identified. We recommend performing sitting and standing lateral view radiographs of the lumbar spine and pelvis to determine spinopelvic mobility in patients awaiting THA.

During a periacetabular osteotomy (PAO), intra-operative assessment of correction of acetabular parameters is typically performed using fluoroscopy of the hip, a technique that has not been shown to produce predictable measurements. Furthermore, paralysing agents are used in order to facilitate dissection and fragment mobilization. The effect of paralysing agents on spino-pelvic posture is yet to be investigated.

This study aims to: 1. Compare the reliability of intra-operative x-rays versus hip fluoroscopy in the assessment of acetabular fragment correction and 2. Evaluate the effect of changes in spino-pelvic alignment on the assessment of acetabular correction. An IRB approved, retrospective review of all patients who underwent a PAO at our institution between 2006–2018 was performed. Patient demographic data was collected and all available imaging studies were retrieved. Patients were excluded if there was no available to review intra-operative AP pelvis x-ray or intra-operative fluoroscopic PA image of the hip.

Using a validated hip analysis software (Hip2Norm), the lateral center edge angle (LCEA) and acetabular index (AI) of plain radiographs were measured. The sacro-femoral-pubic angle (SFP), along with the LCEA and AI of the fluoroscopic image were measured using ImageJ. A oneway ANOVA was used to detect differences between measured parameters in the intra-operative x-ray, the post-operative x-ray and the fluoroscopic image. A total of 93 patients were identified. 26 patients were excluded due to missing data. The mean LCEA in the post-operative, intra-operative, and fluoroscopic groups were as follows: 33.67° (range 5.3° to 52.4°), 30.71°(range 9° to 55.6°), and 29.23°(range 12.4° to 51.4°) respectively. The mean AI in the post-operative, intra-operative, and fluoroscopic groups were as follows: −0.65° (range −18.10° to 27.30°), 0.35°(range −16.10° to 17.20°), and 5.54°(range −11.66° to 27.83°) respectively.

When comparing intra-operative to post-operative plain radiographs, there was no statistically significant difference in AI (ΔAI −1±1.29° p=0.71) or LCEA (ΔLCEA 2.95±1.38° p=0.09). When comparing fluoroscopy to post-operative plain radiographs, there was a statistically significant difference in AI (ΔAI −6.21±1.29° p < 0 .0001) as well as LCEA (ΔLCEA 4.44±1.38° p < 0 .0001). Statistical analysis revealed no influence of demographics (age, BMI, gender), on acetabular correction parameters. The mean SPF angles measured from intra-operative and post-operative x-rays were 69.32±5.11° and 70.45±5.52°. There was a statistically significant difference between these 2 measurements with a ΔSFP of 1.03° (p < 0 .0001).

The results of our study show that the use of intra-operative x-ray for the assessment of LCEA and AI is more reliable than fluoroscopic images. Further, we found a difference in SFP angle, which offers an indirect assessment of pelvic tilt, between the intra-operative and the post-operative plain x-rays. This suggests that there are changes in pelvic tilt during the surgery, which can be attributed to either patient positioning or changes in spino-pelvic posture secondary to the paralysing agents used by the anesthetists. The use of intra-operative x-rays as well as the effect of paralysing agents on spino-pelvic alignment should be considered by surgeons performing PAO's.

Endoprosthetic replacement (EPR) is an available option for the management of massive bone loss around failed knee implants. The aim of this study was to determine the results of knee EPRs performed for non-tumour indications. Since 2007, 85 EPRs were performed for in a single tertiary centre by seven surgeons. Mean age at surgery was 73.5 years (range:35–95) with infection as the most common indication (49%), followed by aseptic loosening (18%), complex primary replacement (16%), fracture (15%) and mechanical failure (2%). Mean follow up was 4 years (range:1–9). Functional outcome was determined using the Oxford Knee Score (OKS). At follow-up, 21 patients were deceased and 2 lost to follow-up. Complication rate was 19%. Of the 7 infected cases, 6 were treated with DAIR (debridement, antibiotics, and implant retention) and one underwent above knee amputation. Four of the patients undergoing DAIR were cleared of infection and 2 are on long-term antibiotics. Accounting for implant revision, loss to follow-up and those on long-term antibiotics as failures, 5-year survival was 89% with an average OKS of 25 (SD=10). This mid-term study shows that distal femur EPR is a valuable option for the increasing burden of complex revision knee surgery

