Diagnosis of Joint, Tendon, And Muscle Pain

A clinician can often diagnose a joint, tendon, and muscle disorder based on the symptoms and on the results of a physical examination. Laboratory tests, imaging tests, or other diagnostic procedures are sometimes necessary to help the clinician make or confirm a diagnosis.

Physical examination: When a person complains of muscle pain, the clinician checks muscles for bulk and texture and for tenderness. Muscles are also checked for twitches and involuntary movements, which may indicate a nerve disease rather than a muscle disease. Clinicians look for wasting away of muscle (atrophy), which can result from damage to the muscle or its nerves or from lack of use, as sometimes occurs with prolonged bed rest. Clinicians also look for muscle enlargement (hypertrophy), which normally occurs with an exercise such as weight lifting. However, when a person is injured, hypertrophy may result from one muscle working harder to compensate for the weakness of another.

Clinicians try to establish the muscles (if any) that are weak and how weak they are. The muscles can be tested systematically, usually beginning with the face and neck, then the arms, and finally the legs. Normally, a person should be able to hold the arms extended, with palms up, for one minute without any sagging, turning, or shaking. Downward drift of the arm with palms turning inward is one sign of weakness. Strength is tested by pushing or pulling while the clinician pushes and pulls in the opposite direction. Strength is also tested by having the person perform certain maneuvers, such as walking on the heels and tiptoes, rising from a squatting position, or getting up and down from a chair rapidly 10 times.

The clinician tests a joint's range of motion and muscle tone by moving the limb around a joint while the person is completely relaxed. Resistance to such movement may be decreased, resulting in observation of a larger range of motion than normal, if the nerve leading to the muscle is damaged. There may be more resistance to such movement and a smaller range of motion when the spinal cord or brain is damaged.

If a person complains of or has observable signs of weakness, clinicians will assess their reflexes using a rubber hammer to tap the person's muscle tendon. Reflexes are involuntary responses of the nerves in the muscles caused by outside stimulus, such as the rubber hammer. Reflexes may be slower than expected when the nerve leading to the muscle is damaged. Reflexes may be more rapid than expected when the spinal cord or brain is damaged.

Laboratory tests: Laboratory tests are often helpful in making the diagnosis of the underlying cause of joint, tendon, and/or muscle pain. A test called an erythrocyte sedimentation rate (ESR) test measures the rate at which red blood cells settle to the bottom of a test tube containing blood. The ESR is increased when inflammation is present. However, because inflammation occurs in so many conditions, the ESR alone does not establish a diagnosis.

The level of creatine kinase (a normal muscle enzyme that leaks out and is released into the bloodstream when muscle is damaged) may also be tested. Levels of creatine kinase may also be increased when there is widespread and ongoing destruction of muscle.

In autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus (lupus), a blood test to identify autoimmune antibodies (antinuclear antibodies) is often used in making the diagnosis.

Nerve tests: Nerve conduction studies measure how well and how fast the nerves can send electrical signals. Nerves control the muscles in the body by electrical signals (impulses), and these impulses make the muscles react in specific ways. Nerve and muscle disorders cause the muscles to react in abnormal ways.

Nerve conduction studies, together with electromyography, help indicate the primary source of the problem causing pain. Electromyography, often performed at the same time as nerve conduction studies, is a test in which electrical impulses in the muscles are recorded to help determine how well the impulses from the nerves are reaching the connection between nerves and muscles (neuromuscular junction) and, from there, the muscles.

X-rays: X-ray imaging is used most often to evaluate painful, deformed, or suspected abnormal areas of bone. Often, X-ray images can help to diagnose fractures, tumors, injuries, infections, and deformities. Also, X-ray images may be helpful in showing changes that confirm a person has a certain kind of arthritis (for example, rheumatoid arthritis or osteoarthritis). X-ray images do not show soft tissues such as muscles, bursae, ligaments, tendons, or nerves.

Arthrography is an X-ray procedure in which a dye is injected into a joint space to outline the structures, such as ligaments, inside the joint. Arthrography can be used to view torn ligaments and fragmented cartilage in the joint.

Dual-energy X-ray absorptiometry (DEXA): The most accurate way to evaluate bone density, which is necessary when screening for or diagnosing osteoporosis, is with dual-energy X-ray absorptiometry (DEXA). In this test, low-dose X-rays are used to examine bone density at the lower spine, hip, wrist, or entire body. Measurements of bone density are very accurate at these sites. To help differentiate osteoporosis (the most common cause of an abnormal DEXA scan) from other bone disorders, doctors may need to consider the person's symptoms, medical conditions, medication use, and certain blood or urine test results as well as the DEXA results.

Computed tomography (CT) and magnetic resonance imaging (MRI): Computed tomography (CT) and magnetic resonance imaging (MRI) scans show more body detail than conventional X-rays. For this reason, CTs and MRIs may be performed to determine the extent and exact location of joint, tendon, or muscle damage. These tests can also be used to detect fractures that are not visible on X-rays. MRI is especially valuable for imaging muscles, ligaments, and tendons. MRI can be used if the cause of pain is thought to be a severe soft-tissue problem (for example, rupture of a major ligament or tendon or damage to important structures inside the knee joint). The amount of time needed to complete a CT is much less than for an MRI.

Bone scanning: Bone scanning is an imaging procedure that is occasionally used to diagnose a fracture, particularly if other tests, such as X-rays and CTs or MRIs, do not reveal the fracture. Fractures may be a cause of joint pain. Bone scanning involves the use of a radioactive substance (such as technetium-99m-labeled pyrophosphate) that is absorbed by any healing bone. The technique can also be used when a bone infection or a metastasis (spread of cancer) is suspected. The radioactive substance is given intravenously and is detected by a bone-scanning device, creating an image of the bone that can be viewed on a computer screen.

Joint aspiration: Joint aspiration is used to diagnose certain joint problems. A needle is inserted into a joint space and fluid (synovial fluid) is drawn out (aspirated) and examined under a microscope. A doctor can often make a diagnosis after microscopic analysis. For example, a sample of synovial fluid may contain bacteria, which confirms a diagnosis of infection. Joint aspiration is usually performed in a doctor's office and is generally quick, easy, and relatively painless. The risk of joint infection is minimal.

Arthroscopy: Arthroscopy is a procedure in which a small (diameter of a pencil) fiber optic scope is inserted into a joint space, allowing the doctor to look inside the joint and to project the image onto a television screen. The skin incision is very small. A person receives local, spinal, or general anesthesia to numb any pain during the procedure. During arthroscopy, doctors can take a piece of tissue for analysis (biopsy), and, if necessary, perform surgery to correct the condition. Disorders commonly found during arthroscopy include inflammation of the synovium lining (a thin, layer of tissue which lines the joint space) called synovitis; ligament, tendon, or cartilage tears; and loose pieces of bone or cartilage. Such conditions affect people with arthritis or previous joint injuries as well as athletes. All of these conditions can be repaired or removed during arthroscopy. There is a very small risk of joint infection with this procedure.

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