Proximal spherical metatarsal osteotomy for the foot with severe hallux valgus.

BACKGROUND: A proximal spherical metatarsal osteotomy was devised to correct not only varus deviation of the first metatarsal, but also dorsiflexion. We expected to increase the medial longitudinal arch by adding plantar flexion at the osteotomy site. To investigate the limitations of this procedure for feet with severe hallux valgus, a followup study was performed on patients with preoperative hallux valgus angles greater than or equal to 40 degrees.

MATERIALS AND METHODS: Forty-eight feet in 37 patients (10 male, 27 female) (60 years; range, 20 to 84 years) were investigated. Mean followup was 4 years and 1 month, ranging from 2 to 8 years. The spherical osteotomy was performed using a curved chisel. A distal soft tissue procedure was done at the same time. Twenty feet received combined operations for their combined deformities.

RESULTS: While 81% of patients were satisfied with the results, 50% of those with preoperative hallux valgus angles greater than or equal to 50 degrees had postoperative hallux valgus angle greater than or equal to 20 degrees. In these patients, correction of metatarsus primus varus was good, but correction of valgus deviation of the hallux was fair. Mean correction toward plantar flexion was 1.5 degrees and no increase in arch height was achieved.

CONCLUSION: The proximal spherical osteotomy could consistently achieve satisfactory results for the patients with hallux valgus angles less than 50 degrees. However, the corrections were worse in feet with more severe deformities. Furthermore, plantarflexion at the osteotomy site was offset by displacement at the first tarsometatarsal joint. If plantarflexion is indispensable, arthrodesis of the tarsometatarsal joint is recommended.