Abstract
After total hip replacement, force generating capacity of gluteal muscles is an impotant parameter on joint contact forces and primary fixation of total hip replacement. Femoral offset is an option to optimize muscle moment arms, especially main abductor Gluteus Medius and Minimus. To investigate relationship with weak gluteal muscles (Gluteus Medius and Minimus) and increased femoral offset, we build a musculoskeletal model. Creating of three-dimensional femur geometry and scaling of the musculoskeletal model according to the subject were performed with computed tomography data. Obtained gait kinematic and kinetic data were applied and to mimic gluteal muscle weakness, the force generating capacities of Gluteus Medius and Minimus reduced (%20-%80). Analysis were done for both anatomical and +10mm offset. Then, muscle and joint reaction forces obtained from musculoskeletal analysis transfered to CT based finite element model to evaluate changes in maximum principle stresses on femur. According to the results of the musculoskeletal analysis, the weakness of the gluteal muscles caused an increase in the activation of Gluteus Maximus, Rectus Femoris and Tensor Fasciae Latae. Effects of +10 mm femoral offset on total abductor muscle activity increased with reduced muscle strength. As a result of the finite element analysis, no significant difference was observed for maximum principle stresses on femur with varying muscle activites. The results of these analyses are important to understand weakness of gluteal muscles and for planning hip surgery.
