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.

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.

Femoroacetabular impingement (FAI) – enlarged, aspherical femoral head deformity (cam-type) or retroversion/overcoverage of the acetabulum (pincer-type) – is a leading cause for early hip osteoarthritis. Although anteverting/reverse periacetabular osteotomy (PAO) to address FAI aims to preserve the native hip and restore joint function, it is still unclear how it affects joint mobility and stability. This in vitro cadaveric study examined the effects of surgical anteverting PAO on range of motion and capsular mechanics in hips with acetabular retroversion.

Twelve cadaveric hips (n = 12, m:f = 9:3; age = 41 ± 9 years; BMI = 23 ± 4 kg/m2) were included in this study. Each hip was CT imaged and indicated acetabular retroversion (i.e., crossover sign, posterior wall sign, ischial wall sign, retroversion index > 20%, axial plane acetabular version < 15°); and showed no other abnormalities on CT data. Each hip was denuded to the bone-and-capsule and mounted onto a 6-DOF robot tester (TX90, Stäubli), equipped with a universal force-torque sensor (Omega85, ATI). The robot positioned each hip in five sagittal angles: Extension, Neutral 0°, Flexion 30°, Flexion 60°, Flexion 90°; and performed hip internal-external rotations and abduction-adduction motions to 5 Nm in each position. After the intact stage was tested, each hip underwent an anteverting PAO, anteverting the acetabulum and securing the fragment with long bone screws. The capsular ligaments were preserved during the surgery and each hip was retested postoperatively in the robot. Postoperative CT imaging confirmed that the acetabular fragment was properly positioned with adequate version and head coverage. Paired sample t-tests compared the differences in range of motion before and after PAO (CI = 95%; SPSS v.24, IBM).

Preoperatively, the intact hips with acetabular retroversion demonstrated constrained internal-external rotations and abduction-adduction motions. The PAO reoriented the acetabular fragment and medialized the hip joint centre, which tightened the iliofemoral ligament and slackenend the pubofemoral ligament. Postoperatively, internal rotation increased in the deep hip flexion positions of Flexion 60° (∆IR = +7°, p = 0.001) and Flexion 90° (∆IR = +8°, p = 0.001); while also demonstrating marginal decreases in external rotation in all positions. In addition, adduction increased in the deep flexion positions of Flexion 60° (∆ADD = +11°, p = 0.002) and Flexion 90° (∆ADD = +12°, p = 0.001); but also showed marginal increases in abduction in all positions.

The anteverting PAO restored anterosuperior acetabular clearance and increased internal rotation (28–33%) and adduction motions (29–31%) in deep hip flexion. Restricted movements and positive impingement tests typically experienced in these positions with acetabular retroversion are associated with clinical symptoms of FAI (i.e., FADIR). However, PAO altered capsular tensions by further tightening the anterolateral hip capsule which resulted in a limited external rotation and a stiffer and tighter hip. Capsular tightness may still be secondary to acetabular retroversion, thus capsular management may be warranted for larger corrections or rotational osteotomies. In efforts to optimize surgical management and clinical outcomes, anteverting PAO is a viable option to address FAI due to acetabular retroversion or overcoverage.

It has been reported that 60-85% of patients who undergo PAO have concomitant intraarticular pathology that cannot be addressed with PAO alone. Currently, there are limited diagnostic tools to determine which patients would benefit from hip arthroscopy at the time of PAO to address intra-articular pathology. This study aims to see if preoperative PROMs scores measured by IHOT-33 scores have predictive value in whether intra-articular pathology is addressed during PAO + scope. The secondary aim is to see how often surgeons at high-volume hip preservation centers address intra-articular pathology if a scope is performed during the same anesthesia event.

A randomized, prospective Multicenter trial was performed on patients who underwent PAO and hip arthroscopy to treat hip dysplasia from 2019 to 2020. Preoperative PROMs and intraoperative findings and procedures were recorded and analyzed. A total of 75 patients, 84% Female, and 16% male, with an average age of 27 years old, were included in the study. Patients were randomized to have PAO alone 34 patients vs. PAO + arthroscopy 41 patients during the same anesthesia event. The procedures performed, including types of labral procedures and chondroplasty procedures, were recorded. Additionally, a two-sided student T-test was used to evaluate the difference in means of preoperative IHOT score among patients for whom a labral procedure was performed versus no labral procedure.

A total of 82% of patients had an intra-articular procedure performed at the time of hip arthroscopy. 68% of patients who had PAO + arthroscopy had a labral procedure performed. The most common labral procedure was a labral refixation which was performed in 78% of patients who had a labral procedure performed. Femoral head-neck junction chondroplasty was performed in 51% of patients who had an intra-articular procedure performed. The mean IHOT score was 29.3 in patients who had a labral procedure performed and 33.63 in those who did not have a labral procedure performed P- value=0.24.

Our findings demonstrate preoperative IHOT-33 scores were not predictive in determining whether intra-articular labral pathology was addressed at the time of surgery. Additionally, we found that if labral pathology was addressed, labral refixation was the most common repair performed. This study also provides valuable information on what procedures high-volume hip preservation centers are performing when performing PAO + arthroscopy.

This study aimed to analyse the incidence, the operative findings and outcomes of hip arthroscopy after periacetabular osteotomy (PAO).

We conducted a retrospective study of prospective collected data to report the operative findings and outcomes of hip arthroscopy for recurrent pain following PAO for acetabular dysplasia. Demographic data, radiographic and arthroscopic findings were analysed. Pre- and post-operative patient reported outcome measures (PROMs) were collected.

Of 184 PAO patients, 15 hips in 15 patients (8.2%) underwent post-PAO hip arthroscopy with 2 males and 13 females at a mean time of 3.9 ±2.9(0.3–10) years. Hip arthroscopy findings included labral tears (15 hips, 100%), chondral damage (11 hips, 73%) with one Beck 1, two Beck 2, four Beck 4, and four Beck 5 damage. There were 8 (53%) isolated labral debridement, 7 (47%) labral repair, and 2 (13%) adhesiolysis. A femoral osteochondroplasty was performed in 4 (27%) hips. Four hips (27%) were finally converted to total hip replacement at a mean delay of 2.3 ±1.4 (0.7–3.2) years post hip arthroscopy and these 4 patients were significantly older than those who were not (p=0.02). There were no significant differences in PROMs pre and post hip scope.

8.2% of patients undergoing a PAO required a hip scope for persistent hip pain. Common post-PAO hip arthroscopy findings included labral tears, chondral changes and femoroacetabular impingement. 27% of patients finally underwent conversion to total hip replacement at a mean follow-up of 4.5 years post hip scope.

Over 62,000 total hip arthroplasty (THA) cases are performed each year in Canada, with an estimated annual healthcare system cost of $1.4 billion and resulting in 4 billion tonnes of waste annually (6,600 tonnes per day). The aims of this study were 1) Assess satisfaction of current/standard set-up amongst different stakeholders. 2) Assess energy, economic and waste cost of current set up and apply lean methodology to improve efficiency 3. Design and test SLIM setup based on lean principles and its ability to be safely implemented into everyday practice.

A Needs Assessment Survey was circulated to OR nursing staff to assess the need for change in the current THA OR setup at an academic tertiary referral hospital. Through feedback, surgeon input, and careful analysis of current instrumentation, the “SLIM setup” was created. Standard instrument tray numbers for elective THA were reduced from 9 to 3 trays. Eighty patients were then randomised to either the standard or SLIM setup. Four staff arthroplasty surgeons each randomised 20 patients to either standard or SLIM setup. OR time, blood loss, 90-day complication rates, cost/case, instrument weight (kg/case), total waste in kg/case (non-recyclable), case set-up time, and number of times and number of extra trays required were compared between groups.

The majority of nursing staff demonstrated dissatisfaction with the current THA setup and felt current processes lacked efficiency. Use of the SLIM setup, was associated with the following savings in comparison to standard (Trays = −6 (720kg/case); Waste = −1.5 kg/case; Cost = − $560 ($50.00 × 6 trays + 10min saved × $26.00 /min OR setup time)). OR time, blood loss and 90-day complication rate were not statistically different (p >0.05); however, set up time was significantly shorter in comparison to standard. Extra instrumentation was opened in < 10% of cases.

A more minimalist approach to THA can be undertaken using the SLIM setup, potentially resulting in cost, energy and waste savings. Estimate savings of $560,000 and 1.65 tonnes reduction in waste per 1,000 THAs performed may be realised.

This matched cohort study aims to (a) assess differences in spinopelvic characteristics of patients having sustained a dislocation following THA and a control THA group without dislocation; (b) identify spinopelvic characteristics associated with risk of dislocation and; (c) propose an algorithm to define the optimum cup orientation for minimizing dislocation risk.

