Bone remodelling in the natural acetabulum is influenced by muscle force‐induced bone stress

Abstract

A modelling framework using the international Physiome Project is presented for evaluating the role of muscles on acetabular stress patterns in the natural hip. The novel developments include the following: (i) an efficient method for model generation with validation; (ii) the inclusion of electromyography-estimated muscle forces from gait; and (iii) the role that muscles play in the hip stress pattern. The 3D finite element hip model includes anatomically based muscle area attachments, material properties derived from Hounsfield units and validation against an Instron compression test. The primary outcome from this study is that hip loading applied as anatomically accurate muscle forces redistributes the stress pattern and reduces peak stress throughout the pelvis and within the acetabulum compared with applying the same net hip force without muscles through the femur. Muscle forces also increased stress where large muscles have small insertion sites. This has implications for the hip where bone stress and strain are key excitation variables used to initiate bone remodelling based on the strain-based bone remodelling theory. Inclusion of muscle forces reduces the predicted sites and degree of remodelling. The secondary outcome is that the key muscles that influenced remodelling in the acetabulum were the rectus femoris, adductor magnus and iliacus.

Hybrid neuromusculoskeletal modeling to best track joint moments using a balance between muscle excitations derived from electromyograms and optimization

“…Furthermore, estimation of hip joint contact forces can currently only be done using optimization-based techniques (Modenese and Phillips, 2011). The hybrid approach could be employed as it estimates excitations for deep hip muscles and adjusts the excitations of superficial hip muscles with multiple compartments (Fernandez et al, 2014). The hybrid model's ability of tracking EMGs and joint moments for each timepoint can enable real-time applications.…”

Activity intensity, assistive devices and joint replacement influence predicted remodelling in the proximal femur

“…Of greater importance might be the consideration of patient specific hip contact and muscle forces, and their pre-to postoperative changes (Jonkers et al 2008). With sufficient input data, multi-patient analysis using this method could be achieved with relatively low computational expense by modifying this verified mesh by freeform deformation (Fernandez et al 2013), and employing mesh morphing to incorporate the effects of surgical variability (Bah et al 2011) and implant sizing.…”

Altered Load Transfer in the Pelvis in the Presence of Periprosthetic Osteolysis

“…Load was applied through the femoral head. Contributing forces from 23 muscle units crossing the hip joint calculated from electromyogra phy assisted methods were included [29,30], These were applied to the FE model using muscle belly centroid paths matched to the origin and insertion of the muscles in question, published by Fernandez et al [30]. Vectors for each force were plotted based on the gait cycle with forces distributed over the origin insertion areas of the pelvis mesh.…”