Orthopedic surgeons use a variety of diagnostic tests to help identify the specific nature of the musculoskeletal injury or disorder and they use the results of these tests to plan an appropriate course of treatment. Here are some of the most frequently used diagnostic tests for musculoskeletal injuries and conditions.
A physician can tell a lot about your health simply by looking at you. Obvious signs and symptoms include weak (atrophied) or asymmetrical muscles, improper alignment, swelling, changes in skin color (such as bruises or redness that might indicate inflammation) and growths such as cysts, calluses or corns.
Palpation means touching. During the physical examination, the doctor may feel the patient’s joints to see if they are warm or swollen, which are signs of inflammation. He or she may apply pressure to a muscle or joint to identify an area of tenderness. Palpation can also be used to identify the location of growths such as tumors or cysts. A physician may place a hand over a joint and ask you to move the joint, particularly if you complain of a “popping” or “snapping” sensation. This enables the physician to feel the tendons as they move over the joint. If one has a joint dislocation, the doctor may palpate the area before attempting to realign the bones.
Range of Motion Testing
Range of motion tests may also be called flexibility tests. They are used to measure how well you can move a joint. Some joints like the thumb and shoulder have a wide range of motion, almost a complete circle. Other joints like the knee are like hinges and have a more limited range of motion. Range of motion tests may be active or passive. In active tests, you do all the movement. In passive tests, the doctor will hold the extremity and move it.
Muscles being soft tissues, do not appear on X-rays. So muscle testing is an important part of the physical examination. Weakness in a muscle may indicate injury to the tendons that connect the muscle to bone, injury to the nerves that enervate the muscle, or a generalized weakness of the muscle itself from disuse. To test the strength of muscles, the physician may ask the patient to move in certain ways while he or she applies a resistive force. For example, the physician may ask you to sit in a chair and then attempt to raise one knee as he presses down on your upper leg or the physician may hold the patient’s elbow at a 90-degree angle and ask to bend the wrist down. Measuring grip strength by asking to squeeze the doctor’s hand is another type of muscle test.
X-rays (radiographs) are the most common and widely available diagnostic imaging techniques. Even if a patient complains about a sprain in the wrist or ankle, the doctor will probably order radiographs to make sure no bone is broken. X-rays are always used for fractures and joint dislocations, and may also be recommended if your doctor suspects damage to a bone or joint from other conditions such as arthritis or osteonecrosis (bone cell death). Bones, tumors and other dense matter appear white or light because they absorb the radiation. Soft tissues and breaks in bone let radiation pass through, making these parts look darker.
Dual-energy X-ray Absorptiometry
Dual-energy X-ray absorptiometry (DEXA) is the most widely used test for measuring bone density. It can accurately and precisely monitor changes in bone density in patients with osteoporosis who are undergoing treatments. This machine takes a picture of the bones, the total body, spine, hip and wrist and calculates their density. It is painless and non-invasive, requiring no special preparations.
For this exam, one has to lie on a padded table while the X-ray scanning machine moves over the body to capture images of the hip, spine or entire body. The exam takes about 20 minutes to complete, and the radiation dosage from the x-ray is less than that used for a chest X-ray. The patient’s bone density and risk of fracture are compared to the “normal” range for people of the same age as well as to the maximum bone density possible.
Laboratory studies of blood, urine or joint (synovial) fluids are used to identify the presence and amount of chemicals, proteins and other substances. The doctor may order various laboratory studies depending on what he or she finds during the initial examination. Some conditions, such as rheumatoid arthritis, may be identified by the presence of a specific substance in your blood. For example, laboratory studies can identify the amount of uric acid in the blood, which is an indicator of gout. A high white blood cell count in joint fluid may indicate severe inflammation or infection. Laboratory tests are usually required before surgeries to identify medical abnormalities.
