Bone Biopsy

 

Definition

Bone biopsy is the removal of a piece of bone for laboratory examination and analysis.

Purpose

Bone biopsy is used to distinguish between malignant tumors and benign bone disease such as osteoporosis and osteomyelitis. This test may be ordered to determine why a patient's bones ache or feel sore, or when a mass or deformity is found on an x ray, CT scan, bone scan, or other diagnostic imaging procedure.

Precautions

The patient's doctor and the surgeon who performs the bone biopsy must be told about any prescription and over-the-counter medications the patient is taking, and about allergies or reactions the patient has had to anesthetics or pain relievers. Special care must be taken with patients who have experienced bleeding problems.

Description

A bone biopsy involves using a special drill or other surgical instruments to remove bone from the patient's body. The procedure usually lasts about 30 minutes and may be performed in the hospital, a doctor's office, or a surgical center.

A drill biopsy is generally used to obtain a small specimen. After the skin covering the bone has been cleansed with an antiseptic and shaved, the patient is given a local anesthetic. The doctor will not begin the procedure until the anesthetic has numbed the area from which the bone is to be removed, but the patient may feel pressure or mild pain when the needle pierces the bone. The surgeon turns the needle in a half-circle to extract a sample from the core, or innermost part, of the bone. The sample is drawn into the hollow stem of the biopsy needle. The sample is then sent to a laboratory, where it is examined under a microscope.

An open biopsy is used when a larger specimen is needed. After the area covering the bone has been cleansed with an antiseptic and shaved, the patient is given a general anesthetic. After the anesthetic takes effect and the patient is unconscious, the surgeon makes an incision and removes a bone specimen. The specimen is sent to the laboratory for immediate analysis. Results of that analysis may indicate that additional surgery should be performed right away.

Preparation

No special preparation is needed for a drill biopsy, but a patient must fast for at least 12 hours before an open biopsy.

Aftercare

Pain medication will be prescribed after a biopsy, and vital signs will be monitored until they return to normal. Most patients can go home in about an hour. If bone was removed from the spine, the patient may stay in the hospital overnight. The surgical site must be kept clean and dry for 48 hours, and the patient's doctor should be notified if any of these symptoms appear:

·         fever

·         headache

·         pain on movement

·         inflammation or pus near the biopsy site

·         bleeding through the bandage at the biopsy site

Risks

Risks include bone fracture, injury to nearby tissue, and infection. Bleeding is a rare complication. Factors that increase risk include:

·         stress

·         obesity

·         poor nutrition

·         chronic illness

·         some medications

·         mind-altering drugs

Normal results

Normal bone is made up of collagen fibers and bone tissue.

Abnormal results

Bone biopsy can reveal the presence of benign disease, infection, or malignant tumors that have spread to the bone from other parts of the body.

Results of this test are considered reliable, but may be affected by:

·         failure to fast before open biopsy

·         failure to obtain an adequate specimen

·         delayed microscopic examination or laboratory analysis

Resources

ORGANIZATIONS

Cancer Group Institute. 1814 N.E. Miami Gardens Drive, North Miami Beach, FL 33179. (305) 651-5070. 〈http://www.cancergroup.com/em19.html〉.

National Institute of Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse. National Institutes of Health. 1 AMS Circle, Bethesda, MD 20892-3695. (301) 495-3675.

KEY TERMS Biopsy— Removal and examination of tissue to determine if cancer is present. Osteomyelitis— An infection of the bone that is usually treated with antibiotics but sometimes requires surgery. Osteoporosis— Thinning and loss of bone tissue.

 

 Bone density test

Definition

A bone density test, also called a bone mineral density (BMD) test, is a measurement of bone mass (thickness and sturdiness), usually taken at the lumbar (lower) spine and hip, the areas most likely to fracture due to low bone mass. Tests range from x-ray scans of the wrist or heel performed with small, portable machines—often in stores or pharmacies—to more accurate and sophisticated tests performed with larger machines in hospitals, radiology centers, or some doctor's offices.

Purpose

The purpose of a bone density test is to evaluate an individual's risk for developing osteoporosis—and, consequently, to assess the likelihood of fracture resulting from the loss of BMD. The National Osteoporosis Foundation lists the major risk factors for developing osteoporosis. These include:

·         Age. People over 50 are at increased risk because bones become weaker and less dense with age.

