Radiologic Outcomes of Plantar Plate Repair through a Plantar Approach for the Dislocated Metatarsophalangeal Joint of the Lesser Toe

Background: : A torn plantar plate (PP) is important pathologic anatomy related to a dislocated or subluxated metatarsophalangeal joint (MTPJ). Traditionally, a torn PP was treated with Weil osteotomy through a dorsal approach. However, because of the limited visualization of the dorsal approach, PP repair through a plantar approach has been proposed as a new technique. This study aimed to radiologically evaluate the outcome of PP repair through the plantar approach using an improved MTPJ overlap distance (MOD) on an anteroposterior view and the degree of subluxation on an oblique view. We also aimed to investigate the potential factors affecting the recurrence of MTPJ instability. Methods: In this study, we included 31 patients who had a subluxated or dislocated MTPJ of the second or third toe and underwent surgical PP repair. PP repair was performed via a plantar approach after shortening metatarsal (MT) osteotomy with a dorsal approach for longer MT bone. We assessed the severity of MTPJ subluxation by measuring the MOD and subluxation subtype on radiographs. Radiologic recurrence was defined as an increase in MOD or change from subluxation type A to subluxation type B. The relationship of recurrence with clinical and radiologic factors was evaluated by comparing the recurred group against the non- recurred group. Results: Shortening MT osteotomy was performed in 26 of 31 cases (84%). Repeated measures analysis of variance comparing preoperation, pin removal, and the latest follow-up MOD values revealed the effectiveness of PP repair through the plantar approach (p < 0.001). The MOD did not significantly change after pin removal and the latest follow-up (p = 0.130), indicating that reduction was well maintained. None of the clinical and radiologic factors were significantly related to recurrence. However, 3 of 12 rheumatoid arthritis (RA) feet (25%) recurred and 3 of 5 recurred cases (60%) were RA feet. This result suggests that RA indicated a tendency for recurrence. Conclusions: PP repair through the plantar approach has the advantage of excellent visualization of a torn PP and direct repair. We, therefore, recommend using the plantar approach for PP repair of the MTPJ.