Do your knees feel wobbly or are your legs giving way? If you answered yes to either one of these questions, then you might be experiencing a condition known as Arthrogenic Muscle Inhibition. That’s a fancy way to say that the muscle weakness is caused by joint arthritis, injury and pain.
As a protective mechanism, the nervous system has reflexes that shut down muscle activity in order to protect the injured body part. In the case of an injured knee, ankle or other joint, doctors have observed significant muscle deactivation in response to joint swelling, pain, and arthritis. 1
In response to knee injury, surgery or arthritis, the quadriceps muscles become very weak. Even the hamstring and buttocks muscles are weakened in order to protect the knee. In response to an ankle injury or other painful process, the lower leg muscles in the calf start to lose their power. Researchers are even able to duplicate this arthrogenic muscle response by simulating joint swelling a...
Studies show muscle weakness after total knee replacement (TKR) is common months and even years after the surgery. This study compares the force produced during a single-leg press after TKR. Nine patients with TKR were compared to nine adults without TKR (the control group). This is the first study to measure force produced by the leg after TKR in a weight-bearing position. It's unique because force is examined across several joints using many muscle groups. This gives a better idea of what's going on in a fully weight-bearing position. Other studies have reported on forces in one joint at a time. Often only the knee extensor muscles are tested. The authors report that there is much less force through the leg with the joint replacement. These measures were lower when compared to the patient's healthy leg and when compared to the control group. This shows that the entire leg, not just one set of muscles, has less power. The researchers suggest that the loss of force in the leg with the TK...
Back pain - nonspecific
The majority of nonspecific back pain is probably caused by muscle strain. This usually responds to 2-5 days of rest and pain medications (such as nonsteroidal anti-inflammatory agents -- ibuprofen, naproxen, aspirin, etc.), followed by gradual return to activities. Medications may be needed to reduce muscle spasms.
Physical therapy is often prescribed to instruct the patient on proper body mechanics (such as good posture and lifting correctly) and to improve strength and flexibility in the spine, abdomen, and legs.
Surgery is not useful for the treatment of nonspecific back pain.
Most cases of nonspecific back pain resolve on their own or respond to treatment. It is helpful to sleep on a firm mattress, with a board under the mattress, or even on the floor. Heat or ice applied to the affected area may provide some relief.
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