Effect of natural full weight‐bearing during standing on the rotation of the first metatarsal bone

Abstract

To evaluate the rotational change in the first metatarsal bone (1MT) of the foot during natural standing using an upright computed tomography (CT) scanner with 320‐detector rows. A total of 52 feet of 28 asymptomatic subjects (aged 23–39 years) were evaluated in the natural standing position with or without weight‐bearing. A foot pressure plate was used to determine the non‐weight‐bearing (NWB) or single leg full‐weight‐bearing (s‐FWB) conditions. CT examinations were performed using a noise index of 15 for a slice thickness of 5 mm, rotation speed of 0.5 sec, and slice thickness of 0.5 mm. The rotation of the 1MT was measured on the coronal CT image, which cut the sesamoids' bellies in the frontal slide of the first metatarsal and sesamoids perpendicular to the longitudinal bisection of the third metatarsal, and compared between the weight‐bearing conditions. Intra‐ and inter‐observer reliabilities of the rotation angle were also evaluated. The intra‐ and inter‐observer correlation coefficients were 0.961 and 0.934, respectively. The 1MT pronation angle was significantly greater in the s‐FWB condition than in the NWB condition (15.2° ± 5.4° vs. 12.5° ± 5.3°, P < 0.01). No sex difference was found in the magnitude of the 1MT pronation angle as a result of weight‐bearing. This study first demonstrated that pronation of 1MT occurs due to natural full‐weight‐bearing in asymptomatic feet. The 1MT's rotational movement under weight‐bearing conditions may relate to the onset and pathogenesis of the hallux valgus. Clin. Anat. 32:715–721, 2019. © 2019 Wiley Periodicals, Inc.

Constraints on variation of weight-shifting by foot during walking in adolescents with valgus alignment of hallux

“…4) was consistent with central overloading in the forefoot reported in two recent HV studies conducted in large groups of participants with disproportionate numbers of women (95% of 679 HV patients [30] and 74% of 764 HV patients [10]). Whereas deflection-size dependence of RFSP distributions in girls might explain inconsistent, often contradictory results presented by previous studies on HV-related loadings [24]; this could make a substantial impact on results, due to the known preponderance of women in HV-studies. Girls exhibited a higher frequency of the lateral-shift pattern, which supported a supination HV etiology, irrespective of the size of deflection, even for very small deflections.…”

“…Additionally, because the medial RFSP is reduced concomitantly with increases in the central RFSP, a medial RFSP reduction might be interpreted as a symptom of central overloading, or even a pronation-based mechanism, because the medial forefoot regions might be poorly visible and sometimes not detected at all. Recent studies that employed the radiological imaging method [24] could not confirm that the pronation mechanism was a distinguishing feature of HV, because this mechanism was also commonly observed during loading in asymptomatic feet.…”

“…Some studies proposed that HV arose from a lateral load transfer that resulted from a reduction in the weight-bearing function of the medial toe [20], which suggested a supination-based mechanism. Others proposed the opposite load distribution, which suggested a pronation-based distribution [24]. Still other studies could not confirm a relationship between hallux deformities and plantar pressure distributions [14], [29].…”

“…Therefore there is a need to investigate functional problems related to different structural states of hallux and new foot assessment methods. Useful information about foot function during walking comes from studies using pedobarography, but they provide inconsistent conclusions [4], [14], [24]. Some studies proposed that HV arose from a lateral load transfer that resulted from a reduction in the weight-bearing function of the medial toe [20], which suggested a supination-based mechanism.…”

Three-dimensional kinematic change of hindfoot during full weightbearing in standing: an analysis using upright computed tomography and 3D-3D surface registration

“…The CT examinations were performed using the following parameters: peak tube voltage, 100 kV; tube current, 10 to 350 mA (using a noise index of 15 for a slice thickness of 5 mm); rotation speed, 0.5 s; and slice thickness, 0.5 mm. No weightbearing, standing (50% weightbearing), and single leg full weightbearing (100% weightbearing) were assessed for each participant [25]. The condition of each weightbearing stance was measured using a pressure mat (BIG-MAT; NITTA Corporation, Osaka, Japan) and pressure calculation system (FootMat; Tekscan, South Boston, MA, USA).…”