Short-term outcomes of AVN CAGE implantation for early-stage osteonecrosis of the femoral head

Purpose: Considering the low survival rate for the numerous hip-preserving procedures developed for treating early-stage osteonecrosis of the femoral head (ONFH), this study aimed to evaluate short-term clinical outcomes following avascular necrosis (AVN) CAGE implantation. Methods: 58 hips with early-stage ONFH (44 with Association Research Circulation Osseous [ARCO] stage 2 and 14 with stage 3A) treated with the AVN CAGE between August 2018 and December 2021 were included. The survival rates were analysed using radiographic progression and conversion to subsequent total hip arthroplasty (THA) as endpoints. Results: The mean follow-up period was 22.2 ± 8.2 months. 11 hips progressed to ARCO stage 3B/4, and 6 underwent THA. The estimated 2-year radiographic survival rates were 89.1% and 59.0% for patients with ARCO stages 2 and 3A, respectively. The estimated 2-year radiographic survival rates were 92.9% and 76.3% for Japanese Investigation Committee type B/C1 and C2, respectively. The overall estimated 2-year THA-free survival rate was 88.9%. Advanced disease stage and a large necrotic area were independent risk factors for radiographic progression. Conclusions: AVN CAGE combined with standard core decompression was a promising hip-preserving option for patients with no signs of collapse, small necrotic areas, or medially located necrotic locations.