Knee pain is one of the most common problems patients come in with to a rheumatologists office. There are multiple causes of knee pain ranging from arthritis to bursitis to tendonitis and so on.
One type of knee pain that is rarely mentioned is the pain from an inflamed medial plica. This is considered an arthritis condition.
In order to understand this type of knee pain, it's important to have an understanding of basic knee anatomy.
The knee is a joint consisting of four bones, the femur (upper leg bone), tibia (the larger of two lower leg bones), the fibula (the smaller of the two lower leg bones), and the patella (the knee cap).
All the articulating (interacting) surfaces of the knee bones are covered with a thin layer of hyaline cartilage, a tough type of gristle, that helps with cushioning and shock absorption.
This entire system is enclosed inside a joint capsule. The capsule is lined with synovium, a type of tissue that provides nourishment and lubrication for the joint.
On occasion, the synovium can form a fold of tissue. This fold can occur above the knee cap, below the knee cap, and between the knee cap and femur, along the inside part of the knee.
When the fold occurs along the inside part of the knee between the patella and the femur, it can cause problems. This is called medial plica syndrome.
Pain in the region of the patella is the most common symptom. A person may also note snapping, clicking, locking, and even a sense of instability. This latter symptom is relatively rare.
Inflammation of the knee capsule, as may occur with arthritis, or trauma can aggravate the pain. In addition, bending and straightening the knee (eg. Stair climbing) can also aggravate the pain of a medial plica.
The diagnosis can be suspected clinically by the history. On examination, the patient may complain of pain located over the medial (inside) part of the joint. A sensation of snapping may be felt when the knee is flexed and straightened.
The diagnosis can be confirmed by magnetic resonance imaging (MRI) scanning.
Usually, a patient will undergo arthroscopy (insertion of a telescope inside the knee joint). At the time of arthroscopy, the medial plica will appear to be thickened and inflamed. The treatment is also rendered arthroscopically.
By introducing a motorized trimmer, the arthroscopist can carefully trim the inflamed plica so it no longer becomes trapped. This procedure is usually curative. We have seen a number of symptomatic medial plica cases that were essentially cured by this arthroscopic approach.
Nathan Wei, MD, FACP, FACR is a rheumatologist and Director of the Arthritis Treatment Center http://www.arthritistreatmentcenter.com. He is a former Clinical Assistant Professor of Medicine at the University of Maryland School of Medicine and consultant to the National Institutes of Health. For more info: http://www.arthritis-treatment-and-relief.com