Fifty patients with a history of THA dislocation (29 posterior-, 21 anterior dislocations) were matched for age, gender, body mass index, index diagnosis, and femoral head size with 100 controls. All patients were reviewed and underwent detailed quasi-static radiographic evaluations of the coronal- (offset; center-of-rotation; cup inclination/anteversion) and sagittal- reconstructions (pelvic tilt, pelvic incidence, lumbar lordosis, pelvic-femoral-angle, cup ante-inclination). The spinopelvic balance (PI-LL), combined sagittal index (CSI= Pelvic-femoral-angle + Cup Anteinclination) and Hip-User-Index were determined. sagittal index (CSI= Pelvic-femoral-angle + Cup Anteinclination) and Hip-User-Index were determined. Parameters were compared between the two groups (2-group analysis) and between controls and per direction of dislocation (3-group analysis).

There were marginal coronal differences between the groups. Sagittal parameters (lumbar-lordosis, pelvic-tilt, CSI, PI-LL and Hip-User-Index) differed significantly. PI-LL (>10°) and standing pelvic tilt (>18°) were the strongest predictors of dislocation risk (sensistivity:70%/specificity:70%). All hips with a standing CSI<195° dislocated posteriorly and all with CSI>260° dislocated anteriorly. A CSI between 200–245° was associated with significantly reduced risk of dislocation (OR:6; 95%CI:2.5–15.0; p<0.001). In patients with unbalanced and/or rigid lumbar spine, standing CSI of 215–245° was associated with significantly reduced dislocation risk (OR:10; 95%CI:3.2–29.8; p<0.001).

PI-LL and standing pelvic-tilt determined from pre-operative, standing, lateral spinopelvic radiograph can be useful screening tools, alerting surgeons of patients at increased dislocation risk. Measurement of the pelvic-femoral angle pre-operatively provides valuable information to determine the optimum, cup orientation associated with reduced dislocation risk by aiming for a standing CSI of 200–245°.

Abstract

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.

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.

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.

Recently, new metallurgical techniques allowed the creation of 3D metal matrices for cementless acetabular components. Among several different products now available on the market, the Biofoam Dynasty cup (MicroPort Orthopedics® Inc., Arlington, TN, USA) uses an ultraporous Titanium technology but has never been assessed in literature. Coping with this lack of information, our study aims to assess its radiological osteointegration at two years in a primary total hip arthroplasty and compares it to a successful contemporary cementless acetabular cup.

This monocentric retrospective study includes 96 Dynasty Biofoam acetabular components implanted between March 2010 and August 2014 with a minimum 2 years radiographic follow-up. Previous acetabular surgery, any septic issue or re-operation for component malposition were exclusion criteria. They were compared to 96 THA using the Trident PSL matched for age, gender, BMI and follow-up. Presence of radiolucencies and sclerotic lines were described on AP pelvis views using the classification of DeLee and Charnley

There was no statistical difference between the two groups concerning demographics and mean follow-up (p> 0.05). Shell's anteversion was similar but inclination was greater in the biofoam group (p=0.006). 27,17% of the Biofoam shells presented radiolucencies in 2 zones or more and 0% of the Trident shells. 11,96% of Biofoam cups showed radiolucencies in the 3 zones of DeLee comparing to 0% of the Trident cups. There was no statistical difference between the Biofoam group (n=54/96) and the Trident PSL group (n=57/96) in pre-operative functional scores for both WOMAC subscales and SF-12. When evaluating last follow-up PROM's, no significant differences were found comparing the entirety of both groups, 56 Biofoam and 51 Trident PSL. No difference was found either when comparing Biofoam patients with ³ 2 zones of radiolucencies (n=15) to the whole Trident group (n=51).

This study raises concerns about radiologic evidence of osteointegration of the Biofoam acetabular cup. Nevertheless, these radiological findings do not find any clinical correlation considering clinical scores. Thus, it may question the real meaning of these high-rated radiolucencies, which at first sight reflect a poorer osteointegration. The first possible limitation with this study is an overinterpretation of the radiographs. Nevertheless, both observers were blinded regarding the patients groups and clinical outcomes and there was a strong inter-observer reliability. Although both cohorts were matched on their demographics and were similar on the cup anteversion, we noticed a slightly lower abduction angle in the Biofoam population. It could reduce the bone-implant coverage area and hence hinders the bony integration, but this difference was small and both groups remained in the Lewinneck security zone. Furthermore, even if patients were matched on age, gender, BMI and follow-up, other variables can influence early osteointegration (smoke status, osteoporosis) and have not been controlled even though we have no reasons to think their distribution could differ in the 2 groups.

The real clinical meaning of these findings remains unknown but serious concerns are raised about the radiographic osteointegration of the Dynasty Biofoam acetabular components. Concerns are all the more lawful that this implants aim to enhance osteointegration.

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.

Aims

Our study aimed to 1) determine if there was a difference for the HOOS-PS score between patients with stiff/normal/hypermobile spinopelvic mobility and 2) to investigate if functional sagittal cup orientation affected patient reported outcome 1 year post-THA.

Hip dysplasia has traditionally been classified based on the lateral centre edge angle (LCEA). A recent meta-analysis demonstrated no definite consensus and a significant heterogeneity in LCEA values used in various studies to define hip dysplasia and borderline dysplasia. To overcome the shortcomings of classifying hip dysplasia based on just LCEA, a comprehensive classification for adult acetabular dysplasia (CCAD) was proposed to classify symptomatic hips into three discrete prototypical patterns of hip instability, lateral/global, anterior, or posterior. The purpose of this study was to assess the reliability of this recently published CCAD.

One thirty four consecutive hips that underwent a PAO were categorized using a validated software (Hip2Norm) into four categories of normal, lateral/global, anterior or psosterior. Based on the prevalence of individual dysplasia and using KappaSize R package version 1.1, seventy four cases were necessary for reliability analysis: 44 dysplastic and 30 normal hips were randomly selected. Six blinded fellowship trained raters were then provided with the classification system and they looked at the x-rays (74 images) at two separate time points (minimum two weeks apart) to classify the hips using standard PACS measurements. Thereafter, a consensus meeting was held where a simplified flow diagram was devised before a third reading by four raters using a separate set of 74 radiographs took place.

Intra-rater results per surgeon between Time 1 and Time 2 showed substantial to almost perfect agreement amongst the raters. With respect to inter-rater reliability, at time 1 and time 2, there was substantial agreement overall between all surgeons (kappa of 0.619 for time 1 and 0,623 for time 2). Posterior and anterior rating categories had moderate and fair agreement at time 1 and time 2, respectively. At time 3, overall reliability (kappa of 0.687) and posterior and anterior rating improved from Time 1 and Time 2.

The comprehensive classification system provides a reliable way to identify three categories of acetabular dysplasia that are well-aligned with surgical management. The term borderline dysplasia should no longer be used.

Aims

Our study aimed to 1) Describe the changes in spinopelvic mobility when transitioning from standing, to ‘relaxed-seated’ and thereafter to ‘deep-seated’ position and 2) Determine the change in spinopelvic mobility types 1 year post-THA compared to preoperatively.

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.

The literature indicates that femoroacetabular impingement (FAI) patients do not return to the level of controls (CTRL) following surgery. The purpose of this study was to compare hip biomechanics during stair climbing tasks in FAI patients before and two years after undergoing corrective surgery against healthy controls (CTRL).

A total of 27 participants were included in this study. All participants underwent CT imaging at the local hospital, followed by three-dimensional motion analysis done at the human motion biomechanics laboratory at the local university. Participants who presented a cam deformity >50.5° in the oblique-axial or >60° in the radial planes, respectively, and who had a positive impingement test were placed in the FAI group (n=11, age=34.1±7.4 years, BMI=25.4±2.7 kg/m2). The remaining participants had no cam deformity and negative impingement test and were placed in the CTRL group (n=16, age=33.2±6.4 years, BMI=26.3±3.2 kg/m2). The CTRL group completed the biomechanics protocol once, whereas the FAI group completed the protocol twice, once prior to undergoing corrective surgery for the cam FAI, and the second time at approximately two years following surgery.

At the human motion biomechanics laboratory, participants were outfitted with 45 retroreflective markers placed according to the UOMAM marker set. Participants completed five trials of stairs task on a three step instrumented stair case to measure ground reaction forces while 10 Vicon MX-13 cameras recorded the marker trajectories. Data was processed using Nexus software and divided into stair ascent and stair descent tasks. The trials were imported into custom written MatLab software to extract peak pelvis and hip kinematics and hip kinetic variables. Non-parametric Kruskal-Wallis tests were used to determine significant (p < 0.05) differences between the groups.

No significant differences occurred during the stair descent task between any of the groups. During the stair ascent task, the CTRL group had significantly greater peak hip flexion angle (Pre-Op=58±7.1°, Post-Op=58.1±6.6°, CTRL=64.1±5.1°) and sagittal hip range of motion (ROM) (Pre-Op=56.7±6.7°, Post-Op=56.3±5.5°, CTRL=61.7±4.2°) than both the pre- and post-operative groups. Pre-operatively, the FAI group had significantly less peak hip adduction angle (Pre-Op=2±4.5°, Post-Op=3.4±4.4°, CTRL=5.5±3.7°) and hip frontal ROM (Pre-Op=9.9±3.4°, Post-Op=11.9±5.4°, CTRL=13.4±2.5°) compared to the CTRL group. No significant differences occurred in the kinetic variables.

