A joint or synovial membrane biopsy refers to a procedure where a sample of the joint lining or synovial membrane is taken.
A joint biopsy is performed to determine why a joint is painful or swollen. It is usually reserved for more difficult cases where the diagnosis is not clear. The test can be used to diagnose bacterial or fungal infections, an abnormal buildup of iron, cancer, or other diseases.
The procedure must be done under very sterile conditions to reduce the risk of infection.
The test is performed either in the doctor's office, clinic, or hospital by a surgeon. There are many different ways to perform this biopsy: through an incision in the joint; with a scope inserted in the joint; or, more typically, by the insertion of a sharp instrument through the skin. The procedure can be taken from any joint, but the most common joint requiring biopsy is the knee. A sharp instrument (trocar) is pushed into the joint space. A needle with an attached syringe is inserted into the joint to withdraw fluid for laboratory analysis. The surgeon may instill numbing medicine into the joint and along the needle track before the needle is withdrawn. The trocar and then the biopsy needle is inserted and specimens taken. After the specimen is taken, both the trocar and the biopsy needle are removed, a bandage is placed over the joint, and the samples are sent to pathology for analysis.
Joint — The point where two bones meet.
Pathology — The branch of medicine that looks at abnormal changes in cells and tissues which signal disease.
Synovial membrane — Membrane lining a joint.
Trocar — A sharp pointed tube through which a needle can be inserted.
Blood tests will be done to check that blood clots properly. A mild sedative may be given before the procedure. With the patient lying down, the skin over the joint is disinfected and a local anesthetic is injected into the skin and tissue just below the skin.
The joint will need rest for at least one day. Normal activity can resume if there is no increased pain or swelling.
There is a chance of joint swelling or tenderness. Rarely, bleeding and infection can occur in the joint, or the biopsy needle could break off or strike a nerve or blood vessel. The risk of infection is higher if the patient has an immune deficiency.
Schumacher, H. Ralph, Jr. "Synovial Fluid Analysis and Synovial Biopsy." In Textbook of Rheumatology, edited by William N. Kelley, et al. Philadelphia: W. B. Saunders Co., 1997.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.