Risk of Chondral Fracture During Implantation of Distal Femur Osteochondral Autograft Plugs: A Human Cadaveric Comparison of Four Different Donor Regions.

Introduction: Distal femoral cartilage lesions can be treated using osteochondral autograft transfer (OAT). When impacting plugs into a recipient site, the cartilage may fracture. This study aimed to analyze OAT donor regions and impaction energies to identify characteristics that lead to fracture.

Methods: Fifteen cadaver femurs were used with OAT plugs harvested from the following regions: lateral and medial trochlea (LT and MT), lateral and medial intercondylar notch (LIN and MIN). Plugs were impacted into a bone surrogate block using a custom anvil-type system with pre-determined impact heights; 30, 50, 70, and 90 mm. Each plug's cartilage was examined and determined to be intact or fractured. Chi-square was used to compare the rate of chondral fracture for each region.

Results: In all, 221 plugs were included. The overall rate of chondral fracture was 45.7%. There was a significant difference in the rate of fracture between regions, with LIN, MIN, LT, and MT, having a fracture rate of 46.6%, 62.7%, 25.0%, and 51.9%, respectively (P = 0.001). An impact height of 30 mm resulted in a fracture rate of 17.7%. Increasing the impact height from 30 to 50 mm resulted in significantly increased chondral fracture risk (P = 0.001).

Conclusion: Different donor regions have varying rates of chondral fracture during OAT plug impaction, with the lateral and medial trochlea being the most resistant to chondral fracture at lower forces. Increased impact energy increases risk of chondral fracture. Surgeons should maintain caution and utilize lower impact energy when inserting OAT plugs.