Patellar Instability: Imaging Findings.

Patellofemoral instability results from impaired engagement of the patella in the trochlear groove at the start of flexion and may lead to pain and lateral patellar dislocation. It occurs most frequently in adolescents and young adults during sporting activities. Trochlear dysplasia, patella alta, and excessive lateralization of the tibial tuberosity are the most common risk factors for patellar instability. The main role of imaging is to depict and assess these anatomical factors and highlight features indicating previous lateral dislocation of the patella.

Variation in knee balance as a function of hip-knee-ankle angle and joint line obliquity in robotic assisted total knee arthroplasty.

PURPOSE: To describe the mediolateral (ML) gap balance in pre-resection arthritic knees undergoing robot-assisted (RA) total knee arthroplasty (TKA) within the nine phenotypes of the Coronal Plane Alignment of the Knee (CPAK) classification. METHODS: A total of 1124 RA TKA cases were retrospectively reviewed. ML balance was calculated using a digital ligament tensioning device following tibial resection and prior to any femoral resection throughout flexion (10°, 40°, and 90°). Lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were landmarked intra-operatively and adjusted for wear based on hip-knee-ankle angle (HKA). Knees were then subdivided into CPAK categories based on the arithmetic HKA (aHKA) and joint line obliquity (JLO). Differences in balance between CPAK phenotypes were compared. RESULTS: For aHKA, a greater medial gap was observed in varus compared to neutral or valgus knees at 10° (5.2 ± 3.0 mm vs 3.3 ± 3.2 mm vs - 0.4 ± 5.0 mm respectively; p < 0.0001). A similar trend was observed for JLO in distal apex compared to neutral and proximal apex knees at 10° (3.4 ± 3.6 vs 1.1 ± 5.0 vs - 2.4 ± 6.3 respectively; p < 0.0001). The greatest ML balance differences were found when combining JLO and aHKA at 10° (type I vs type VI: ∆6.6 mm; p < 0.0001). CONCLUSION: There is a high degree of variability in arthritic ML balance within and between each CPAK phenotype. A single alignment philosophy based on bony landmarks alone may not be sufficient to balance all knees. Utilisation of robotics and digital ligament tensioning devices serves as important adjuncts to characterize the patient-specific soft tissue profile.

Influence of shelf acetabuloplasty on the outcomes of total hip arthroplasty in hips with dysplasia: a case-control study.

INTRODUCTION: Total hip arthroplasty (THA) in young adults, especially in those with hip dysplasia, is affected by wear and acetabular fixation problems. Shelf acetabuloplasty is performed to delay THA in patients with acetabular dysplasia. Thus, we conducted a retrospective, continuous case-control study at a single healthcare facility to analyze (1) the influence of prior shelf acetabuloplasty on the survival of a subsequent THA and (2) the functional outcomes. MATERIALS AND METHODS: We evaluated 105 patients (124 THA) who underwent THA due to hip dysplasia: 54 patients (61 THA) were included in the THA post-shelf acetabuloplasty group (case group) and 51 patients (63 THA) in the THA for dysplasia group (control group). RESULTS: At 15 years' follow-up, 89% of patients (95% CI: 84-91%) in the shelf group and 83% (95% CI: 81-90%) in the dysplasia group had not undergone surgical revision. This difference between groups was not statistically significant (p = 0.566). The functional outcomes were satisfactory in both groups; however, they were significantly better in the dysplasia group than in the shelf group based on the Merle d'Aubigne and Postel score (16.9 vs 16.0 min-max: 14-18 vs 3-18) (p = 0.01), Harris Hip score (90.0 vs 84.7, min-max: 62-100 vs 22-100) (p = 0.017), and the Oxford-12 (18/60 vs 21/60, min-max: 45-12 vs 51-12) (p = 0.04). CONCLUSION: Shelf acetabuloplasty before THA does not negatively affect THA survivorship. The functional outcomes appear to be better in the hips that did not undergo shelf acetabuloplasty, although the results were good in both groups.

Fully oral targeted antibiotic therapy for Gram-positive cocci-related periprosthetic joint infections: a real-life before and after study.

BACKGROUND: The optimal length of the intravenous antibiotic treatment of periprosthetic joint infections (PJIs) generally ranges from one to six weeks and is a matter of debate. Most antibiotics active against Gram-positive cocci (GPC) exhibit both high oral bioavailability and bone diffusion. Thus, early oral therapy may be a reasonable option in GPC-related PJIs. METHODS: A 2 year before and after monocentric study that aimed to compare two antibiotic strategies. Empirical intravenous postoperative antibiotic treatment was followed by 7 to 10 days of intravenous targeted therapy ('before' group) or by full orally targeted antibiotic treatment ('after' group). The primary outcome was a treatment failure during follow-up. RESULTS: A total of 93 patients were analysed, 43 and 50 in the before and the after groups, respectively. Both groups were comparable in terms of surgical procedures, comorbidities, microbiological documentation and infection site. Antibiotics prescribed to our patients had high oral bioavailability and bone diffusion with rifampicin/fluoroquinolone combinations being the most frequent antibiotic regimens. Both hospital stay and intravenous antibiotic treatment mean durations were shorter in the before group than in the after group [15.0 versus 11.0 days; (P < 0.01) and 13.0 versus 7.0 days; P < 0.001, respectively]. The remission rate assessed after at least a year of follow-up was comparable in the before and the after groups (hazard ratio = 0.70; 95% CI 0.30-1.58). CONCLUSIONS: Full oral targeted antibiotic therapy using a drug regimen with high oral bioavailability and good bone diffusion is an option for the treatment of patients with GPC-related PJIs.

