We explored the tibiofemoral contact forces and the relative contributions of muscles and external loads to those contact forces during various gait tasks. Second, we assessed the relationships between external gait measures and contact forces. A calibrated electromyography-driven neuromusculoskeletal model estimated the tibiofemoral contact forces during walking (1.44 ± 0.22 m s−1), running (4.38 ± 0.42 m s−1) and sidestepping (3.58 ± 0.50 m s−1) in healthy adults (n = 60, 27.3 ± 5.4 years, 1.75 ± 0.11 m, and 69.8 ± 14.0 kg). Contact forces increased from walking (∼1–2.8 BW) to running (∼3–8 BW), sidestepping had largest maximum total (8.47 ± 1.57 BW) and lateral contact forces (4.3 ± 1.05 BW), while running had largest maximum medial contact forces (5.1 ± 0.95 BW). Relative muscle contributions increased across gait tasks (up to 80–90% of medial contact forces), and peaked during running for lateral contact forces (∼90%). Knee adduction moment (KAM) had weak relationships with tibiofemoral contact forces (all R^2 < 0.36) and the relationships were gait task-specific. Step-wise regression of multiple external gait measures strengthened relationships (0.20 < R^2 < 0.78), but were variable across gait tasks. Step-wise regression equations from a particular gait task (e.g. walking) produced large errors when applied to a different gait task (e.g. running or sidestepping). Muscles well stabilized the knee, increasing their role in stabilization from walking to running to sidestepping. KAM was a poor predictor of medial contact force and load distributions. Step-wise regression models results suggest the relationships between external gait measures and contact forces cannot be generalized across tasks. Neuromusculoskeletal modelling may be required to examine tibiofemoral contact forces and role of muscle in knee stabilization across gait tasks.
This project makes available a modified version of the gait2392 model to calculate knee contact forces at the medial and lateral compartment using the equilibrium equations from Winby et al. (2009) J Biomechanics 42, 2294-2300. This approach can be used to calculate knee contact forces in EMG-driven approaches.
This project makes available a modified version of the gait2392 model that:
* allows calculating the moments acting at two contact points identified for the knee joint.
* allows calculating the muscle moment arms with respect to this contact points (frontal plane)
* can be used to calculate joint contact forces at the medial and lateral compartments using the equations provided in Winby et al. (2009) J Biomechanics 42, 2294-2300.
* can be used to calculate knee contact forces in EMG-driven approaches.
From this project it is possible to download a modified version of the gait2392 model that allows to compute the knee joint moments at the medial and lateral compartments and muscle moment arms with respect to two contact points between femur and tibia. Contact points are modelled as hinges perpendicular to the frontal plane.
Together with the model, some notes about the knee model and how it compares to other models in the literature are made available.