Abstract
Introduction
Previous anthropometric studies have reported gender differences in distal femoral morphology. After total knee arthroplasty, females have a higher prevalence of medial or lateral femoral component overhang, which could be responsible for postoperative knee pain and decreased range of motion. Consequently, gender-specific knee prostheses were designed to accommodate female morphology. However, to date, very few studies have investigated the knee morphology of Japanese adults and possible gender differences. The purpose of this study was to examine the distal femoral morphology of Japanese patients, to characterize anatomical differences between men and women, and to evaluate the need to create gender-specific knee prostheses.
Material and Methods
We evaluated 107 knees in 17 male and 90 female Japanese patients for total knee arthroplasty (TKA)[fig.1]. The medial-lateral (ML) and anteroposterior (AP) dimensions of the knees at different levels evaluated intraoperative measurement, and ML/AP aspect ratios were calculated.
Results
On the distal femoral cut surface, the mean ML widths were 74.8 mm for men and 65.5 mm for women. Such values were generally smaller compared to data from European and North American studies. In this study, the mean ML/AP aspect ratios were 1.21 for men and 1.13 for women, higher than those from non-Asian regions. The ML/AP ratios of Japanese patients were negatively correlated with distal femoral AP length.
Discussion
The dimensions and sizes of the human femur have been reported in the literature, as measured by dissection of cadaver knees, plain radiographs or CT scans of living subjects, or other means. Compared to data on knees from European and North American populations, femoral ML/AP ratios were smaller for a given AP length in Japanese individuals. In addition, the mean AP and ML distances of the distal femur of Japanese individuals were smaller than those of Western populations, which could be associated with differences in height or other physical and skeletal characteristics. Several studies reported significant gender difference in the ML/AP ratio. Because of the shapes of the distal femur were more trapezoidal for women and more rectangular for men. After TKA, females have a higher prevalence of medial or lateral femoral component overhang, which could be responsible for postoperative knee pain and decreased range of motion. Our results suggest that gender-specific knee prostheses may prevent such postoperative complications.
Conclusions
Japanese women had a relatively narrower femoral width for a given AP length than men. Our study suggests the utility of Japanese-specific implants and provides useful insights for manufacturers to design components of appropriate sizes and aspect ratios for Japanese TKA patients.
