A three-dimensional computed tomography study of distal femoral morphology in Japanese patients: Gender differences and component fit

- We examine the distal femoral morphology and variation patterns for TKA in Japanese patients.
- The ML/AP ratio was negatively correlated with the distal femoral AP length in both male and female.
- The existing femoral components for female tended to be too large for a given AP measurement.
- In male, the prosthetic designs tended to be smaller than the morphologic data in the ML width.
- Our study provides evidence for exploring the need for male-specific TKA components.

BackgroundPrevious anthropometric studies have reported gender differences in distal femoral 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 male and female, and to evaluate the need to create gender-specific knee prostheses.Material and methodsWe evaluated 80 knees in 40 male and 40 female Japanese patients scheduled for total knee arthroplasty (TKA). The mediolateral (ML) and anteroposterior (AP) dimensions of the knees at different levels were measured preoperatively using three-dimensional computed tomography, and ML/AP aspect ratios were calculated.ResultsOn the distal femoral cut surface, the mean ML widths were 74.9 mm for male and 65.1 mm for female, and the mean AP lengths were 63.4 mm for male and 58.9 mm for female. Such values were generally smaller compared to data from European and North American studies. In this study, the mean ML/AP aspect ratios were 1.31 for male and 1.25 for female, higher than those from non-Asian regions. The ML/AP ratios of Japanese patients were negatively correlated with distal femoral AP length.ConclusionsJapanese female had a relatively narrower femoral width for a given AP length than male. 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.