knee injury and thigh shaking

Our user asked: "Here is a little background. I injured my knee in Oct and was my main issues were a sublaxation of my patellar tendon which was causing my knee not to track correctly and a sprained MCL. I have had 4 months of physical therapy and now I am having injections into my knee to lubricate it so that it stops popping and grinding because of cardlidge damage. Here is my issue now. When I am sitting and I hold my leg straight out and then bend it back my entire thigh shakes. I showed my doctor and he said he had never seen a leg move like that and suggested I tried to strengthen my quad muscle and see if that helps. I have been working out on a regular basis now for months and I am doing all the exercises the PT gave me. Do you have any suggestions on exercises that can help me strengthen my leg so that it does not shake? I've looked on this web site at the exercises and I do most of them. Would doing balancing exercises help strenghthen it? If it is still shaking this week (which it's going to be) I am being sent back to physical therapy but I am trying to avoid going back and paying that lovely copay! Thanks for all of your help!"

Ask a PT Response: "Closed chain single leg activities such as single leg squats, single leg reach, lunges, etc are some exercises which PT's can prescribe to their patients to help strengthen their quads. Machines such as leg presses and squat racks, etc are equipment PT's may have their patients utilize to also assist with quad strengthening. Electrical stimulation in conjunction with quad sets, short arch quads, long arch quads, and standing terminal knee extension can assist with facilitating increase quad strength as well. If you have participated in PT in the past and have been doing your exercises, than maybe you may need more advanced exercises to stress your weak quads more if that is truly the cause of your shaking."