Our bones are held together at a joint by tough, fibrous bands of tissue called ligaments. Smooth cartilage, which provides a low-friction surface for movement, covers the ends of bones. A layer of tissue, called synovium, lines the joint space. It is this membrane that produces a fluid which lubricates the joint and nourishes the cartilage.
A condition characterized by the inflammation of the synovium is called synovitis. This joint disease does not often occur alone; it usually accompanies some form of another type of joint disease - arthritis.
Inasmuch as the function of the synovium is to secrete a lubricating fluid (synovial fluid), swelling and distension are likely because of irritation or injury due to excessive secretion. The forcing of blood into the joint cavity worsens the condition.
Occurrence of synovitis in a person without a history of any injury may begin with a low-grade inflammatory condition brought forth by other conditions, such as tuberculosis or rheumatoid arthritis. In such a case, medical attention is immediately required. Some metabolic disturbance - the inherent character of which may not be clear sans special tests - can likewise cause this joint disease.
In synovitis, there is often pain and movement of joint is limited, due mainly to the distension which causes the ligaments to be stretched and interfere with the normal ease of movement. The simple form of this joint disease is most commonly caused by a sprain injury, with the knee joint being the most commonly affected. In cases when there is too much of the synovial fluid, the patella (kneecap) is felt as if suspended in the fluid. The "floating" kneecap may then be also felt to hit against the bone beneath it once it is quickly squeezed backward with the leg held straight downward.
Bed rest is advised for the person with synovitis. If the joint disease is related to an injury, ice packs should be applied to the affected joint for the first twenty-four hours; thereafter, the ice packs should be replaced with hot fomentations applied thrice each day to the joint. Applying pressure to the involved part with the use of an elastic bandage will help.
Distinguishing between a simple sprain and an injury involving a fracture is not easy for a person without medical training. Similarly, it is not easy to determine the true nature of synovitis. It is therefore important that a physician is consulted if the presence of the joint disease is suspected.
1. "Synovitis," on MedicaLook - http://www.medical-look.com/Joint_pain/Synovitis.html
2. "Synovitis" - http://www.healthscout.com/ency/68/628/main.html