Primary total hip replacement in Ficat-Arlet stage 3 and 4 osteonecrosis: a retrospective study at a minimum 12-year follow-up.

INTRODUCTION: Results of total hip replacement (THR) for aseptic osteonecrosis are controversial and conflicting according to implant type and generation. The present study consisted in a retrospective assessment of implant survival in primary THR for aseptic osteonecrosis, using a cemented stem, standard polyethylene press-fit acetabular component, and metal-metal bearing. The study hypothesis was that THR results are equivalent between aseptic osteonecrosis and osteoarthritis of the hip. MATERIAL AND METHOD: A single-center retrospective study included 54 patients with metal-on-metal THR for femoral head osteonecrosis. The main endpoint was revision surgery for all causes, whether implant related or procedure related; secondary endpoints were complications and progression in clinical scores. RESULTS: Mean follow-up was 13.9 ± 1.6 years (range 12.0-17.1 years). Eighteen of the 54 patients (33.3%) died. Implant survival at last follow-up was 93.8% (95% CI, 87.1-100). There were 12 complications (22.2%): 1 intraoperative, 5 (9.3%) immediate postoperative, and 6 (11.1%) long term. Clinical assessment found a significant 43.1 point improvement in mean Harris score (p = 8.4E-33) and a 5.6 point improvement in mean PMA score (p = 2.9E-22). CONCLUSION: Survival in primary THR for aseptic osteonecrosis was good. Follow-up needs to be rigorous to screen for onset of complications. Primary THR is thus justified in Ficat-Arlet stage 3 and 4 aseptic osteonecrosis of the hip. LEVEL OF EVIDENCE: IV.

Hip preserving surgery for avascular hip necrosis: does terminating exposure to known risk factors improve survival?

Introduction: Avascular necrosis of the hip is rarely detected in early pre-radiographic stages (Arlet-Ficat stages I and II) where conservative treatment would still be possible. Studies of risk factors were often merely descriptive. The aim of the present study was to make a retrospective assessment of treatment survival rate for conservative management of avascular hip necrosis according to whether exposure to avoidable risk factors is eliminated or not. The study hypothesis was that eliminating avoidable risk factors is effective and reduces the risk of failure, and hence of hip replacement. Material and method: A single-center retrospective study was performed for conservatively managed avascular hip necrosis. Thirty-seven consecutive hips in 34 patients underwent decompression drilling, with a minimum 3-year follow-up. Known risk factors for osteonecrosis were classified as avoidable or non-avoidable. Results were analyzed according to the elimination of avoidable risk factors. The main endpoint was survival, with failure defined as femoral head collapse and/or recourse to total hip replacement. Avoidable risk factors (corticosteroids, smoking, alcohol consumption, blood pressure elevation, hypercholesterolemia) persisted for 17 hips (45.9%) and were prevented for 15 (40.5%). Five patients (5 hips: 13.5%) did not show preoperatively identified risk factors. Groups were demographically comparable. Results: Mean follow-up was 7.5 ± 3.7 years (range, 3.1-16.0 years). At last follow-up, there was a significant difference in survival at cumulative 9-year follow-up between patients with no risk factors (100%), with risk factors eliminated (59.3%; 95% CI, 0.273-0.012), and with persisting risk factors (23.5%; 95% CI, 0.013-0.458) (p = 0.001). Discussion: No studies were found in the literature assessing the survival of hip preserving surgery according to persistence or elimination of known risk factors for osteonecrosis. Eliminating risk factors significantly improved the survival rate for conservative treatment of femoral head necrosis.

Does augmented core decompression decrease the rate of collapse and improve survival of femoral head avascular necrosis? Case-control study comparing 184 augmented core decompressions to 79 standard core decompressions with a minimum 2 years' follow-up.

INTRODUCTION: Avascular necrosis of the femoral head often progresses to femoral head collapse if not treated. Conservative treatment yields highly variable results and is not standardised, mainly because it is typically evaluated in small patient populations. This led us to conduct a large retrospective comparative study with the goals of 1) analysing survival and functional outcomes, 2) looking for differences in survival between core decompression techniques (standard versus augmented), and 3) studying the risk factors for femoral head collapse and revision by arthroplasty. HYPOTHESIS: Core decompression limits the number of patients who suffer femoral head collapse requiring arthroplasty at 2 years' follow-up. METHODS: This multicentre, comparative, retrospective study analysed 330 patient records (1975-2016) where at least 2 years' follow-up was available. Sixty-two patients were excluded from the analysis: 5 had a stage III with collapse, 5 were lost to follow-up, 2 died within 24 months of the procedure and 50 had incomplete data. The study included 263 patients with a mean age of 42 years (15.7-70). In the Ficat classification, there were 51 cases of stage I necrosis, 186 cases of stage II and 22 cases of stage II with crescent sign (transition stage). The Kerboull angle on radiographs was between 5° and 20° in 40 patients, between 20° and 40° in 107 patients, between 40° and 60° in 52 patients and more than 60° in 29 patients. A standard core decompression was done in 79 patients and an augmented one in 184 patients. The more severe AVN cases (stage II) were more likely to be treated by augmented CD (160/184 patients, 87%) than by standard CD (48/79 patients, 61%) (p<0.001). RESULTS: In the 263 patients, the overall survival (no arthroplasty at 2 years) was 73% (196/263). At 2 years, the survival rate (without arthroplasty) was 71% (56/79) in the standard CD group versus 76% (140/184) in the augmented CD group. This difference was significant when adjusted for Ficat stage and Kerboull angle [HR=0.457, 95% CI (0.247-0.844) (p=0.012)]. When the survival data was adjusted to the Ficat stage, augmented CD was better than standard CD with 10-year survival of 58.1% vs. 57.9% (p=0.0082). More than 30% necrosis volume increased the risk of failure [HR=3.291 95%CI (1.494-7.248) (p=0.0031)]. Also, a Kerboull angle above 60° increased the risk of failure [HR=3.148 95%CI (1.346-7.5) (p=0.0083)]. CONCLUSION: After 2 years, CD for non-collapsed femoral head AVN prevents collapse and revision to arthroplasty in 73% of cases (196/268). Augmented CD improves the 2-year survival and the long-term survival after adjusting for preoperative characteristics (Kerboullangle and Ficat stage). The risk of collapse and need for arthroplasty is greater in patients with 30% necrosis volume on MRI and Kerboull angle above 60°. LEVEL OF EVIDENCE: III; retrospective case-control study.