BACKGROUND. Hybrid total hip arthroplasty (THA) commonly recognized as cementless hemi-spherical acetabular component combined with cemented femoral stem. We have done so called “reverse” hybrid THA with cemented socket and cementless stem and compared with all-cemented THAs. PATIENTS AND METHODS. We have been collecting data on total hip arthroplasty since November, 1993. Reverse hybrid hip replacements were used mainly from February, 2001. We evaluated data on 272 reverse hybrid THAs (223 patients) from this year onward until May, 2010, and compared the results with those from 283 all-cemented THAs (237 patients) between 1993 and May, 2010. Eighty percent or more of patients had diagnosed as secondary osteoarthritis of the hip joint due to dysplasia in our hospitals. Highly cross linked ultrahigh molecular polyethylene (CLP) socket was introduced in October, 1999. We used conventional (not cross linked polyethylene) socket for 82 hips (cemented group-1) operated before October, 1999 and CLP socket for 201 hips (cemented group-2) in all-cemented cases. We used the Kaplan-Meier method for estimation of prosthesis survival and relative risk of revision. The endpoint was radiological loosening or revision. Socket linear wear rates were also assessed in radiographically. Clinical assessment was performed using the Japanese Orthopedic Association (JOA) scores and Merle d'Aubigne & Postel scores. RESULTS. We have 12 hips (11 sockets and 1 stem) with radiological loosening in all cemented series and no hips in reverse hybrid series. A case with stem loosening in all cemented THAs had fractured stem without bony support due to massive osteolysis caused by heavy polyethylene wear. All of the loosening cases had conventional polyethylene socket and six of them were revised. Socket linear wear rates were calculated as 0.171 +/− 0.069, 0.030+/− 0.027, and 0.035+/− 0.026 mm per year for cemented group-1, group-2 and reverse hybrid cases, respectively. Clinical scores were significantly improved those at the time of final follow up compared with those of preoperative assessment. There were significant differences between conventional and cross linked polyethylene cases. We found no significant difference survival to that from cemented THR at 12 years (all cemented: 96.1% (95% CI: 92.7–99.1); reverse hybrid: 100%) (Figure 1). DISCUSSION AND CONCLUSION. With a follow-up of up to 12 years, reverse hybrid THAs performed well, and similarly to all-cemented THRs from the same time period. The reason for loosening was mainly bone loss and osteolysis due to polyethylene socket wear. It is no problem if the stem was installed by cemented or cementless fixation, because the rates of stem loosening were very low in the current study. The reverse hybrid method might therefore be an alternative to all-cemented THR. Longer follow-up time is needed to evaluate whether reverse hybrid hip arthroplasty has any advantages over all-cemented THA