Mapping and Crosswalk of the Oxford Hip Score and Different Versions of the Hip Disability and Osteoarthritis Outcome Score.

BACKGROUND: Patient-reported outcome measures such as the Oxford-12 Hip Score and Hip Disability and Osteoarthritis Outcome Score (HOOS) are used in daily orthopaedic practice to evaluate patients. Because different studies use different scores, it would be important to build conversion tables between scores (crosswalk) to compare the results of one study with those of another study. Various mapping methods can be used to develop crosswalk tables that convert Oxford-12 scores to the HOOS (and its derivatives, including the HOOS physical function short form, HOOS joint replacement, and HOOS-12) and vice versa. Although prior studies have investigated this issue, they are limited to short forms of the HOOS score. Consequently, they cannot be applied to hip preservation surgery and do not include quality-of-life items, whereas the Oxford-12 Hip Score is used for all hip evaluations. QUESTIONS/PURPOSES: We prospectively studied the Oxford-12 and HOOS and its derivatives to (1) determine which version of the HOOS has the best mapping with the Oxford-12, (2) define the most-appropriate mapping method using selected indicators, and (3) generate crosswalk tables between these two patient-reported outcome measures. METHODS: The study enrolled 500 adult patients before primary THA (59% men [294 of 500 patients]) with hip osteoarthritis or avascular necrosis of the femoral head who completed the HOOS and Oxford-12. Patients were recruited from January 2018 to September 2019 in a tertiary-care university hospital, and we included all primary THAs in patients older than 18 years with a BMI lower than 35 kg/m2 and greater than 18 kg/m2. After a minimum of 6 months of follow-up, 39% (195 of 500) of the patients were assessed using the same tools. To determine which version of the HOOS mapped best to the Oxford-12 and what the most-appropriate mapping method was, we used preoperative data from all 500 patients. Because there is no consensus on the method to establish crosswalk, various mapping methods (linear regression, tobit regression, and quantile regression) and equating methods (linear equating and equipercentile method) were applied along with cross-validation to determine which method was the most suitable and which form of the HOOS provided the best result according to different criteria (mean absolute error, r2, and Kolmogorov-Smirnov distance).To generate crosswalk tables, we created a conversion table (between the Oxford-12 and the HOOS form that was chosen after answering our first research question and the method chosen after answering our second question) using preoperative and postoperative data (n = 695). This table was meant to be simple to use and allows easy conversions from one scoring system to another. RESULTS: The Oxford-12 and HOOS were strongly correlated (Pearson correlation coefficient range 0.586-0.842) for the HOOS subcategories and HOOS physical function, HOOS joint replacement, and HOOS-12. The correlation between the HOOS-12 and Oxford-12 was the strongest (r = 0.825). According to the three different criteria and five methods, the HOOS-12 was the best suited for mapping. The goal was to minimize the mean absolute error (perfect model = 0), have a Kolmogorov-Smirnov distance as close as possible to 0, and have the r2 as close as possible to 1. Regarding the most-suitable method for the crosswalk mapping (research question 2), the five methods generated similar results for the r2 (range 0.63-0.67) and mean absolute error (range 6-6.2). For the Kolmogorov-Smirnov distance, the equipercentile method was the best (Kolmogorov-Smirnov distance 0.04), with distance reduced by 43% relative to the regression methods (Kolmogorov-Smirnov distance 0.07). A graphical comparison of the predicted and observed scores showed that the equipercentile method provided perfect superposition of predicted and observed values after mapping. Finally, crosswalk tables were produced between the HOOS-12 and Oxford-12. CONCLUSION: The HOOS-12 is the most complete and suitable form of the HOOS for mapping with the Oxford-12, while the equipercentile method is the most suitable for predicting values after mapping. This study provides clinicians with a reliable tool to crosswalk between these scores not only for joint arthroplasty but also for all types of hip surgeries while also assessing quality of life. Our findings should be confirmed in additional studies. CLINICAL RELEVANCE: The resulting crosswalk tables can be used in meta-analyses, systematic reviews, or clinical practice to compare clinical studies that did not include both outcome scores. In addition, with these tools, the clinician can collect only one score while still being able to compare his or her results with those obtained in other databases and registries, and to add his or her results to other databases and joint registries.

Influence of Geometry and Extent of Coating on Survival of Cementless Distal-Locking Revision Stems at 7 to 18 Years.

