Association of Normal vs Abnormal Meary Angle With Hindfoot Malalignment and First Metatarsal Rotation: A Short Report.

BACKGROUND

Recent work has reported a significant association between first metatarsal (M1) rotation and hindfoot alignment, with the finding of a moderate association between the calcaneal moment arm (CMA) and 2 M1 pronation angular measures: Saltzman (r = 0.641, P < .01) and Kim (r = 0.615, P < .01). The aim of the current post hoc investigation was to determine if this association is related with Meary angle.

METHODS

We reanalyzed previously published data set separating patients into 2 groups: (1) those with normal Meary angle (n = 128) and (2) those with abnormal Meary angle (n = 147). Hindfoot alignment and M1 rotation were measured on weightbearing computed tomography. Statistical analyses were performed to evaluate for association between these variables among the groups.

RESULTS

The correlation between CMA and M1 rotation of the entire cohort was r = 0.577 (Saltzman ankle) and r = 0.540 (Kim angle). For the subset with a normal Meary angle, this association was negligible (Saltzman and Kim angles, r = 0.194 and 0.240, respectively). Conversely, for the abnormal Meary angle subset, the association was substantial (Saltzman and Kim angles, r = 0.733 and 0.675, respectively).

CONCLUSION

Patients presenting with an abnormal Meary angle and hindfoot deformity have a high likelihood of manifesting a proportionate degree of M1 rotation.

LEVEL OF EVIDENCE: Level III, Retrospective Cohort Study.