The objective of this study was to produce linear and nonlinear viscoelasti
c models of eight majorj ligaments in the human ankle/foot complex for use
in computer models of the lower extremity. The ligaments included in this s
tudy were the anterior talofibular (ATaF), anterior tibiofibular (ATiF), an
terior tibiotalar (ATT), calcaneofibular (CF), posterior talofibular (PTaF)
, posterior tibiofibular (PTiF), posterior tibiotalar (PTT), and tibiocalca
neal (TiC) ligaments. Step relaxation and ramp tests were performed. Back-e
xtrapolation was used to correct for vibration effects and the error introd
uced by the finite rise time in step relaxation tests. Ligament behavior wa
s found to be nonlinear viscoelastic, but could be adequately modeled up to
15 percent strain using Fung's quasilinear viscoelastic (QLV) model. Failu
re properties and the effects of preconditioning were also examined. [S0148
-0731(00)01001-3].