Biomechanical and functional analysis of the pins and rubbers tractions system for treatment of proximal interphalangeal joint fracture dislocations.

摘要

INTRODUCTION: Dynamic external fixation systems are considered as optimal devices for treatment of fracture dislocations of the proximal interphalangeal joint (PiP). The pins and rubbers traction system (PRTS) is cheap, easy to assemble and comfortable and allows early mobilization of the affected digit. We investigated the influence of different wire positions and rubber strength and provided a follow-up of five consecutively treated patients. METHODS: Sixteen cadaver fingers (dig 2-5) were included into the biomechanical study. Forces for flexion of the PiP joint (30 degrees, 60 degrees, and 90 degrees) were measured by pulling the flexor digitorum profundus tendon; width of the PiP joint was assessed radiologically. Measurements were obtained prior and after assembly of PRTS and were repeated with three different types of rubbers and two different positions of the retention wire (distal and proximal). The clinical part of the study included five patients (21-72 years) who were treated using the PRTS. Mean follow-up was 272 days. RESULTS: The PRTS increased flexion force of the PiP joint. Proximal position of the retention wire increased forces for 30 degrees flexion. Different rubber strengths did neither increase PiP width nor influence flexion forces. In the clinical part of the study total range of motion was 74 degrees and DASH score was 10.1. Pinch grip of the affected digit was 72% of the unaffected side. DISCUSSION: The PRTS allows for efficient treatment of intraarticular fractures with PiP involvement. Although standardized positioning of the wires is important, proximal position of the retraction only increased forces for 30 degrees flexion.