SAT0056 Radiographic Relationship between Hallux Valgus Deformity and Fore-Mid-Hindfoot Deformity in Rheumatoid Arthritis: Evaluation Grouped by the Existence of 2ND MTP Joint Dorsal Dislocation

Background Several midfoot deformities are described to progress hallux valgus (HV) deformity [1]. Involvement of hindfoot deformity in the 1st ray deformity is also suggested [2]. In rheumatoid foot, complicated deformity in foot are often seen. Especially, dorsal dislocation of lesser toe MTP joint combined with HV is frequently observed in rheumatoid arthritis (RA) cases. Currently, clarified and comprehensive evaluations in RA foot deformity has not been done. Objectives In this study, relationship between radiographic findings through hind to forefoot and HV angle was evaluated in RA cases, while grouping by existence of 2nd MTP joint dorsal dislocation. Methods X-ray pictures at standing position in 160 RA feet and ankles were evaluated. 1st MTP Larsen grade, existence of 2nd MTP dorsal dislocation, HV· M1M2· M1M5 angle, shape of 1st mtetatarsal head [3] and position of sesamoid [4] which are index for pronation of 1st metatarsal, metatarsus primus varus (MPV) angle, M1M2 diastasis [5], angle between talus and navicular [6] (index for pronated foot), internal arch (IA) angle, Tibio-Calcaneal (TC) angle, distance between the axis of tibia and calcaneus (calcaneal lateral offset) were measured, and evaluated. Results M1M2 angle and HV angle correlated (R2=0.7) in the group without 2nd MTP joint dislocation (D0), while dislocation group (D2) showed relatively weak correlation (R2=0.3). The mean HV angle in D0 was 21±14.1°, while 45±16.8° in D2, that was significantly greater (P