Age‐ and sex‐associated morphological variations of metatarsal torsional patterns in humans

Abstract

It has been demonstrated that the torsional patterns of the metatarsal heads are associated with the presence or absence of the medial longitudinal arch in hominoid feet. The relatively untwisted second metatarsal is unique in humans, but that of the African apes is much more inverted, suggesting that the torsion of the second metatarsal might represent the overall shape and flatness of the foot. Some clinical studies have recently argued that the onset of foot pathologies such as hallux valgus might be related to the torsional pattern of the metatarsals. However, to date, no studies have systematically investigated the morphological variations of the torsional patterns of human metatarsals. In this study, therefore, the aim was to clarify the age- and sex-associated variations in the torsional patterns of human metatarsals using three-dimensional computed tomography. The torsion angles of the five metatarsals were calculated by defining the dorsopalmar vector of the metatarsal base and the vector corresponding to the rotational axis of the metatarsal head. The present result demonstrated that the second metatarsals of females were significantly more inverted with increasing age. Flat foot is known to be most common in elderly women. Whether there is a cause-effect relationship between second metatarsal torsion and flattening of the medial longitudinal arch has yet to be answered, but this study suggested that torsion of the second metatarsal might possibly be used as an indicator for the early diagnosis of flat foot and associated foot pathologies. Clin. Anat. 30:1058-1063, 2017. © 2017 Wiley Periodicals, Inc.

First Metatarsal Rotation in Hallux Valgus Deformity

“…Specifically, this study demonstrated that patients with HV have significantly greater pronation of the M1 head with an M1 intrinsic bony twist as seen with other long bones (eg, femoral anteversion, tibial external torsion) than those without HV. This phenomenon has been further confirmed by Kitashiro et al and Cruz et al 16,48 Also using WBCT-derived CAD models, Campbell et al again demonstrated a significant difference in M1 pronation between HV and controls; however, his method considered the rotational status of the second metatarsal as the reference. 9…”

“…40,63,71 Summarizing the outcomes of these contributions, HV is considered to be a complex pathologic process, varying in presentation and severity, with several potential etiological factors. M1 pronation is associated with 3 conditions that have been implicated in the pathogenesis of hallux valgus, namely, decreased arch angles, 29 hypermobility, 25,34,35,46,47 and torsional changes 16,48,62 of the first ray.…”

“…In this CT-based study of 27 women with HV compared to 12 controls without HV, on average, the M1 head was 13 degrees more pronated in the HV group, suggesting that in some patients with HV the M1 may be intrinsically twisted. 16,48…”

“…4,26 Then, either from genetic programming or perhaps stress on a rotated M1 head in the growing child, an intrinsic torsional deformity can develop as is commonly found in the growing tibia or femur (see label B in Figure 1). 16,48,62 Any M1 rotation will naturally lead to unbalancing of metatarsophalangeal joint reaction forces and stress on the medial metatarsophalangeal ligaments. As these stretch, the M1 head slides medially, accentuating the unbalancing of the joint reaction forces.…”

Three-Dimensional Analysis of the First Metatarsal Bone in Minimally Invasive Distal Linear Metatarsal Osteotomy for Hallux Valgus

“…The coordinate system of the first metatarsal was defined to describe rotational deformity on the preoperative first metatarsal according to previous research 21,38 (Figure 2). The rotation angles and translation distances of the postoperative distal ends from the preoperative distal ends were calculated from the differences in the rotation matrices in the same coordinate systems of the first metatarsal bone.…”