Evaluation of Knee Donor and Elbow Recipient Sites for Osteochondral Autologous Transplantation Surgery in Capitellar Osteochondritis Dissecans

Background: Osteochondral autologous transplantation surgery (OATS) has been advocated for treatment of osteochondritis dissecans (OCD) of the capitellum in adolescents. However, little information is available regarding the optimal knee harvest site to match the contour and cartilage thickness of the recipient elbow lesion. Purpose: To characterize the capitellar anatomic structure in adolescents with and without OCD and to compare these measurements to normal adolescent knees to identify the optimal site for osteochondral graft harvest. Study Design: Controlled laboratory study. Methods: Twenty-one patients with OCD were analyzed. Twenty-two patients with normal elbows and 25 age-, weight-, and height-matched patients with normal knees were also identified. Cartilage radii of curvatures (ROCs) in the sagittal and coronal-axial planes were measured on magnetic resonance imaging (MRI) of normal capitella and 5 sites (posterior lateral femoral condyle, medial and lateral middle trochlear ridges, and medial and lateral inferior trochlear ridges) in normal knees. Differences in ROC between the knee donor and capitellar recipient sites were calculated based on a 10-mm osteochondral plug diameter. Results: Overall, the mean apex differences between graft and recipient sites ranged from 0.4 to 0.9 mm, and mean edge differences ranged from 0.5 to 1.4 mm in the coronal-axial dimension. Of all knee sites tested, the posterior lateral femoral condyle had average ROCs (19.1 mm sagittal; 14.1 mm axial) most like the capitellum (10.6 mm sagittal, 12.6 mm coronal-axial), resulting in minimal apex and edge differences (apex difference = -0.6 mm; coronal-axial side difference = -0.5 mm; no sagittal side difference). Of the anterior nonweightbearing sites, the inferior medial trochlear ridge (28.3 mm sagittal ROC; 13.2 mm coronal-axial ROC) demonstrated the lowest apex and side differences when compared with the capitellum (apex difference = -0.8 mm; coronal-axial side difference = -0.8 mm; no sagittal side difference). The frequently used middle lateral trochlear ridge (28.8 mm sagittal; 8.7 mm coronal-axial ROCs) had the largest side difference (apex distance = -0.8 mm; coronal-axial side difference = -1.4 mm; no sagittal side difference). Conclusion/Clinical Relevance: In cases where a large single-plug OATS is considered, a 10-mm plug from the anterior nonweightbearing aspect of the distal femur is calculated to result in 1 mm of articular incongruity at the recipient capitellum. The inferior medial trochlear ridge should be considered as a donor site for OATS procedures for OCD given its accessibility and favorable geometry.