Our findings are in line with the Rylander and colleagues (2013) who also found that hip sagittal ROM did not improve following corrective surgery. Their study included a mix of cam and pincer-type FAI, and had a mean follow-up of approximately one year. Our cohort included only cam FAI and they had a mean follow-up of approximately two years, indicating with the extra year, the patients still did not show sagittal hip kinematics improvement. In the frontal plane, there was no significant difference between the post-op and the CTRL, indicating that the postoperative FAI reached the level of the CTRLs. This is in line with recent work that indicates a more medialized hip contact force vector following surgery, suggesting better hip stabilization.

The effectiveness of total hip replacement as a surgical intervention has revolutionized the care of degenerative conditions of the hip joint. However, the surgeon is still left with important decisions in regards to how best deliver that care with choice of surgical approach being one of them especially in regards to the short-term clinical outcome. It is however unclear if a particular surgical approach offers a long-term advantage. This study aims to determine the influence of the three main surgical approaches to the hip on patient reported outcomes and quality of life after 5 years post-surgery.

We extracted from our prospective database all the patients who underwent a Total Hip Replacement surgery for osteoarthritis or osteonecrosis between 2008 and 2012 by an anterior, posterior or lateral approach. All the pre-operative and post-operative HOOS (Hip disability and Osteoarthritis Outcome Score) and WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) scores were noted. Analysis of covariance (ANCOVAs) were used to study the relationship between amount of change in HOOS and WOMAC subscales (dependant variables) and approach used, by also including confounding factors of age, gender, ASA (American Society of Anaesthesiologists) score, Charnley score and Body Mass Index. A total of 1895 patients underwent a primary total hip arthroplasty during the considered period. Among them, 367 had pre-operative and ≥5 years post operative PROM scores (19.47%)

The mean follow-up for the study cohort was 5.3 years (range 5 to 7 years) with, 277 at 5 years, 63 at 6 years, and 27 at 7 years. In the posterior approach group we had 138 patients (37.60%), 104 in the lateral approach (28.34%) and 125 in the anterior approach (34.06%). There were no significant differences between the 3 groups concerning the Charnley classification, BMI, Gender, ASA score, side and pre-operative functional scores. We did not observe any significant difference in the amount of change in HOOS and WOMAC subscales between the 3 groups. There were no differences either in the post-operative scores in ultimate value.

Our monocentric observational study shows that these three approaches provide predictable and comparable outcomes on HRQL and PROMs at long-term follow-up both in terms of final outcome but also in percent improvement. This study has several limitations. We excluded patients who underwent revision surgery leaving the unanswered question of how choice of surgical approach could lead to different revision rates, which have an impact on the functional outcomes. Moreover, even if we controlled for the most important confounders by a multivariate analysis model, there is still some involved cofounders, which could potentially lead to a bias such as smoking, socio-economical status or femoral head diameter. But we do not have any reason to think that these parameters could be unequally distributed between the three groups. Finally, our study cohort represents of 19.47% of the complete cohort. The fact that not all patients have PROM's was pre-determined as eight years ago we instituted that only 1 in 5 patients that returned their pre-operative questionnaire would get their PROM's at follow-up. Despite this, our statistical power was sufficient.

Introduction

Patients with reduced lumbar spine mobility are at higher risk of dislocation after THA as their hips have to compensate for spinal stiffness. Therefore our study aimed to 1) Define the optimal protocol for identifying patients with mobile hips and stiff lumbar spines and 2) Determine clinical and standing radiographic parameters predicting high hip and reduced lumbar spine mobility.

Aims

The aims of the study were to determine the differences in spinopelvic mobility between a cohort of hip OA patients and a control group for the 1) standing to relaxed-seated and 2) standing to deep-seated task.

Developmental dysplasia of the hip (DDH) is a common risk factor of early osteoarthritis (OA), with insufficient coverage of the femoral head by the acetabulum which leads to excessive cartilage stresses in the hip joint. Knowledge of the molecular health of cartilage using MRI may diagnose and stage chondral disease, but more importantly allows for treatment stratification and prognostication. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is a validated MRI technique for detecting early loss of proteoglycan (PG). However, it requires an injection of contrast agent and exercise prior to the scan. MRI techniques such as T1ρ and T2 mapping have also been shown to be sensitive to early biochemical changes in cartilage but can be performed without any contrast injection. In this study we evaluate three quantitative MR techniques (dGEMRIC, T1ρ and T2 mapping) in patients with DDH. Our hypothesis is that both T1ρ and T2 correlate with dGEMRIC, and thus may be effective non-contrast based techniques for biochemical cartilage mapping in DDH hips.

Seven informed and consented patients (mean age: 31.1 years) with DDH were enrolled in this IRB approved MRI study before surgery. DDH was defined as a lateral center-edge angle under 25º and acetabular index >13º on the plain x-ray. All subjects underwent two successive MRI sessions at 3T: In the first cartilage T1ρ and T2 mapping were performed. After leaving the scanner the subjects were injected with 0.4ml/kg Dotarem (i.v.), walked for 15min and rested for 25min before returning into the MRI. dGEMRIC (T1post) mapping was initiated approximately 45min after the injection. Image post-processing, registration and cartilage segmentation was performed with Matlab. The joint was subdivided into anterior and posterior regions in the sagittal plane and into lateral, intermediate and medial zones in the transverse plane, resulting in six region of interest (ROIs): antero-lateral, antero-intermediate, antero-medial, postero-lateral, postero-intermediate and postero-medial. The correlation between the dGEMRIC and T1ρ and dGEMRIC and T2 were evaluated using Spearman's Rho and tested for significance.

The analysis of all six cartilage ROIs for all subjects resulted in a significant (p < 0 .001) negative correlation (Rho = −0.50) between the dGEMRIC index (T1post) and the T1ρ relaxation time. The dGEMRIC index and T2 correlated positive (Rho = 0.55) and significant (p < 0 .001).

Although this pilot study has a small sample size a negative correlation between dGEMRIC and T1ρ was found in patients with DDH. Both methods are known to probe the PG content of cartilage, where a decreased PG content leads to lower dGEMRIC index and an increased T1ρ value. The correlation coefficient was moderate, but significant, which shows that T1ρ mapping as an effective tool to probe the cartilage PG content similar to dGEMRIC. A comparable, but positive correlation was found between dGEMRIC and T2. T2 is sensitive to the cartilage collagen content with a decreased T2 value in degenerated cartilage. In symptomatic DDH, where an onset of OA is assumed, both PG depletion and collagen decay are in progress and can be evaluated using these mapping techniques.

Cam-type femoroacetabular impingement (FAI) is a common cause for athletic hip injury and early hip osteoarthritis. Although corrective cam FAI surgery can improve patient reported outcome measures (PROMs), it is not clear how surgery affects muscle forces and hip joint loading. Surgery for FAI may redistribute muscle forces and contact forces at the hip joint during routine activities. The purpose of this study was to examine the muscle contributions and hip contact forces during gait in patients prior and after two years of undergoing surgery for cam FAI. Kinematics and kinetics were recorded in 11 patients with symptomatic cam FAI as they completed a gait task. Muscle and hip contact forces during the stance phase were estimated using musculoskeletal modelling and static optimization in OpenSim. All patients reported improvements in PROMs. Post-operatively, patients showed reduced forces in the long head of the biceps femoris at ipsilateral foot-strike and in the rectus femoris at the contralateral foot-strike. The reduced muscle forces decreased sagittal hip moment but did not change hip contact forces. This was the first study to evaluate hip muscle and contact forces in FAI patients post-operatively. Although hip contact forces are not altered following surgery, muscle forces are decreased even after two years. These findings can provide guidance in optimizing recovery protocols after FAI surgery to improve hip flexor and extensor muscle forces.

Total hip arthroplasty (THA) is one of the most successful surgery. However, patients' expectations have increased over the last two decades in regards to hip function after joint replacement, the patients assume to return their daily and sport activities without major limitations. This presentation will examine the effect of surgical approaches and implant designs as well as rehabilitation protocol on the clinical and biomechanical outcomes after THA. The new implant designs for THA aim to improve joint function whereas the surgical approaches intend to reduce muscle damage to regain muscle strength. One important determinant measured from gait analysis is the hip abduction moment as the abductors play a key role in stabilizing the pelvis in the frontal plane, particularly in phases of transition, such as the single leg stance in walking or stair climbing. This showed that muscle strength needs to be preserved. To minimize the risk of hip joint instability, a strong focus of implant development has been carried out. To illustrate this important concept within the context of gait analysis, I will present two studies that examine the influence of surgical approach and biomechanical reconstruction; and the second, is a prospective RCT comparing a dual mobility implant to a standard total hip replacement.

Introduction

The resultant cup orientation depends upon the orientation of the pelvis at impaction. No studies to date have assessed whether patient-position during total hip arthroplasty (THA) has an effect on cup orientation. This study aims to 1) Determine the difference in pelvic position that occurs between surgery and radiographic, supine, post-operative assessment; 2) Examine how the difference in pelvic position influences subsequent cup orientation and 3) Establish whether pelvic orientation, and thereafter cup orientation, differences exist between THAs performed in the supine versus the lateral decubitus positions.

