Surgery for hallux valgus with proximal crescentic osteotomy causes variable postoperative pressure patterns.

We prospectively evaluated the results of plantar pressure measurement in 32 patients (43 feet) who had a proximal crescentic osteotomy of the first metatarsal with a modified McBride procedure. The procedure's effectiveness in increasing weightbearing under the first ray, decreasing pressure under the second metatarsal head, and the relationship of radiographic measurements of first metatarsal length and position to postoperative pressure measurements were evaluated. Mean followup was 29 months. Average peak pressure increased postoperatively under the second metatarsal head. Almost identical numbers of feet had first metatarsal elevation (12) or depression (11) greater than 2 mm. Radiographic evidence of first metatarsal elevation, but not shortening, was associated with diminishing peak pressure and pressure-time integral under the first metatarsal head and hallux. Five feet that had first metatarsal elevation greater than 2 mm had new second metatarsal transfer lesions develop. Eleven feet preoperatively and nine feet postoperatively had symptomatic second metatarsal pressure lesions. One lesion persisted, 10 resolved, and eight new lesions developed. Control of the crescentic osteotomy in the sagittal plane was unpredictable despite modification of the surgical technique to plantarly displace the distal segment of the first meta-tarsal. Although average second metatarsal pressure increased postoperatively, there was variability in the correlation of radiographic change and pedobarographic measurements.