What is a flexor tendon injury?
The fingers are flexed by the flexor muscles on the forearm. While the actual muscle bellies are located on the forearm, the flexor tendons that originate from them extend over the wrist to the phalanges of the fingers. The long fingers each have two flexor muscles and tendons, one superficial and one deep. The superficial tendons extend to just above the first finger joint and bend it, while the deep tendons extend to the distal phalanx and bend it. From the metacarpophalangeal joint, these two tendons run close together in a channel, the digital canal. Here in particular, the tendons are very superficial and can be injured quickly. However, an injury is possible along the entire length of the tendon. Injury to the tendons in the digital canal is particularly critical, as adhesions can quickly form here, impairing the gliding of the tendons. The same basically applies to the thumb, but here there is only one long flexor tendon that extends to the distal phalanx.
What are the causes of flexor tendon injuries?
The most common cause is direct trauma from a cut. Crush injuries or severely displaced fractures can lead to tearing of the tendons. Infections can lead to destruction of the sliding layer and the tendons. Chronic inflammatory diseases such as rheumatoid arthritis can also lead to destruction of the tendons through aggressive inflammation of the gliding layer. Tearing of otherwise healthy tendons without direct trauma is extremely rare. However, massive mechanical overload can lead to the tendon being torn out, particularly in the case of the deep flexor tendon, together with a piece of bone at the end of the finger. The same basically applies to the thumb.
What are the symptoms of a flexor tendon injury?
A complete severing of a flexor tendon leads to a corresponding loss of flexion in the affected finger. If the tendon is only partially severed, flexion can be weakened and painful. An infection or inflammation causes swelling, redness and pain with restricted movement in the area of the affected finger.
How is the diagnosis made?
The medical history and localization of any open injury usually lead to a suspected diagnosis. A complete tendon transection can practically always be diagnosed without additional examinations by means of a precise clinical examination. Incomplete transections can often only be reliably detected or ruled out by surgical exploration. An ultrasound examination can be helpful in unclear cases, especially if the injury is not completely recent. Occasionally, an MRI examination can also be helpful.
How is a flexor tendon injury treated?
Complete tendon transections must be treated surgically.