Introduction

The mechanisms of how spinal arthrodesis (SA) affects patient function after total hip replacement (THA) remain unclear. The objectives of this study were to a) Determine how outcome post-THA compares between patients with- and without-SA, b) Characterize sagittal pelvic changes that occur when moving between different functional positions, and test for differences between patients with- and without-SA, and c) Assess whether differences in sagittal pelvic dynamics are associated with outcome post-THA.

Introduction

The changes in sagittal spino-pelvic balance from standing to sitting in patients with end-stage osteoarthritis (OA) of the hip remain poorly characterized. Our aim was to 1) investigate the contribution of sagittal spino-pelvic movement and hip flexion when moving from a standing to sitting posture in patients with hip OA; 2) determine the proportion of OA-patients with stiff, normal or hypermobile spino-pelvic mobility and 3) identify radiographic parameters correlating with spino-pelvic mobility.

The current study aimed to determine the influence of acetabular coverage and intraarticular pathology on post-operative functional outcomes of arthroscopy for cam type FAI.

Based on 762 hip scopes performed by a single surgeon between 2013 and 2016, we excluded patients with previous surgery on the hip, mixed FAI, surgical hip dislocation, and missing outcome scores. From this, 97 hips between the ages 17 and 48 that underwent arthroscopy for cam deformity were identified for analysis. Every patient received a partial capsulotomy, cam resection and either labral repair or resection. Measurements for acetabular coverage consisted of pre-operative lateral edge angle (LCEA) (mean 30°, range: 15.4°–40°) and three-dimensional anterior and posterior acetabular coverages. Intraoperative Beck scores were acquired from operative reports, and Hip Disability and Osteoarthritis Outcome Score (HOOS) was collected pre- and post-operatively.

Significant post-operative improvement was found in scores of all categories of the HOOS (p < 0.05). However, improvement in HOOS was not correlated with the LCEA, anterior coverage, or posterior coverage. There was a trend toward lower Beck grades (1–3) resulting in better HOOS outcomes than higher Beck grades (4–5). Also, lower Beck grades showed significantly lower alpha angle (mean = 55.86) than higher grades (mean = 73.48).

We showed that cam FAI arthroscopic resection improved patient outcome, and confirmed the relationship between the Beck score and functional outcome. However, functional improvement was not related to acetabular coverage suggesting that the so-called “borderline” dysplasia is not a useful radiographic indicator for surgical management.

In approximately 20 years, surgical treatment of femoro-acetabular impingement (FAI) has been widely accepted, and its indications refined. However, the current approach of the disease prevents a good understanding of its pathophysiology, and numerous uncertainties remain. Comprehending inter-individual spine-hip relations (SHRs) can further clarify the pathophysiology of impingement, and explain occasional surprising mismatch between clinical assessment and imaging or intraoperative findings. The rational is simple, the more the spino-pelvic complex is mobile (sagittal ROM) and the more the hip is protected against hip impingement but would probably become at risk of spine-hip syndrome if the spino-pelvic complex comes to degenerate. Grouping patients based on their spine-hip relation can help predict and diagnose hip impingement, and assess the relevance of physiotherapy. With the proposed new classification of FAIs, every patient can be classified in homogeneous groups of complexity of treatment. The primary aim of this paper is to raise awareness of the potential impact that the spine-hip relations have on the hip impingement disease. Two new classifications are proposed, for FAIs and SHRs that can help surgeons in their comprehension, and could be beneficial in clinical and research areas.

Dual mobility (DM) bearing implants reduce the incidence of dislocation following total hip arthroplasty (THA) and as such they are used for the treatment of hip instability in both primary and revision cases. The aim of this study was to compare lower limb muscle activity of patients who underwent a total hip arthroplasty (THA) with a dual mobility (DM) or a common cup (CC) bearing compared to healthy controls (CON) during a sit to stand task.

A total of 21 patients (12 DM, 9 CC) and 12 CON were recruited from the local Hospital. The patients who volunteered for the study were randomly assigned to either a DM or a CC cementless THA after receiving informed consent. All surgeries were performed by the same surgeon using the direct anterior approach. Participants underwent electromyography (EMG) and motion analysis while completing a sit-to-stand task. Portable wireless surface EMG probes were placed on the vastus lateralis, rectus femoris, biceps femoris, semitendinosus (ST), gluteus medius and tensor fasciae latae muscles of the affected limb in the surgical groups and the dominant limb in the CON group. Motion capture was used to record lower limb kinematics and kinetics. Muscle strength was recorded using a hand-held dynamometer during maximal voluntary isometric contraction (MVIC) testing. Peak linear envelope (peakLE) and total muscle activity (iEMG) were extrapolated and normalized to the MVIC and time cycle for the sit to stand task. Using iEMG, quadriceps-hamstrings muscle co-activation index was calculated for the task. Nonparametric Kruskal Wallace ANOVA tests and Wilcoxon rank sum tests were used to identify where significant (p < 0.05) differences occurred.

The DM group had greater iEMG of the ST muscle compared to the CC (p=0.045) and the CON (p=0.015) groups. The CC group had lower iEMG for hamstring muscles compared to the DM (p=0.041) group. The DM group showed lower quadriceps-hamstrings co-activation index compared to the CON group and it approached significance (p=0.054). The CC group had greater anterior pelvis tilt compared to both DM (p=0.043) and the CON (p=0.047) groups. The DM also had larger knee varus angles and less knee internal rotation compared to both groups, however this never reached significance. No significant differences in muscle strength existed between the groups.

Higher ST muscle activity in the DM group is explained by the reduction in internal rotation at the knee joint as the ST muscle was more active to resist the varus forces during the sit-to-stand task. Reduced quadriceps activity in the CC group is explained by increased pelvic anterior tilt as this would shorten the moment arm and muscle length in the quadriceps, ultimately reducing quadriceps muscle activity. The reduced co-activation between quadriceps and hamstrings activity in the DM group compared to the CC and CON groups is related to better hip function and stability. Combining lower co-activation and larger range of motion for the DM group without impingement, this implant seems to offer better prevention against THA subluxation and less wear of the implant.

The incidence of lateral femoral cutaneous nerve (LFCN) neuropraxia after anterior approach total hip arthroplasty has been reported to occur in up to 50% of patients. In the vast majority of cases there has been no functional impact it is unknown if symptoms persist or diminish over time. The aim of this study was to examine the natural history LFCN neuropraxia in a previously reported cohort of individuals after anterior approach total hip arthroplasty.

One hundred and forty three consecutive patients underwent direct anterior hip approach (DAA) between September 2006 and February 2009 of which 107 had been identified with LCFN neuropraxia. These 107 patients (39 THA; 68 HR; 44 Female & 63 male; mean age 55.4 (38.4–88.8)), were provided a self-reported questionnaire for sensory deficits associated with LFCN as well as severity of symptoms on a 10 point visual analogue scale (VAS). These were done at initial assessment and latest follow-up.

Sixty of the 107 patients (56%) completed their questionnaires at a mean follow-up of 5.4 years (24 THA; 36 HR). Twenty-two percent (13 of 60: 8 men & 5 women) had complete resolution of their symptoms (9 HR and 4 THR). Of the 47 patients (78%) still reporting symptoms of LFCN neuropraxia, the mean score on VAS decreased from a mean of 2.32 (SD:2.11) to 1.74 (SD:1.99). No limitation in activities was reported for 90% of patients (54 out of the 60). Of the 6 patients (10%) with limited activity they reported a mean VAS score of 4.4 (SD: 3.6 range of 0–8.4). The LFCN symptoms did not appear to be directly related to their activity limitation.

While LFCN neuropraxia can be a common complication following direct anterior approach hip replacement, almost a quarter of patients will have complete resolution of symptoms and the majority will have a decrease in their symptomatology. LFCN neuropraxia following DAA hip arthroplasty does not appear to lead to any functional limitations and is associated with a low score on VAS.

With the rapid evolution of surgical techniques every practicing surgeon will need to introduce new skills into their practice. Despite evidence that introducing a new surgical technique is associated with a learning curve during which there are reduced surgical and patient outcomes, there are no suggested protocols in place to support a surgeon in safely introducing a procedure into established practice. The purpose of this pilot study was to compare the effects of a mentored approach to learning new technical skills in practice to an unmentored approach.

A mentorship partnership and learning protocol was developed between a learning surgeon and an expert in the Direct Anterior Approach (DAA) total hip arthroplasty. After training in the technique the learning surgeon was directly supported in the first 3 cases and mentored for the first 15 cases.

