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


METHODS
Mobility 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.


RESULTS
Total 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.


CONCLUSIONS
Dynamic 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.
Institute for Biomedical Engineering, University of Rostock, F. Barnewitz-Str, 4, D-18119 Rostock, Germany. heiner.martin@uni-rostock.de
Heiner
H
Martin
Ulf
U
Bahlke
Albrecht
A
Dietze
Volker
V
Zschorlich
Klaus-Peter
KP
Schmitz
Thomas
T
Mittlmeier
D000293:Adolescent; D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005471:Fluoroscopy; D005684:Gait; D006215:Hallux Valgus / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008682:Metatarsal Bones / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008683:Metatarsophalangeal Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008875:Middle Aged; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular; D012399:Rotation; D013639:Tarsal Bones / Q000000981:diagnostic imaging* / Q000503:physiopathology; D013997:Time Factors; D014741:Video Recording; D016474:Weight-Bearing; D055815:Young Adult