Introduction. Reverse hybrid total hip replacement (THR) offers significant theoretical benefits but is uncommonly used. Our primary objective was to evaluate implant survival with all cause revision and revision for aseptic loosening of either component as endpoints. Patients/Materials & Methods. Data was collected prospectively on 1, 088 (988 patients) consecutive reverse hybrid THRs. Mean patient age was 69.3 years (range, 21–94) and mean follow-up was 8.2 years (range, 5–11.3). No patients were lost to follow-up. Overall, 194 (17.8%) procedures were performed in patients under 60 years, 666 (61.1%) were performed in female patients and 349 (32.1%) were performed by a trainee. Acetabular components were ultra-high molecular weight polyethylene in 415 (38.1%) hips, highly cross-linked polyethylene in 669 (61.5%) hips and vitamin E stabilised polyethylene in 4 (0.4%) hips. Femoral stems were collared in 757 (69.7%) hips and collarless in 331 (30.3%) hips. Femoral head sizes were 28 mm in 957 (87.9%) hips and 32 mm in 131 (12.1%) hips. Survival analysis was performed using Kaplan Meier methodology. Log rank tests were used to asses differences in survival by age, gender, head size and surgeon grade. Results. Ten-year implant survival (122 hips at risk) was 97.2% (95% CI 95.8–98.1%) for all cause revision (Figure 1), 100% for aseptic acetabular loosening and 99.6% (95% CI 99.0–99.9%) for aseptic stem loosening (Figure 2). There was no difference in implant survival by age (p = 0.39), gender (p = 0.68), head size (p = 0.76) or surgeon grade (p = 0.20) for all cause revision. There was no difference in survival by gender (p = 0.12), head size (p = 0.38) or surgeon grade (p = 0.76) for stem revision. Four (0.4%) stems failed at mean 2.5 years (range, 0.6–4.8) because they were undersized. These were associated with patient age under 60 years (p = 0.015). Discussion. This is the largest reported study on the outcomes of reverse hybrid THR in a consecutive series of patients at medium to long term follow-up. Cemented acetabular components are less costly than uncemented cups and offer other significant benefits such as improved fixation in osteoporotic or pathological bone, reduced risk of intraoperative periprosthetic fracture, easier revision and local antibiotic delivery which can reduce deep infection rates. Advantages of uncemented stems over cemented stems include biological fixation, shorter operating times, fewer adverse pulmonary events and reduced proximal stress shielding. Our results indicate high implant survival rates at ten-year follow-up with low rates of aseptic loosening (0.4%). Meticulous surgical technique is required to avoid stem undersizing which may lead to early failure particularly in younger patients. Conclusion. This study confirms that reverse hybrid THR offers highly successful outcomes, irrespective of age, gender, head size and surgeon grade. For any figures and tables, please contact the authors directly

Introduction. Total hip arthroplasty (THA) for a highly dislocated hip can be problematic and technically challenging. Our previous study on cemented THA with subtrochanteric femoral shortening osteotomy revealed a high incidence (20%) of non-union. Therefore, in 2008, we introduced reverse hybrid THA using S-ROM stem for the treatment of a highly dislocated hip. The purpose of this study was to assess the short-term clinical outcomes of this new method. Patients and methods. Between 2008 and 2014, 13 consecutive reverse hybrid THAs were performed on nine female patients with highly dislocated hips. The average age at the time of operation was 66 years (range, 55–85 years). The acetabular component was fixed in the true acetabulum with bone cement. Transverse osteotomy was performed below the lesser trochanter to shorten the femur and to prevent over-lengthening. The proximal sleeve of the S-ROM stem was then fixed within the proximal fragment, and the distal fin provided rotational stability of the distal fragment. Thus, the two fragments were fixed to each other with the S-ROM stem, and the resected segment was longitudinally cut for grafting at the junction. The postoperative follow-up period was an average of 4 years (range, 1–7 years), and no patients were lost. Preoperative and final Japanese Orthopaedic Association (JOA) hip score, operation time, bleeding amount, intraoperative and postoperative complications, bone healing at the osteotomy site, implant loosening, and revision surgery were retrospectively investigated. Results. The mean JOA hip score improved from 56 points preoperatively to 82 points postoperatively. The operation time and amount of bleeding were an average of 208 min and 643 g, respectively. The mean length of femoral resection was 4 cm (range, 2–6 cm), and the tip of the greater trochanter migrated an average distance of 7 cm (range, 5–9 cm) distally. The calculated limb lengthening was an average of 3 cm (range, 2–4 cm). Intraoperative fracture was seen in two patients, but no repeat operation was required. Two patients experienced postoperative dislocation in their hips, but additional surgery was not necessary. Postoperative nerve palsy did not occur in any patient, and all the osteotomy sites showed complete bone union. There was no implant loosening seen in any patient, and there was also no need for revision surgery. Discussion and conclusions. To achieve satisfactory outcomes with this method, resection of necessary and sufficient length of femur and accomplishment of adequate fixation between the proximal and distal fragments are necessary. In this study, dislocation occurred in two patients, and no nerve palsy was seen. Larger femoral heads may be recommended to eradicate dislocations. In cases where metaphysis of the femur is hypoplastic or the medullary canal is wide, reaming and stem insertion should be carefully performed. In this series, no additional surgery was required for the intra- and post-operative complications, and the osteotomy sites achieved bone union in all patients. Therefore, we recommend the use of this method, although longer follow-up periods are necessary