When the Orthopedic specialist suspects that the patient has a blockage in the blood vessels of the legs or arms he may prescribe an ultrasound test. An ultrasound uses high-frequency sound waves that echo off the body. This creates a picture of the blood vessels. The Doppler audio system transmits the “swishing” sound of the blood floor. This is a noninvasive test that has no side effects.
Two very different kinds of tests may be called bone scans. One type tests the density of the bone and is used to diagnose Osteoporosis. This type of bone scan uses narrow X-ray beams or ultrasound to see how solid the bone is. No preparation is required for this test, which takes only a few minutes and has no side effects.
The second type of bone scan is used to identify areas where there is unusually active bone formation. It is frequently used to pinpoint stress fracture sites or the presence of arthritis, infection, or cancer. About three hours before the scan, the patient will be given a dose of mildly radioactive substance called “technetium” through an intravenous line (IV). This substance occurs naturally in the body and is used in the bone formation process. The bone scan itself is performed about three hours later, which gives the bone time to absorb the technetium. As the patient lies on a table, a special nuclear camera takes a picture of the entire body. This process takes 30 to 90 minutes. Areas of abnormal bone formation activity will appear brighter than the rest of the skeleton.
Computed Tomography (CT Scan)
A CT scan (Computed Tomography) combines X-rays with computer technology to produce a more detailed, cross-sectional image of the body. It may be ordered if the doctor suspects a tumor or a fracture that doesn’t appear on X-rays (such as in the collarbone or pelvis) or in case of severe trauma to the chest, abdomen, pelvis, or spinal cord. The process is painless. The patient is asked to lie motionless on a table as it slides into the center of the cylinder-like CT scanner. An X-ray tube slowly rotates around the patient, taking many pictures from all directions. A computer combines the images to produce a clear, two-dimensional view on a television screen. One may need to drink or be injected with barium sulfate or a dye so that certain parts of the body can be seen more clearly.
Magnetic Resonance Imaging (MRI)
An MRI (magnetic resonance image) uses magnetic fields and a sophisticated computer to take high-resolution pictures of one’s bones and soft tissues, resulting in a cross-sectional image of your body. It can be used to help diagnose torn muscles, ligaments and cartilage, herniated discs, hip or pelvic problems and other conditions. The MRI creates a magnetic field around the patient, then pulses radio waves to the area of the body to be pictured. The radio waves cause the tissues to resonate. A computer records the rate at which the body’s various parts (tendons, ligaments, nerves) give off these vibrations and translates the data into a detailed, two-dimensional picture. If one has implants, metal clips or other metal objects in the body this needs to be informed to the doctor before undergoing an MRI scan.
Discography is a test used to determine whether the discs, (the cushioning pads that separate the bones of the spine), are the source of back pain. It may be performed before surgery to positively identify the painful disc(s).
Before the procedure begins, the patient will be given antibiotics and relaxation medications through an IV line. Medication is used to numb the skin over the test site. During the procedure, the doctor insists a needle into one or more discs and injects a contrast dye. The patient will feel pain when the dye is introduced into the problem disc. Afterward, a CT scan will show any changes in the disc size or shape. One may experience some muscle discomfort after the procedure; the doctor can prescribe pain relievers to ease the discomfort.
Arthrography is often used to help diagnose the cause of the unexplained joint pain. A contrast iodine solution is injected into the joint area to help highlight the joint structures, such as the ligaments, cartilage, tendors and joint capsule. Several X-rays of the joint are taken, using a fluoroscope, a special piece of x-ray equipment that immediately shows the image. The patient may be asked to fast prior to the exam. During the examination, the patient may be asked to move the joint into various positions as the images are taken. It is normal to experience some discomfort or tingling during the procedure. If the patient may be pregnant, or is allergic to iodine or shellfish, this must be notified to the physician as the patient may be at a higher risk of complications.
An electromyography (EMG) records and analyzes the electrical activity in the muscles. It is used to learn more about the functioning of nerves in the arms and legs. For example, a fracture of the upper arm bone (humerus) may tear or pinch the radial nerve. An EMG can be used to identify the damage if nerve function doesn’t return within 4 months of injury. Usually, one can get the results immediately after the test.