Outcomes (surgical times, estimated blood loss, canal fit and fill, acetabular inclination and version, and complications) for the learning surgeons first 30 cases were assessed and compared to another learned cohort (first 30 cases of a percutaneously assisted total hip arthroplasty) integrated into practice without the support of a mentor. This data allow for the comparison of learning curves between the 2 techniques

Use of a mentored approach to the introduction of a new surgical skill was demonstrated to be a safe and more efficient than with an independent introduction of skills. The surgical times and learning curve were reduced and anectodatly the surgeons stress level was markedly reduced with a mentored approach. These findings support further work into surgical mentorship for the safe introduction of surgical skills in practice.

Cam-type femoral acetabular impingement (FAI), is a common structural hip deformity and thought to be a leading cause of early hip osteoarthritis. Although patients who undergo surgical correction notice improved clinical function it is unclear what impact this has on the overall health of the cartilage. T1rho MRI cartilage mapping has been shown to be a reliable imaging technique to assess the proteoglycan (PG) content potentially serving as a biomarker. This study analyses post surgical changes in T1rho levels in hip joints treated with cam FAI.

Eleven patients with a mean age of 38 (all males) underwent pre and post T1Rho Cartilage mapping of their hips at a mean time of 20 months post surgical intervention. The acetabulum was spatially divided into 4 main regions of interest (ROI), with levels of T1Rho in cartilage quantified as a whole and in each spatial segment. T1Rho signal is inversely correlated with level of PG content.

All patients demonstrated loss of PG content on pre-op imaging with a T1Rho of 33.5ms+2.6ms. Preop T1rho levels were found to significantly correlated with the difference between pre-op and post-op T1rho in entire hip cartilage (R: 0.73; p=0.016). This correlation was reflected both in the anterolateral quadrant (R: 0.86; p=0.002), and in the posteriosuperior quadrant (R:0.70; p=0.035). Additionally, significant correlation was found between improvement of WOMAC pain score over time, and difference of T1rho values over time in the most lateral 3mm slice of the anterolateral quadrant (R: 0.81; p=0.045). Significant correlation was found between pre-op alpha angle at 1:30 and difference between pre-op and post-op total cartilage T1rho content (R: −065;p=0.038).

T1Rho Cartilage mapping of the hip is a useful biomarker in the assessment of the surgical management of Cam type FAI. This preliminary data provides some evidence that surgical correction of the deformity can help minimise disease progression.

With the growing number of individuals with asymptomatic cam-type deformities, elevated alpha angles alone do not always explain clinical signs of femoroacetabular impingement (FAI). Differences in additional anatomical parameters may affect hip joint mechanics, altering the pathomechanical process resulting in symptomatic FAI. The purpose was to examine the association between anatomical hip joint parameters and kinematics and kinetics variables, during level walking.

Fifty participants (m = 46, f = 4; age = 34 ± 7 years; BMI = 26 ± 4 kg/m²) underwent CT imaging and were diagnosed as either: symptomatic (15), if they showed a cam deformity and clinical signs; asymptomatic (19), if they showed a cam deformity, but no clinical signs; or control (16), if they showed no cam deformity and no clinical signs. Each participant's CT data was measured for: axial and radial alpha angles, femoral head-neck offset, femoral neck-shaft angle, medial proximal femoral angle, femoral torsion, acetabular version, and centre-edge angle. Participants performed level walking trials, which were recorded using a ten-camera motion capture system (Vicon MX-13, Oxford, UK) and two force plates (Bertec FP4060–08, Columbus, OH, USA). Peak sagittal and frontal hip joint angles, range of motion, and moments were calculated using a custom programming script (MATLAB R2015b, Natick, MA, USA). A one-way, between groups ANOVA examined differences among kinematics and kinetics variables (α = 0.05), using statistics software (IBM SPSS v.23, Armonk, NY, USA); while a stepwise multiple regression analysis examined associations between anatomical parameters and kinematics and kinetics variables.

No significant differences in kinematics were observed between groups. The symptomatic group demonstrated lower peak hip abduction moments (0.12 ± 0.08 Nm/kg) than the control group (0.22 ± 0.10 Nm/kg, p = 0.01). Sagittal hip range of motion showed a moderate, negative correlation with radial alpha angle (r = −0.33, p = 0.02), while peak hip abduction moment correlated with femoral neck-shaft angle (r = 0.36, p = 0.009) and negatively with femoral torsion (r = −0.36, p = 0.009). With peak hip abduction moment in the stepwise regression analysis, femoral torsion accounted for a variance of 13.3% (F(1, 48) = 7.38; p = 0.009), while together with femoral neck-shaft angle accounted for a total variance of 20.4% (R² change = 0.07, F(2, 47) = 6.01; p = 0.047).

Although elevated radial alpha angles may have limited sagittal range of motion, the cam deformity parameters did not affect joint moments. Femoral neck-shaft angle and femoral torsion were significantly associated with peak hip abduction moment, suggesting that the insertion location of the abductor affects muscle's length and its resultant force vector. A varus neck angle, combined with severe femoral torsion, may ultimately influence muscle moment arms and hip mechanics in individuals with cam FAI.

The Spine Adverse Events Severity System (SAVES) and Orthopaedic Surgical Adverse Events Severity System (OrthoSAVES) are standardised assessment tools designed to record adverse events (AEs) in orthopaedic patients. The primary objective was to compare AEs recorded prospectively by orthopaedic surgeons compared to trained independent clinical reviewers. The secondary objective was to compare AEs following spine, hip, knee, and shoulder orthopaedic procedures.

Over a 10-week period, three orthopaedic spine surgeons recorded AEs following all elective procedures to the point of patient discharge. Three orthopaedic surgeons (hip, knee, and shoulder) also recorded AEs for their elective procedures. Two independent reviewers used SAVES and OrthoSAVES to record AEs after reviewing clinical notes by surgeons and other healthcare professionals (e.g. nurses, physiotherapists). At discharge, AEs recorded by the surgeons and independent reviewers were recorded in a database.

AE data for 164 patients were collected (48 spine, 52 hip, 33 knee, and 31 shoulder). Overall, 98 AEs were captured by the independent reviewers, compared to 14 captured by the surgeons. Independent reviewers recorded significantly more AEs than surgeons overall, as well as for each individual group (i.e. spine, hip, knee, shoulder) (p2), but surgeons failed to record minor events that were captured by the independent reviewers (e.g. urinary retention and cutaneous injuries; AEs Grade 0.05). AEs were reported in 21 (43.8%), 19 (36.5%), 12 (36.4%), and five (16.1%) spine, hip, knee, and shoulder patients, respectively. Nearly all reported AEs required only simple or minor treatment (e.g. antibiotic, foley catheter) and had no effect on outcome. Two patients experienced AEs that required invasive or complex treatment (e.g. surgery, monitored bed) that had a temporary effect on outcome.

Similar complication rates were reported in spine, hip, knee, and shoulder patients. Independent reviewers reported more AEs compared to surgeons. These findings suggest that independent reviewers are more effective at capturing AEs following orthopaedic surgery, and thus, could be recruited in order to capture more AEs, enhance patient safety and care, and maximise different complication diagnoses in alignment with proposed diagnosis-based funding models.

Introduction

Although femoral neck fractures remain a concern in short term failures for hip resurfacing, acetabular component position and fixation are increasingly being recognized as causes of mid term failures for hip resurfacing. This study aimed to evaluate the migration pattern of a cobalt chrome, beaded acetabular component for a metal on metal hip resurfacing.

Introduction

Modern cementless press fit stems rely on early fixation and stability for osteointegration and longterm success with early migration increasing the risk of failure. The Ein Bild Roentegen Analyse Femoral Component Analysis (EBRA-FCA) methods allow accurate measurement of femoral stem subsidence without the need for Tantalum markers. The degree of subsidence of femoral stems in the first two years has been shown to be highly predictive of failure when using the cut off value of 1.5 mm. We aimed to measure the early migration pattern of a titanium alloy, tapered, plasma and hydroxyapatite coated femoral stem and any factors associated with subsidence.

Purpose: A growing body of literature confirms that idiopathic OA is frequently caused by subtle, and often radiographically occult, abnormalities at the femoral head-neck junction or acetabulum that result in abnormal contact between the femur and acetabulum. This condition, known as femoroacetabular impingement, is a widely accepted cause of early OA of the hip. MRI is the imaging modality that is most sensitive in detecting cam morphology. There is currently little published data regarding the prevalence of abnormalities of the femoral head-neck junction in patients without hip pain or previous hip pathology. The primary aim of this project is to examine the incidence of cam morphology in a population without hip pain or pre-existing hip disease using non-contrast MRI.

Method: Two hundred asymptomatic volunteers underwent magnetic resonance imaging targeted to both hips. Subjects were examined at the time of MRI to document internal rotation of the hips at 90 degrees flexion and to assess for a positive impingement sign. The mean age was 29.4 years (range 21.4–50.6); 77.5% were Caucasian and 55.5% female. The Nötzli alpha angle was measured on oblique axial images through the middle of the femoral neck for each hip. A value greater than 50 degrees was considered consistent with cam morphology. Measurements were performed independently by two musculoskeletal radiologists.