Aims. To investigate the effect of polyethylene manufacturing characteristics and irradiation dose on the survival of cemented and reverse hybrid total hip arthroplasties (THAs). Methods. In this registry study, data from the National Joint Registry of England, Wales, Northern Ireland and the Isle of Man (NJR) were linked with manufacturing data supplied by manufacturers. The primary endpoint was revision of any component. Cox proportional hazard regression was a primary analytic approach adjusting for competing risk of death, patient characteristics, head composition, and stem fixation. Results. A total of 290,770 primary THAs were successfully linked with manufacturing characteristics. Overall 4,708 revisions were analyzed, 1,260 of which were due to aseptic loosening. Total radiation dose was identified as a risk factor and included in the Cox model. For statistical modelling of aseptic loosening, THAs were grouped into three categories: G1 (no radiation); G2 ( > 0 to < 5 Mrad); and G3 ( ≥ 5 Mrad). G1 had the worst survivorship. The Cox regression hazard ratio for revision due to aseptic loosening for G2 was 0.7 (95% confidence interval (CI) 0.58 to 0.83), and for G3 0.4 (95% CI 0.30 to 0.53). Male sex and uncemented stem fixation were associated with higher risk of revision and ceramic heads with lower risk. Conclusion. Polyethylene irradiation was associated with reduced risk of revision for aseptic loosening. Radiation doses of ≥ 5 Mrad were associated with a further reduction in risk. Cite this article: Bone Joint Res 2020;9(9):563–571

Introduction: Revision rate after THA in the younger age groups is still unacceptable high and might up to 20% after 10 years. The aim of this investigation is to evaluate risk factors for later revision in patients younger than 50 years at surgery based on the NARA database (Nordic Arthroplasty Register Association). Materials and Methods: 14,610 primary THA from Denmark, Sweden, and Norway, operated from 1995 to 2007, were included. 49.4% was males, the diagnosis was idiopathic osteoarthrosis (OA) in 46%, childhood disease in 26%, inflammatory arthritis (IA) in 12%, non-traumatic osteonecrosis in 9% and fracture in 6%. 49% of the THA’s were uncemented, 27% cemented, 14% hybrid, and 8% were inverse hybrid THA’s. Cox multiple regression, adjusted for diagnose, age, gender, calendar year and surgical approach, was used to calculate prosthesis survival with any revision as end-point. RR= relative risk (CI= confidence interval). Results: The overall 10-year survival was 83%. There was no difference between gender (RR=0.94 (0.82–1.07)). IA had a 37% reduced risk of revision compared with OA (RR=0.67 (0.54–0.84)), whereas there was no difference between childhood disease and primary osteoarthrosis. Overall, cemented, uncemented and reverse hybrid THA had a better survival than hybrid THA. Hybrid THA had 24% increased risk compared with cemented (RR=1.24 (1.04–1.49)). There were no difference between cementless and cemented (RR=1.07 (0.92–1.26)). Interestingly, the inverse THA had lower revision rate than cemented THA in men (RR=0.50 (0.25–0.99)). The risk for revision due to aseptic loosening was lowest in cementless THA and reduced to RR=0.55 (0.44–0.69) compared with cemented THA. Discussion: and Conclusion: Choice of prosthetic concept for younger patients is still of debate. The present study including only patients younger than 50 years of age, showed that overall cemented, uncemented and reverse hybrid THA, had better survival than traditional hybrid. The risk for revision due to aseptic loosening was higher in cemented than cementless THA

