Effects Of Wearing Shoes And Foot Strike Patterns On In Vivo Kinematics Of The Tibiotalar And Subtalar Joint During Running Based On The High-speed Dual Fluoroscopic Imaging System

Objective: The injury rate of running that is popular around the world is 16.7%-79.3%,resulting in huge direct and indirect economic losses.Shoe effect and foot strike patterns are two main factors analyzing the influence of running in the lower extremities and foot injuries.However,there is no unified conclusion for the relationship between these two factors and foot kinematics.The technical deficiencies of traditional motion capture systems based on the reflective markers limit studies on in vivo foot biomechanics.The dual fluoroscopic imaging system has enabled the accurate and noninvasive measurements of the dynamic and static activities in the joints of the body and is not affected by the movement of soft tissue and the motion artifact.It can effectively compensate for the defects of traditional measurement methods and has been applied in the field of clinical medicine and biomechanics.Therefore,this study aims to determine the effect of wearing shoes and foot strike patterns in in-vivo foot kinematics while running using the first high-speed dual fluoroscopic imaging system in China to clarify the potential relationships between foot movement and injuries and provide scientific reference for runners and running coaches to choose foot strike patterns reasonably.Method: Fifteen recreational healthy male runners underwent the foot CT scan for the construction of 3D models and local coordinate systems.The fluoroscopic images of the foot during the stance period were acquired under wearing shoes with rearfoot strike pattern and barefoot condition with rearfoot strike pattern and forefoot strike pattern.Radiographic images were acquired at 100 Hz while the participants ran at a speed of 3 m/s ± 5% on a platform.The kinematics results of the tibiotalar and subtalar joints under those three conditions above were calculated by 3D–2D registration.Paired sample t-test was used to compare the 6DOF data of the tibiotalar and subtalar joint under shoe effect(rearfoot strike pattern under barefoot condition & rearfoot strike pattern under shoe condition)and foot strike patterns(rearfoot strike pattern & forefoot strike pattern under barefoot condition).Cohen’s d statistic was used to test the effect size.The significance level was set to 0.05.Results: 1).The peak dorsiflexion angle(p=0.011,Cohen’s d=0.76),peak plantarflexion angle(p=0.038,Cohen’s d=0.59),and the flexion and extension range of the tibiotalar joint(p<0.001,Cohen’s d=2.02)with barefoot condition were significantly larger than the shod condition.2).The peak dorsiflexion angle(p=0.02,Cohen’s d=0.68),peak eversion angle(p=0.014,Cohen’s d=0.72),and the eversion of the subtalar joint during 50%–80% of the stance phase with shod condition were significantly larger than the barefoot condition.3).The forefoot strike pattern increased the peak plantarflexion angle(p=0.007,Cohen’s d=0.81),peak internal rotation angle(p<0.001,Cohen’s d=1.50),and the internal rotation of the tibiotalar joint during 0-20% of the stance phase.The forefoot strike pattern decreased the eversion almost throughout the stance phase of the subtalar joint.Conclusion: 1)Shoe effect: In running with rearfoot strike pattern,wearing shoes decreased the flexion and extension range of the tibiotalar joint and increased the peak dorsiflexion angle of the subtalar joint,which effectively overcome the weakness of traditional measurement methods could only obtain the motion of the single ankle joint.And wearing shoes significantly increased the peak eversion angle(12.7%)of the subtalar joint,future studies are needed to explore the association between the eversion of the subtalar joint and running related injuries.2)Foot strike pattern: In barefoot running,forefoot strike pattern decreases the eversion of the subtalar joint during the stance phase and increases the internal rotation of the tibiotalar joint in the early stance.