Results: Twenty-six percent of volunteers had at least one hip with cam morphology: 20% had an elevated alpha angle on either the right or the left side, and 6% had bilateral deformity. The average alpha angle was 42.6 degrees on the right (SD=7.9) and 42.4 degrees on the left (SD=7.7). Internal rotation was negatively correlated with alpha angle (p< .05). Patients with an elevated alpha angle on at least one side tended to be male (p< .01).

Conclusion: The high prevalence of cam morphology in asymptomatic individuals is critical information in determining the natural history of FAI as well as establishing treatment strategies in patients presenting with pre-arthritic hip pain.

Purpose: The short-term results of metal-on-metal hip resurfacing (HR) have been excellent. However, extensile approaches such as the posterior and trochanteric slide have been used to ensure proper component placement. The minimally invasive (MI) anterior Hueter approach is both muscle and vascular sparing to the femoral head. The purpose of this study is to evaluate the learning curve of this approach in performing hip resurfacing.

Method: The first 50 MI HR done by a single high volume arthroplasty surgeon were compared with his previous fifty procedures performed through a trochanteric slide osteotomy, with respect to (BMI, sex, etiology and age) were comparable (p=.372,.122,.143 and .353, respectively).

Results: Overall, the traditional transtrochanteric lateral approach took significantly longer to perform compared to MI RAH (97 versus 109 minutes, p=0.014). If we exclude the first 25 MI RAH cases (mean, 106 minutes), the difference is greater (89 versus 109 minutes, p=0.002). The mean femoral component stem to femoral shaft angle (SSA) was not significantly different between the two groups (MI RAH=142.7, lateral approach=140.0, p=0.053). The cup abduction angle (CA) was slightly different between the two groups (MI RAH 42.5°, lateral approach=39.2°, p=0.03). More patients had cup abduction angles in the 45°–55° range (p=0.009) in the MI HR group but none had a cup angle over 55° of abduction in either group. On the femur side, component positioning was comparable.

Conclusion: Based on our early results, the anterior-Hueter approach is a reasonable alternative to more extensile surgical approaches. Like any MI approach to hip surgery, great care has to be taken not to put the cups too vertical. Further long-term studies as well as comparisons to other approaches such as the posterior approach will determine if the anterior approach can be recommended for hip resurfacing.

Purpose: Femoroacetabular impingement (FAI) has recently been described as a cause of adult hip pain and a precursor of hip osteoarthritis. Pincer type is secondary to acetabular retroversion or coxa profunda and Cam type is secondary to lack of concavity/offset of the antero-lateral femoral head-neck junction. Purpose of this study was to determine the prevalence of bilateral deformity in patients with cam type FAI as well as the presence of associated acetabular abnormalities.

Method: One hundred and thirteen patients with symptomatic cam impingement (alpha (α) angle of Notzli > 55.5°) of at least one hip were evaluated. Eighty-two males, 31 females with an average age of 37.9 yrs (16–55). Standardized AP pelvis and bilateral Dunn views were reviewed. Alpha angle of Notzli was measured on Dunn views. Cam impingement was defined by α angle > 55.5 on the Dunn view and Pincer impingement was defined by the presence of either acetabular retroversion or coxa profunda. Statistical analysis was done using the two tailed paired t-test, chi-square test and intra-class correlation coefficient. Odds Ratios were calculated using conditional logistic regression.

Results: Eighty-eight patients (77.8%) had bilateral deformity and 27% had symptoms in both hips. Mean α angles were higher for bilateral impingement deformity than for the impingement side only when unilateral deformity was present (72.10 versus 64.50, p< 0.001). Forty-four percent of hips with an impingement deformity also had a pincer deformity, either acetabular retroversion or coxa profunda. Painful hips had a statistically significant higher mean alpha angle than asymptomatic ones (69.70 versus 63.10, p< 0.001)). Comparing hips with α angles of 61–70 with those < 60 found an odds ratio of being painful of 2.59 (95% CI: 1.32–5.08, p=0.006). Hips with α angles > 71 had an odds ratio of being painful of 2.54 (95% CI: 1.3–4.96, p=0.007).

Conclusion: The majority of patients with cam type FAI have bilateral deformities and an associated acetabular deformity less commonly. The severity of the deformity at the femoral head neck junction is a significant determining factor for the development of hip symptoms. This information is important as we better define the natural history of this deformity as well as devise effective treatment strategies.

The femoroacetabular conflict is a recognized cause of hip pain in young patients. It is associated with rim tears. Two types of conflict have been described: impingement due to retroversion of the acetabulum and «cam effect» associated with insufficient head/neck offset. A recent subject of debate has been isolated treatment of the rim tear without treating the often unrecognized bone anomaly. The purpose of this study was to assess short-term outcome after surgical remodeling of the head/neck junction for the treatment of femoroacetabular conflicts.

Material and methods: There were 37 hips (18 men and 16 women) with chronic pain for more than three months. Mean patient age was 41 years (range 24–52). Preoperative 3D CT and MRI with gadolinium arthrography were available for all patients. Surgical remodeling of the head/neck junction via digastric trochanterotomy with surgical dislocation was performed. Preoperatively, the mean Notzli alpha angle was 65.6° (range 42–95°). Among the 34 patients, only four practiced sports requiring large range hip motion. MRI revealed a rim lesion in all patients. The following tests were performed: UCLA hip test, WOMAC (Western Ontario McMaster Osteoarthritis) index, and SF-12.

Results: Mean follow-up was 2.5 years (range 2–4); pre- and postoperative scores were: WOMAC 59.2 and 81.0 (p< 0.001), UCLA scores 4.2 and 7.9 for pain, 7.3 and 9.0 for gait, 6.2 and 8.5 for function, 4.3 and 6.9 for activity (p< 0.05). The physical component of the SF-12 improved from 37.4 to 44.2 (p< 0.006) and the mental component from 46.0 to 51.6 (p< 0.03). None of the hips required revision to modify the joint configuration. Two complications were noted: one rupture of the greater trochanter and one heterotopic ossification requiring resection. Osteonecrosis was not observed. The trochanter implants were removed in nine patients because of pain.

Discussion: The femoroacetabular conflict results from insufficient concavity of the anterolateral head/neck junction associated with a rim tear. Correction of the bony anomaly provided significant short-term functional improvement both for the hip and for the patient’s general health. Correction of the offset by surgical dislocation of the hip is effective and safe treatment of the femoroacetabular conflict with preservation of the rim.

Fourteen hips with osteoarthritis had femoral head blood flow measured with laser Doppler flowmeter while undergoing during total hip replacement through a modified lateral approach. Mean age sixty-five years (48–77); eight males & six females. Two measurements were taken within the femoral head one after anterior hip dislocation and one after simulated notching of the femoral neck. All hips had a significant decrease in blood flow with a median percentage decrease of 76% (range 4.4–90.4). During surface arthroplasty of the hip, notching of the femoral neck may not only mechanically weaken the bone but also put the femoral head at risk of osteonecrosis.

To evaluate femoral head blood supply in patients with osteoarthrtis of the hip undergoing simulated notching of the femoral neck during total hip replacement and its potential implications in hip resurfacing.

During surface arthroplasty of the hip, notching of the femoral neck may not only mechanically weaken the femoral neck but also put the femoral head at risk of osteonecrosis and subsequent femoral loosening.

It would appear that the retinacular vessels (extraosseous blood supply) are as important in the arthritic femoral head as they are in the nonarthritic state, contradicting the notion that arthritic femoral heads in humans rely mainly on an intraosseous blood supply.

Fourteen hips with a diagnosis of degenerative arthritis had femoral head blood flow measured with laser Doppler flowmeter while undergoing during total hip replacement through a modified lateral approach. With the femoral head exposed and leg in neutral position, a 3.5mm drill hole was made into the anterior lateral quadrant and the fiber optic probe of the laser Doppler flowmeter (Moor Instruments, Wilmington Delaware, 20mW laser, wavelength 780nm) was inserted. Mean age was sixty-five years (48–77). Eight males and six females. Two measurements were taken one after anterior hip dislocation and one after simulated notching of the femoral neck. All but four hips had a significant decrease of more than 50% in blood flow after neck notching with a median percentage change of 76% (range 4.4–90.4), p< 0.001.

Eighty-three patients (ninety hips) with well-fixed cementless socket retained during revision of a femoral component were reviewed. At revision, 33% of patients had acetabular osteolysis and 52% were grafted. At mean follow-up 9.6 years (5.5 – 15.9) after femoral revision and 14.8 years (7.1–20.2) after primary arthroplasty, survivorship was 96.5% (95% CI, 91.5% to 100%) at five years and 81%(95% CI, 61% to 99%) at ten years after femoral revision. Revision of a cementless acetabular component solely on the basis of the duration that it was in vivo or whether a previous revision had been done does not appear to be warranted.

Removal a well fixed cementless acetabular component can result in an increased operative morbidity. Data that can be used to predict the long-term survival of retained well-fixed cementless acetabular components are therefore needed.

Retention of the well-fixed cementless acetabular component during femoral revision is a predictable technique.

Revision of a cementless acetabular component solely on the basis of the duration that it was in vivo or whether a previous revision had been done does not appear to be warranted.

