Autograft bone grafting via surgical hip dislocation for collapsed necrotic femoral head: a mid-term retrospective study

To investigate the mid-term outcomes of surgical hip dislocation combined with bone graft impacting and non-vascularized iliac crest bone flap implanting in the treatment of post-collapse osteonecrosis of femoral head (ONFH). From October 2014 and April 2020, 111 patients (121 hips) with ONFH were retrospectively reviewed. Assessment parameters included the Visual analog scale (VAS) pain scores and Harris hip score (HHS). Follow-up end points were set as total hip arthroplasty (THA). Conversion to THA was selected as the definitive endpoint, representing an objective clinical failure requiring intervention, whereas radiologic re-collapse lacks standardized definition and may not consistently correlate with symptomatic progression or necessitate revision surgery. Therefore, it was not used in this study. Kaplan–Meier survival analysis was used to examine the survival rate. Multivariate Cox regression analysis was used to investigate the risk factors associated with conversion to THA, including age, etiology, duration of pain, combined preserved angle (CPA), and hip joint medial space ratio (MSR). Pre- and postoperative variables of HHS in the different groups were assessed. The average follow-up time was 53.82 ± 25.36 months. The mean VAS score and HHS were significantly improved at the final follow-up compared with preoperative values (p < 0.001). By the time of the last follow-up, 19 hips failed and reached the end point of observation. The overall survival rate was 84.30% at 60 months. Multivariate Cox regression analysis revealed that CPA and MSR were independent factor associated with conversion to THA. These findings establish CPA and MSR as crucial preoperative prognostic indicators and patient selection tools. Clinical outcomes was affected by age, duration of pain, JIC classification, combined preserved angle (CPA), and hip joint medial space ratio (MSR). Surgical hip dislocation combined with non-vascularized iliac crest bone flap bone grafting is an effective treatment on post-collapse ONFH with satisfactory mid-term results, particularly when patients are selected based on favorable preoperative CPA (> 118.73°) and MSR (≤ 20.35%) values. Multicenter studies with longer follow-up are needed to further validate the efficacy of this procedure in post-collapse ONFH.