This document summarizes a statistical shape model of the thumb carpometacarpal (CMC) joint that was developed to investigate age and sex differences in CMC joint morphology. The model was created using manual segmentations of 50 CMC joints from CT scans. Principal component analysis identified the first seven modes as describing over 95% of the shape variation. While age did not correlate with any modes, sex strongly correlated with the first mode related to overall joint size, with males tending to have larger joints than females. The shape model will enable automated segmentation of clinical CT scans to further investigate differences in a larger cohort.