BACKGROUND: We aimed to compare the long-term clinical outcomes, complications, and survival of 2 revision stems with different geometries, extents of coating, and distal-locking mechanisms. METHODS: We retrospectively compared outcomes at a minimum of 7 years following revision THA using 2 proximally coated distal-locking stems: 98 Ultime first-generation (G1) and 116 Linea second-generation (G2) stems. Ten-year Kaplan-Meier survival was assessed considering stem re-revision for any reason and for aseptic reasons. At final follow-up, Harris Hip Score and Oxford Hip Score were collected, and any thigh pain or complications were noted. RESULTS: Considering re-revision for any reason, survival was 69% for G1 stems and 91% for G2 stems. Considering re-revision for aseptic reasons, survival was 77% for G1 stems and 92% for G2 stems. Re-revisions were due to fracture of 6 G1 stems but no G2 stems. Complications that required reoperation without stem or cup removal occurred in 3 of the G1 stems and 1 of the G2 stems. Compared to the G1 stems, the G2 stems resulted in better Harris Hip Score (83 vs 71, P = .001), Oxford Hip Score (22 vs 27, P = .019), less thigh pain (4% vs 39%, P < .001), and fewer nonoperated complications (9% vs 15%). CONCLUSION: The second-generation stem had significantly better survival and clinical outcomes than the first-generation stem. The differences in survival and clinical outcomes could be attributed to the larger coated surface of the G2 stem and to the fact that the G1 stem was originally intended as a temporary implant to be followed by de-escalation.

Patellofemoral design enhancements reduce long-term complications of postero-stabilized total knee arthroplasty.

PURPOSE: Few studies investigated whether trochlear and patellar design enhancements improve long-term outcomes of total knee arthroplasty (TKA). This study aimed to compare the long-term survival and complication rates of two consecutive generations of the same TKA system with identical tibiofemoral geometry, but different patellofemoral designs. METHODS: The authors retrieved the records of 93 patients (104 knees) operated with the HLS II system and 116 patients (122 knees) operated with HLS Evolution system. Patients were evaluated preoperatively and at a minimum of 10 years noting all complications. Kaplan-Meier (KM) survival was compared for two endpoints: (1) revision of all components and (2) revision of any component. RESULTS: From the HLS II series, the incidence of revision of all components was 6.4%, and of any component was 9.8%. From the HLS Evolution series, the incidence of revision of all components was 4.1%, and of any component was 5.1%. Comparing the survival at equivalent follow-up of 14 years, considering revision of all components, the HLS II had higher survival than the HLS Evolution (98.9% vs 95.9%), while considering revision of any component, the HLS II had lower survival than the HLS Evolution (93.0% vs 94.9%). The differences in survival of the two implants were not significant, neither at equivalent follow-up of 14 years (n.s.), nor at maximum follow-up of each cohort (n.s.). The complication rate was higher for the HLS II series compared to the HLS Evolution (28% vs 12%, p = 0.009), but patellofemoral complications were not more frequent (8% vs 6%, n.s.). CONCLUSIONS: Though the differences in survival of the two implants were not significant, conflicting findings are observed due to partial revisions for patellar fractures (5 in the HLS II series and 1 in the HLS Evolution series) which could be related to patellofemoral design enhancements. This study highlights the importance of patello-femoral geometry, which is often overlooked in TKA. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.

Cementless revision femoral stems application of press-fit principles and clinical outcomes.

BACKGROUND: Cementless femoral stems are currently used in revision total hip arthroplasty (THA) with the surgeon choosing between various fixation modes. The outcomes are good in the medium term; however, some failures have been attributed to technical errors during implantation. When the decision has been made to use a press-fit implant, the impact of the surgeon's technique on the functional outcomes have not been explored in-depth. This led us to carry out a retrospective study on a large population of total hip arthroplasty patients which aims were achieved press-fit to (1) determine the impact of the type of primary fixation (with and without press-fit) on the functional outcomes; (2) specify the effect of stem length on the functional scores when diaphyseal press-fit is achieved and (3) analyse the main reasons why a true press-fit effect was not achieved (three-point fixation). HYPOTHESIS: There is a relationship between the primary fixation method by press-fit of a revision femoral stem and the functional outcomes. PATIENTS AND METHODS: We performed a retrospective analysis of a continuous cohort of 244 THA revision cases with a mean follow-up of 6.1 ± 3.5 years (range, 2-18). The femoral area in which close contact was achieved (shared interface between the bone and implant) was used to define various types of press-fit fixation. The functional outcomes were determined using the Harris Hip Score (HHS) and the Merle d'AubignéPostel score (MAP score) out of 12 points (pain and walking items). RESULTS: The post-operative HHS averaged 90.83 ± 7.51 for proximal press-fit and 80.14 ± 14.93 with no press-fit (p = 0.01). The MAP averaged 10.83 ± 1.03 for proximal press-fit and 9.75 ± 2.09 with no press-fit (p = 0.09). The MAP score was worse for long diaphyseal press-fit than for short press-fit (p = 0.02). Use of a long stem with an endofemoral route or an overly small femoral window in patients with a curved femur is the main reason that three-point fixation occurred instead of press-fit. CONCLUSIONS: While press-fit is an effective concept, it is a demanding one that requires the surgeon to choose the correct surgical strategy for the patient's anatomy. A meticulous surgical technique is required to achieve proximal press-fit or at a minimum, short diaphyseal press-fit.

Global radiological score for femoral cementless revision stem.

