Background: Claims that there are dramatic differences in anterior condylar anatomy between the sexes have led to the design of total knee implants with thinner anterior condyles specifically for use in women. We had observed, in our patients, differences in anterior condylar anatomy that appeared to be highly variable and dependent on the size, height, and ethnicity of the patient as well as his or her sex. Because of this observed variability, we sought to determine if differences in anterior condylar anatomy between the sexes actually exist.
Methods: Two hundred and twelve randomly selected magnetic resonance images (112 of men and 100 of women) were evaluated. The anterior condyle was defined as the area of bone anterior to the anterior femoral cortex, 10 mm above the joint line. The medial and lateral heights of the anterior condyles were measured in millimeters directly from magnetic resonance imaging data obtained in two planes. The so-called aspect ratio was calculated to determine whether patient size had an effect on the size of the anterior condyles.
Results: On the basis of the numbers available, there was no significant difference (p = 0.16) between the sexes with regard to lateral condylar height. The average difference was only 0.5 mm. There was a significant difference (p = 0.001) between men and women with regard to medial condylar height. However, the average difference was only 1.1 mm. While the difference between the sexes with regard to anterior condylar height was nominal, the measurements were highly variable regardless of sex. On the basis of the numbers available, there were no significant differences between men and women with regard to the condylar aspect ratios.
Conclusions: The difference in anterior condylar anatomy is mentioned as one of three reasons for the need for a so-called gender-specific knee implant. The aspect ratio reported here, which is a surrogate for patient size, seems to negate any difference in anterior condylar anatomy based on sex. We have shown that anterior condylar anatomy is highly variable regardless of sex. We believe that implants as well as surgical techniques should be designed with the variability of anterior condylar anatomy taken into account and with an attempt to reproduce such anatomy regardless of sex.
Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants of less than $10,000 from DePuy Orthopaedics. In addition, one or more of the authors or a member of his or her immediate family received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from a commercial entity (DePuy Orthopaedics). Also, a commercial entity (DePuy Orthopaedics) paid or directed in any one year, or agreed to pay or direct, benefits of less than $10,000 to a research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which one or more of the authors, or a member of his or her immediate family, is affiliated or associated.
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Investigation performed at the OrthoCarolina Hip and Knee Center, Charlotte, North Carolina
- Copyright © 2009 by The Journal of Bone and Joint Surgery, Incorporated
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