Tendon injuries can result from a sudden tensile force or laceration. Injuries that result in large gaps in the tendon, such as occurs after laceration of the finger flexor tendons, re- quire surgical repair and suturing to hold the ends together during healing.
Tendons respond to injury in a way that is similar to that of skin and other connective tissues. An initial phase of inflammation is followed by a reparative phase in which surrounding cells enter the site and produce a collagen scar, after which remodeling occurs over time. Controversy still exists as to whether the invading cells come from within the tendon (intrinsic cells) or from the surrounding tis- sues (extrinsic cells). The strength of the heal- ing tendon is significantly lower than the un- injured tendon in the initial phase of healing, and strength does not increase until 3 weeks after injury. With improved techniques of tendon suture repair, early motion is now possible after tendon lacerations. This movement is thought to improve the functional outcome by minimizing adhesion formation.