Three-dimensional CT comparison of sesamoid position between hallux valgus with sesamoid dislocation and normal feet

Sesamoid displacement is a characteristic feature of hallux valgus; however, its three-dimensional positional changes relative to the surrounding bony structures remain unclear.

To compare the three-dimensional position of the lateral sesamoid in hallux valgus with sesamoid dislocation and in normal feet using computed tomography.

Retrospective comparative study.

Feet with hallux valgus and sesamoid dislocation (Group A) were compared with normal feet (Group B). Three-dimensional computed tomography reconstructions were used to evaluate the spatial relationship between the lateral sesamoid and adjacent bones. Distances between the center of the lateral sesamoid and the second metatarsal were measured along the mediolateral (X-axis), dorsoplantar (Y-axis), and straight-line axes. Additional measurements included distances from the lateral edge of the lateral sesamoid to the distal shaft of the third metatarsal and to the lateral center of the first metatarsal head.

The straight-line distance between the lateral sesamoid and the second metatarsal did not differ significantly between groups. However, the lateral sesamoid was positioned significantly more laterally and dorsally in Group A. The distance to the distal third metatarsal shaft was significantly greater, whereas the distance to the lateral center of the first metatarsal head was significantly shorter in Group A.

Hallux valgus with sesamoid dislocation is characterized by three-dimensional dorsolateral displacement of the lateral sesamoid without a change in straight-line distance. This displacement may mechanically impede first metatarsal reduction and should be considered during surgical correction.