The Evaluation of Refrigerated and Frozen Osteochondral Allografts in the Knee

Between 1998 and 2002, 25 patients who were treated with a refrigerated or frozen allograft were evaluated. The mean patient age was 48 years. The mean lesion size was 4.5 cm. Validated outcome instruments [Knee Society Score, Western Ontario and McMaster University Score] were used. Clinical and radiographic evaluations were performed pre-operatively and at the most recent follow-up. Histological and electron microscopic analysis was performed on grafts prior to implantation. Clinical follow-up averaged 46 months (range 24 60 months). The Western Ontario and McMaster University Score improved from 46 + 24 to 66 + 22 (p = 0.003). The Knee Society Score improved from 104 + 43 to 132 + 42 (p = 0.01). No correlation was noted between graft type and histological or electron microscopy scoring. Post-operative mechanical alignment was not correlated with an improvement in Western Ontario and McMaster University Score (p = 0.19) or Knee Society Score (0.27). Six patients (24%), all refrigerated allografts, were failures and underwent knee arthroplasty. Seventy-six percent of implanted frozen and refrigerated osteochondral allografts are in place 4 years after surgery. Frozen allografts appear to be surviving as well as refrigerated grafts. The use of magnetic resonance imaging may enable the evaluation of graft incorporation and articular cartilage integrity.