PURPOSE: The purpose of this study was to evaluate the outcomes of total hip arthroplasty (THA) revision with cementless stems using a numeric global radiological score (GRxS) that summarizes two previously validated scores: secondary bone stock (SBS) and osseointegration-secondary stability (O-SS). METHOD: One hundred fifty cases of THA were evaluated at a mean follow-up of 6.5 ± 3.7 years. The GRxS combines the SBS, which evaluated cortical bone thickness, bone density and bone defects in each Gruen zone and the O-SS, which evaluated the location and extent of a single radiolucent line. To calculate the GRxS, the SBS and O-SS were each expressed on a 10-point scale and given equal weighing. The final result was a number out of 20. The GRxS was used to assign a radiological grade to each THA case: very good (20), good (18-15), average (13-12), or poor (≤ 10). The numerical mean (Nm) was calculated for each grade. The inter- and intra-observer reproducibility was evaluated. RESULTS: The inter-observer reproducibility was good (0.8) and the intra-observer reproducibility was very good (0.9). The GRxS was considered very good in 46 cases (Nm 20), good in 57 cases (Nm 16.6), average in 25 cases and poor in 22 cases. There was a significant relationship between the GRxS and the Harris Hip and Postel Merle d'Aubigné scores (p < 0.0001), and the initial bone stock (p = 0.0001). CONCLUSIONS: The GRxS is reliable and reproducible. This information can be used by surgeons to adapt the surgical technique to bone characteristics (especially during revision cases) and to compare the outcomes of different implant designs.

Incidence of Adverse Reactions to Metal Debris From 28-mm Metal-on-Metal Total Hip Arthroplasties With Minimum 10 Years of Follow-Up: Clinical, Laboratory, and Ultrasound Assessment of 44 Cases.

BACKGROUND: Total hip arthroplasty with metal-on-metal (MoM) bearings has been suspected to cause adverse reactions to metal debris (ARMD), with the incidence varying greatly by implant type and patient gender. The prevalence of ARMD from small-diameter MoM bearings in women is unknown, especially after 10 years of follow-up (FU). METHODS: Cementless 28-mm MoM total hip arthroplasty bearings (Metasul) were implanted consecutively in 42 active women between 1996 and 2002. They were reviewed after a minimum of 10 years' FU with clinical, laboratory, radiological, and ultrasound assessments. RESULTS: Mean FU was 15.9 years (range, 13-18). The mean Postel-Merle d'Aubigné and Oxford scores were 16.9 (range, 13-18) and 15.1 (range, 12-24), respectively, at FU. Mean cup inclination angle was 46.3° (range, 35°-57°). No femoral osteolysis was detected, but limited acetabular osteolysis (11%) over the screw holes occurred in 5 cases. No liquid or solid synovial reactions or ARMD were apparent on ultrasound, even in the 5 cases of pelvic osteolysis. Mean chromium levels were 1.32 µg/L (range, 0.1-7.9) and cobalt levels were 1.85 µg/L (range, 0.35-13.6). Cobalt was >3 µg/L in only 3 cases. The 15.9-year survivorship was 95% (range, 94.1%-98.9%). CONCLUSION: Reliable results were obtained with 28-mm MoM bearings, notably in young, active patients. This implant configuration requires very accurate positioning. No ARMD was seen in this group at 16 years' FU.

Metallic ion release after knee prosthesis implantation: a prospective study.

INTRODUCTION: Metal-on-metal (MoM) hip replacement bearings produce metallic ions that can cause health complications. Metallic release also occurs with other materials, but data on metallic ion levels after knee arthroplasty are sparse. We postulate that knee replacement generates elevating metallic ions (chromium (Cr), cobalt (Co) and titanium (Ti)) during the first year after implantation. PATIENTS AND METHODS: This ongoing prospective study included all patients who underwent the same type of knee arthroplasty between May and December 2013. Cr, Co and Ti levels were measured in whole blood at pre-operation and one-year follow-up (6 and 12 months). Clinical and radiographic data (range of motion, Oxford, International Knee Society (IKS) and satisfaction scores) were recorded. RESULTS: In 90 patients, preoperative Cr, Co and Ti metallic ion levels were respectively 0.45 µg/l, 0.22 µg/l, 2.94 µg/l and increased to 1.27 µg/l, 1.41 µg/l, 4.08 µg/l (p < 0.0001) at last one-year follow-up. Mean Oxford and IKS scores rose, respectively, from 45.9 (30-58) and 24.9 (12-52) to 88.3 (0-168) and 160.8 (93-200) (p < 0.001). CONCLUSION: After the implantation of knee arthroplasty, we found significant blood elevation of Cr, Co and Ti levels one year after implantation exceeding the normal values. This metallic ion release could lead to numerous effects: allergy, hypersensitivity, etc.

The risks of pulmonary embolism and upper gastrointestinal bleeding beyond 35days after total hip replacement for coxarthrosis among middle-aged patients: A cross-over cohort.

