Establishing a Sonography Protocol for Evaluation of the Flexor Digitorum Profundus Tendon in the Hand.

Objective: Currently, no standardized sonography protocol for evaluating the distal flexor tendons in the hand exists. The aims of this research were to 1) establish an image acquisition protocol to standardize assessment and 2) describe typical variations in the morphology of flexor tendons in healthy individuals.

Materials and methods: A sonography protocol was developed, refined, and deployed in a cohort of healthy volunteers to collect images and cine clips of flexor tendons beginning at the mid-palm through insertion at the distal phalanx. Longitudinal and cross-sectional images of the tendons were measured at each joint space (e.g., the metacarpophalangeal, proximal interphalangeal, and distal phalangeal joints). Through an iterative process, images from each location were compared across participants.

Results: The anatomic patterns and unique presentations of hand flexor tendons in 15 healthy volunteers were identified and described, including the bifurcation of the flexor digitorum superficialis tendon and the atypical presentation of muscle bellies in the distal hand. Best practices for imaging and morphologic variability were described in a final detailed imaging protocol.

Conclusion: A detailed sonography protocol was established, and standardization in imaging practices using such a protocol should be considered when scanning tendons in the distal hand to enhance rigor and reliability in clinical and research evaluations of the flexor tendons.