·         Gender. Although men get osteoporosis, women are more likely to develop the disease. Women have less bone tissue than men and lose bone more rapidly due to estrogen loss during and after menopause.

·         Family and personal history of fractures. Heredity and sustaining a prior fracture as an adult may increase a person's fracture risk.

·         Race. Although Caucasian and Asian women are more likely to develop osteoporosis, all postmenopausal women are at risk for developing the disease.

·         Bone structure and body weight. Small-boned and thin women (less than 127 pounds) are at increased risk.

·         Menopause and menstrual history. Menopause, whether natural or surgical, increases the risk of developing osteoporosis. Also, women who stop menstruating due to disorders like anorexia or bulimia, or because of excessive physical exercise, may also lose bone tissue and develop osteoporosis.

·         Lifestyle. Smoking, drinking excessively, consuming an inadequate amount of calcium, or getting little or no weight-bearing exercise, increases the risk of osteoporosis.

·         Medications and chronic diseases. Some medications used to treat disorders such as rheumatoid arthritis, endocrine disorders (such as thyroid disease or type 1 diabetes), seizure disorders, and gastrointestinal diseases may experience side effects that lead to bone damage and osteoporosis.

Thus, bone density tests are most often administered to:

·         Women 65 and older without risk factors and younger postmenopausal women with risk factors.

·         Those with certain medical conditions or a family history of osteoporosis.

·         Those taking certain types of medications that affect bone density.

·         Those who have had a fracture or whose prior x rays have revealed a bone-density problem.

If low bone mass is detected on a bone density test, the test is usually repeated two to three years later to monitor a person's response to treatment and thereafter at the physician's discretion.

Precautions

Because the most widely used bone-density tests emit low-dose radiation, pregnant women should discuss any health risks with their healthcare provider before testing.

Description

Bone in humans and other mammals is generally classified into two types. Cortical bone, also known as compact bone, forms the dense, outer surface around the bone at the end of joints and the vertebrae. Trabecular bone, also known as cancellous or spongy bone, is found deep inside the outer shell.

Although there are several types of imaging studies that evaluate bone density, the dual-energy x-ray absorptiometry (DEXA) is considered the “gold standard”—that is, the most accurate—in measuring bone mineral density. Machines called densitometers use two x rays having different energy levels to measure the density of calcium and other minerals in the bone. The denser the bones, the less of the x rays are able to pass through them. These machines are able to detect cortical bone loss of as little as 2% per year and can produce better images than other types of equipment.

The test selected depends on the equipment available, the area of the body to be tested, and the cost. Tests performed on portable equipment are less costly but are also less accurate and are usually used for preliminary screening.

The major types of BMD tests are listed below:

·         In the DEXA, which uses less radiation than a chest x ray, a person lies on his or her back on a padded table, then on their side for the 10- to 20-minute procedure. The machine takes pictures of the lumbar spine and hip.

·         Peripheral DEXA (P-DEXA) tests, often performed in doctors' offices, measure bone density in the legs and arms only. These are usually performed sitting down.

·         Single-photon absorptiometry (SPA) uses a radioactive substance to measure BMD in the wrist or heel and takes about 10 to 20 minutes.

·         Dual-photon absorptiometry (DPA), which measures BMD in the spine, hip, and total body, takes about 20 to 40 minutes, and the cost is higher than SPA.

·         Quantitative computed tomography (QCT) is a type of CT scan. This test emits more radiation than the DEXA and measures trabecular bone—rather than cortical bone like the DEXA—and only measures BMD in the spine. Although the test, which requires lying down on a padded table, takes about 10 to 15 minutes, it is the most costly BMD test and is not as accurate as the DEXA tests or DPA.

·         Peripheral QCT measures BMD in the wrist only.

·         Ultrasound testing that uses sound waves, measures BMD in the heel.

Preparation

There are a few simple things to keep in mind when preparing for a bone density test.

·         Wear comfortable clothing that contains no metal buttons, buckles, or zippers, and remove metal jewelry so that changing into a gown before the test will be unnecessary.

·         Bring a list of all current prescription, over-the-counter drugs, and vitamins and supplements and include information on dosages, frequency, and duration of use.

·         Do not take any medication or supplements containing calcium—including antacids such as Tums or Rolaids, calcium supplements, multivitamins, or medication for osteoporosis for 24 hours before the test.

