Mid-term results of joint-preserving procedures by a modified Mann method for big toe deformities in rheumatoid patients undergoing forefoot surgeries

This study aimed to evaluate joint-preserving procedures by a modified Mann method for rheumatoid forefoot deformities and their functional outcomes in the mid-term. Eleven feet in seven patients underwent forefoot surgery using a modified Mann method for the big toe, combined with offset osteotomy or resection arthroplasty of the lesser toes. The mean follow-up period was 3.6 years. The mean score on the Japanese Society for Surgery of the Foot scale for rheumatoid arthritis foot and ankle joints improved from 44.0 to 72.0. The mean hallux valgus angle improved from 39.4° to 20.5° and the mean M1M5 angle improved from 31.1° to 25.8°. However, deformities involving a hallux valgus angle of more than 25.0° recurred in three feet at the latest follow-up, although the patients did not complain of any symptoms from the recurrence. Improvement in the Sharp score for joint space narrowing was observed in the big toe, indicating better congruity of the metatarsophalangeal joint. For restraint of rheumatoid forefoot deformities, a modified Mann method, combined with offset osteotomy or resection arthroplasty, was satisfactory for not only improving the foot function, but also preserving the metatarsophalangeal joint mobility.