Fig 1.
(a) Rat knee geometry, (b) motion and loading during gait from a musculoskeletal model, and (c) FRPE material properties from indentation tests were implemented into (d) the FE model. e) Knee tissues’ mechanical responses were evaluated during the stance phase of the gait cycle.
Fig 2.
Gait data for the computational model of the rat knee joint.
External-internal and valgus-varus moments, and flexion-extension rotation. In addition, anterior-posterior, distal-proximal, and medial-lateral translational forces were implemented in the FE model of the knee joint. The inputs of the FE joint model (joint kinematics and translational forces), which were applied in the reference point, were similar to previous experimental studies with Sprague-Dawley rats [30–35].
Table 1.
Material parameters implemented for cartilage and menisci.
Table 2.
Summary of the parameters varied in the parametric analysis.
Bold numbers indicate the reference case for the finite element model.
Fig 3.
Maximum principal stress distribution in the femoral and tibial cartilages, and menisci calculated from the FE model of the knee joint during the stance phase of the gait cycle (Lat: lateral: Med: medial).
The cartilage stresses obtained from the FE model agree with previous numerical studies on mice knee joints under axial compressive forces [20,23].
Fig 4.
Total tibiofemoral joint reaction force in the (a) medial and (b) lateral compartments, respectively.
Translations (c-e) and rotations (f, g) of the tibia with respect to the femur during the stance phase of gait are also presented.
Fig 5.
Average contact pressure, maximum principal strain, maximum principal stress, and fluid pressure in the contact area of the medial (a, c, e, and g) and lateral (b, d, f, and h) tibial cartilage surfaces during the stance phase of gait.
The contact stresses were similar to a previous study published by Gardner-Morde et al. [22] where average contact stresses in the medial and lateral compartment at the reference loading state were 0.4 and 0.1 MPa, respectively.
Fig 6.
Forces transmitted through the cruciate ligaments (ACL and PCL) and collateral ligaments (MCL and LCL) of the knee joint during the stance phase of gait.