Biomechanics of the flexor tendons

An understanding of the biomechanics of the flexor tendon system is essential to proper evaluation and treatment of disorders of the upper extremity. The flexor tendons are essentially cables that transmit forces developed by muscle contraction in the forearm to the fingers, moving and stabilizing the joints. The versatility of the human hand-its ability to perform precise manipulation and forceful grasping-stems from the organization of the flexor tendons and their ability to generate varying degrees of force at different locations. This discussion of the biomechanics of the digital flexor tendons begins with a review of their molecular and cellular composition and structure, their organization within the hand in the complex pulley system, and the way their relationship to the joints and bones of the hand governs organized movement. This article concludes with a discussion of physiologic and pathologic conditions that affect flexor tendon function and of clinical biomechanics as it applies to tendon transfers and flexor tendon repair.