Investigation of first ray mobility during gait by kinematic fluoroscopic imaging-a novel method

Heiner Martin,Albrecht Dietze,Thomas Mittlmeier,Ulf Bahlke,Volker Zschorlich,Klaus-Peter Schmitz

doi:10.1186/1471-2474-13-14

Abstract

BackgroundIt is often suggested that sagittal instability at the first tarso-metatarsal joint level is a primary factor for hallux valgus and that sagittal instability increases with the progression of the deformity. The assessment of the degree of vertical instability is usually made by clinical evaluation while any measurements mostly refer to a static assessment of medial ray mobility (i.e. the plantar/dorsal flexion in the sagittal plane). Testing methods currently available cannot attribute the degree of mobility to the corresponding anatomical joints making up the medial column of the foot. The aim of this study was to develop a technique which allows for a quantification of the in-vivo sagittal mobility of the joints of the medial foot column during the roll-over process under full weight bearing.MethodsMobility of first ray bones was investigated by dynamic distortion-free fluoroscopy (25 frames/s) of 14 healthy volunteers and 8 patients with manifested clinical instability of the first ray. A CAD-based evaluation method allowed the determination of mobility and relative displacements and rotations of the first ray bones within the sagittal plane during the stance phase of gait.ResultsTotal flexion of the first ray was found to be 13.63 (SD 6.14) mm with the healthy volunteers and 13.06 (SD 8.01) mm with the patients (resolution: 0.245 mm/pixel). The dorsiflexion angle was 5.27 (SD 2.34) degrees in the healthy volunteers and increased to 5.56 (SD 3.37) degrees in the patients. Maximum rotations were found at the naviculo-cuneiform joints and least at the first tarso-metatarsal joint level in both groups.ConclusionsDynamic fluoroscopic assessment has been shown to be a valuable tool for characterisation of the kinematics of the joints of the medial foot column during gait.A significant difference in first ray flexion and angular rotation between the patients and healthy volunteers however could not be found.

Highlights

It is often suggested that sagittal instability at the first tarso-metatarsal joint level is a primary factor for hallux valgus and that sagittal instability increases with the progression of the deformity
Despite the fact that three-dimensional motions occur at the medial foot column during weight-bearing [2,8] it appears that the major component of motion for the first metatarsal can be located in the sagittal plane [7]
The few studies employing dynamic gait examination methods revealed a higher scatter of normal first ray sagittal plane motion and did not show any significant association between the static measure of first ray mobility and dynamic first ray motion [7,14]

Summary

Introduction

It is often suggested that sagittal instability at the first tarso-metatarsal joint level is a primary factor for hallux valgus and that sagittal instability increases with the progression of the deformity. Hypermobility of the first ray, mainly due to plantar arch and Lisfranc joint ligaments laxity, is assumed to predispose for hallux valgus in a certain subset of patients [1,2] The fraction of these patients with manifested instability of the first ray Excessive pronation is believed to occur during gait due to ligamentous laxity which may delay supination of the midtarsal and subtalar joints, decreases the rigidity of the foot during the terminal stance phase and adversely affects the push-off mechanics [7]. The two most frequently applied devices possess similar diagnostic accuracy and yield an average normal dorsal mobility between 4.9 mm and 5.2 mm [13] According to these methods, 8 mm of sagittal motion was regarded as the threshold of first ray hypermobility [13]. The few studies employing dynamic gait examination methods revealed a higher scatter of normal first ray sagittal plane motion and did not show any significant association between the static measure of first ray mobility and dynamic first ray motion [7,14]

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