In vivo indentation of lower extremity limb soft tissues.

In vivo rate-controlled indentation tests were conducted on the soft tissues of the residual limbs of five individuals with trans-tibial amputation and the right calf of five nonamputees. Force relaxation trials were also conducted. The cyclic indentation tests indicated that the bulk soft tissue response to compressive load is nonlinear and rate-dependent. Inter- and intrasubject stiffness variations were observed. The force relaxation studies indicated that approximately 55-95% relaxation may occur, with equilibration typically occurring in less than 60 s. Most of this relaxation (35-80%) occurred within 5 s after loading.