Prophylactic anticoagulation is recommended up to 35days after total hip replacement (THR). Although several observational studies have assessed the incidence of thrombotic events or bleeding events after THR, the corresponding measures of association have never been studied concomitantly. Here, we evaluated the duration of the elevated risks (relative to the baseline risk) of both venous thromboembolic events and bleeding events after THR for coxarthrosis among middle-aged patients. This was a population-based, cross-over cohort study of data extracted from the French national inpatient database between 2007 and 2013. We included middle-aged patients (aged 45 to 69) having undergone THR for coxarthrosis. We compared the numbers of pulmonary embolisms (PEs) (respectively upper gastrointestinal bleedings (UGIBs)) following the THR with the numbers occurring during three unexposed periods one year later. This enabled us to estimate the odds ratio (OR) [95% confidence interval (CI)] for each of six successive 35-day intervals. The study included 108,099 patients. The ORs for PE were respectively 12.4 (95% CI, 8.6-17.8) (absolute risk difference rate per 100,000 (ARD/100,000)=130) and 5.0 (95% CI, 3.4-7.4) (ARD/100,000=52) for the first two 35-day intervals, and the risk was close to 1 thereafter. The risk of UGIB fell quickly, with an OR of 6.5 (95% CI, 4.6-9.1) (ARD/100,000=83) and 0.8 (95% CI, 0.4-1.6) for the first two 35-day intervals, respectively. The majority of UGIBs occurred during the inpatient stay for THR. Among middle-aged patients, the risk of a PE remains elevated beyond 35days after THR for coxarthrosis, whereas the risk of a UGIB remains elevated for the first 35days only.

Cementless Total Hip Arthroplasty With Metasul Bearings Provides Good Results in Active Young Patients: A Concise Followup.

BACKGROUND: A primary concern of younger, more active patients who have undergone total hip arthroplasty (THA) is the longevity of the implant. Cementless fixation and hard-on-hard bearings are recognized as options to enhance THA durability. Earlier, we published a series of 83 cementless primary THAs using 28-mm metal-on-metal (MoM) bearings in patients aged 50 years or younger; here we provide concise followup on that same group after an additional 8-year survey period. QUESTIONS/PURPOSES: (1) What is the long-term survivorship of cementless primary THA using 28-mm MoM bearings in patients aged 50 years or younger? (2) What are the clinical and radiographic results of cementless THA in this active patient population? (3) Can any of the observed implant failures or adverse events be attributed to the metallic nature of the bearing couple? METHODS: We retrospectively reviewed 83 cementless THAs performed in three institutions over a decade (1995-2004) in 68 patients with 28-mm MoM articulation. All patients (15 bilateral) had a median age of 42 years (range, 24-50 years) at the time of the index procedure and 56 of them (82% [70 hips]) had activity level graded Devane 4 or 5 before significant hip pain. A 28-mm Metasul™ articulation was used with an Alloclassic-SL™ cementless stem in all cases paired with three different cementless titanium acetabular components (one threaded and two press-fit cups) from the same manufacturer. Survivorship analysis was calculated according to Dobbs life table, patient clinical results were evaluated with use of the Postel-Merle d'Aubigné scoring system, radiographic analysis was performed by independent observers, and cobalt level was determined in whole blood. RESULTS: The 15-year survivorship (33 hips at risk) for revision for any reasons (four hips) and for aseptic loosening (one hip) was 96% (95% confidence interval [CI], 81%-99%) and 99% (95% CI, 85%-99.9%), respectively. The median Merle d'Aubigné-Postel score remained stable at 17 points (range, 10-18). Thus far, we have not observed pseudotumors or other adverse reactions to metallic debris. Eight hips have undergone reoperation: trochanteric suture removal (one), psoas tendon impingement (two), and five revisions for periprosthetic fracture (one), late infection (two), acetabular osteolysis (one, as a result of polyethylene backside wear), and one hydroxyapatite-coated cup for aseptic loosening. None of the complications, failures, or revisions observed so far could directly be related to the metallic nature of the 28-mm Metasul bearings used in this selected group of patients. CONCLUSIONS: The current survey at 13-year median followup has not yet indicated any long-term deleterious effects related to dissemination of metallic ions. Two senior authors continue to use 28- or 32-mm Metasul™ bearings with cementless THA components in young and active patient populations. Longer followup with a more sophisticated imaging study is necessary to confirm this so far positive report. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Do the Reasons for Ceramic-on-ceramic Revisions Differ From Other Bearings in Total Hip Arthroplasty?

