Computational Hip Simulations in Patients with Femoroacetabular Impingement Syndrome during Various Tasks

Femoroacetabular impingement syndrome (FAIS) is a clinical hip disorder consisting of imaging findings, clinical signs and symptoms that indicate premature contact between the acetabulum and the proximal femur during hip movements. Although FAIS seems to develop as a result of an abnormal distribution of hip joint loads, there is still little knowledge about the in vivo distribution of HJRF. HJRF can be obtained non-invasively using in silico models. MSK models are among the computational models that can be used to calculate joint forces requiring a shorter simulation time. The current project's goal is to use the software AnyBody Modeling System to implement MSK models and run MSK simulations in order to better understand the relationship between hip kinetics and FAIS. Because different activities require different HJRF, an analysis of hip loads during various tasks (gait, double leg squat, and single leg squat) was performed. For gait and double leg squat tasks, MSK models of 10 FAIS patients and 10 healthy controls were implemented, while MSK models of 8 patients and controls were implemented for single leg squat. The pipeline used to perform MSK simulations was validated using a 5-subject gait dataset from a publication by Moreira et al., which allowed to statistically compare the outputs of the implemented models to their published results using SPM. There were no differences in terms of hip kinematics and kinetics between patients and controls for gait and double leg squat. In the single leg squat, people with FAIS showed lower proximodistal HJRF and flexion HJA compared to healthy controls. In FAIS patients, proximodistal HJRF, flexion HJM, and flexion HJA were found to be lower in the involved leg compared to the uninvolved one. Smaller HJRF and HJM values in FAIS patients may represent a strategy of reduced muscle forces to avoid pain and symptoms during high demand tasks such as the single leg squat. More research is needed to implement more complex MSK models, which may include both subject-specific hip geometry from MRI reconstruction and hip muscle behavior analysis from EMG data.