By James M. Ray, MD
Maybe you have AMI. Arthrogenic Muscle Inhibition presents itself as marked weakness of the quadriceps muscle, seen as muscle atrophy. This is partly due to the lack of motor neuron recruitment and neural inhibition that prevents the brain from fully activating the quadriceps mechanism. This translates into muscle weakness, instability and loss of motion. If you have ever experienced a significant knee injury you know how hard it is to rehab the injury to return to a level of function and strength.
Lately, new information has surfaced explaining the reason behind marked muscle atrophy even after intensive physical therapy. Once the knee has been injured or even undergone surgery the proprioceptive mechanisms are disrupted. The brain no longer can sense the spatial relationship of the knee to force, speed, direction and spatial position. The excellent surgeon performing the ACL reconstruction or Total Knee Replacement cannot replace or recreate the mechanoreceptors. These structures are permanently loss, and in most cases do not regenerate.
The brain has lost the connection and is unable to return the quadriceps muscle tone, strength and function to pre-injury levels. Our focus through the years has been on recreating normal anatomy to improve function to as close to normal post-injury/surgery as possible. The science and technology have improved to satisfy the surgeons ability to provide advanced expertise to improve our outcomes. However, what has been lacking is our understanding of how the brain recruits motorneurons to the quadriceps after injury or surgery.
The bottom line is, after injury or surgery do not pass on the rehab. One must continue to listen to the therapist. Motion is key for function. Full extension and flexion allow normal walking. Flexion contractures of the knee or keeping the knee bent through ambulation increases energy expenditure and causes anterior knee pain and limited motion. Lack of full motion may also lead to excessive scarring or arthrofibrosis. Pain also plays a role in AMI development. Make sure to communicate with the therapist and your physician when it comes to pain management. Opioids may not be the answer. The lack of full motion and quadriceps strength may make the knee feel unstable. This could lead to reinjury.
Ask your therapist or medical professional about AMI. If you have any concerns about your knee injury, knee surgery or questions about return to play or work, please come by and see us at Naples-Clinic Ortho Urgent Care.
James M. Ray, MD
James M. Ray, MD is an orthopedic surgeon who graduated Medical School in 1979 from Louisiana State University. Dr. Ray trained in Orthopedic Surgery at Orlando Health, Orlando, Florida. He was a Sports Medicine Fellow at the University of Wisconsin, Madison. He was also an Academic Physician as an Assistant Professor of Orthopedics/Sports Medicine at the University of Kentucky, Lexington. He has a master’s degree in Executive Health Administration from the University of Florida, Gainesville. He has traveled with numerous Sports Teams Nationally and Internationally. He is now interested in treatment and management of Orthopedic injuries, arthritis, and chronic problems limiting function. He specializes in Quality-of-life issues using IV therapies, biologic injectables and immune boost treatments.
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