Gender-Based Morphometric Analysis of the Distal Femur in Patients Undergoing Total Knee Arthroplasty

Background Total knee arthroplasty (TKA) is the definitive treatment for end-stage knee osteoarthritis; however, prosthesis-bone mismatch remains common and may compromise functional outcomes. Variations in distal femoral morphology related to sex and ethnicity contribute significantly to implant mismatch, particularly in Asian populations, where available implants are largely based on Caucasian anatomical data. Objective This study aimed to assess sex-based differences in distal femoral morphology in Indian patients undergoing TKA by evaluating specific intraoperative morphometric parameters: mediolateral (ML) width, anteroposterior (AP) length, medial and lateral AP lengths, intercondylar (IC) distance, and ML/AP aspect ratio. A secondary objective was to analyze the correlation between AP and ML dimensions to determine their utility in guiding implant sizing and minimizing prosthesis mismatch. Methods This prospective observational study included 50 patients undergoing primary TKA at a tertiary care center over one year. Intraoperative measurements of distal femoral dimensions, including ML width, AP length, medial and lateral AP lengths, and IC distance, were obtained using a vernier caliper. Aspect ratios (ML/AP×100) were calculated. Statistical analysis was performed using IBM SPSS Statistics for Windows, Version 20.0 (IBM Corp., Armonk, New York, United States), and sex-based comparisons and regression analyses were conducted. Results The mean age of patients was 48.98 years, with females constituting 80% of the cohort. The mean ML and AP dimensions were 66.06 mm and 58.64 mm, respectively, with a mean ML/AP ratio of 1.13. All measured parameters were significantly larger in males compared with females (p<0.05). The ML/AP ratio was also significantly higher in males (1.18 vs. 1.09). Regression analysis demonstrated a moderate correlation between AP length and ML width in females (R²=0.255), males (R²=0.495), and the combined cohort (R²=0.407), indicating that AP dimension alone is an incomplete predictor of ML width. Conclusion Significant sex-based differences exist in distal femoral morphology among Indian patients undergoing TKA. The moderate correlation between AP and ML dimensions suggests that reliance on AP-based implant sizing alone may result in prosthesis mismatch. These findings emphasize the need for population- and sex-specific implant designs to optimize surgical outcomes in TKA.