Mapping of Cartilage Depth in the Knee and Elbow for Use in Osteochondral Autograft Procedures

Abstract

Background: Osteochondritis dissecans (OCD) of the elbow is a problematic condition that affects a fair number of young athletes. One treatment option is the use of osteochondral autografts, which are commonly taken from donor sites on the less weightbearing surfaces of the knee. Purpose: To use magnetic resonance imaging (MRI) to assess the cartilage depths of sites in the knee and elbow that are commonly used as donor and recipient sites to optimize depth matching for osteochondral autograft procedures. Study Design: Descriptive laboratory study. Methods: All knee and elbow MRI scans acquired from 3-T machines in patients aged 16 to 25 years within a single hospital system were reviewed. Studies were excluded if there had been previous surgery on the joint or if there were significant chondral defects in the areas to be measured. All cartilage depth measurements were independently performed by 3 different physicians to the nearest 0.01 mm. At the elbow, 6 locations on the capitellum and 2 on the trochlea were chosen. At the knee, 4 locations along the anterior-lateral femoral condyle, 5 surrounding the intercondylar notch, and 1 on both the medial- and lateral-posterior femoral condyles were chosen. Results: There were 111 knee MRI (74 male, 37 female) and 94 elbow MRI (85 male, 9 female) scans that met all inclusion criteria. The average cartilage depths from each investigator were then averaged to provide an overall mean depth at each location. All average cartilage depths within the knee were thicker than those in the elbow, where the averaged mean thickness of all the 8 measured sites was 1.27 mm (range, 0.78-1.63 mm). Within the knee, the thinnest areas of cartilage, and therefore closest matches, were discovered at the posterior pole of the medial femoral condyle (mean ± SD, 1.95 ± 0.46 mm) and at the distal-most anterior-lateral femoral condyle (1.85 ± 0.46 mm). The average variance between the mean cartilage depths measured by each investigator for each location was 0.12 mm in the elbow and 0.22 mm in the knee. Conclusion: Average cartilage depths in the knee were thicker than those in the elbow at all sites measured. The thinnest areas in the knee were the posterior aspect of the medial femoral condyle and the distal-most aspect of the anterior-lateral femoral condyle. Clinical Relevance: This study provides the surgeon with meaningful data on average cartilage depths at common donor sites in the knee and recipient sites in the elbow.