Arthritis in the First Metatarsophalangeal Joint After Proximal Opening Wedge Osteotomy for Moderate to Severe Hallux Valgus Deformity

Abstract

Category: Bunion Introduction/Purpose: Over recent years, a proximal opening wedge osteotomy (POWO) using a novel low-profile plate have gained in popularity for the correction of moderate to severe hallux valgus. However, the proximal opening wedge osteotomy was known to increase the length of the first metatarsal, resulting in tightening of the soft tissues around the first metatarsophalangeal (MTP) joint and predisposing to jamming of the joint and subsequent arthritis. The purpose of this study was to evaluate the arthritic change of first MTP joint after POWO using a low-profile plate for correction of moderate to severe hallux valgus. Methods: We retrospectively reviewed 100 consecutive POWOs using a low-profile plate performed in 87 patients with moderate to severe hallux valgus deformity. After excluding 17 cases, 83 cases in 73 patients were included. For clinical assessment, VAS, the American Orthopaedic Foot and Ankle Society (AOFAS) forefoot score and Foot and Ankle Outcome Score (FAOS) were obtained. The hallux valgus angle (HVA), the intermetatarsal angle (IMA), the relative first metatarsal length which is the first metatarsal length divided by the second metatarsal length and the first MTP joint radiographic arthritic grade by Coughlin and Shurnas were assessed on standard weight bearing radiographs of the foot for radiographic evaluation. Results: Mean follow-up period was 16.1 (12-45) months. The mean VAS, AOFAS score and most of FAOS subscales improved significantly. Significant corrections in the HVA and IMA were obtained and the mean increase in the relative first metatarsal length was 3.8% at last follow-up (P < 0.001). There were 15 (18.1%, 15/83) cases of the first MTP joint arthritis at last follow-up (Radiographic grade I: 5, II: 8, III: 2). Of 62 cases using a large wedge plate (≥5.0 mm), 12 (19.4%, 12/62) cases showed poorer outcomes and a significant progression of the arthritic grade at last follow-up (Fisher's exact test, P=0.031) comparing to using a small wedge plate (< 5.0 mm) (Table 1). Conclusion: The POWO using a low-profile wedge plate is effective and reproducible technique for correction of moderate to severe hallux valgus deformity. However, the exacerbation of preexisting first MTP joint arthritis and the subsequent arthritis can occur after POWOs using a large wedge plate (≥5.0 mm) at short to mid-term follow-up. Therefore, POWOs with a low-profile wedge plate should be used judiciously for correction of moderate to severe hallux valgus.