MITCHELL & SCARF OSTEOTOMY FOR HALLUX VALGUS. STUDY OF THE OUTCOME WITH PLANTAR PRESSURES

Abstract

Introduction Hallux valgus (HV) leads to altered load-bearing function of the foot but there is no adequate evidence to show the restoration of load bearing function post-deformity correction where transfer metatarsalgia is the common complication. This study describes a retrospective review conducted on individuals who have undergone Mitchell and Scarf osteotomy for severe HV deformity.

Method Clinical records and radiographs were reviewed. Clinical evaluation was done using American Orthopaedic Foot and Ankle Society (AOFAS) scores and plantar pressures recorded using the Musgrave system analysing the average pressure, peak pressure distribution and contact time of the various regions of foot during the gait cycle. A control group of 15 individuals with 20 normal feet was included for comparison. Statistical analysis was carried out using ANOVA and correlation tests.

Results Twenty-two Mitchell and 22 Scarf osteotomies were performed on 28 patients with follow up ranging from 13 to 62 months. The average postoperative AOFAS scores following Mitchell and Scarf osteotomy were 74 and 84 respectively.

Pedobarograph findings: Post-Mitchell osteotomy, an insufficiency of hallux was seen, which overloads the second and third metatarsal heads. Post-Scarf osteotomy resulted in reduced peak pressures under first, second and third metatarsal heads and hallux with reduced push off during late stance phase. More pressure is transferred through heel, midfoot and lateral metatarsal heads. The centre of pressure progression is central in both the study groups. The outcome of the procedure depends on the load bearing characteristics of hallux and not the first metatarsal head.

Conclusion Mitchell osteotomy leads to abnormal load bearing characteristics of the forefoot with an unfavourable outcome. However, the Scarf procedure does not restore the load bearing characteristics to normal. A prospective study may be more valuable.