HALLUCAL ROTATION - A METHOD OF MEASUREMENT AND RELATIONSHIP TO BUNION DEFORMITY

A method for measuring hallucal rotation on weightbearing tangential r adiographs is described, Under controlled conditions using cadaver spe cimens, 10 degrees changes in hallucal rotation were associated with a mean change in radiographically measured rotation of 10.6 degrees (S. D. = 2.3 degrees). A clinical study of 30 control patients and 39 pati ents presenting with a chief complaint of a bunion deformity was under taken to assess the reliability of the measurement method. The overall reliability was high for both groups (r = 0.98), A significant differ ence was found between mean values for hallucal rotation in the two gr oups (P < 0.005). There is a modest association between increasing val gus deviation and increasing rotation of the hallux (r = 0.43, P < 0.0 1). This study suggests that bunion deformities Involve variable degre es of axial and coronal plane rotations of the first metatarsophalange al joint and that the concept of a planar ''hallux valgus'' deformity may insufficiently describe this three-dimensional clinical condition.