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.

Ethnic and Gender Differences in the Functional Disparities after Primary Total Knee Arthroplasty

“…Although this is a relatively large sample, more conclusive data, including further demographic subgroup analysis, can be drawn from larger studies. Fourth, we can make no comments regarding the debate regarding anatomic gender differences [2,9] or the role of gender-specific implants [18,23,27]. We found women had higher BMI at surgery; the magnitude of effect is unclear.…”

The John Insall Award: Both Morphotype and Gender Influence the Shape of the Knee in Patients Undergoing TKA

“…There is today growing evidence that male and female knees are different in geometry [5,6,10,14,[17][18][19]. For this reason, it seems logical to consider the development and use of gender-specific knee implants that more closely replicate the gender-specific anatomy, thereby optimizing the implant fit to the patient's individual geometry [1,[7][8][9].…”

“…They therefore refuted the hypothesis of inferior clinical outcome for women after TKA when standard components were used, and based on their study, the development of specific knee implants for female patients could not be supported. In another recent paper, Merchant et al reviewed the orthopaedic literature in an attempt to determine whether women had worse results than men after TKA when traditional gender-neutral components are used [19]. The overall results of the 19 published studies that fulfilled the authors' criteria for inclusion failed to demonstrate worse results for women than for men and in fact just the opposite was true.…”

“…These authors therefore concluded the theory that places woman at a disadvantage to men when gender-neutral components are used is not correct. Based on the clinical data available from these studies, the need for gender-specific implants therefore cannot be really supported [17,19].…”

Gender comparison of clinical outcomes post high-flex total knee arthroplasty

“…Although, the available literature, supports a little of gender specific prostheses. A systematic review by Merchant et al summarized that the evident anatomic contrasts amongst the female as well as male knee were because of small size and height of female but not of gender, essentially [15].…”