De Quervain's syndrome is a common condition which affects the two tendons (abductor pollicis longus & extensor pollicis brevis) on the radial aspect (i.e. the thumb side) of the wrist, where they pass over the bone and under a pulley or "retinaculum".
De Quervain's causes pain and usually quite subtle swelling at the radial side of the wrist (figure 1). The pain occurs on use of the hand and thumb, especially when lifting something heavy with the hand in an "ulnar-deviated" position (figure 2), and can be rather severe. Occasionally the tendons get trapped under the retinaculum, which leads to locking or loss of movement of the thumb, in a similar fashion to a trigger finger. For reasons that are not fully understood, it commonly affects mothers of young babies in the first year after the child's birth.
De Quervain's is usually easily diagnosed from the history and examination findings. Tenderness over the tendons as they pass over that part of the radius bone, and the presence of pain on combined ulnar deviation of the wrist and flexion of the thumb ray, which is known as Finkelstein's test, confirm the diagnosis. If the diagnosis is in doubt, imaging using either an ultrasound or MRI scan can be helpful.
If the symptoms are mild, a combination of anti-inflammatory tablets and splintage of the thumb and wrist can serve to control the pain. However, more often than not it is necessary to carry out a steroid injection into the retinacular sheath around the two tendons. This is usually very effective in the majority of patients, but in about 20% of people the pain returns after three to six months. A second injection can be carried out, but if the pain returns again a small operation is required under local anaesthetic, to divide the retinaculum over the tendons.
Steroid injections into this part of the wrist can cause a change in the colour of the skin (usually creating a pinkish or lighter pigmentation), or loss of the layer of fat under the skin, which while not painful, can be cosmetically a little displeasing. The risk of these cosmetic complications is 10 to 15%.