The multiplanar effect of first metatarsal osteotomy on sesamoid position.

The standard classification system used to measure the sesamoids in the evaluation of hallux abductovalgus is a uniplanar description of a multiplanar deformity. Additionally, it cannot accurately describe a true measure of sesamoid positional change in the perioperative period because the first metatarsal is laterally transposed during corrective surgery. The intended emphasis of this investigation is to evaluate the sesamoid position in multiple planes relative to a stationary anatomical landmark following first metatarsal osteotomy for the surgical correction of hallux abductovalgus deformity. A retrospective radiographic review of 46 feet in 38 patients demonstrated statistically significant (P < .001) differences between preoperative and postoperative values for the first intermetatarsal angle, hallux abductus angle, sesamoid rotation angle, tibial sesamoid position, and tibial sesamoid grade. However, there was no significant difference in the sesamoid position in both the transverse (P = .07) and frontal (P = .29) planes when measured relative to the stationary second metatarsal. Based on the preceding results, the appropriate expected surgical outcome of hallux abductovalgus correction may be to relocate the first metatarsal on top of the relatively immobile sesamoids.