Autologous Chondrocyte Implantation Combined with High Tibial Osteotomy for Spontaneous Osteonecrosis of the Knee with a Relatively Large Cartilage Lesion in Elderly Patients

Objective This study aimed to evaluate clinical outcomes and cartilage repair following autologous chondrocyte implantation (ACI) combined with high tibial osteotomy (HTO) in elderly patients with spontaneous osteonecrosis of the knee (SONK) presenting with large cartilage defects. Design Eleven knees of 11 patients with SONK (lesion size ≥4 cm 2 ) aged 60 years or older underwent ACI and concomitant opening-wedge HTO. Patients were followed for at least 1 year. Clinical outcomes were assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS). Cartilage repair was evaluated arthroscopically using the International Cartilage Repair Society (ICRS) grade and histologically using the ICRS II score at second-look arthroscopy. Results The overall KOOS improved significantly from a preoperative value of 38.4 ± 8.5 to a 1-year postoperative value of 77.8 ± 10.9 ( P < 0.01). Arthroscopy showed cartilage repair to normal or nearly normal in 91% of cases. The mean histological ICRS II score was 67.5 ± 16.2. No postoperative complications or need for additional surgical interventions was observed. Conclusions ACI combined with HTO provides good clinical and histological outcomes in elderly patients with SONK and large cartilage defects. This approach represents an effective joint-preserving treatment option, even in patients aged 60 years or older.