Total hip arthroplasty (THA) in teenagers is uncommon and previously associated with poor survival rates. However it is sometimes the only option remaining to relieve pain and improve function in patients with advanced hip disease. We report on the clinical and radiological outcomes of THA in teenage patients. Medical records and radiographs of all consecutive teenage patients undergoing THA at a tertiary referral centre between 2006–2011 were reviewed. Mean follow-up was 3.4 years (range 0.6–6.8) with 9 patients having at least 5 years follow-up. Post-operative Harris hip, Oxford hip (OHS) and University of California Los Angeles (UCLA) activity scores were recorded. 51 THAs were performed in 43 patients (21 male, 22 female) with a mean age of 17 years (range 12–19). The 5 most common indications were slipped upper femoral epiphysis osteonecrosis 15 (29.4%), developmental hip dysplasia osteonecrosis 5 (9.8%), multiple/spondylo-epiphyseal dysplasia 5 (9.8%), chemotherapy-induced osteonecrosis 4 (7.8%) and idiopathic osteonecrosis 4 (8.2%). 46 (90%) were uncemented THAs and 5 (10%) were reverse hybrid THAs with 7 computer assisted design/manufacture (CADCAM) femoral implants. Articular bearings were ceramic/ceramic in 40 (78.4%), metal/metal 6 (11.8%), metal/polyethylene 3 (5.9%) and ceramic/polyethylene 2 (3.9%). The survival rate was 96% with 2 acute head revisions for 1 sciatic nerve palsy and 1 instability. Other complications (8.2%) included 1 dislocation, 1 sciatic nerve palsy that resolved, 1 surgical site infection and 1 unexplained pain. At latest follow-up, the mean Harris hip score was 90 (68–99), OHS was 42 (32–48) and UCLA activity score was 6 (4–9). Radiological analysis showed 2 patients with lucent lines around the acetabular component, but no signs of osteolysis or wear. As one of the largest studies on teenagers undergoing THA, we report good clinical and radiological outcomes at short to intermediate term follow-up

Introduction: There is an increasing interest in surface replacement arthroplasty (SRA) as an alternative to conventional THA (cTHA) in young and active patients. However, there has been considerable variability in reported outcomes. National joint registry reports have shown increased revision rates compared to cTHA. We analysed outcome measured as non-septic revision rate within two years for SRA in the NARA data base (Nordic Arthroplasty Register Association). Materials and Methods: 1638 SRA and 163802 cTHA with age up to 73 years and a non-fracture diagnosis, operated from 1995 to 2007, were compared using Cox multiple regression including age, gender, diagnosis, nation and prosthesis type with cTHA divided into cemented, uncemented, hybrid and reversed hybrid fixation. Men below 50 years of age (460 SRA and 7185 cTHA) were analysed as a subset. The SRA cohort with a mean follow-up 1,8 years was also analysed with the same method including age, gender, diagnosis, number of performed SRA per hospital and the four most commonly used prosthesis designs. In an additional analysis femoral head diameter was added, reducing the number of cases to 1552. results are presented as relative risk (RR) with 95 % confidence interval(CI). Results: SRA had a more than twofold increased revision risk compared to cTHA, RR=2,50 (1,67–3,70), which increased to 3,63 (2,42–5,44) when compared with all cemented THA. In the subpopulation of men below 50 years of age, there was no difference between SRA and any of the cTHA cathegories. Within the SRA group RR was reduced by male gender, RR=0,46 (0,25–0,86), in hospital performing > 70 SRA (RR=0,26, 0,11–0,60) and with use of BHR (Birmingham Hip Resurfacing) compared to all other designs (RR=0,27, 0,12–0,61). The size of the femoral head diameter had no significant influence on the early revision rate. Discussion and Conclusion: Surface replacement arthroplasty has an increased risk of early revision compared to conventional and cemented THA except for men below 50 years of age. There is a learning curve on the hospital level. Cases with secondary osteoarthritis were comparatively few and were mainly caused by pediatric hip disease. SRA might become an alternative for young men, but our follow up is too short to determine if this indication remains in the longer perspective

Aims

We studied the outcomes of hip and knee arthroplasties in a high-volume arthroplasty centre to determine if patients with morbid obesity (BMI ≥ 40 kg/m²) had unacceptably worse outcomes as compared to those with BMI < 40 kg/m².