calculate the medial and lateral contact loads on the knee

[Aseel Ghazwan]

Hi all,

I'm trying to compute the medial and lateral components of the joint reaction force at the knee. The centre of each compartment (medial and lateral contact points) is at ±25% of the tibial plateau width relative to the midpoint between the markers positioned over the femoral condyles

Is it possible to do that in CEINMS? if so can you offer some advice or Help...

Thanks
Aseel

[Claudio Pizzolato]

Hi Aseel,

yes, it is possible to calculate knee contact forces with CEINMS, but the current public version doesn't do it automatically.

To calculate medial and lateral contact force we use the formulation of Winby et al. (2009), which requires the calculation of external joint moments about medial and lateral condyles, calculation of moment arms of each muscle relatively to medial and lateral condyles, and calculation of the muscle forces. Muscle forces can be calculated through CEINMS, but you will need an OpenSim model implementing a modified knee mechanism to be able to calculate external joint moments and muscles moment arms.

Claudio

[Lauri Stenroth]

Hi,

I would be also interested to learn how to do this. Would I need to use a modified model such as this: https://simtk.org/projects/med-lat-knee, or can I modify the standard OpenSim model (e.g. gait2392) to be able to calculate knee abduction/adduction moment and muscle moment arms relative to medial/lateral contact points?

Best wishes,
Lauri Stenroth

[Claudio Pizzolato]

Hi Lauri,

to calculate knee contact forces we start from the knee model described in Saxby et al. (2016), which allow us to calculate moment arms to respect of the medial and lateral condyles. Then, CEINMS implements a balance contact model (Winby et al., 2009) to solve for medial and lateral contact forces. Also, it has been shown that minimising the peak knee contact force during the calibration phase improves the contact force estimates (Gerus et al. 2013), which is something to consider.

I have to check if the gait2392 with the knee model is publicly available (I didn't create, so I have to ask the authors). In the next days (weeks more likely) I will also write a guide/tutorial on how to estimate knee contact forces with CEINMS, since it's a common question.

Claudio


Refs
Saxby, D. J., L. Modenese, A. L. Bryant, P. Gerus, B. Killen, K. Fortin, T. V. Wrigley, K. L. Bennell, F. M. Cicuttini and D. G. Lloyd (2016). "Tibiofemoral contact forces during walking, running and sidestepping." Gait Posture 49: 78-85.

Winby, C. R., D. G. Lloyd, T. F. Besier and T. B. Kirk (2009). "Muscle and external load contribution to knee joint contact loads during normal gait." J Biomech 42(14): 2294-2300.

Gerus, P., M. Sartori, T. F. Besier, B. J. Fregly, S. L. Delp, S. A. Banks, M. G. Pandy, D. D. D'Lima and D. G. Lloyd (2013). "Subject-specific knee joint geometry improves predictions of medial tibiofemoral contact forces." J Biomech 46(16): 2778-2786.

[Lauri Stenroth]

Hi Claudio,

Thanks for the information. Looking forward to your guide/tutorial.

Best wishes,
Lauri