Common diagnostic tests used to diagnose problems within the musculoskeletal system use blood and urine samples. Both can reveal levels of various minerals and other substances indicating disease or a musculoskeletal disorder. Levels of certain proteins in the blood may also help diagnose a disease. Other tests include a bone or muscle biopsy, analysis of joint fluid and measurement of muscle or nerve function.
Nerve Conduction Studies
Measuring the electrical activity of muscles when a muscle fiber contracts can determine if the muscles and nerves are working properly. A technique called Truax biography will show these nerve conduction patterns, which change in various muscle and nerve diseases. According to Cedars-Sinai Medical Center, a physician can distinguish between disorders affecting the muscle fibers, defects at the junction of the nerve and muscle and disorders caused by nerve conduction defects. Measuring the speed at which nerve impulses travel along a nerve shows whether the nerves transmitting impulses to the muscles are functioning normally.
Antibody Tests
The body’s immune system produces antibodies, or proteins, in response to foreign substances. These antibodies circulate in the blood and bind to the foreign substance to destroy it. In autoimmune disorders, the body’s immune system produces antibodies against its own tissues. The National Institute of Arthritis and Musculoskeletal and Skin Diseases explains that rheumatoid factor, RF, is an antibody test used to diagnose rheumatoid arthritis. Another test that is often ordered is the anti-CCP antibody test, which can detect antibodies to cyclic citrullinated peptide, or anti-CCP. In individuals with rheumatoid arthritis, this test will come back positive. The test can be positive even years before the onset of symptoms. These tests done in combination have shown to be particularly useful and accurate in diagnosing rheumatoid arthritis.
Sedimentation Rate
An erythrocyte sedimentation rate, ESR, measures how quickly red blood cells fall to the bottom of a test tube. Swollen or inflamed joints often contain an abundance of blood proteins that stick together, making them heavier than single cells. Measuring how fast these cells fall to the bottom of the tube indicates the level of inflammation.
Muscle Biopsy
A muscle biopsy entails removing a small sample of the muscle to use in the diagnosis of various musculoskeletal abnormalities, such as pain and inflammation and muscle wasting. Examining the muscle fibers under a microscope can reveal abnormalities. According to the U.S. National Library of Medicine, a muscle biopsy can identify muscular disorders, metabolic defects, muscle infections and diseases of the connective tissue and blood vessels.
Arthrocentesis
Arthrocentesis involves a physician inserting a hollow, thin needle into the affected joint and aspirating or removing a small sample of synovial fluid to check for increased levels of white blood cells, which can indicate the presence of a bacterial infection.
References
- National Institute of Arthritis and Musculoskeletal and Skin Diseases: Rheumatoid Arthritis
- Cedars-Sinai: Nerve Conduction Studies
- National Institute of Arthritis and Musculoskeletal and Skin Diseases: Arthritis
- U.S. National Library of Medicine, Medline Plus: Muscle Biopsy
- Journal of the American Medical Association: Septic Arthritis
