Conversion to Extension Contracture as a Means of Correction of Severe Flexion Contracture of the PIP Joint Using a Modified Dynamic External Fixator.

Background: This is a retrospective case series investigating the outcomes using a dynamic external fixator (DEF) for treatment on severe flexion contractures at the proximal interphalangeal (PIP) joint. Severe flexion contractures of the PIP joint occurring after multiple operations and neglected over a long period of time are difficult to treat. The recurrence of contracture, even after successful treatment, is inevitable in patients with severe cases. In this study, we defined the severity of PIP joint contracture based on the active range of motion (ROM), soft tissue condition, and duration of the contracture. We also illustrated the strategy, results, and complications of using a DEF with rubber bands in these severe cases. Methods: We studied 11 fingers of 10 patients with PIP joint contracture treated by DEF. These were fixed at a small arc and neglected for an average 4.1 years (range, 1-9 years). The temporal Kirshner wire (K-wire) fixation after achieving an extension via DEF was maintained for 9.1 weeks on average. We retrospectively reviewed the results of these patients with an average 2-year follow-up. Results: Our method yielded favorable results upon retrospective evaluation. The average active ROM of the affected PIP joint improved from 90/96° to 34/83° with a functional arc and good patient satisfaction. The elastic force induced by strong rubber bands was safe and effective. The first step of joint space widening was the key to obtaining a successful joint extension afterwards. Serious progression of osteoarthritis at the PIP joint and pin-site fracture were a complication in each one case. Conclusions: In this study, we evaluate the surgical strategy of using DEFs powered by elastic torque from rubber bands to treat severe cases of flexion contractures of fingers. We first created extension contracture intentionally, followed by promoting flexion movement during follow-up in this group of patients.