Eighty-three consecutive patients (ninety hips) in whom a well-fixed cementless socket had been retained during revision of a femoral component were reviewed. Mean patient age was fifty-four. At the time of revision, 33% of the patients had acetabular osteolysis of which 52% were grafted. At a mean follow-up 9.6 years (5.5 – 15.9) after femoral revision and 14.8 years (7.1–20.2) after primary arthroplasty, 94.5% of the sockets remained in place. With any revision as end point, survivorship was 96.5%(95% CI, 91.5% to 100%) at five years and 81%(95% CI, 61% to 99%) at ten years after femoral revision. With failure of cementless socket as end point (i.e. loosening, deficient locking mechanism), survivorship was 100% (95% CI, 100%) and 94% (95% CI, 82%–100%) at five and ten years after femoral revision and 100% (95% CI, 100%) and 94% (95% CI, 82%–100%) at ten and fifteen years after primary arthroplasty. No cases showed recurrence or expansion of pelvic osteolysis. The overall incidence of dislocation was 15%.

Ninety-four hips with a mean patient age 34.2 (range 15– 40) with a metal/metal surface arthroplasty (SA) were reviewed with 71% men and 14% with previous surgery. The Chandler risk index was calculated as well as the SA risk index (SARI). At a mean follow-up three years, three hips were converted at a mean of twenty-seven months (two to fifty), and ten patients had significant radiological changes. Mean SARI for the thirteen problematic hips versus remaining hips was significantly higher, 4.7 and 2.6, respectively (p=0.00). If SARI > 3 the relative risk of early problems is twelve times greater than if SARI ≤3.

The purpose of this study was to evaluate the early outcome of a hybrid metal on metal surface arthroplasty of the hip in patients forty years and younger and identify potential risk factors.

Surface Arthroplasty Risk Index can help identify patients who may be at increased risk of early failure following metal on metal surface arthroplasty.

Proper patient selection and careful surgical technique may minimize early failures with the re-introduction of surface arthroplasty of the hip.

Ninety-four hips mean age 34.2 (range 15– 40) with metal/metal surface arthroplasty (SA) were reviewed with 71% men and 14% with previous surgery. The Chandler risk index was calculated and SA risk index (SARI). Mean follow-up three years (range 2–5), three hips were converted at a mean of twenty-seven months (2–50), and ten patients had significant radiological changes. Mean SARI for these thirteen problematic hips versus remaining hips was significantly higher, 4.7 and 2.6, respectively (p=0.00). The mean angle between the prosthesis stem and femoral shaft in the problematic group was significantly smaller than the remaining hips (p=0.03): 133° and 139°, respectively. If SARI > 3 the relative risk of early problems is twelve times greater than if SARI ≤3.

Thirty-seven hips in thirty-four patients, mean age forty-one, underwent surgical dislocation of the hip with chondro-osteoplasty for the treatment of femoroacetabular impingement. At a mean follow-up of 2.1 years (2.0–4.0), the pre & post-operative outcome scores were for the: WOMAC 59.2 to 81.0 (p< 0.001), UCLA Hip Scores for pain 4.2 to 7.6;walking 7.3 to 8.6;function 6.2 to 8.1;activity level 4.3 to 6.9 (p< 0.05); and SF-12 physical 37.4 to 48.0 (p< 0.003) & mental 46.0 to 51.6 (p< 0.01). No hips have undergone further reconstructive surgery. Complications: one failure of fixation of the trochanteric osteotomy and one excision of bilateral ectopic ossification. No cases of osteonecrosis.

The purpose of our study was to evaluate the early clinical results and quality of life outcome after chondro-osteoplasty of the femoral head/neck junction for the treatment of femoroacetabular impingement.

An offset correction by surgical dislocation of the hip joint is a safe and an effective procedure in the treatment of femoroacetabular impingement commonly associated with labral tears.

Femoro acetabular impingement is a due to an absence of concavity at the anterolateral head neck junction associated with labral pathology. At short-term followup correction of the bony abnormality has improved functional outcome both from a disease-specific and health-related standpoint.

Thirty-seven hips (eighteen males; sixteen females) with persistent hip pain mean age forty-one (twenty-four to fifty-two) underwent 3-Dimensional CT of the pelvis and MR Arthrography prior to undergoing surgical dislocation with chondro-osteoplasty of the femoral head/neck junction. Preoperatively, the mean alpha angle of Notzli was 65.6(range, 42.0–95). At a mean follow-up of 2.1 years (2.0–4.0), the pre & post-operative outcome scores were for the: WOMAC 59.2 to 81.0 (p< 0.001), UCLA Hip Scores for pain 4.2 to 7.6;walking 7.3 to 8.6;function 6.2 to 8.1;activity level 4.3 to 6.9 (p< 0.05); and SF-12 physical 37.4 to 48.0 (p< 0.003) & mental 46.0 to 51.6 (p< 0.01). No hips have undergone further reconstructive surgery. Complications: one failure of fixation of the trochanteric osteotomy and one excision of bilateral ectopic ossification. No cases of osteonecrosis. Nine hips had removal of painful internal fixation.

Fifty-six hips, mean age 40.4 underwent surface arthroplasty (SA) and twenty-eight hips, mean age 37.2 underwent hemiresurfacing (HSR). Diagnosis was osteo-necrosis in all. UCLA hip function and activity score, SF-12 physical, and Harris Hip score were significantly (p< 0.05) better for SA versus HSR. However, 2 SA were revised to THR, and 5 had evidence of femoral loosening. There was no evidence of femoral loosenings in the hemiresurfacing group. The median femoral component size was significantly larger in HSR than SA. Although the functional results are inferior with HSR, patients are at greater risk of femoral loosening with the full surface arthroplasty.

To determine if differences in outcome exist between HSR and MMSA at five years of follow-up in a group of patients with Ficat Stage III and IV osteonecrosis.

Treatment of osteonecrosis of the hip in the young adult still remains a challenge. The continued use of conservative prosthetic solutions should help minimize the morbidity of revision hip surgery.

Although the functional clinical outcome of MMSA is superior to HSR, patients are at greater risk of femoral loosening. Use of a larger femoral component in MMSA may decrease the risk of femoral loosening.

Eighty-four hips with osteonecrosis were treated with a resurfacing implant: fifty-six with a metal-metal SA, mean age 40.4 and twenty-eight, mean age 37.2 with a hemiresurfacing when the acetabular cartilage was minimally damaged. Male/female ratio was 73%/27% for HSR and 87%/13% for MMSA. Mean follow-up of 4.5 years, UCLA hip scores were significantly (p< 0.05) better for MMSA versus HSR for function (9.3 vs. 7.9) and activity (6.8 vs. 5.5) but not for pain (9.3 vs.8.6) and walking (9.5 vs. 9.0). SF-12 scores were comparable for the mental component but significantly better in the MMSA group (48.4 vs. 38.1, p= 0.001) for the physical component. Harris Hip Score was significantly better for MMSA (92.3 vs. 83.3, p=0.001). 2 MMSA were revised to THR, and five presented with evidence of femoral loosening. There was no evidence of femoral loosenings in HSR. Median femoral component size was significantly larger for HSR (50.0 vs. 46.0, p= 0.001).

3-D finite element model of a resurfaced femoral head was composed. Five configurations of cement layer were analyzed and the transient heat transfer analysis during cement polymerization was performed. Peak temperature at the bone-cement interface temperature was lower than 40 oC when there was no or 1.5 mm cement penetration but reached 54 oC and 74 oC with 6 mm penetration and 6 mm penetration plus a cement –filled cyst of 1 cm3, respectively. With deep cement penetration, and a large cement-filled cyst, the peak temperatures exceeded bone thermal osteonecrosis at 55 oC.

To evaluate using a finite element analysis model, the possibility of bone thermal necrosis secondary to cement in resurfacing arthroplasty of the hip.

With deep cement penetration, and the presence of a large cement-filled cyst, the peak temperatures were in the range of bone thermal osteonecrosis 55 oC.

Cementing technique in resurfacing arthroplasty should strive to strike a balance between fixation and avoiding bone thermal necrosis by excessive cement penetration. This information could explain why femoral head cysts > 1cm are a risk factor for femoral loosening after resurfacing arthroplasty and excessive cement penetration could lead to femoral neck fracture.

3-D finite element model of a hemispherical resurfaced femoral head was composed of a metal shell with a diameter of 46 mm. Five configurations of cement layer were analyzed a) no penetration into the bone, b) 1.5 mm penetration, c) 6 mm penetration, d) 6 mm penetration and a 1 cm3 cement filled cyst, and e) 6 mm penetration and 2 cm3 cement-filled cyst. The transient heat transfer analysis during cement polymerization was performed in a series of time steps. The temperature within the bone and cement was lower than 40 oC when there was no or 1.5 mm cement penetration into the femoral head. In contrast, the peak temperature at the bone-cement interface reached 54 oC and 74 oC and 63 oC with 6 mm penetration and 6 mm penetration plus a cement –filled cyst of 1 cm3, respectively.

