What Is the Extensor Digitorum?

The extensor tendon injuries are mostly open, with many cutting injuries, often accompanied by neurovascular injuries or bone and joint injuries, and closed lacerations can also occur. After a tendon rupture, the corresponding joint loses its function. For example, if the superficial flexor tendon is broken, the proximal interphalangeal joint cannot be flexed; the deep flexor tendon is broken, which is manifested as the distal interphalangeal joint cannot be flexed. Since the internal hand muscles are still intact, the metacarpophalangeal joint flexion is not affected. Different parts of the extensor tendon are broken, and their corresponding joints cannot be extended, and deformities can occur.

Basic Information

Visiting department

orthopedics

Common causes

Sharp cut injuries, chainsaw injuries, assault fingers caused by closed injuries, crush injuries, etc.

Common symptoms

Interphalangeal joints cannot flex

Contagious

no

Causes of extensor tendon injury

The most common causes of this disease are sharp cutting injuries, chainsaw injuries, assault fingers caused by closed injuries, and crush injuries. Often associated with neurovascular injury or bone and joint injury, closed lacerations can also occur.

Clinical manifestations of extensor tendon injury

The clinical manifestations of this disease are mainly the loss of mobility of the corresponding joints after tendon rupture.

1. Superficial flexor tendon rupture

The corresponding interphalangeal joint cannot flex.

2. Finger rupture of deep flexor tendon

The distal interphalangeal joint cannot be flexed.

3. Both the deep and shallow flexor tendons are broken

The distal and proximal interphalangeal joints cannot be flexed. Since the internal hand muscles are still intact, the metacarpophalangeal joint flexion is not affected.

4. Rupture of different parts of the extensor tendon

Their corresponding joints cannot be stretched and deformities can occur.

Extremity tendon injury examination

The disease is mostly caused by sharp cutting injuries, chainsaw and so on. For the traumatic factors that cause the disease, it is easy to diagnose; for cases caused by closed injuries, a physical examination is required, and the diagnosis can be made according to its characteristic clinical manifestations. However, special attention should be paid to patients who have been diagnosed with extensor tendon injury in area I, regardless of fresh or old injuries, and should undergo X-ray examination of the fingers before treatment to see if there is any damage to the terminal joints.

Diagnosis of extensor tendon injury

The disease can be diagnosed based on its characteristic clinical and simple physical examinations, such as joint function tests on the affected area.

Extensor tendon injury complications

All types of injuries in this disease can be combined with joint capsule injury, or avulsion fractures and joint dislocations at the extensor tendon attachment. The latter two types of injuries are common. The typical signs after injury are hammer-shaped fingers and terminal extensor fingers. Hyperextension of the near interphalangeal joint.

Treatment of extensor tendon injury

Rupture of extensor tendon

Most of them are poking injuries. The distal interphalangeal joint is suddenly flexed and the extensor tendon attachment point is torn off. Local cutting injuries can also be severed. Presented with hammer finger deformities, some patients with avulsion fractures.

(1) Suture the tendon after open wound debridement. Place the finger in the distal interphalangeal joint overextend and the proximal interphalangeal joint flexion to relax the extensor tendon. Fix it with plaster or aluminum plate for 4-6 weeks.

(2) The closed wound is fixed in the above position for 4-6 weeks. If it is accompanied by a large avulsion fracture, early surgery can be performed by "pulling out the wire" to fix the fracture, and external plaster or aluminum splint.

(3) The old tendon retracts due to old injuries , and scars are formed at the rupture, which makes the tendon relax. Those who have little effect on the function may not be dealt with. If the functional impact is large, surgical treatment is performed, an S-shaped incision is made on the dorsal side of the distal interphalangeal joint, the flap is opened, and the myometrium is sutured with overlap. Postoperatively, it was fixed in the above position for 4-6 weeks.

2. Rupture of the extensor tendon central bundle

When flexing the fingers, the dorsal side of the proximal interphalangeal joint protrudes, which is vulnerable to injury, often accompanied by rupture of the central bundle. The central bundle and the bilateral bundles are normally on the back side of the long axis of the finger. After the central bundle is broken, the lateral bundle can still extend the fingers. If the central bundle is not repaired in time, with the flexion of the fingers, both sides of the bundle gradually slide to the palm, at this time the side bundles can not play the role of finger extension, but the proximal interphalangeal joint is flexed, and the distal interphalangeal joint is overextended, forming Typical "buttonhole" deformity.

3. Injury to the back of the hand, back of the wrist, and forearm extensors

All the extensor tendons should be sutured at stage I for better results. When the back of the wrist is broken, the corresponding part of the dorsal transverse ligament of the wrist and the synovial sheath should be cut to make the tendon directly under the skin.

Prevention of extensor tendon injury

This disease is mainly caused by traumatic factors, so paying attention to production safety, doing good occupational protection, and preventing wrist injuries are the key to the prevention and treatment of this disease.