Tendon disorders

Trigger finger

For reasons which are often obscure, the opening of the flexor tendon sheath (the Al pulley) thickens and snares the tendon which may secondarily develop a small nodule. When the proximal interphalangeal joint is flexed it locks and then snaps into extension. This often starts only on awakening, and then gradually occurs more frequently during the day. If it does not resolve with a steroid injection into the sheath, then release of the pulley at the level of the metacarpophalangeal joint (distal palmar crease) is successful, watching for the neurovascular bundle. In infants, the thumb can trigger; this often resolves spontaneously by the age of 1 year, but if not surgery is needed, being aware that in the thumb the digital nerves run close to the midline (not the midlateral line as they run in the fingers). In rheumatoid arthritis, the triggering is caused either by synovitis or by a nodule in the tendon. Synovectomy, and if necessary excision of a slip of flexor digitorum superficialis, is safer than division of the pulley — the latter can worsen the tendency to ulnar drift of the metacarpophalangeal joints.

De Quervain’s disease

The extensor pollicis brevis tendon and abductor pollicis longus tendon run in a compartment beneath the extensor retinaculum. This compartment can constrict the tendons, causing pain at the base of the thumb. Usually occurring spontaneously in middle-aged women, it is also associated with late pregnancy and overuse. Finkelstein’s test is positive there is pain over the radial side of the wrist when the patient’s thumb is grasped and the hand is quickly abducted ulnarward. Splintage, nonsteroidal anti-inflammatory medi­cation, steroid injection and ultrasound may help. Surgical decompression is often required, avoiding the superficial radial nerve (lest a very troublesome neuroma occurs) and remembering that there are often extra septae and slips of tendon — the condition will persist if these are overlooked.