Lower limb injury is becoming an increasingly important concern
in vehicle safety for both occupants and pedestrians. To enable
vehicle manufacturers to better understand the biomechanical
effects of design changes, it is deemed beneficial to employ a
biomechanically fidelic finite element model of the human lower
limb.
The model developed in this study includes long bones (tibia,
fibula, femur) and flat bone (patella) as deformable bodies. The
pelvis and foot bones are modeled as rigid bodies connected to the
femur and tibia/fibula via rotational spring-dashpots. The knee is
defined by scanned bone surface geometry and is surrounded by the
menisci, major ligaments, and patellar tendon. Finite elements used
to model include 6- and 8-node solids for cartilage, menisci,
surrounding muscles, and cancellous bone; 3- and 4-node shells for
skin and cortical bone; and nonlinear spring-dashpots for
ligaments. Anatomical, physiological, and material properties data
are from the literature while the bone surface geometry was scanned
by a commercial source.
Validation against published cadaver test results consisted of
tibia and femur 3-point bending (lateral-medial and
anterior-posterior) and whole limb lateral knee shear. Validation
was performed under both static and dynamic loading conditions,
until bone failure or ligament rupture. Additional dynamic
validation with the lower limb in a seated orientation has not been
completed, limiting current applications to the pedestrian impact
condition. The validated models were employed to examine the effect
of axial compressive force (the physiological condition) on tibia
and femur lateral-medial and anterior- posterior bending under
static conditions.