Oarsman’s wrist (intersection syndrome)
The muscles that move the thumb backwards and outwards are attached to the forearm bones and their tendons wind round the thumb side of the lower forearm to attach to bones in the thumb. At that point they cross over the two tendons that straighten the index finger and middle fingers, making a point of potential friction as the structures exert tension in different directions. This can produce tenosynovitis at the wrist or, more commonly at the point where the muscle attaches to its tendon (musculotendinous junction). It usually comes on with overuse of the thumb and wrist, as used in the rowing action (thus ‘oarsman’s wrist) or with unaccustomed and excessive use of scissors.
Patients will complain of pain in the lower forearm when moving the thumb and on stretching the thumb across the palm with the wrist bent downwards. There may also be a creaking or squeaking sensation on the thumb side of the forearm as the thumb is moved, known as crepitus.
Physiotherapy can help by applying a specific massage technique called frictions gently across the painful site with advice on resting from the aggravating activity. Ice and electrotherapy, usually ultrasound, can be used to relieve pain and to promote recovery.