Osteochondral Allograft Donor-Host Matching by the Femoral Condyle Radius of Curvature.

BACKGROUND: Conventional osteochondral allograft (OCA) matching, requiring orthotopic, size-matched condyles, and narrow surgical time windows often prohibit timely transplantation.

HYPOTHESIS: The femoral condyle radius of curvature (RoC) is an appropriate, isolated criterion for donor-host matching in fresh OCAs, potentially enhancing matching efficiency when compared with conventional matching techniques.

STUDY DESIGN: Descriptive laboratory study.

METHODS: In part 1 of this study, 3-dimensional digital reconstructions of 14 randomly selected, cadaveric distal femoral hemicondyles were performed. Each condyle was divided into anterior, middle, and posterior zones. A virtual best-fit grid was applied to each, and each zone's sagittal- and coronal-plane RoCs were determined. Seven nonorthotopic OCA transplantations were performed based on RoC matching with 1-mm tolerance, and the preoperative and postoperative surface geometry were quantified to assess the accuracy of articular surface restoration. Of note, each donor-host pair did not match by the conventional method. In part 2 of this study, 12 cadaveric distal femora were categorized by size and digitized in the aforementioned manner. Simulated circular defects measuring 20, 25, and 30 mm in diameter were introduced into each zone. OCA matches were determined based on donor and host RoCs, and the total number of potential matches (of 71 total comparisons) was recorded as a percentage for each simulated defect. Finally, the results of RoC matching were compared with the conventional method for simulated defects in all zones of both the medial and lateral femoral condyles.

RESULTS: Part 1: The mean surface deviation after OCA transplantation was -0.09 mm, with a mean maximum protrusion at any point of 0.59 mm. Part 2: Using the RoC, 20-mm defects had a 100% chance of being matched. Defects of 25 and 30 mm had a 91% and 64% chance of being matched, respectively. Compared with the conventional method, the RoC method yielded a 3.2-fold greater match rate for lesions of the medial and lateral femoral condyles ( P = .02).

CONCLUSION: This investigation shows that femoral condyle RoCs in the sagittal and coronal planes may be useful, alternative matching criteria, expanding on current standards.

CLINICAL RELEVANCE: These matching criteria may increase the number of available matches, reduce wait times for patients, and reduce the number of wasted grafts.