Tendon Injuries

Tendons are the cords which connect muscles to bones. When a muscle contracts, the tendon is pulled like a string, and the joint it attaches to will move. Tendons must therefore be in continuity with both muscle and bone if the muscle is to move the joint.

Tendons can be disrupted either by a sharp injury (where the tendon is divided by, for instance, a kitchen knife), or an overstretching of a joint (where the tendon is torn off the bone - an avulsion injury). Some diseases will cause the tendons to become thinner and weaker, so that they are unable to transfer the normal forces, and tear easily (attrition).

A complete tendon injury is usually obvious, since the joint normally powered by that tendon, will not move actively. The affected joint can be passively pushed, but will not move in one direction under its own steam.

Sharp tendon divisions are usually obvious and straightforward to diagnose. They are best repaired surgically although they always take a number of weeks to heal. The tendon repair must be protected during that phase, usually by wearing a rigid splint which prevents excessive movement and, therefore, re-rupture of the repaired tendon during the prolonged healing phase.

Healing in avulsion injuries also takes approximately 6 weeks for the tendon to regain its strength, and the joints must be splinted in a position such that the torn tendon ends lie closely opposed. Some avulsion injuries require an operation to reattach the tendon to bone. This is usually necessary in the more powerful muscles, where it is difficult to splint the joint in a position where the torn tendon ends lie close to one another.

Tendons which bend joints are called flexors. Tendons which straighten joints are called extensors. Flexors are stronger than extensors because they need to generate enough power to grip objects tightly, where as extensors only need enough power to act against gravity and open the fingers up. Repair of flexor tendons demands greater input in the whole treatment programme - both with a more experienced surgeon and a specialist rehabilitation team of physiotherapist and occupational therapist.

One of the commonest closed tendon injuries in the hand is the mallet finger - when the tip of the finger droops after a tear in the extensor tendon. This topic is covered in depth elsewhere on this site.

Recovery after tendon injury is not always complete. A permanent loss of part of the range of movement is commonplace, because the healed, but scarred, tendon does not glide as smoothly. Re-rupture is not unusual, although most surgeons would only expect to see this in around 5% of cases. A motivated patient who follows their rehabilitation regime closely and attends all their regular therapy sessions is less likely to experience these problems.

The American Association of Orthopaedic Surgeons provide more detailed information about flexor tendon injuries here