Additional Diagnostic Tests

The physician, as does the athletic trainer, often performs a detailed musculoskeletal examination. Often, the physician and the athletic trainer will discuss and compare their individual findings. Because the physician is legally charged with the diagnosis and course of treatment, he or she may have to acquire and compare additional in- formation, which may come from roentgenograms (x-rays), arthrography, arthroscopy, or myelography or through newer imaging techniques such as computed tomography (CT), bone scanning, magnetic resonance imaging (MRI), and sonography. Other tests might include electromyography, determining nerve conduction velocity, synovial fluid analysis, blood testing, and urinalysis.

Blood Testing

The physician may decide to run a complete blood count (CBC) on the athlete for many different reasons. The most common reasons are to screen for anemia (too few red cells) or infection (too many white cells).  Samples may be taken in q syringe from a vein in the arm or from a needle stick in the finger. A routine CBC addresses the following:

1. Red blood cell count looks at the number of cells per unit volume to detect anemias, prolonged infections, iron deficiencies, internal bleeding, and certain types of cancers.
2. Hemoglobin levels are closely associated with red blood cell count and tend to reflect overall blood volume.
3. Hematocrit measures how much of the total blood volume is made up of red blood cells. A low hematocrit indicates certain types of anemias.
4. White blood cell count is used to determine the presence of bacteria. Differentiation of white cell types microscopically can identify specific types of infection.
5. A deficiency in the platelet count can lead to dangerous internal bleeding. Normal laboratory values for the CBC are summarized in Table 10-5.

Urinalysis

Urinalysis is a common test that can yield a large quantity of information.  In most cases a sample of urine in a small dry container is all that is needed. If the urine will not be analyzed within 1 hour the sample should be refrigerated. The following are among the concerns addressed in a routine urinalysis

1. The pH refers to how acid or alkaline the urine is. It may be acidic in cases of diabetes or dehydration. Alkaline urine is present in urinary tract infections and kidney disease.
2. Presence of glucose in the urine may indicate diabetes.
3. Presence of ketones, a by-product of fat metabolism, may also indicate diabetes.
4. Presence of nitrate indicates infection.
5. If bacteria are present, a urine culture may be necessary to determine the specific bacteria causing an infection.
6. The presence of certain drugs.

Roentgenograms (X-rays)

• An x-ray examination is designed to rule out serious disease such as an infection or neoplasm.

• It assists the physician in determining fractures and dislocations or any bone abnormality that may be present.

Arthrography

• Arthrography is the visual study of a joint through x-ray study after injection of an opaque dye, air, or a combination of air and opaque dye into the joint space.

• This procedure can show the disruption of soft tissue and loose bodies in the joint.

Arthroscopy

• The fiber optic arthroscope is widely used by orthopedists in surgery.

• It is considered more accurate than the arthrogram but is more invasive, requiring anesthesia and a small incision for the introduction of the arthroscope into the joint space.
• While the arthroscope is in the joint, the surgeon can perform surgical procedures such as removing loose bodies and, in some cases, suturing torn tissues.

Myelography

• During myelography an opaque dye is introduced into the spinal canal (epidural space) through a lumbar puncture. While the patient is tilted, the dye is allowed to flow to different levels of the spinal cord.
• Using this contrast medium, physicians can detect conditions such as tumors, nerve root compression, and disk disease, as well as other diseases within the spinal cord.

Computed Tomography

Computed tomography penetrates the body with a thin fan-shaped x-ray beam, producing a cross-sectional view of tissues. Unlike x-ray studies, this viewing can be performed from many angles. As the machine scans, a computer compares the many views; these electrical signals are then processed by a computer into a visual image (Figure 10-7, B).

Bone Scanning

• A bone scan involves the introduction of a radioactive tracer such as technetium-99 intravenously.

• By imaging the entire skeleton or part of a skeleton, bony lesions in which there is some inflammation, such as stress fractures, can be detected (Figure 10-7, C).

Magnetic Resonance Imaging

• Magnetic resonance imaging surrounds the body with powerful electromagnets, creating a field as much as 600,000 times as strong as that of the earth.
• The magnetic current focuses on hydrogen atoms in water molecules and aligns them; when the current is shut off, the atoms continue to spin, emitting an energy that is detected by the computer.
• The hydrogen atoms in different tissue spin at different rates, thus producing different images.
• In many ways MRI provides clearer images than CT scanning. Despite its expense it is currently the test of choice by physicians for detecting soft-tissue lesions (Figure 10-7, D). .

Sonography

• Sonography is the use of sound waves to view the interior of the body.

• It uses a piezoelectric crystal that converts electrical pulses into vibrations that can penetrate the body.

• The sound waves reflect back to the crystal, which reconverts them into electrical signals and forms a picture.

Electromyography

Various muscular conditions can be detected by using electromyography. Electromyography refers to a muscular contraction that follows an electrical stimulation.

• The procedure consists of inserting a thin electrode needle into the muscle to be studied.
• Motor unit potentials can be observed on an oscilloscope screen or from a graphic recording called an electromyogram.
• Denervated muscles, as well as nerve root compression or other nerve compression sites, can be detected by electromyography.

Nerve Conduction Velocity

Determining the conduction velocity of a nerve may provide key information to the physician about a number of neuromuscular conditions.

• After a stimulus is applied to a peripheral nerve, the speed with which a muscle action occurs is measured.

•  Delays in conduction might indicate nerve compression or other muscular or nerve disease.

Synovial Fluid Analysis

On occasion, the physician will opt to make an analysis of an athlete's synovial fluid.

• The purpose of this test is to detect whether an infection is present.
• The test also confirms the diagnosis of gout and differentiates non-inflammatory joint disease such as degenerative arthritis from inflammatory conditions such as rheumatoid arthritis.