Relationships Between First Metatarsal and Sesamoid Positions and Other Clinically Relevant Parameters for Hallux Valgus Surgery.

Relationships between hallux valgus (HV) and other measurements within the first ray have been extensively studied. It is becoming more popular to correct HV deformity with tarsometatarsal joint arthrodesis while internally (varus) rotating the first metatarsal. This, in turn, reduces the sesamoid position when viewed in the dorsoplantar projection on radiographs. However, it has been shown that not all HV deformities have pathological external (valgus) rotation of the first metatarsal. In this study, we explored the relationships between frontal-plane rotations of the first metatarsal as well as the sesamoids, and other factors not limited to the first ray, to better understand the pathological process of HV deformity and to assist in surgical planning. We found that when adjusting for these covariates, the only factor associated with first metatarsal external rotation was having less metatarsus adductus. Sesamoid rotation, on the other hand, was independently associated with the HV angle, tibial sesamoid position, and medial column collapse. When surgically treating HV, correction of sesamoid rotation may need to be prioritized.