Extensor Tendon Injury

Extensor tendons help to straighten your fingers and cock your wrist back. The finger extensor tendons lie just under the skin on the back of the fingers and wrist. In the forearm, the tendons are under the skin and fatty tissue. This makes them at risk for even shallow lacerations or punctures of the skin. Some parts of the extensor tendon are very thin and can be torn easily, even by jamming your finger. If these injuries are not treated, it may be hard to straighten finger or thumb joints. Sometimes, it may just be difficult to extend your wrist. Sometimes, an injury to one of the many wrist extensor tendons can go unnoticed.

Common Extensor Tendon Injuries

A mallet finger refers to a drooping of the tip of the finger or thumb. This happens when the tendon is no longer attached to the last bone at the tip of the finger. Common causes include:

An object striking the end of the finger
Forceful bending of the small joint. This can happen even when scrubbing something with the fingers bent.

The main reasons for loss of attachment are:

Tearing of the tendon from the bone
Sharp cut of the small tendon through the skin
A fracture at the tendon attachment to the small bone (mallet fracture)

A Boutonniere deformity is when the middle joint of a finger is stuck in a bent position. The causes include:

Tearing of the central extensor tendon at or just before the middle finger joint
Sharp cut of tendon from a puncture or laceration directly over the joint

If injuries to the extensor tendon are not treated, the middle joint can become permanently bent and affect the position of the smaller joint at the end of the finger.

A dorsal hand and wrist extensor tendon injury can happen from cuts on the back of the hand, which can injure the extensor tendons. This can make it difficult to straighten the joints at the knuckles of the finger, in addition to lifting the thumb up.

Treatment

The kind of treatment depends on the type of injury. Treatment options can include splinting and surgery. Hand therapy is commonly needed afterward. This helps to reduce stiffness of the joints.

Mallet Fingers
Treatment of mallet finger depends on the kind of injury. For tearing of the tendon without any sharp injuries, treatments can include:

Splinting of the tip of the finger in a straight position: This puts the two ends of the torn tendon very near each other and allows the two ends to heal together without surgery. The joint is held straight at all times (24/7) including for bathing or skin care. Six to eight weeks of continuous splinting is generally required. After that, the splint may only be required at nighttime.

When the tendon is cut, the treatment can include:

Cleansing the wound and the joint, if involved
Surgical repair of the tendon
Splinting after surgery
For people who can’t use a full-time splint, a temporary wire may be placed to hold the joint straight.

For mallet fractures, the treatment depends on the kind of fracture. Wen the joint position is not affected, the treatments can include:

Splinting the finger straight. X-rays are used to make sure the broken ends are close to each so that they can heal. Splinting lasts 4-6 weeks, then the patient can begin moving the finger again.
Sometimes, the bone fragments are pinned back into position. Splinting is applied.

Loss of normal joint position can happen with larger bone fragments. In these secnarios, the treatment options may include:

Splinting
Pinning in good position

In children, the fracture often happens at the growth area (growth plate):

If the fragments are out of position, repositioning is recommended. This should happen before the fracture starts to heal (<10 days).
If good position is not possible, surgery may be needed to align the bones.
Splinting can be difficult with children. The joint may be pinned until there is healing.

Boutonniere Deformity
A Boutonniere deformity may not develop right away after a tear or cut of the central tendon. If the central part and the side tendons are cut/torn, the deformity may be seen right away. Treatments are based on the extent of the injury:

A closed tear of only the central part may be treated with a splint for about 6 weeks.
An open wound with the tendon cut is best treated by suturing the tendon in surgery. Pinning the joint (5-6 weeks) keeps the joint straight during healing.

If the deformity has been untreated for too long, straightening it for repair may not be possible. There are many different types of surgeries to correct the stiff type of flexed finger, but the results are often not as good.

Dorsal Hand and Wrist Extensor Tendon Injuries
Tendons cut over the back of the hand may cause drooping of the large joints of the fingers or thumb. These almost always require surgery. Repairs often give good results.

Hand therapy can be an important part of recovery for extensor tendon injuries and may be ordered during the period after surgery or splinting. It may be beneficial during the period after surgery or during splinting. Based on the severity or level of the extensor tendon injury, immobilization may be required to decrease stress on the tendon. Custom splinting is used to provide protective and guided mobility of the affected finger(s) while maximizing tendon glide and mobility to the uninvolved fingers. Discuss your best treatment options with your hand surgeon.

This content is written, edited and updated by hand surgeon members of the American Society for Surgery of the Hand. Find a hand surgeon near you.

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