Sex differences in photon-counting detector computed tomography-derived scaphotrapeziotrapezoid joint morphometrics.

OBJECTIVE

The scaphotrapeziotrapezoid (STT) joint transmits load between the wrist and thumb. Despite its clinical importance, it has received less diagnostic attention than adjacent wrist and thumb joints. CT-derived three-dimensional models offer the ability to improve measurement of articular space by evaluating subchondral articular surfaces, which can be quantified using articular morphometrics. The objectives of this study were to investigate whether articular surface areas, interosseous proximities, and carpal bone positions differ between sexes.

MATERIALS AND

METHODS

Thirty participants (50% female, median age 27.0 years) were prospectively recruited to a cohort study of normative wrist imaging and biomechanics. Carpal bones were meshed from CT-based segmentations using a marching cubes algorithm. Rigid body kinematic parameters of individual bones were calculated. Carpal bone postures were defined using projection angles between bone centroids. Articular surface areas and interosseous proximity distributions between adjacent bones were calculated. Morphometrics were compared between sexes using Wilcoxon rank sum or two-tailed Kolmogorov-Smirnov tests as appropriate.

RESULTS

Median articular surface area was significantly smaller in females than in males at the trapeziotrapezoid but not scaphotrapezium or scaphotrapezoid joints. Interosseous proximity distributions were closer in females at all joints (scaphotrapezium, 1.19 versus 1.42 mm; scaphotrapezoid, 1.15 versus 1.43 mm; trapeziotrapezoid, 0.45 versus 0.65 mm). Distal bones were more dorsally translated in females.

CONCLUSION

This study quantifies sex-stratified morphological variations at the STT joint. Interosseous proximity distributions may guide interpretation of imaging-derived STT joint space and can serve as reference ranges for studies of STT arthrokinematics.