Gender Disparity between Absolute versus Relative Size of Condylar Chondral Defects: An MRI Analysis

Surgical repair of articular cartilage defects in the knee currently utilizes surgical algorithms based on absolute defect size. These algorithms, which have not been validated, are currently utilized not only by surgeons but also by insurance carriers for justification of reimbursement policy. However, current algorithms do not account for morphological differences between individual patients and defect size relative to condylar dimension. We hypothesized that a significant difference in relative defect size compared with condylar dimension may exist between individuals. A 3T magnetic resonance imaging from 220 skeletally mature patients, 110 males and 110 females, were analyzed. Exclusion criteria included degenerative arthritis, anatomical defects, poor image quality, and genetic abnormalities such as dwarfism. Utilizing a radiological curved measurement probe, the femoral condylar articular width was obtained for both the medial and lateral condyles. The mean condylar width from a reproducible anatomic location representing the maximal condylar dimension was measured. Statistical analysis was performed using a two-sample t-test. The lateral condyle articular cartilage width (mm) for males and females was 31.62 ± 3.54 and 26.53 ± 3.70, respectively (p < 0.0001). The medical condyle articular cartilage width was 27.26 ± 4.42 and 23.05 ± 4.11 (p < 0.00001). There was a width variation up to 22.66 mm between male patients and 22.10 mm between female patients. Differences up to 28.26 mm were found between males and females. A condylar defect measuring 10 mm represents as little as 24.29% of a condyle in some males versus as much as 77.46% in smaller females. Existing surgical algorithms for condylar chondral defects apply absolute size to patients regardless of individual condylar variations. Our study suggests the relative sizes of the defect vary significantly from male to female patients as well as within the same gender. Future studies may investigate clinical outcomes utilizing surgical algorithms that take into account these differences.