Hello,
I was wondering if it is possible to observe the location of the joint reaction force within a joint using OpenSim?
I'm using a shoulder model and would like to be able to see where the joint reaction force is being applied within the glenohumeral joint.
I have have produced successful static optimizations for my tasks (different isometric positions) and have also tried using the joint reaction tool under Analyze. I applied my forces file, selected the desired joint, applied the force to the parent (glenohumeral), and expressed the force in the frame of the humerus.
The problem is that with every task the joint reaction force is always applied directly to the origin of the humerus (0,0,0).
Any suggestions help. Thanks.
Locate Joint Reaction Force within a Joint
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Alex Denton
- Posts: 15
- Joined: Thu Oct 04, 2018 7:01 am
Re: Locate Joint Reaction Force within a Joint
Hi Alex,
I think this is just the way joint reaction force works as an analysis. As part of the tool you select the frame that the force is reported in, and subsequently this sets the location (i.e. at 0,0,0 of the humerus for your GH joint). As such, unless you change the frame the location won't change. If you're interested in the force at a specific location I guess you could place a frame at this location and report the joint reaction forces in this frame. I've also seen the GH joint reaction vector be used to estimate an intersection with/location on the glenoid (i.e. direction of the vector) in work by both Chadwick (see 'Real-Time Simulation of Three-Dimensional Shoulder Girdle and Arm Dynamics') and Vidt (see 'Modeling a rotator cuff tear: Individualized shoulder muscle forces influence glenohumeral joint contact force predictions').
Aaron
I think this is just the way joint reaction force works as an analysis. As part of the tool you select the frame that the force is reported in, and subsequently this sets the location (i.e. at 0,0,0 of the humerus for your GH joint). As such, unless you change the frame the location won't change. If you're interested in the force at a specific location I guess you could place a frame at this location and report the joint reaction forces in this frame. I've also seen the GH joint reaction vector be used to estimate an intersection with/location on the glenoid (i.e. direction of the vector) in work by both Chadwick (see 'Real-Time Simulation of Three-Dimensional Shoulder Girdle and Arm Dynamics') and Vidt (see 'Modeling a rotator cuff tear: Individualized shoulder muscle forces influence glenohumeral joint contact force predictions').
Aaron