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Background: In the context of acetabular reconstruction, bone defects can be filled with processed or unprocessed bone allografts. Published data are often contradictory on this topic and few studies have been done comparing processed allografts to fresh-frozen ones. This led us to conduct a large study to measure the factors impacting the survival of THA revision: (1) type of allograft and cup, (2) technical factors or patient-related factors., Hypothesis: Acetabular reconstruction can be performed equally well with frozen or processed morselized allografts., Materials and Methods: This retrospective, multicenter study of acetabular reconstruction included 508 cases with a minimum follow-up of 5 years. The follow-up for the frozen grafts was shorter (7.86 years±1.89 [5-12.32]) than that of the processed grafts (8.22 years±1.77 [5.05-15.48]) (p=0.029). However, the patients were younger at the time of the primary THA procedure in the frozen allograft group (51.5 years±14.2 [17-80]) than in the processed group (57.5 years±13.0 [12-94]) (p<0.001) and were also younger at the time of THA revision (67.8 years±12.2 [36.9-89.3] versus 70 years±11.7 [25-94.5]) (p=0.041)., Results: There were more complications overall in the frozen allograft group (46/242=19.0%) than the processed allograft group (35/256=13.2%) (p=0.044) with more instances of loosening in the frozen group (20/242 [8.2%]) than in the processed group (6/266 [3.3%])(p=0.001). Conversely, the dislocation rate (16/242=6.6% vs. 17/266=6.4%) (p=0.844) and infection rate (18/242=7.4% vs. 15/266=5.7%) (p=0.264) did not differ between groups. The subgroup analysis reveal a correlation between the occurrence of a complication and higher body mass index (BMI) (p=0.037) with a higher overall risk of complications in patients with a BMI above 30 or under 20 (p=0.006) and a relative risk of 1.95 (95% CI: 1.26-2.93). Being overweight was associated with a higher risk of dislocation (relative risk of 2.46; 95% CI: 1.23-4.70) (p=0.007). Loosening was more likely to occur in younger patients at the time of the procedure (relative risk of 2.77; 95% CI: 1.52-6.51) (p=0.040) before 60 years during the revision. Lastly, patients who were less active preoperatively based on the Devane scale had an increased risk of dislocation (relative risk of 2.51; 95% CI: 1.26-8.26) (p=0.022)., Discussion: Our hypothesis was not confirmed. The groups were not comparable initially, which may explain the differences found since the larger number of loosening cases in the frozen allograft group can be attributed to group heterogeneity. Nevertheless, morselized allografts appear to be suitable for acetabular bone defect reconstruction. A randomized study would be needed to determine whether frozen or processed allografts are superior., Level of Evidence: III, comparative retrospective study., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Background: Various factors contribute to instability of total hip arthroplasty (THA), with implant orientation being a major contributor. We performed a case-control study with computed tomography (CT) data to determine whether: 1) orientation contributes to THA instability and 2) a safer target zone for stability than Lewinnek's classic safe zone can be defined., Material and Methods: We included prospectively 363 cases of THA dislocation that occurred during the calendar 2013 year in 24 participating hospitals. Of the 128 dislocations that occurred in patients who underwent THA at these centers, 56 (24 anterior, 32 posterior) had CT scans, thus were included in the analysis. The control group was matched 4:1 based on implant type, year of implantation, age, sex, bearing types and THA indication. Of the 428 matched control THA cases, 93 had CT scans. In all, the CT scans from 149 cases (56 unstable, 93 stable) were analyzed to determine the acetabular cup's inclination and anteversion, and the femoral stem's anteversion., Results: In the unstable THA group, cup inclination was 46.9°±7.4°, cup anteversion was 20.4°±10.8° and stem anteversion was 14.2°±9.9°. In the stable THA group, cup inclination was 44.9°±5.3° (P=0.057), cup anteversion was 22.1°±5.1° (P=0.009) and stem