First metatarsal head-shaft angle: a method of determination.

The distal metatarsal angle (DMAA) is a measurement of the relationship between the longitudinal axis of the first metatarsal and the articular surface of the metatarsal head. We measured the DMAA on radiographs with and without markers on the articular edges and compared them with measurements of the anatomic specimens. Based on the studies, the significance of the radiographic measurements to the actual DMAA and the normal distribution of the measurement were determined.