Aim

Advocates of Debridement-Antibiotics-and-Implant-Retention (DAIR) in hip peri-prosthetic joint infection (PJI) argue that a procedure not disturbing a sound prosthesis-bone interface is likely to lead to better survival and functional outcome compared to revision. However, no evidence supports this. This case-control study's aims were to compare outcome of DAIRs for infected 1° total hip arthroplasty (THA) with outcomes following 1° THA and 2-stage revisions of infected 1° THAs.

Introduction

The burden of peri-prosthetic joint infection (PJI) following hip and knee surgery is increasing. Endoprosthetic replacement (EPR) is an option for management of massive bone loss resulting from infection around failed lower limb implants.

Debridement, antibiotics and implant retention (DAIR) is a surgical option in the treatment of prosthetic joint infection (PJI). It is thought to be most appropriate in the treatment of early (≤6 weeks post-op) PJI. Most studies to-date reporting on DAIRs in hip PJI have been underpowered by reporting on small cohorts (n= <45), or report on registry data with associated biases and limitations. In our, tertiary referral, bone infection unit we consider DAIR to be a suitable option in all cases of PJI with a soundly fixed prosthesis, with early or late presentation, especially in patients who are too elderly or infirm to undergo major surgery.

Aim: To define the 10-year outcome following DAIR in hip PJI and identify factors that influence it.

We retrospectively reviewed all DAIRs performed in our unit between 1997 and 2013 for hip PJI. Only infected cases confirmed by histological and microbiological criteria were included. Data recorded included patient demographics and medical history, type of surgery performed (DAIR or DAIR + exchange of modular components), organism identified and type/duration of antibiotic treatment. Outcome measures included complications, mortality rate, implant survivorship and functional outcome.

121 DAIRs were identified with mean age of 71 years (range: 33–97). 67% followed an index procedure of 1° arthroplasty. 53% included exchange of modular components. 60% of DAIRs were for early onset PJI. Isolated staphylococcus was present in 50% of cases and 25% had polymicrobial infection. At follow-up (mean:7 years, range: 0.3 – 18), 83 patients were alive; 5- and 10- year mortality rates were 15% and 35% respectively. 45% had a complication (persistence of infection: 27%, dislocation: 10%) and 40% required further surgery. Twenty hips have been revised to-date (17%). Performing a DAIR and not exchanging the modular components was associated with an almost 3× risk (risk ratio: 2.9) of subsequent implant failure (p=0.04). 10-yr implant survivorship was 80% (95%CI: 70 – 90%). Improved 10-year implant survivorship was associated with DAIR performed for early PJI (85% Vs 68%, p=0.04). Functional outcome will be discussed.

DAIR is a particularly valuable option in the treatment of hip PJI, especially in the early post-operative period. Whenever possible, exchange of modular implants should be undertaken, however DAIRs are associated with increased morbidity even in early PJI. Factors that predict success of DAIR in late PJI need to be identified.

INTRODUCTION

Metal-on-metal hip resurfacing (MoMHRA) requires a new standardized radiographic evaluation protocol. Evaluation of the acetabular component is similar to total hip arthroplasty but the femoral component requires different criteria since there is no component in the femoral canal and the metallic femoral implant overlies the junctions between bone-cement and cement-prosthesis. Lucencies around the metaphyseal HRA femoral stem can be described with the femoral zonal system into 3 peg-zones (Amstutz' et al) but this doesn't account for bony changes of the femoral neck away from the stem. This study proposes a new femoral zonal system for radiographic HRA assessment. We tested the efficacy of radiographs in identifying a problem by reviewing 711 radiographs of resurfaced hips and correlating radiographic features to outcome.

Introduction

Solid or cystic pseudotumour is a potentially destructive complication of metal on metal (MoM) couples, usually needing revision surgery. However, complete clearance of the pseudotumour is unlikely at times. This prospective case-controlled study reports cases which had recurrence after revision surgery for pseudotumour related to metal on metal hip couples.