Introduction and Aims: To review the medium-term clinical and x-ray results of metal-on-metal Surface Arthroplasty (MMSA) in DDH, using the Conserve Plus™.

Method: Fifty hips (44 patients, avg. age 42.7 years) with DDH were treated with hybrid MMSA. Seventy-five percent were female. Ten percent had prior osteotomies. Twenty-five percent had acetabular cysts that were grafted and 64% had femoral cysts (> 1cm in size) and one was grafted. All cases were Crowe Class 1 or 2. A posterior approach was used in all but one case.

Results: Mean follow-up was 4.9 years (3.8–7.8). UCLA hip scores were 3.2, 5.9, 5.5 and 4.4 pre-op and 9.2, 9.5, 9.4 and 7.1 at last follow-up for pain, walking, function and activity. SF-12 scores normalised. Range of motion was 126.6 degrees, 80.5 degrees and 83.2 degrees at last follow-up for flexion, abduction-adduction, and rotation arcs. Four hips were converted to THA: 2 for femoral neck fracture at two and five months, one for recurrent subluxations due to poor offset and impingement due to prior multiple osteotomies, and one for femoral component aseptic loosening. Four technical complications successfully resolved: one trochanteric non-union, one post-op dislocation (closed reduction), one component mismatch (acetabular component exchange) and one femoral nerve palsy. X-ray analysis: two patients presented complete radiolucencies around the metaphyseal stem.

Conclusion: SA is stable, except for one subluxation due to impingement with poor offset compared to seven to 10% with THA. The socket fixation is secure without adjunct fixation with grafts incorporating whereas prior SA with PE were poor due primarily to socket loosening. Femoral bone preparation is critical to avoid fractures and loosening.

Introduction: THR is still the standard of care for young arthritic patients. However, failure rates remain high at 10 years follow-up, with rates of up to 33% in all cemented designs and 10.5% in cementless designs. With the arrival of new, more wear-resistant bearings, Surface Arthroplasty (SA) has become a viable and promising solution for this patient population. The purpose of the present study was to investigate the results of a metal-on-metal (M/M) hybrid SA and identify appropriate criteria for patient selection.

Method: The first 400 hips (of 620) in 355 patients underwent M/M hybrid surface arthroplasty. Mean age 48.2; 73% males, 27% females; 198 Charnley Class A; 139 Class B and 18 Class C. Diagnosis at surgery: OA 64%, DDH 11%, ON 9%, Post-traumatic 8%, Inflammatory arthritis 3%, SCFE and LCP 4%, Melorheostosis 0.3%.

Results: Mean follow-up 5.2 years (3.9–7.8). Average UCLA hip scores post-op: pain 9.4, walking 9.5, function 9.4, and activity 7.7. The SF-12 physical and mental components were respectively, 31.2 and 46.8 pre-op and 50.1 and 53.0 post-op. Fifteen hips were converted to THA (nine in the first 102): two neck fractures, 10 femoral loosenings, one socket protrusio due to over-reaming, one subluxation due to impingement and one sepsis. The three most important risk factors for femoral loosening and radiolucencies were large cyst formation (p=0.0067), female gender (p=0.0001), and lighter weight in male patients (p=0.0003). The occurrence of femoral loosening or lucency was 18% for the first 100 cases, 9% for the second, 8% for the third, and 1% for the last 100 cases.

Conclusion: Clinical results are excellent, despite very high activity levels. The experience with SA of all cemented metal/UHMWPE bearing demonstrated failure rates of 15 to 33% at three years. At longer follow-up, the preliminary experience is encouraging (3.75% failure rate). Dislocation is rare, and acetabular fixation secure. Initial femoral fixation is critical, as the fixation area is small, especially with osteopenia and cystic degeneration. Cementing the femoral metaphyseal stem appears as a meaningful technical improvement towards the prevention of early femoral radiolucencies. None of the 59 cemented metaphyseal stem had any radiolucency at last review.

Introduction and Aims: The purpose of this study was to validate in a clinical series a method to measure femoral component migration in surface arthroplasty based on the principles of EBRA-FCA.

Method: The first 400 hybrid MMSA in 355 patients have an average of 3.5 years follow-up (range two to six years). The average age was 48 years, 73% were men and 35% had secondary osteoarthritis. All patients were evaluated prospectively at three months and then yearly. We reviewed the x-rays of 26 hips that had undergone metal-on-metal resurfacing using EBRA-FCA. Minimum follow-up was 3.5 years. Group 1was free of any clinical or radiographic signs of loosening (17 hips); group 2 had failed from femoral component aseptic loosening (nine hips). Mean age for the whole group was 50.7 years (28–67). Sixty-six percent were male and 63% were operated for osteoarthritis. We recorded migrations of 2mm or greater and the time to initiation of migration.

Results: Group 2 showed significantly greater migration than group 1, respectively: 4.57 mm versus 1.62mm for centre of the head (p=0.005), 4.51mm versus 1.05mm for stem tip (p=0.001). Initial migration was significantly sooner in group 2 versus group 1: 19 months versus 29.2 months (p=0.030). In group 2, the average time to first migration detected with EBRA-FCA was significantly less than time to first clinical symptoms: 19 months versus 29.5 months (p=0.003). More importantly, the time to detection of significant migration was shorter than the time to detection of the first metaphyseal stem radiolucency: 19 months versus 24.3 months (p=0.028).

Conclusion: EBRA-FCA represents a reliable tool to measure migration of femoral component, which may become essential in the assessment of the clinical performance of MMSA. It is best used in large clinical series with standardised x-ray technique and limiting the number of observers.

Introduction and Aims: There is a relationship between the anatomy of the hip joint and the development of arthritis. A common cause of hip pain in the young adult that can lead to arthritis is acetabular dysplasia. More recently, femoroacetabular impingement has been described as another cause of hip pain. The purpose of our study was to evaluate the applicability of pelvic computed tomography (CT) with three-dimensional surface rendering to evaluate femoro-acetabular impingement.

Method Thirty-six hips (30 patients; 17 males; 13 females) with persistent hip pain, mean age 41 (37–52), underwent three-dimensional CT of the pelvis, as well as MRI arthrography with gadolinium enhancement. On 3D CT, the concavity of the femoral head-neck junction (offset), alpha angle as described by Notzli was calculated to depict the anterior femoral neck contour. The concavity of the posterior aspect of the head neck junction was measured as the beta angle. The same measurements were made in 20 hips, consisting of randomly selected patients with no prior history of hip pathology or pain (mean age 37; 13 males; eight females).

Results The mean alpha angle for the symptomatic group was 66.4 (39–94) and 43.8 (39.3–48.3) for the control group (p=0.001). All symptomatic hips had abnormal findings on MRA: labral tears in all; cartilage delamination/ulceration in 14 hips; herniation pits in six hips. The majority of labral tears and delamination were located in the antero-superior quadrant. In the surgical treated group, all MRA findings were confirmed. The mean beta angle was significantly smaller (increase concavity) in the symptomatic versus the controls: 40.2 versus 43.8 (p=0.011). Interestingly in the symptomatic group the beta angle was significantly lower than the alpha angle (p< 0.02), but not in the controls.

Conclusion: 3D CT with surface rendering and multiplanar reformation is useful to determine degree of bone buttressing of the anterior femoral head-neck junction quantitatively assessed by alpha angle measurement, which is elevated in patients with femoro-acetabular impingement. With a greater posterior concavity i.e. small beta angle in the symptomatic group versus the control, subclinical slipped femoral epiphysis remains a plausible cause of this deformity.

To review short to medium term results of a metalon-metal (M/M) hybrid surface arthroplasty (SA) for a young and active patient population.

The first 300 hips (of 564) in 263 patients underwent M/M hybrid surface arthroplasty (cementless acetabular and cemented femoral components). Demographics: mean age 48.4; 75% males, 25% females; 141 Charnley Class A; 109 Class B and 13 Class C. Diagnosis at surgery: OA 67%, DDH 10.3%, ON 8.3%, Post-traumatic 6.7%, Inflammatory arthritis and Rheumatoid Disease 4%, SCFE and LCP 3.4%, Melorheostosis 0.3%.

Mean follow-up 3.6 years (2.5–5.9). Average UCLA hip scores post-op: pain 9.4, walking 9.5, function 9.4 and activity 7.7. Average Harris Hip Score was 92.8. The SF-12 physical and mental components were respectively, 31.4 and 47.2 pre-op and 49.9 and 52.9 post-op. DEXA data suggests preservation or restoration of neck BMD.

The experience with SA of all cemented metal/ UHMWPE bearing demonstrated failure rates of 15%–33% at 3 years. At longer follow-up, the preliminary experience is encouraging (3.6% failure rate) and eventual conversions to THR are facilitated with unipolar heads. The technique preserves femoral and ace-tabular bone, dislocation is rare, and acetabular fixation secure. Initial femoral fixation is critical as the fixation area is small, especially with osteopenia and cystic degeneration. The percent of potentially adverse radiographic changes was much greater in the first 100 cases, during the time of development of instrumentation, technique, and bearing optimisation.