anteversion was 13.4°±4.4° (P=0.362). The optimal total anteversion (cup+stem) of 40-60° was achieved in 16.5% of unstable THA cases and 13.9% of stable THA cases, thus this parameter does not predict stability (odds ratio [OR] of 0.40, P=0.144). The cup was positioned in Lewinnek's safe zone in 44.6% of patients in the unstable group and 68.2% of those in the stable group (OR 3.74, P=0.003). A target zone defined as 40-50° inclination and 15-30° anteversion was better able to distinguish between unstable cases (23.2%) and stable cases (71.6%) resulting in an OR of 13.91 (P<0.001)., Discussion: Implant positioning was the only risk factor for instability found in this study. Moreover, our findings reinforce the theory put forward by other authors that Lewinnek's safe zone is not specific enough to differentiate between stable and unstable THA implantations. The target zone for acetabular cups proposed here (40-50° inclination and 15°-30° anteversion) is related to a lower risk of instability. This orientation can be used as a guide, but must be combined with other technical elements to optimize stability. By balancing stability and biomechanics, the 40-50° inclination and 15°-30° anteversion target zone redefines the optimal positioning window., Level of Evidence: III case-control study., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Introduction: Dislocation after total hip arthroplasty (THA) is a leading reason for surgical revision. The risk factors for dislocation are controversial, particularly those related to the patient and to the surgical procedure itself. The differences in opinion on the impact of these factors stem from the fact they are often evaluated using retrospective studies or in limited patient populations. This led us to carry out a prospective case-control study on a large population to determine: 1) the risk factors for dislocation after THA, 2) the features of these dislocations, and 3) the contribution of patient-related factors and surgery-related factors., Hypothesis: Risk factors for dislocation related to the patient and procedure can be identified using a large case-control study., Patients and Methods: A multicenter, prospective case-control study was performed between January 1 and December 31, 2013. Four patients with stable THAs were matched to each patient with a dislocated THA. This led to 566 primary THA cases being included: 128 unstable, 438 stable. The primary matching factors were sex, age, initial diagnosis, surgical approach, implantation date and type of implants (bearing size, standard or dual-mobility cup)., Results: The patients with unstable THAs were 67±12 [37-73]years old on average; there were 61 women (48%) and 67 men (52%). Hip osteoarthritis (OA) was the main reason for the THA procedure in 71% (91/128) of the unstable group. The dislocation was posterior in 84 cases and anterior in 44 cases. The dislocation occurred within 3 months of the primary surgery in 48 cases (38%), 3 to 12 months after in 23 cases (18%), 1 to 5years after in 20 cases (16%), 5 to 10years after in 17 cases (13%) and more than 10years later in 20 cases. The dislocation recurred within 6 months of the initial dislocation in 23 of the 128 cases (18%). The risk factors for instability were a high ASA score with an odds ratio (OR) of 1.93 (95% CI: 1.4-2.6), neurological disability (cognitive, motor or psychiatric disorders) with an OR of 3.9 (95% CI: 2.15-7.1), history of spinal disease (lumbar stenosis, spinal fusion, discectomy, scoliosis and injury sequelae) with an OR of 1.89 (95% CI: 1.0-3.6), unrepaired joint capsule (all approaches) with an OR of 4.1 (95% CI: 2.3-7.37), unrepaired joint capsule (posterior approach) with an OR of 6.0 (95% CI: 2.2-15.9), and cup inclination outside Lewinnek's safe zone (30°-50°) with OR of 2.4 (95% CI: 1.4-4.0)., Discussion: This large comparative study isolated important patient-related factors for dislocation that surgeons must be aware of. We also found evidence that implanting the cup in 30° to 50° inclination has a major impact on preventing dislocation., Level of Evidence: Level III; case-control study., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

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.

