How well do you know the back of your hand? Toward evidence-based knowledge

Familiarity with the back of one's hand has long been used as a reference c riterion for knowledge despite a lack of supporting evidence. The present s tudy prospectively tests normal subjects' knowledge of dorsal hand features . Sixty surgical, medical, and allied hospital employees (30 men, 30 women) were asked 5 questions with binary answers about features on the dorsum of their dominant hands while their hands were concealed. The proportion of c orrect answers to each question ranged from 0.45 to 0.65, and none was sign ificantly different from 0.50. Similarly, the mean percentage of correct an swers for all subjects and all questions was 54%, which was not significant ly different from 50%. Thus, the accuracy of the answers approximated rando m guesses. Hand specialists scored significantly higher (75%) than other oc cupation groups. Men and women scored equally as a whole. These data refute the use of the hand idiom as a reference criterion for knowledge. Copyrigh t (C) 2001 by the American Society for Surgery of the Hand.