Morphologic difference and size mismatch in the medial and lateral tibial condyles exist with respect to gender for unicompartmental knee arthroplasty in the Korean population.

PURPOSE: The purpose of this study was to characterize the geometry of the proximal tibia in both genders in the Korean population. Anthropometric data on the medial and lateral tibial condyles of the osteoarthritic knees of 149 males and 814 females were obtained using three-dimensional magnetic resonance imaging. METHODS: In the medial and lateral proximal tibial condyles, the anteroposterior (AP) dimension, widest dimension (WD) at defined points, and condylar aspect ratio were evaluated. These measurements were compared with similar dimensions of the tibial components from five commonly used unicompartmental knee arthroplasty (UKA) designs in Korea. RESULTS: Both the AP dimension and WD in the medial and lateral tibial condyles of the male patients were significantly greater than those of the female patients (P < 0.05). In addition, the AP dimension and WD were greater in the medial than in the lateral tibial condyle (P < 0.05). There was WD overhang in three and two prostheses in the medial and lateral tibial condyles, respectively. A decrease in the condylar aspect ratio with an increasing AP dimension was found in the medial and lateral tibial condyles for both the male and female patients. CONCLUSIONS: Smaller medial and lateral tibial condylar dimensions are more frequent in Korean women than in Korean men. This study highlights the finding that conventional UKA designs lead to size mismatch in the Korean population and may indicate an important guideline on proper gender-specific UKA tibial prostheses with different WD/AP dimension aspect ratios. In addition, this study suggests that the shape of the medial tibial plateau is different to that of the lateral plateau, which can lead to a mediolateral overhang for medial UKA in an attempt to optimize the AP coverage. LEVEL OF EVIDENCE: III.