Joint Hyperlaxity and Volar Plate Dynamics: MRI-Based Comparative Evaluation of the PIP Joint

Background: The volar plate (VP) is a key stabilizer of the proximal interphalangeal joint (PIPJ), and its biomechanical behavior may be altered in individuals with joint hypermobility. Objective: This study aimed to evaluate the spatial dynamics of the VP and its relationship with the center of joint motion and flexor digitorum profundus (FDP) tendon in individuals with and without joint hyperlaxity using MRI. Methods: Thirty-two healthy volunteers (16 hyperlax, 16 controls) underwent MRI imaging of both index fingers at five flexion angles (0°, 30°, 60°, 90°, full flexion) and under passive and isometric loading conditions. Key parameters measured included distances from the joint center to VP attachments, VP-FDP tendon distance, and the length between VP ends.