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

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Methods</p> <p>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.</p> <p>Results</p> <p>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.</p> <p>Conclusions</p> <p>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.</p> <p>A significant difference in first ray flexion and angular rotation between the patients and healthy volunteers however could not be found.</p

Biomechanical analysis of functional adaptation of metatarsal bones in statically deformed feet

We analysed the functional adaptation of the first and second metatarsal bones to altered strain in flexible flatfoot. Fifty consecutive women (20–40 years of age) were enrolled: 31 patients with a flexible flatfoot and metatarsalgia (59 feet) and 19 controls with asymptomatic feet (37 feet). They were compared for cortical thickness (medial, lateral, dorsal and plantar) of the two bones. The null hypothesis of no overall difference between the deformed and healthy feet with regard to cortical thicknesses of the two bones was rejected in a multivariate test (p = 0.046). The groups differed significantly only regarding dorsal cortical thickness of the second metatarsal, which was around 18.1% greater in the deformed feet (95% confidence interval: 7.7–28.4%, p < 0.001). Hypertrophy of the dorsal corticalis of the second metatarsal bone appears to be the main metatarsal adaptive reaction to altered strain in the flexible flatfoot