Purpose: Fresh osteochondral allograft (FOCA) transplantation has been an effective treatment option with promising long-term clinical outcomes for focal post-traumatic or intra-articular lesions in the knee for young, active individuals. The goal of this study was to assess the osteochondral allograft to characterize the histopathologic features of early and late graft failure, as well as prolonged graft survival.

Method: We examined histological features of thirtyfive fresh osteochondral allograft specimens retrieved at the time of subsequent graft revision, osteotomies or total knee arthroplasty.

Results: The graft survival time in our samples ranged from one to twenty-five years based on their time to reoperation. Histological features of early graft failures were lack of chondrocyte viability, loss of matrix cationic staining, and features of mechanical instability. Histological features of late graft failures were fracture through the graft, active and incomplete remodelling of the graft bone by the host bone, and resorption of the graft tissue by synovial inflammatory activity at graft edges. Histological features associated with long-term allograft survival included viable chondrocytes, functional preservation of matrix, and complete replacement of the graft bone with the host bone. These long-term histological findings correlate clinically with excellent Oxford Knee Scores (mean 17.5) in age-matched cohorts with allograft transplants surviving 20 (mean 20.9) years or longer.

Conclusion: Given chondrocyte viability, long-term allograft survival depends on graft stability by rigid fixation of host bone to graft bone. With the stable osseous graft base, the hyaline cartilage portion of the allograft can survive and function for 25 years or more.

Total hip replacement in patients with Gaucher’s disease with symptomatic osteonecrosis of the femoral head is controversial because of the high early failure rates. We describe four patients who had an uncemented total hip replacement following enzyme replacement therapy for a median of two years and one month (1 to 9.8 years) prior to surgery, and who remained on treatment. At operation, the bone had a normal appearance and consistency. Histopathological examination showed that, compared with previous biopsies of untreated Gaucher’s disease, the Gaucher cell infiltrate had decreased progressively with therapy, being replaced by normal adipose tissue. The surfaces of viable bone beyond the osteonecrotic areas showed osteoblasts, indicating remodelling. In one case acetabular revision was carried out after 11 years and eight months. The three remaining patients had a mean follow-up of six years and four months (3.3 to 12 years). We recommend initiating enzyme replacement therapy at least one to two years prior to total hip replacement to facilitate bone remodelling and to allow implantation of uncemented components in these young patients.