CORONAL PLANE ROTATION OF THE FIRST METATARSAL

A method for measuring first metatarsal rotation on weightbearing tang ential radiographs is described. Under controlled conditions using cad aver specimens, 5 degrees changes in first metatarsal rotation were as sociated with a mean change in radiographically measured rotation of 5 .4 degrees (SD = 1.7 degrees). A clinical study of 30 hallux valgus an d 30 control patients was undertaken to assess the reliability of the method of measurement. The overall reliability was high for both hallu x valgus and control patients (r = 0.93 and 0.95, respectively). In th ese two groups, no significant difference was found between the mean v alues for first metatarsal rotation. Likewise, we found no correlation between first metatarsal rotation measured on tangential standing ('' sesamoid'' view) radiographs and the first metatarsophalangeal angle o r the intermetatarsal 1-2 angle measured on anteroposterior standing r adiographs.