The Rotational Positioning of the Bones in the Medial Column of the Foot: A Weightbearing CT Analysis

Background: Malrotation of medial column bones of the foot has been advocated as an important factor in foot conditions such as hallux valgus and progressive collapsing foot deformity. Although stated as a deformity component, variances of normality in the general population are not completely understood. This study intended to describe the rotational profile of all medial column bones using weightbearing computed tomography (WBCT) images in a cohort of patients with different foot and ankle problems.

Methods: In this retrospective study, 110 feet of 95 consecutive patients that received a WBCT for assessment of different foot and ankle pathologies were included. Measurements were performed by a blinded fellowship-trained orthopedic foot and ankle surgeon. Rotation of the navicular, medial cuneiform, proximal and distal first metatarsal as well as proximal phalanx of the first toe were recorded. Positive values were considered pronation and negative values were considered supination. Rotational profile of each bone/ segment was assessed by ANOVA and comparison between each segment was performed using Wilcoxon Each-Pair analysis. P-values of less than 0.05 were considered significant.

Results: On average, a rotational positioning in pronation (internal rotation) was observed for all medial column bones. The navicular (43.2°, CI 41.1°-45.3°) and the proximal metatarsal (33.9°, CI 31.8°-36.0°) showed the highest mean rotation values. The medial cuneiform presented the lowest mean pronation (6.1°, CI 4.0°-8.3°). Comparison between each bone segment demonstrated statistically significant differences of rotational alignment for the different bones (p<0.0001), with the exception of the distal metatarsal and proximal phalanx, that had similar amounts of pronation. A zig-zag rotational pattern of alignment was observed from proximal to distal, with relative supination/pronation of adjacent medial column bones.

Conclusion: The overall rotational profile of medial column bones was found to be in absolute pronation, most pronounced at the navicular and proximal first metatarsal, with significant differences in the amount of pronation when comparing most of the medial column bones. The presented data may be utilized as reference/ baseline values of medial column rotation, supporting future prospective, comparative and controlled studies.Level of Evidence: IV.