PROXIMAL SPHERICAL METATARSAL OSTEOTOMY FOR THE FOOT WITH SEVERE HALLUX VALGUS

Abstract

To investigate the limitation of proximal spherical metatarsal osteotomies for feet with severe hallux valgus, a follow-up study was performed on the patients whose preoperative hallux valgus angles were 40 degrees or more.

Forty-eight feet in 37 patients (11 male, 37 female, 60 years range 20 to 84 years) were investigated. Mean follow-up was 4 years and 1 month ranging from two to eight years. The spherical osteotomy, performed using a curved chisel, was devised for correcting not only varus deviation of the first metatarsal but also pronation and dorsiflexion. A distal soft tissue procedure was done at the same time. Twenty feet received combined operations for their combined deformities.

Eighty-one percent of the patients were satisfied with the results. However, six of twelve patients whose preoperative hallux valgus angles were 50 degrees or more were unsatisfactory. Mild metatarsalgia remained in eight feet at the follow-up, but no new metatarsalgia developed in any patients. The mean value of the hallux valgus angle improved from 46.6 degrees to 11.1 degrees. The patients whose preoperative hallux valgus angle were 50 degrees or more showed 16.4 degrees of average hallux valgus angle at follow-up. Their results varied widely and most of them had inadequate correction. The mean correction toward plantar flexion was 0.7 degrees. Average shortening of the first metatarsal was 3.4mm. The shortening of the first metatarsal had not caused worsening of metatarsalgia if adequate correction of hallux valgus was achieved and malunion toward dorsi-flexion was prevented.

The proximal spherical osteotomy could consistently achieve satisfactory results for the patients whose hallux valgus angles are under 50 degrees. However, the results were worse in feet with more severe deformities. Other procedures for hallux valgus or proper combined operations were necessary for such patients.