Defining a Relationship Between the Tibial Plateau and Posterior Femoral Condyles.

Introduction Anatomic research has demonstrated significant differences in native knee morphology between genders and ethnicities. These studies have traditionally evaluated femoral morphology. However, no studies have yet investigated possible relationships between the posterior femoral condyles and the tibial plateau. Our study sought to demonstrate this relationship, and evaluate its strength when stratified by gender and race. Methods An international database of CT scans of non-arthritic knees was accessed, and, using computer software, length measurements of regions of interest were recorded. Measurements included medial-lateral width of the posterior femoral condyles (FW) and width of the tibial plateau (TW). These measurements were compared. Statistical analysis was performed for the entire population, and subsequently for the population stratified by gender and ethnic groupings. Results The review included 373 non-arthritic knees, each from unique patients. The cohort consisted of 184 males (49.3%), and 189 females (50.6%). 117 patients were from Japan (31.4%), 100 were from India (26.8%), 87 were from Korea (23.3%), 43 were from China (11.5%), and 26 were from North America (7.0%). Average age was 57.6 years ± 8.6 years. The width of the proximal tibia was positively correlated to posterior femoral condylar width, R2=0.83. Gender stratification weakened the correlation, with female patients demonstrating an R2 of 0.64, and male patients R2 of 0.60. Ethnic stratification strengthened relationships in Japanese (R2 = 0.87), North American (R2 = 0.89), and South Korean (R2 = 0.88) patients; and weakened them in Indian (R2 =0.72) and Chinese (R2 = 0.82) patients. Discussion This study is the first to use CT to demonstrate the strength of tibiofemoral relationships for individual demographic groups. These findings highlight important differences in morphology, and may be used to inform implant design, selection, stocking, and supply. Further, these data may help identify patients who require differentially-sized tibial and femoral components preoperatively.