Background: Revision total hip arthroplasty (reTHA) for peri-prosthetic fracture (PPF) is increasingly performed but still ranks fourth among reasons for reTHA in registries. In France, no specific registry is available and the frequency of PPF among reasons for THA revision is therefore unknown. Here, our objectives were to determine the relative frequency of PPF as a reason for reTHA, to identify patient-related and primary-THA-related factors associated with reTHA for PPF, to describe reTHA modalities for PPF, and to determine the morbidity and mortality associated with reTHA for PPF., Hypothesis: PPF is the second most common reason for reTHA, after loosening., Methods: Consecutive reTHA procedures performed in 30 French centres over a 2-year period were collected prospectively. Repeat revisions and revisions of hemi-arthroplasties were excluded. The epidemiological, clinical, and surgical data needed to answer the questions of the study were collected., Results: PPF was the second leading reason for reTHA (249/2107, 11.8%). Vancouver type B2 fractures were the most common (n=127 [51.5%]). Compared to patients who underwent reTHA for reasons other than PPF, those with reTHA for PPF were older at primary THA (67.9 years versus 57.7 years) and more often had intra-operative complications (16.9% versus 11.6%); furthermore, the primary THA was more often cementless (62.7% versus 42.7%) with a dual-mobility cup (20.6% versus 11.1%). At reTHA, the patients with PPF were older (77.6 years versus 69.2 years), had worst medical condition (mean ASA score, 2.4 versus 2.1) and less physically active (mean Devane score, 2.1 versus 2.4). The patients with reTHA for PPF had a shorter time to revision (9.8 years versus 11.4 years), a longer operative time (144 minutes versus 128 minutes), and more frequent use of the posterior approach (77% versus 67%) with a cementless dual-mobility cup (78% versus 60%) and a cementless revision femoral stem (72% versus 50%). Morbidity and mortality rates were high (5.9% operative complication rate and 12% of surgical complications with 4.8% mortality within the first 3 months) however, these results were similar to those in the rest of the cohort., Discussion and Conclusion: PPF is the second most common reason for reTHA, a result that is at variance with data in national registries., Level of Evidence: Level IV, prospective observational cohort study., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Introduction: Infection is a serious complication of total hip arthroplasty (THA) and is one of the most frequent causes of failure. The goal of this study was to evaluate the importance of infection among the different causes of revision THA and identify any risk factors specifically associated with this cause of revision., Materials and Methods: All patients who underwent a first revision of THA were included in a prospective multicenter study. Postoperative clinical and radiological evaluation and follow-up of morbidity and mortality were performed at 3 months., Results: Two hundred forty out of 2107 revisions (11.4%) were performed for infected THA, which was the third cause after aseptic loosening (42.3%) and peri-prosthetic fractures (11.8%). These patients had a higher BMI associated with co-morbidities and lower clinical scores than patients with other causes of revision. One-stage revision was performed in most cases (66%) with replacement of the complete implant in 86% of cases, resulting in longer surgery compared to that for other causes. Male gender (OR 2.3), avascular necrosis (OR 2.4), arthroplasties with dual mobility cups (OR 2.5) and a Rottinger anterolateral approach (OR 3.4) were all associated with an increased risk of infection., Discussion: Some of these risk factors are not or have rarely been reported in the literature. They should be taken into consideration to help in the prevention and continuing battle against THA infection., Level of Evidence: Level IV, prospective cohort study., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Introduction: Dislocation following total hip arthroplasty (THA) may require surgical revision, and is one of the most frequent causes for revision in national registers. The goals of this study were to determine the characteristics of revision THA for dislocation and identify the typical features of hips revised due to dislocation., Materials and Methods: A prospective multicenter study (30 centers) was performed in first revision THA performed between January 1, 2010 and December 31, 2011 (multiple revisions were excluded)., Results: Two hundred nineteen (10.4%) of all first revisions (2153 cases in 2107 patients) were for dislocation, which was the fifth cause of revision. There were 135 men and 84 women, mean age 65.9 years old (24.3-92.4) at primary THA and 72.9 years old (31.9-98.8) at revision. Revision surgery was performed a mean 7.1 years (± 7.1) after primary THA. The predictive risk factors for dislocation were: a 22.2mm diameter femoral head (risk × 2.4), a posterolateral approach (risk × 1.7), older age (risk × 1.1), an elevated rim liner for primary THA (risk × 6.6). The use of a dual mobility cup did not influence the rate of revision for dislocation (8.8%) compared to the use of a flat rim liner (9.1%)., Discussion: The 10.4% rate of revision of THA for dislocation seems markedly lower than the results in the literature both for frequency and ranking. The use of elevated rim or constrained liners designed to decrease the risk of dislocation does not improve results compared to standard liners., Level of Evidence: Level IV, prospective prognostic study without a control group., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)