Osseous Integration after Fresh Osteochondral Allograft Transplantation to the Distal Femur: A Prospective Evaluation Using Computed Tomography

OBJECTIVE: Fresh osteochondral allograft transplantation (OCA) is an increasingly available option for patients with damage to the bone-cartilage complex of the distal femur. This study prospectively assesses osseous integration and early clinical results following fresh OCA with single or multiple cylindrical grafts to the femoral condyle. DESIGN: Patients with grade 4 International Cartilage Repair Society (ICRS) defects of the distal femur were treated with OCA. Outcome measures were collected preoperatively and postoperatively at 6, 12, and 24 months. Computed tomography (CT) scans obtained at 6 months were used to assess degree of osseous incorporation regionally. RESULTS: Thirty-four patients, with a mean age of 34.5 years (range, 15-61), with a mean femoral osteochondral lesion of 5.7 cm(2) (range, 1.5-15.0) due to focal osteoarthritis, osteochondritis dissecans, and avascular necrosis, are reported. Statistically significant (P < 0.05) mean improvement in outcome scores at 2 years included Knee Injury and Osteoarthritis Outcomes Score (KOOS) pain, sports and recreation, quality of life, and International Knee Documentation Committee (IKDC). CT imaging indicated grafts implanted to direct weightbearing regions had >75% incorporation (20/26 grafts) compared to <50% incorporation in the indirect weightbearing regions (8/14 grafts). A greater degree of incorporation and earlier outcome improvement were found after single (n = 23) compared to multiple (n = 11) grafts. CONCLUSION: CT scans were used to assess osseous incorporation of fresh osteochondral allografts in a cohort that showed significant improvements after 2 years. Single-graft implantation is associated with stable incorporation of a greater percentage of the graft. Lesser incorporation appears more frequently with grafts in posterior indirect weightbearing regions of the condyle and multiple contiguous grafts.