Comparison of Computed Tomography Articular Surface Geometry of Male Versus Female Thumb Carpometacarpal Joints

BACKGROUND: Given the predilection of first carpometacarpal (CMC) joint osteoarthritis in women compared with men, we aim to determine the differences in first CMC joint surface geometry and congruence between young healthy males and females. METHODS: Wrist computed tomographic scan data of 11 men and 11 women aged 20 to 35 years were imported into 3-dimensional software programs. The first metacarpal and the trapezium were aligned in a standardized position according to landmarks at key points on Gaussian and maximum curvature maps. Measurements of joint congruence and surface geometry were analyzed, including joint space volume, distance between the bones at the articular surface edges, area of the joint space, and radii of curvature in the radial-ulnar and volar-dorsal planes. RESULTS: The mean thumb CMC articular space volume was 104.02 ± 30.96 mm³ for females and 138.63 ± 50.36 mm³ for males. The mean first metacarpal articular surface area was 144.9 ± 10.9 mm² for females and 175.4 ± 25.3 mm² for males. After normalizing for size, the mean thumb CMC articular space volume was 119.4 ± 24.6 mm³ for females and 117.86 ± 28.5 mm³ for males. There was also no significant difference for the articular space volume, articular surface distances, articular space, and mean radii of curvatures. CONCLUSIONS: This study found that there are sex differences in the first CMC joint articular volume without normalizing for size; however, there are no sex differences in first CMC joint articular volume, curvature characteristics, or joint congruence of young, healthy patients after normalizing for joint size.