ECU FCU Tendon Disorders

Extensor Carpi Ulnaris Tendon Disorders

Common sporting associations with extensor carpi ulnaris tendinopathy include tennis, hockey and golf. The tendon it lies in a sulcus on the posterolateral aspect of the ulnar head.

Immediately overlying the tendon is a sub sheath which is attached on the radial and ulnar sides of the tendon to the bony styloid. The radial attachment is small, the ulnar attachment is more expanded and designed to resist tendon subluxation. Overlying these is the extensor retinaculum.

Subluxation occurs as a result of ulnar quadrant failure. Failure may occur either from disruption of the sub sheath itself or from a gradual delamination and separation of the ulnar attachment to bone.

Tendon subluxation may be apparent on static MR depending on the position of the wrist during the examination. The diagnosis is more easily made by using dynamic ultrasound where, on successive pronation and supination the tendon can be seen to sublux. Patients complain of pain on passive supination.

Tendinopathy and tenosynovitis are common, however patients may also complain of pain with or without a clicking sensation due to subluxation of the tendon from its fibro-osseous tunnel. Tenosynovitis is also appreciated on MR or ultrasound images. Increased fluid in the tendon sheath associated with signal or ultrasound changes within the tendon itself allow easy diagnosis of the stages of the disease.

PITFALL: The normal tendon often has a small central fibrous area which mimics focal tendinopathy.

A prominent or previous injury to the ulnar styloid predisposes to extensor carpi ulnaris tendinopathy. Rarely infective tenosynovitis may occur. In these instances, the degree of synovial thickening on MR or ultrasound in association with marked enhancement of the tenosynovium or increased doppler signal are prominent. Aspiration will yield purulent material though it should be appreciated that chronic calcific tendinopathy may mimic all of these findings.

Flexor Carpi Ulnaris

Inserts into the pisiform
Prone to calcific tendinopathy
Friction of pisiform can occur as occupation hazard of mouse users
Pisiform inserts via pisihamate and pisimetacarpal ligaments
These can be injured in tennis