BACKGROUND: Despite widespread use of ceramic-on-ceramic (CoC) in total hip arthroplasty (THA) during the past 10 years, little is known about why revisions are performed in hips with this bearing or the time elapsed before revision. QUESTIONS/PURPOSES: The purposes of this study were: (1) Do the reasons for first revision differ between CoC bearings and other bearing couples? (2) Does the time to revision differ between CoC and other bearing couples? (3) Are there unique reasons for revisions of CoC bearings? METHODS: All members of the Société Française de Chirurgie Orthopédique et Traumatologique (SoFCOT) who performed ≥ 30 revisions per year were invited to participate in this multicenter, prospective, observational study. Our data represent 12% of the revision procedures performed in France. A total of 2107 first revisions of THA (from January 2010 to December 2011) were done in 2107 patients (1201 females [57%] and 906 males [43%]; median age, 73 years; age range, 17-104 years) at the time of surgery after a median of 11 years (range, 0 day-42 years) after the primary THA. There were 238 of 2107 (11%) CoC, 148 of 2107 (7%) metal-on-metal (MoM), and 1721 of 2017 (82%) metal-on-polyethylene (MoP) bearings. RESULTS: The reasons for reoperation differed according to the bearing component: (1) for the MoP reference bearing (odds ratio [OR]; 95% confidence interval), cup loosening occurred in 698 of 1721 hips (41%), periprosthetic fracture in 220 of 1721 hips (13%), and osteolysis in 213 of 1721 hips (12%); (2) for CoC, cup loosening occurred in 41 of 238 hips (17%) (OR, 0.31 [0.22-0.43; p < 0.001), infection in 39 of 238 hips (16%) (OR, 1.63 [1.12-2.37]; p = 0.01), and dislocation in 23 of 238 hips (10%) (OR, 0.9 [0.57-1.42]; p = 0.9); (3) for MoM, cup loosening occurred in 28 of 148 hips (19%) (OR, 0.34 [0.22-0.52]; p < 0.001), adverse reaction to metallic debris in 26 of 148 hips (18%) (OR, 18.12 [9.84-33.4]; p < 0.001), and infection in 16 of 148 hips (11%) (OR, 1 [0.59-1.73]; p = 0.9). In comparison with MoP, osteolysis was rarely the reason for revision in CoC (four of 238 hips [2%]; OR, 0.12 [0.05-0.33]; p < 0.001), but this bearing was frequently revised because of iliopsoas irritation (18 of 238 hips [8%]; OR, 4.9 [2.7-9]; p < 0.001). The time elapsed before revision differed between bearings: median of 3 years (range, 3 days to 28 years) for CoC and 4 years (range, 14 days to 37 years) for MoM versus a median 13 years (range, 0 day to 42 years) for MoP (p < 0.001). Thirty-seven of the 238 revisions (16%) were directly related to ceramic use (ceramic breakage [n = 23], squeaking [n = 6], impingement [n = 7], incorrect ceramic insert insertion [n = 1]). No factors were identified that contributed to breakage of the 12 bulk ceramic components (eight heads, four inserts, four of 12 Delta ceramic). No factors were associated with squeaking, iliopsoas irritation, or impingement, but component orientation was not assessed. CONCLUSIONS: The reasons and time to first revision differed between CoC and other bearings. CoC THAs are revised earlier and are sensitive to mechanical problems such as impingement, squeaking, and ceramic rupture that did not disappear with introduction of Delta ceramics and large-diameter (≥ 36 mm) bearings. CoC was rarely revised for osteolysis, but a high rate of iliopsoas irritation requires further investigation. LEVEL OF EVIDENCE: Level III, therapeutic study.

Return to sport after patellar dislocation or following surgery for patellofemoral instability.

Patellofemoral instability may occur in a young population as a result of injury during sporting activities. This review focuses on return to sport after one episode of dislocation treated no operatively and as well after surgery for chronic patellofemoral instability. With or without surgery, only two-thirds of patients return to sports at the same level as prior to injury. A high-quality rehabilitation programme using specific exercises is the key for a safe return to sporting activities. To achieve this goal, recovery of muscle strength and dynamic stability of the lower limbs is crucial. The focus should be directed to strengthen the quadriceps muscle and pelvic stabilizers, as well as lateral trunk muscle training. Patient education and regularly performed home exercises are other key factors that can lead to a successful return to sports. The criteria for a safe return to sports include the absence of pain, no effusion, a complete range of motion, almost symmetrical strength, and excellent dynamic stability. Level of evidence IV.

Do the porous custom implants have a position consistent with the planning and allow anatomical reconstruction of hip center of rotation in complex acetabular revisions Paprosky III?

INTRODUCTION: In revision total hip arthroplasty (THA), the advent of porous custom-made triflange acetabular implants with 3D scan planning offers a new perspective to improve implantation accuracy and anatomical restoration of the center of rotation (COR). This issue was investigated using CT-scan as the measurement tool, but in limited series (±10 cases) and without investigating the factors that may influence errors in positioning. Therefore we performed a retrospective study aiming to: (1) assess the placement accuracy of such implants with respect to the preoperative planning, (2) examine whether the volume of bone to be resected in order to apply the implant had an impact on this accuracy, (3) assess if errors in position at surgery had any influence on function, complications and survival. HYPOTHESIS: Preoperative planning could be accurately reproduced when implanting porous custom-made acetabular implants, and that accuracy would decrease in proportion to the volume of bone to be resected METHOD: Twenty patients undergoing THA revision with porous custom-made acetabular implants were included in this single-center retrospective study. Mean follow-up was 17.9 months ± 9.4 [2-45.1]. Preoperative planning was performed using 3D scanographic modeling. A post-operative CT scan was performed to assess implantation accuracy in terms of orientation and COR restitution. Demographic data, Oxford scores, complications and survival were recorded. RESULTS: Mean deviation from the preoperative planning in inclination, anteversion and rotation were 4.3 ° ± 2.5, 6.1 ° ± 4.7, and 7 ° ± 4.6, respectively. Restoration of the COR showed a mean deviation of 2.1 ± 1.3 mm anteroposteriorly, 2.5 ± 2 mm mediolaterally and 2.2 ± 1.3 mm proximodistally. In total, 45% (9/20) of implants were positioned with perfect restoration of orientation (±10 °) and COR (±5 mm). The mean planned bone resection was 8.1 ± 4.9 cm3, with placement accuracy and COR restitution decreasing significantly when the volume of bone to be resected exceeded 2.7 cm3. One dislocation was found (5%, 1/20). Survival at last follow-up was 100%, the mean Oxford score at follow-up was 31.7 ± 7.9 [16-52], without being influenced by errors in position or COR restitution. CONCLUSION: In total 45% of the implants restored an orientation and a COR as planned, particularly when the volume of bone to be resected is less than 2.7 cm3. Although these are complex cases with large amounts of bone loss, 3D manufacturing could give us hope of greater precision. The link between better precision and low bone resection volume could be an area to develop with the manufacturer in order to improve results. LEVEL OF EVIDENCE: III; diagnostic using CT in transversal retrospective study.

