High Knee flexion angle ,Wrapping Surface

[Rohan Kothurkar]

I am using Rajagopal model. when i increase knee flexion angle over 140 , muscle path changes. What should i do?

[Thomas Uchida]

I am using Rajagopal model. when i increase knee flexion angle over 140 , muscle path changes. What should i do?

The first thing you should do (when using any model) is make sure you're using it correctly. The authors state in the paper (Rajagopal et al., "Full-body musculoskeletal model for muscle-driven simulation of human gait", http://nmbl.stanford.edu/wp-content/upl ... 505900.pdf) that the model was tested for knee flexion angles of 0 to 120 degrees. The model was later extended by Lai et al. (see https://simtk.org/projects/model-high-flex/) to accommodate up to 140 degrees of knee flexion. You may need to adjust the model slightly if you require an even greater range of motion.

[Rohan Kothurkar]

Yes sir i know that. even i can use( https://simtk.org/projects/high-hip-flex )Danilo Catelli model. but i face same problem at higher flexion even if i edit wrapping surface. Same thing happens after certain flexion angle. i know how to edit wrapping surfaces but don't understand why muscle changes path. How to adjust model? Please guide me.

[Thomas Uchida]

There are a couple possible explanations for your observation. I think they have since been resolved, but there were some bugs in the visualizer related to muscle wrapping, so you should confirm that the muscle moment arm is in fact changing abruptly. If so, you could modify the model to prevent this from occurring---for example, by adding ConditionalPathPoints and/or additional wrap surfaces.