Stress distribution in transtibial monolimb at various typical subphases of stance

Analyzing the stress distributions in monolimb under the typical subphases of stance as a guide for the designing of monolimb, a three-dimensional finite element model including the soft tissue and bone of stump is established based on a real geometry of an endoskeletal transtibial monolimb. The loads corresponding to five typical subphases of the stance of Heel Strike, Foot Flat, Mid-Stance, Heel Off and Toe Off are applied to the model respectively to obtain the stress distributions in monolimb. Von Mises stress is used for analysis. The stresses in the monolimb and soft tissue at Heel Off are the highest of all. At Heel Off, the maximal Von Mises stresses in prosthetic shank, socket and the border section are 30 MPa, 18 MPa and 32.1 MPa respectively, and the maximal normal stress on the surface of soft tissue is 703.8 kPa. Heel Off is the most disadvantageous subphase of stance for transtibial monolimb. So it's necessary for monolimb structure to meet the requirement of intensity at Heel Off subphase.