A Multi-segment Dynamic Foot Model And Its Application In Foot And Ankle Clinical Problems

Human foot is complex and the relevant movement between the bones is hard to measure in vivo.Results obtained from finite element methods and cadaver gait simulation are not satisfying enough so that the pathology and etiology researches of foot diseases and the improvements of clinical treatments are in stagnation.So,a validated dynamic multi-segment human foot model through gait simulation is critical in foot and ankle surgery and clinic.The kinetic and kinematic information of foot bones is also valuable.The innovative work of this paper includes the following aspects:(1)Developed the soft tissue and bones models of human foot based on CT images and constructed dynamic foot model in MSC.ADAMS.The model included fore-foot,mid-fore-foot,mid-foot,rear-foot,tibia and talus and plantar soft tissue.Adjacent solid models were combined using spherical joint or revolute joint.Plantar soft tissue and solid models were tied together.(2)Defined the contact properties between ground and foot model.Applied tibia kinetic and kinematic data obtained from experiments and ligament forces in gait simulation.Compared the ground reaction force and range of motion of foot joints with literature and the consistence validated the reliability and accuracy of this model.(3)Applied the validated foot model in the etiology analysis of plantar fasciitis.Two types of physical treatments adopted in clinic were simulated according to experiment data.The elongation of plantar fascia during treatments were compared and an improved method was put forward combining Achilles tendon stretch and plantar fascia stretch.(4)The pathology of ankle sprain was analyzed by simulating different ankle movements.The effluence of plantarflexion angle and inversion angle exerting on ligaments was quantified.The simulation results showed that the forces in anterior tibiotalar ligament and anterior talofibular ligament increased along with the increase of plantarflexion and inversion angles while anterior tibiotalar ligament was more sensitive to inversion angle.Meanwhile,the postures of ankle when ligament ruptured were recorded by adding sensors in MSC.ADAMS. The safe range of motion of ankle can provide guidance for rehabilitation of ankle sprain and the design of braces.Multi-segment human foot model is an important research tool in kinematic and kinetic simulation analysis of human foot in daily activities.It is also an innovative method in etiology and treatment research of foot and ankle diseases.