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Objective To study the influence of foot progression angle on tibial shock during running. Methods The normal, toe-in and toe-out gait of fifteen healthy adults was tested during running trials on a treadmill. The differences in tibial shock (impact peak, average loading rate, instantaneous loading rate and maximum tibia acceleration) for runners at different foot progression angles were analyzed to explore the influence of foot progression angle on tibial shock. The changes in sagittal plane trunk angle, strike pattern, stride frequency and step width of runners under three gaits were also compared to explore its possible causes. Results Compared with normal gait, the maximum tibial acceleration of toe-in and toe-out gait was increased by 19.3% and 24.5%, impact peak was increased by 7.6%, average loading rate was increased by 7.9% and 9.5%, instantaneous loading rate was increased by 3.9% and 10-.9%, with significant statistic differences. No significant changes were found in sagittal plane trunk angle, strike pattern, stride frequency and step width. Conclusions Foot progression angle might be an another gait parameter which affected tibial shock during running in addition to other related known gait parameters such as sagittal plane trunk angle, strike pattern, stride frequency and step width，which would provide an important reference for prevention of tibial stress fracture.
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PURPOSE: We evaluated the degree of femoral and tibial torsion in, and the efficacy of two operative procedures for, resistant idiopathic clubfoot with toe-in gait. MATERIALS AND METHODS: Thirty one feet in 23 patients (average age at the time of revision surgery 4.3 years) were studied. CT was used to determine femoral anteversion and tibial torsion. Two different operative procedures were applied, depending on the degree of toe-in gait: group 1 (10 feet whose toe-in gait was not severe) - soft tissue release, anterior tibial tendon transfer and mid-foot (cuboid closing and cuneiform opening) osteotomy; group 2 (21 feet which had relatively severe toe-in gait) - supramalleolar external rotation osteotomy of the distal tibia (SEROT), along with the same procedure as group 1. Mean follow-up period after revision surgery was 6.3 years. Results were assessed radiologically and clinically with the Dimeglio classification and Clubfoot Assessment Protocol. RESULTS: The mean femoral anteversion and external-tibial torsion of the affected side were increased. Twenty eight of 31 feet (90.3%) demonstrated excellent or good results. In group 2, we obtained 19 excellent (90.5%) and 2 good (9.5%) results. Group 1 had 6 excellent (60%), one good (10%) and 3 fair (30%) results. CONCLUSION: Surgical treatment of the relapsed clubfoot with toe-in gait including soft-tissue release, tendon transfer and mid-foot osteotomy, along with SEROT in cases of severe toe-in gait, is effective in correcting residual clubfoot deformities.