Favorable 10-year outcomes of osteochondral autologous transplantation for spontaneous osteonecrosis of the knee following subchondral insufficiency fracture with optimal alignment correction.

PURPOSE

The long-term effect of osteochondral autologous transplantation (OAT) on spontaneous osteonecrosis of the knee (SONK) following subchondral insufficiency fracture remains unclear. This study aimed to evaluate the long-term survivorship and clinical outcomes of OAT for SONK, with a focus on factors associated with clinical success.

METHODS

Patients who underwent OAT for SONK between 1998 and 2009 were retrospectively reviewed. Survivorship was assessed using Kaplan-Meier analysis, with revision surgery as the endpoint. Clinical outcomes were evaluated using the International Knee Documentation Committee (IKDC) subjective score obtained preoperatively and at final follow-up. Clinical failure was defined as an IKDC score below the patient acceptable symptom state (PASS; 62.1 points). The association between final IKDC score and postoperative femorotibial angle (FTA) was analyzed using linear and quadratic regression.

RESULTS

A total of 33 OATs were included (mean age: 64.6 ± 8.0 years; mean lesion size: 3.9 ± 1.7 cm). High tibial osteotomy was performed in 15 patients with FTA > 180°, and 24 patients were followed for ≥ 10 years (mean: 13.7 ± 3.4 years). One arthroplasty was performed at 14.2 years, yielding a 15-year survival rate of 88%. The IKDC score improved significantly (35.0 ± 12.6 to 70.6 ± 14.1, p < 0.001), with a clinical success rate of 79.2%. Quadratic regression showed optimal postoperative FTA between 163.1° and 178.3° for achieving PASS.

CONCLUSIONS

OAT may provide favorable long-term survivorship and clinical outcomes in SONK, particularly when postoperative alignment is appropriately corrected.