Measurement of a number of indices of hand and movement angles in pianists with overuse disorders.

Abduction angles of the thumb and little finger, hand span, length of thumb, middle finger and little finger were measured using radiographs of the right hand with the thumb and the little finger abducted, in a comparative study of 220 pianists with overuse disorder and 62 unaffected pianists. Overuse disorders included tenosynovitis, lateral and medial epicondylitis, forearm flexor muscle pain, distal tendinitis of the wrist extensors and flexors and intrinsic muscle pain. Hand span or other hand size parameters showed significant differences, while abduction angles showed no difference. The patients' group had smaller hand size than the controls when analyzed for tenosynovitis, epicondylitis and muscle pain. From these results we hypothesize that pianists with small hands tend to hyper-abduct and hyper-extend the thumb to attain greater hand span. Their little finger is also stiffer and the hypothenar muscle and the wrist flexors need greater strength to resist the reaction force in each piano key.