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Gender-Specific Knee Replacements A Technology Overview
This Technology Overview was prepared using systematic review methodology, and summarizes the findings of studies published as of November, 2006 on gender specific knee replacements. As a summary, this document does not make recommendations for or against the use of gender specific knee replacements. It should not be construed as an official position of the American Academy of Orthopaedic Surgeons. Readers are encouraged to consider the information presented in this document and reach their own conclusions about gender specific knees
The American Academy of Orthopaedic Surgeons (Academy) has developed and is providing this Technology Overview as an educational tool. Patient care and treatment should always be based on a clinician’s independent medical judgment given the individual clinical circumstances.
Are There Gender Specific Knee Anatomic Differences?
Differences in bony anatomy have been well documented between male and female knees. Men have larger femurs than women (anterior-posterior height, transepicondylar width, height of the lateral and medial condyles).Furthermore, for the same anterior-posterior dimension of the distal femur, women have a narrower medial-lateral width. Rotatory differences exist with the trochlear groove rotated somewhat externally relative to the epicondylar axis in females and somewhat internally in males.
Anatomic differences in the patellofemoral joint are also present between males and females. Females have a larger Q angle, larger ratio between the length of the patellar tendon and the greatest
diagonal length of the patella on a lateral knee radiograph (patella alta), and a more negative congruence angle (indicating that the lowest portion of the patella is more medial relative to a line bisecting the sulcus angle). While women have higher average Q angles as compared to men and a higher minimum Q angle, maximum values for Q angles do not differ greatly between sexes. Of note is that men and women of the same height have similar Q angles and taller people have slightly lower Q angles. Thus the higher average Q angle in women as compared to men may be related to the larger overall height of men compared to women.
In addition to anatomic differences, patellofemoral joint biomechanics varies between sexes. Male cadaveric specimens had greater patellofemoral contact area as compared to female specimens at knee flexion angles greater than 30 degrees. This is logical given the larger size of the patella in males as compared to females. However, mean patellofemoral contact pressures were significantly increased in female as compared to males at 0 degree and 30 degrees of knee flexion and peak pressures were statistically significantly higher in women at 0 degree, 30 degrees and 60 degrees of knee flexion.
Difference in soft tissue characteristics, physical activities and psychological makeup have also been discussed by some relative to sex-differences but are beyond the scope of this Overview.