Assessing Flexor Tendon and Subsynovial Connective Tissue (ssct) Excursion with Colour Doppler Ultrasound

Patients with carpal tunnel syndrome present with fibrosis of the subsynovial connective tissue next to the flexor tendons, which is that shear forces play a role in injury development. To better link ergonomic factors with underlying pathomechanics, we used ultrasonography to measure relative motion of the long finger flexor digitorum superficialis and the adjacent subsynovial connective tissue during repetitive finger tasks. Sixteen participants completed three cyclical finger movements (metacarpophalangeal, proximal and distal interphalangeal joints, and full finger flexion/extension) in three wrist postures (30° flexion, 0°, 30° extension) with full motion analysis of the long finger and wrist. Relative displacements between the flexor tendon and subsynovial connective tissue increased linearly (by 32.3%) from 30° wrist extension to 30° wrist flexion (F(2,30) = 16.2, p < 0.01). This shows that the wrist may be more prone to shear injuries in wrist flexion. We are currently integrating the data into an analytical model that predicts flexor tendon and subsynovial connective tissue motion as well as risk of injury in the workplace.