Flexor Tendon Injuries

Flexor tendons help bend the fingers, thumb, wrist, and hand. Injuries can happen after cuts, tendon rupture, or tendon separation and may affect the ability to make a fist or move the hand normally.

Figure 1: Flexor muscles and tendons moving from the forearm into the hand
Figure 1. An example of forearm muscles and attached tendons as they move into the hand. The red muscles become cordlike tendons that attach to hand bones to provide movement.

Movement in the hand and fingers is controlled by a system of muscles and tendons located in the forearm, wrist, and hand. Tendons connect muscles to bone. When a muscle contracts, or tightens, the muscles power the tendons to move our bones. The ability to bend our fingers to make a fist is controlled by the flexor tendons.

Causes

Most commonly, tendon injuries result from lacerations, or cuts. A laceration to the forearm, hand, or wrist can result in injury to the flexor tendons. When a flexor tendon injury happens, there can be an inability to bend the fingers, thumb, or wrist.

Even small lacerations can result in significant problems with movement if they occur in an important location. Not all tendon injuries are due to lacerations. In some cases, the injury can occur if the tendon end pulls away from bone, if the tendon ruptures due to wear, or if the tendon-muscle interface separates. If you lose motion in part of your arm, tendon injury should be considered a possible cause even without a cut.

Signs and Symptoms

If a tendon is completely ruptured or lacerated, you will not be able to bend part of your arm or hand. This lack of movement can involve just a small area in your hand, or it can involve the inability to move multiple joints in the arm. The level of impairment depends on where the injury is located.

The flexor tendons in the arm, wrist, and hand are very close to nerves and arteries. It is not unusual to have numbness, tingling, and a lot of bleeding after a tendon is lacerated because these other important structures can also be injured. For any laceration, it is wise to see a doctor as soon as you can, especially if you notice any change in arm or hand function.

Treatment

If you are worried about a flexor tendon injury, see a hand surgeon right away. These injuries are often easier to treat early after injury. Flexor tendon injuries do not heal by themselves and frequently require surgery to put the injured tendon back to its normal position.

When surgery is required, a splint and hand therapy may be used after the procedure to protect the repair and aid recovery. Typically, any additional injured structures are repaired at the same time as the tendon.

Recovery

Tendon injuries can result in scarring and stiffness after surgery. It is not unusual to need additional surgery to improve stiffness. Hand therapy is typically started after the procedure to aid recovery. It is important to follow the surgeon's instructions to avoid re-injury.

Many people can have good outcomes after tendon repairs, but this is not true in every case. Even when people do well after flexor tendon injuries, the recovery can take many months to complete.