Comparison of SHD-IBG and PVIBGT in ONFH including mechanical and pathological analysis of failure cases

Abstract Background : At present, there is a lack of relevant research on the efficacy difference between SHD combined with IBG and PVIBGT in the treatment of ARCO stage II and III osteonecrosis of the femoral head(ONFH). Purposes: This study aims to conduct a retrospective analysis of the treatment of ARCO stage II and III femoral headnecrosis treatment. Firstly, this study intends to compare the effectiveness of surgical hip dislocation (SHD) combined with impacting bone grafts (IBG) and pedicled vascularised iliac bone graft transfer ( PVIBGT) in treating ARCO stage II and III femoral headnecrosis at 1 year postoperatively. Secondly, it examines the therapeutic efficacy of SHD combined with IBG in patients over a postoperative follow-up period of 2.5-11 years (an average of 77 months) to assess the long-term effectiveness. Lastly, the study investigates patients who suffered from hip preservation failures from both groups to better comprehend failure reasons and also to develop viable strategies for increasing clinical hip preservation rates. Methods: 30 patients (34 hips) with ARCO stage II and III femoral head necrosis were selected from the Affiliated Hospital of Nanjing University of Traditional Chinese Medicine (Jiangsu Provincial Hospital of Traditional Chinese Medicine) between January 2012 and July 2022. They were divided into group A(SHD combined with IBG) and group B (PVIBGT) according to different surgical methods. Firstly, based on Harris score and imaging data, a controlled study was conducted to analyse and compare the 1-year effect of PVIBGT on the micro-circulation within the femoral head at 1 year postoperatively; Secondly,based on Harris score, imaging data, and semi-quantitative analysis of postoperative DCE-MRI, the patients in Group A underwent a 2.5-11years (an average of 77 months) follow-up to assess the medium and long-term efficacy of SHD combined with IBG hip preservation treatment; Lastly,based on Micro-CTimaging data, mechanical finite element analysis, DCE-MRI and pathological study of the femoral head removed from patients with hip preservation failure in the two groups, the reasons for the failure of hip preservation were comprehensively analyzed in the two groups. Results: Group A: 11 males (13 hips), 4 females (4 hips); Group B: 9 males (11 hips), 6 females (6 hips).Patients in Group A received 2.5-11 years of aftercare (an average of 77 months), while patients in Group B received at least 1 year of aftercare. The THA conversion rates were 11.8% in Group A and 11.8% in Group B respectively, which were concluded after the follow-up. Firstly, the average Harris scores of the two groups at 1 year after surgery: preoperative: 70.7, 1 year after surgery: 78.9 in group A; preoperative: 69.5, 1 year after surgery: 81.5 in group B. The differences were statistically significant (P<0.05).Compared to the preoperative period,quantitative analysis by DCE-MRI showed an increase in perfusion in the necroticarea and an improvement in hyperperfusion in the repair-responsive area one year after the surgery. Secondly, in group A, the hip preservation rate was 88.2% at 2.5-11 (average of 77 months) years of follow-up, and the mean Harris score at the last follow-up was 73.2. Semi-quantitative analysis of postoperative DCE-MRI showed that the perfusion curves of necrotic and repaired areas were similar to those of the normal area. This suggests the instability within the femoral head had been effectively improved, and the perfusion had partially recovered. Thirdly, according to Micro-CT and pathologica studies of patients with hip preservation failure in these two groups , all these patients' femoral head was significantly collapsed and deformed. Their trabeculae was thin and partially disorganized, with fractures in the subchondral bone and separation of the cartilage from the subchondral bone. The necrotic areas had sparse trabeculae, disorganized arrangement, loss of continuity, and disappearance of cells in the trabecular traps. Additionally, there was a variety of tissue hyperplasia, including connective tissues and neovascularization. The necrotic area was covered with fibrous tissue, and partial restoration was observed in the repair area. Bone tissue in the necrotic area was replaced with fibrous tissue. Mechanical finite element analysis showed that the maximum equivalent force was observed in the weight- bearing area and the cortical bone surrounding the shaft of femurand.The result of DCE-MRI showed that the repair reaction area exhibited abnormal hyperperfusion. Conclusion: After comparing the 1-year postoperative effectiveness of SHD-IBG and PVIBGT, as well as the mid-to-long-termfollow-up of SHD-IBG for 2.5-11 years (average of 77 months), both surgical operations have shown the ability to delay the progression of necrosis of the femoral head. Additionally, the comprehensive analysis of patients with failed hip preservation in both groups indicates that both operations are effective in treating femoral head necrosis. However, it is noticeable that neither procedure is effective for ARCO stage II and III femoral head necrosis with extensive involvement of the lateral column. Level of EvidenceLevel III , Retrospective and Comparative Study.