Proximal opening-wedge osteotomy of the first metatarsal for hallux valgus using a low profile plate.

Background: This retrospective study was conducted to evaluate the results of the proximal (basal) opening-wedge osteotomy of the first metatarsal for correction of symptomatic hallux valgus deformity, using a low profile plate.

Methods: The procedure was performed by a single surgeon over an 18-month period. Forty-six patients (64 feet) were treated for symptomatic hallux valgus with an average follow up of 20 months. A proximal opening-wedge osteotomy of the first metatarsal and fixation with a low profile plate in combination with a distal soft tissue release with the same postoperative protocol was used in all the patients. Improvement in the hallux valgus angle (HV) and I---II intermetatarsal angle (IM I---II) as well as the AOFAS forefoot score pre and postoperatively (obtained retrospectively from the medical records), were recorded; in particular, the length of the first metatarsal was noted pre- and postoperatively.

Results: The HV and IM I---II angles improved by a mean of 14.7 degrees and 6.4 degrees, respectively. The AOFAS forefoot score improved from a mean of 51.3 to 86.8. The mean increase in the length of the first metatarsal was 2.3 mm. Of the more significant complications, five patients developed a hallux varus (early in the series), one of which was symptomatic, and there was one non-union requiring bone graft.

Conclusions: The proximal opening wedge osteotomy of the first metatarsal in combination with a distal soft tissue release and stable fixation of the low profile plate was an effective method for correcting a moderate hallux valgus deformity. Guidance provided by the "First Metatarsal Opening Wedge Angle Reference Chart'' was found to be helpful for the IM I-II angle correction.