ACL Reconstruction Knee Assessment

[Will Madison]

My research area is Kinematic research for ACL. Both ACL injury and reconstruction commonly result in quadriceps inhibition and atrophy requiring extended rehabilitation to reserve. An accurate assessment of muscle is critical prior to an athlete returning to normal activity.

My problem is that traditional assessment techniques are not effective in closed-chain activities, such as dynamometry. SEMG also has disadvantages in comparison within an individual and person to person.

Any solution or suggestion?

Thanks in advance.

Will

[Ton van den Bogert]

Re: ACL Reconstruction Knee Assessment

You can probably set up a Biodex or Cybex to do dynamometry on a leg press exercise, but this has the problem that the force measurement is a result of hip and knee extensors combined. Deficits in knee function may not be detected that way.

To separate out the contributions from hip and knee moments, you need to perform the closed chain task with the foot on a 3D force plate, not a 1D load cell. Then you can calculate hip and knee joint moments and even (with a joint model) internal forces in the knee.

Rafael Escamilla has a few publications on this kind of work, look for "Escamilla RF" on Pubmed between 1998 and 2001.

Ton van den Bogert

[Matthew Tenan]

Re: ACL Reconstruction Knee Assessment

Will,
It might be helpful if you elaborated on what you are interested in regarding the "assessment of muscle" before return to play. Are we interested in muscle activation (pattern, amplitude, etc)? Force production? Tremor? Endurance time?

As an athletic trainer, I know one of the typical factors used is a 'return' to the 1:1 ratio of hamstring/quadriceps power through isokinetic dynamometry (OKC). Is this what you are speaking about when you say they are not effective?

Matt Tenan

[Brian Schulz]

Re: ACL Reconstruction Knee Assessment

I've got a closed-chain dynamometer that works pretty well (http://www.biologicengineering.com/). Its footplate only has four 1D load cells, so you get COP position and normal force for both feet combined, but they've built versions of this device in the past with full 3D force plates and might be willing to make a custom version for you. You might also be able to attach your own left and right foot force plates on top of the existing footplate.