Can the minimal clinically important difference (MCID) for the Oxford score, KOOS and its derivatives be identified in a French sample of total knee arthroplasties?

CONTEXT: To assess the effect of a surgical procedure on a patient, it is conventional to use clinical scores before and after the procedure, but it is increasingly common and recommended to weight the results of these scores with the notion of minimal clinically important difference ("MCID"). This MCID should be determined using either the data distribution method based on score variation, or the anchor method, which uses an external question to categorize the results. MCIDs vary from one population to another, and to our knowledge there has been no investigation in France for total knee arthroplasties (TKAs). We therefore conducted a prospective study on a population of TKAs in order to: 1) Define MCID in France on a population of TKAs for the Oxford score, KOOS (Knee injury and Osteoarthritis Outcome Score) and its derivatives, 2) Determine whether MCID for these scores in France is comparable to results in the literature. HYPOTHESIS: Is the MCID for total knee arthroplasty in France comparable to other results in the literature? MATERIAL AND METHOD: This was a prospective observational study in which 218 patients (85 men, 133 women) with a mean age of 72 years [27-90] who had undergone a primary TKA out of 300 initially included responded, before and after surgery, to the Oxford-12, KOOS and Forgotten Joint Score (FJS) questions (mean follow-up 24 months). MCID was calculated using the distribution method as well as the anchor method ("improvement 1 to 5" and "improvement yes or no"). RESULTS: At a mean follow-up of 24 months [18-36], the Oxford-12 score increased from 16 ± 8 [0-41] to 34 ± 11 [6-48] (p < 0.001), all components of the KOOS score were improved and the FJS at follow-up was 47 ± 32 [0-100]. For the anchor "improvement 1 to 5", there were 14 unimproved patients, 23 patients in identical condition and 179 patients improved by surgery. For the anchor "are you improved yes/no", there were 8 unimproved patients, 22 in identical condition and 187 surgically-improved patients. The mean MCID for all methods (anchor method and distribution) was 10 [7-13] for Oxford-12, 12 [12-12] for KOOS Symptom, 14 [12-17] for KOOS Pain, 12 [11-14] for KOOS Function, 14 [12-16] for KOOS Sport, 15 [15-16] for KOOS Quality of Life (QOL), 11 [10-12] for KOOS 12, 15 [12-18] for KOOS 12 Pa in. 12 [12-13] for KOOS 12 Function, 15 [15-15] for KOOS 12 QOL, 14 [13-14] for KOOS Physical Function Short-form (PS) and 14 [13-16] for KOOS Joint Replacement (JR). DISCUSSION: The MCID for the Oxford-12, KOOS and its derivatives scores in a French population is comparable to that observed in other populations in the literature. LEVEL OF EVIDENCE: IV; prospective study without control group.

Are CPR (Contact Patch to Rim) distance anomalies associated with the occurrence of abnormal noises from ceramic-on-ceramic THA?

INTRODUCTION: The ceramic-on-ceramic couple in total hip arthroplasties (THA) has the advantage of excellent wear resistance and the bioinert nature of its debris. Noise occurring from this friction torque is a common complication, the contributing factors of which are debated. The noise is caused by a lack of lubrication, due in most part to the positioning of the acetabular cup. The study of metal-on-metal couples identified that the calculation of the Contact Patch to Rim (CPR) distance provides information on lubrication defects and also that it is correlated with the wear of metal-on-metal implants. This CPR distance is not recognized to be correlated with the occurrence of noise for the ceramic-on-ceramic couple at a caliber ≤ 36mm. We therefore conducted a retrospective case-control study to assess: 1) The influence of the CPR distance on noise occurrence; 2) Whether other factors associated to noise occurrence exist? HYPOTHESIS: Our hypothesis was that a low CPR distance was correlated with noise occurrence. METHOD: This was a case-control study with 3 controls for each case, analyzing 21 THAs (21 patients) with noise compared to 63 THAs without noise (63 patients) matched for age, sex and body mass index. These patients were taken from a continuous retrospective series of 96 patients for 104 total hip arthroplasties (THA) with a single operator and 4th generation Biolox Delta ceramic-on-ceramic single implant, performed between 2007 and 2012. The calculation of the CPR distance was then performed for both groups using measurements of inclination angles, anteversion angles, and implant data regarding the head/insert contact angle, head/insert diameter and clearance. RESULTS: At the mean follow-up of 7.1 years±1.2 [5 to 9.6], the mean CPR distance was lower in the noise group 10mm±3.3 [3.8 to 16.4] than in the control group 14.8mm±4.3 [7.3 to 24.4] (p=0.0007). The mean inclination angle was higher in the noise group 45.1°±7.8 [31 to 62] than in the control group 41.2°±7.2 [26 to 56] (p=0.04). The occurrence of noise was independent of anteversion, head caliber, cup diameter, neck length and stem size, and stem type (standard or lateralized). CONCLUSION: A low CPR distance was correlated with the occurrence of noises, similarly a steep inclination was correlated with the occurrence of noises. LEVEL OF EVIDENCE: III; Retrospective case-control study.