Nerve Conduction Study (NCS)
Nerve conduction studies are often done along with an electromyogram to determine if a nerve is functioning normally. It may be recommended if a person has symptoms of carpal tunnel syndrome or other ulnar nerve entrapment. The doctor conducting the test will tape wires (electrodes) to the skin in various places along nerve pathway. Then the doctor stimulates the nerve with an electric current. As the current travels down the nerve pathway, the electrodes placed along the way capture the signal and measure its speed. In healthy nerves, electrical signals can travel at speeds of up to 120 miles per hour. If the nerve is damaged, however, the signal will be slower and weaker. By stimulating the nerve at various places, the doctor can determine the specific site of the injury.
Intrathecal Contrast Enhanced CT Scan
This test uses contrast dye to visualize the spinal canal and nerve roots in the spine. It may be used to help diagnose back problems such as spinal stenosis, particularly in patients with pacemakers or others who cannot have an MRI. The physician applies a numbing medication to the skin, which may sting for several minutes. The doctor uses X-ray guidance to inject a very low dose of contrast fluid (dye) into the spinal fluid. The CT scan is then administered. Although no special preparations are required, strict bed rest is necessary for at least 24 hours after the test to prevent spinal headaches. These headaches can occur because some of the fluid that surrounds the brain and spinal cord may leak out through the injection site. The test itself may take several hours because it may take that long for the dye to reach the area of concern.
Joint Aspiration and Analysis
Joint aspiration may be both a diagnostic test and a treatment option. In conditions such as bursitis, there is a fluid build-up that results in swelling and pressure. A similar fluid build-up around the joints can occur with injuries and arthritis.
Aspiration, or removing the fluid through a syringe, can reduce swelling and relieve pressure. The doctor will swab the skin with an antibacterial solution before inserting the aspirating needle. The patient may feel some pressure and pain as the needle is inserted, but this should be relieved as the fluid is removed.
After the test, the doctor may send the fluid to a laboratory for analysis. In an injury situation, there may be blood present in the fluid or fat droplets from bone marrow, which indicates the presence of a fracture. The analysis can also determine if the fluids result from an infection or an inflammatory response.
Quantitative Computer Tomography
Quantitative computer tomography (QCT) is used to measure bone mineral density (BMD) for osteoporosis. It is similar to a normal CT scan, but uses a computer software package that determines bone density in the hip or spine. This technique provides for true three-dimensional imaging and reports BMD as true volume density measurements. This enables the physician to focus on a particular area.
A muscle biopsy is a procedure used to diagnose diseases involving muscle tissue. Tissue and cells from a specific muscle are removed and viewed microscopically. The procedure requires only a small piece of tissue to be removed from the designated muscle.
The tissue sample is obtained by inserting a biopsy needle into the muscle. As it is removed from the muscle, a small piece of the tissue remains in the needle. The physician may insert the biopsy needle multiple times in different parts of the muscle to obtain an adequate sample for testing.
A muscle biopsy is performed to assess the musculoskeletal system for abnormalities. Various disease processes can cause muscle weakness or pain. These conditions may be related to problems with the nervous system, connective tissue, vascular system, or musculoskeletal system.
Venography is used to determine whether you have a blood clot in your leg, a condition called deep vein thrombosis. This is a serious condition because if the clot breaks free, it could travel to your lungs, creating a potentially fatal condition called pulmonary embolism.
In this test, a contrast solution (or dye) is slowly injected into your legs as you lie on a tilting X-ray table. The dye causes a warm, flushed feeling in the leg. X-rays are taken to identify the location of the clot. After the test, a clear fluid is injected in the same spot to clear the dye from your veins. The test takes less than an hour and can be done on an outpatient basis.
Article written by:
Dr. Mani Ramesh
Consultant Orthopedic Surgeon
Apollo Hospitals, Chennai