Validation of the talar-second metatarsal angle as a standard measurement for radiographic evaluation

Radiographs provide valuable information for assessing osseous foot deformities and aid in accurate diagnosis. The radiographic angular measurements can be used to establish a relationship between the forefoot and the hindfoot that will present valuable information about normal versus pathologic alignment of the foot. The talar-first metatarsal (T1M) angle is frequently used as one of these angles in this capacity; however, there are limitations to the anteroposterior T1M angle. We present a more consistent, reproducible, and accurate measurement for determining foot abnormalities in the transverse plane using the T2M angle instead of the T1M angle.

Seventy feet in 35 participants (12 men and 23 women) were considered for this study. Individuals were selected on the basis of the established inclusion and exclusion criteria. Anteroposterior radiographs were taken in the angle and base of gait, the neutral calcaneal stance position (NCSP), and the resting calcaneal stance position (RCSP). Three observers measured these angles using three different methods.

The mean ± SD T2M angle was 2.95° ± 7.16° in NCSP and 18.61° ± 7.21° in RCSP. No significant differences were found among the measurements made by the three observers using slightly varying procedures in NCSP and RCSP (P > .05). The intraclass correlation coefficients among the measurements were 0.905 in NCSP and 0.937 in RCSP. Bland-Altman plots showed very good agreement between the measurements made by the three observers.

The anteroposterior T2M angle gives a consistent and reproducible measurement that provides accurate information about foot alignment.