When your knee is locking, it is an indication of a problem within the knee joint. A locked knee freezes in a straight or bent position producing pain and limiting motion.
Causes for knee locking
When the knee locks, it is usually due to one of the following conditions: a torn meniscus, loose fragments floating inside the joint or pain that is so severe it limits movement of the knee.
- Torn meniscus – Two menisci, a lateral and a medial, are located between the large bone of the thigh (femur) and the larger of the two bones in the lower leg (tibia). These horseshoe-shaped menisci function as shock absorbers for the joint, help distribute body weight, provide joint stability and keep the bones from rubbing together. Sudden twisting or blows to the knee can cause a meniscal tear. When this happens, fragments of the meniscus sometimes become caught between the femur and tibia, causing the knee to lock.
- Loose fragments – Small pieces of bone or cartilage floating inside the joint can cause the knee to catch or lock. These loose bodies may be due tofracture, trauma, inflammation or non-cancerous tumors. Certain medical conditions such as osteoarthritis or rheumatoid arthritis can also cause tissue death within the knee joint resulting in loose fragments.
- Knee pain – Severe pain in the knee can restrict movement making it difficult to determine whether the knee joint is actually locked or the pain is so intense as to impede movement.
Diagnosing reason for locking knee
An examination by an orthopedic surgeon can typically determine whether or not knee locking is due to pain or a mechanical issue. X-rays may be helpful in identifying the exact cause of a locked knee but meniscal tears and smaller fragments may not be visible on x-ray.
Magnetic resonance imaging(MRI) uses a magnet and pulsating radio wave energy to capture a 3D image of the inside of the knee joint to diagnose the cause of a locked knee. MRI can often pinpoint problems not visible on w-ray.
Treatment of locking knee
Treatment of a locked knee is determined by the cause of the problem. Initial treatment of meniscal tears should be aimed at controlling swelling and inflammation. R.I.C.E. therapy, which stands for rest, ice, compression and elevation, is often recommended along with anti-inflammatory medications and physical therapy. Some patients can then gradually return to their normal activities, while others require surgical treatment.
Arthroscopic knee surgery is a minimally invasive procedure performed through a series of small incisions. This allows the orthopedic surgeon to visualize the injury and suture or trim the damaged meniscus.
Loose fragments are also typically removed through an arthroscopic procedure. Very large bodies may require an open procedure – arthrotomy – for removal.