Cementless metal-on-metal versus ceramic-on-polyethylene hip arthroplasty in under-50 year-olds with 20 to 22 years' follow-up: Was it a good idea to abandon the small-diameter metal-on-metal bearing?

In 2005 and 2011, we reported results for a comparative study of two types of 28-mm bearing (metal-on-metal (MoM) and ceramic-on-polyethylene (CoP) in active patients with respectively 5 and 12 years' follow-up. The present report is an update at a mean 20 years' follow-up, addressing 2 issues: (1) implant survival at a mean 20 years; and (2) long-term complications with the metal-on-metal bearing. Twenty-eight millimeters MoM bearings show good survival at 20 years in young active subjects. Two groups of cementless hip prostheses were compared: Metasul™ 28mm MoM versus 28mm CoP. The MoM group comprised 30 patients (39 hips), with a mean age of 40±6.7 years [range, 22.6-49 years], and the CoP group comprised 32 patients (39 hips), with a mean age of 40.5±8.7 years [range, 15-50 years]. The groups were matched in 2005 for age, activity level and preoperative Harris score. At a mean 20±5.3 years' follow-up [range, 5-23 years], in the MoM group 2 hips (5%) showed limited non-progressive acetabular osteolysis, not requiring revision surgery; in the CoP group, there were 21 revision procedures (54%), including 15 for polyethylene wear. In the MoM group, the median total blood cobalt concentration was 1.03g/L [range, 0.3-3.5] and the median chromium concentration was 1.07g/L [range, 0.3-3.2]. Twenty-year all-cause survival was 100% in the MoM group, and 46% (95% CI, 37-59%) in the CoP group (p<0.0001). At long-term follow-up, MoM implants showed better survival than CoP implants in a young active population. Level of evidence: III, matched case series.

Long-term results (after a mean 11.3years, and up to 22years, of follow-up) of the Legacy Constrained Condylar Knee (LCCK™) in primary total knee arthroplasty.

INTRODUCTION: The use of a sliding prosthesis in total knee arthroplasty (TKA) with increased stress is an intermediate solution in primary surgery, between posteriorly stabilized prostheses and hinged prostheses, in cases of ligamentous laxity and/or loss of bone substance. Favorable results have been reported in the medium term but to our knowledge, this type of prosthesis has not been evaluated in Europe beyond 10 years of follow-up. We therefore conducted a retrospective study in order to carry out: 1) the study of the survival of the Legacy Constrained Condylar Knee (LCCK™) prosthesis in primary surgery, 2) the analysis of complications, functional scores and radiographic data, 3) the analysis of the link between the diaphyseal filling rate and prosthetic loosening. HYPOTHESIS: The LCCK™ sliding prosthesis with increased constraint has equivalent long-term survival and clinical results to standard posteriorly stabilized TKA and superior to hinged TKA. MATERIAL AND METHOD: A retrospective series of 141 LCCK™ implanted in 134 patients between 1997 and 2010 was analyzed. Survival was assessed with censoring through an evaluation of partial or total revision of the implants. The functional results were evaluated using the IKS and Oxford 12 scores. Data regarding the Canal Fill Ratio (CFR) and the presence of pathological periprosthetic lines were also collected. RESULTS: The average follow-up was 11.3±5.3years with a maximum follow-up of 22.7years. Survival at 20years was 90.8% [95% CI: 83.7-95.7]. The rate of early complications was 13.5% (19/141), predominantly comprised of venous thrombosis (6/141), hematomas (3/141 including two requiring surgical drainage), stiffness (3/141) and early infections (3/141). The rate of late complications was 17% (24/141), led by stiffness (4.4%; 6/141), infections (2.9%; 4/141) and hardware failure (2. 2%; 3/141). Ten of the 141 patients (7.1%) had LCCK failure, including 3 (2.1%) for stiffness, 3 (2.1%) for hardware failure, 2 (1.4%) for infection, 1 (0.7%) for laxity and 1 (0.7%) for a periprosthetic fracture. No aseptic loosening was found. The total IKS score went from 65 [0-116] to 143 [79-200] at follow-up, the IKS knee score went from 30 [0-66] to 85 [44-100], and the IKS function score went from 35 [0-70] to 57 [0-100]. The Oxford score went from 14 [2-25] to 34 [15-48] at follow-up. Only two patients (1.4%) presented with a partial periprosthetic line. The tibial CFR was 0.81 and the femoral CFR was 0.76. The influence of the CFR could not be analyzed due to the absence of loosening. DISCUSSION: The LCCK™ prosthesis in primary surgery has good medium-term survival, a significant improvement in functional scores and a complication rate comparable to posteriorly stabilized prostheses. The complication rate is lower than that of hinged prostheses. LEVEL OF EVIDENCE: IV; single-center retrospective study.