Sex differences in the radial grooves in the first extensor compartment

De Quervain tenosynovitis affects the first extensor compartment of the wrist and occurs more frequently in females. This high prevalence could not be explained by soft tissue. As the osseous anatomy has been mostly neglected, we aimed to compare the distal radius between the sexes. We evaluated the presence of a bony ridge on the floor of the first extensor compartment on CT images with multiplanar imaging. We included 244 wrists (72 females, 172 males) in the study. A bony ridge was present in 58 (23.8 %) and absent in 186 (76.2 %) wrists. A ridge was present in 24 (33.3 %) wrists among females and 34 (19.8 %) wrists among males. A groove with a bony ridge was statistically associated with females. We observed two tendon groove morphologies for the first extensor compartment. A groove with a bony ridge occurs more frequently in females. Further research is needed to clarify the relationship between the high frequency of a bony ridge and increased prevalence of de Quervain tenosynovitis in females.