The female knee: anatomic variations and the female-specific total knee design

Abstract

The concept and need for a gender-specific or female-specific total knee prosthesis have generated interest and discussion in the orthopaedic community and the general public. This concept relies on the assumption of a need for such a design and the opinion that there are major anatomic differences between male and female knees. Most of the information regarding this subject has been disseminated through print and Internet advertisements, and through direct-to-patient television and magazine promotions. These sources and a recent article in a peer-reviewed journal, which support the need for a female-specific implant design, have proposed three gender-based anatomic differences: (1) an increased Q angle, (2) less prominence of the anterior medial and anterior lateral femoral condyles, and (3) reduced medial-lateral to anterior-posterior femoral condylar aspect ratio. We examined the peer-reviewed literature to determine whether women have had worse results than men after traditional TKAs. We found women have equal or better results than men. In addition, we reviewed the evidence presented to support these three anatomic differences. We conclude the first two proposed differences do not exist, and the third is so small that it likely has no clinical effect.

Level of evidence: Level IV, systematic review. See the Guidelines for Authors for a complete description of levels of evidence.

Fig. 1

This diagram depicts a cross section of the distal femur. PCL = posterior condylar line; SL = sulcus line (parallel to PCL; represents the anterior cut during TKA); LAH = lateral anterior height; MAH = medial anterior height. The average anterior lateral condyle height and anterior medial condyle height for men are 13.7 mm and 10.6 mm, respectively, whereas those for women are 12.3 mm and 9.0 mm, respectively.