·         Do not schedule a bone-density test within two weeks of a nuclear medicine procedure (like a bone scan) or within one week of any test that uses a contrast medium (like a barium enema or an angiogram).

QUESTIONS TO ASK YOUR DOCTOR

·         Why do I need this test?

·         How long will the test take?

·         Will any medications that I am taking interfere with the test?

·         Can I take calcium supplements or vitamins before the test?

·         Can I eat and drink normally before the test?

·         How much radiation will I be exposed to?

·         How do I get the results of my bone density test?

·         How often will I need to repeat this test?

Aftercare

There is no aftercare required after a bone density test.

Complications

There are usually no complications that result from bone density tests.

Results

The results of a DEXA exam are reported in two numbers: an age-matched number (called the Z score) and young-normal number (called the T score). The Z score compares an individual's results to those of his or her age group. Z scores are used in younger men and in women who are premenopausal with other risk factors.

The T score, which is used in postmenopausal women and in elderly men, compares the results to the “norm,” that is, a healthy 30-year-old of the same sex and race—the age at which peak bone density is achieved. The DEXA results indicate if the bones tested are more (+), less (−), or the same density as a healthy 30-year old. Ranges for interpreting T scores are listed below. The results of BMD tests are noted as “standard deviation” (distance or spread) from the norm:

·         Optimal = BMD above +1.0 standard deviation (SD)

·         Borderline = between a +1.0 SD and a −1.0 SD

·         Low, or osteopenia = between a −1.0SD and a −2.5SD

·         Osteoporosis = below a −2.5 SD

KEY TERMS Bone scan —An imaging study (such as a magnetic resonance imaging [(MRI] or computed tomography [CT]) used to determine bone abnormalities rather than bone mineral density. Contrast medium (or agent) —A substance usually injected, swallowed, or used as an enema, before an x-ray image is taken to increase the visual contrast between an internal area of the body under study from the surrounding tissue. Menopause —The cessation of menstruation. Nuclear medicine —A subspecialty of radiology that uses small amounts of radioactive material attached to drugs for the purpose of diagnosing or treating certain medical conditions. Osteopenia —Low bone mass or density. Osteoporosis —Bone density measured as −2.5standard deviations below the norm of a healthy 30 year old. If left untreated, osteoporosis can lead to loss of height, fractured or broken bones, a stooped or hunchback position, and severe pain. The National Osteoporosis Foundation reports that osteoporosis affects 10 million Americans, and most of those affected are women.

 

Caregiver concerns

A physician orders the procedure (often a person's family doctor, orthopedist—if a bone has been fractured or broken—or endocrinologist). The test is often done on an outpatient basis in a radiology center, hospital, or sometimes in a doctor's office. The test results are read and interpreted by a radiologist, then forwarded to the physician who ordered the test.

If test results show osteoporosis, the doctor may prescribe medications and will discuss calcium and other vitamin and mineral supplementation as well as lifestyle issues such as level of activity, other medications, smoking and alcohol intake, and weight. If osteopenia (low bone mass) is diagnosed, the physician may also discuss pharmacologic treatment and lifestyle changes to avoid disease progression. Osteopenia is considered a serious risk factor for developing osteoporosis and is common in people over 50. In addition, fractures may occur in people with osteopenia as well as those with osteoporosis, so close follow-up with a physician after diagnosis is important.

Resources

BOOKS

Bonnick, Sydney. The Osteoporosis Handbook: Every Woman's Guide to Prevention and Treatment.

Winters-Stone, Kerri. Action Plan for Osteoporosis (Action Plan for Health). Champaign, Ill.: Human Kinetics Publishers, 2005.

PERIODICALS

Crutchfield, Diane B. “Testing and Treating Osteoporosis.” Diane B. Crutchfield. Geriatric Times(March 1, 2004):8.

Olson, Ann F. “Osteoporosis detection: is BMD testing the future?” The Nurse Practitioner (June 2007):3.

Schuit S.C., van der Klift M., Weel A.E., et al. “Fracture incidence and association with bone mineraldensity in men and women: the Rotterdam Study.” Bone 34 (2004):195–202.

OTHER

Veracity, Dani. “Bone density sharply enhanced by weight training, even in the elderly.”Naturalnews.comhttp://www.naturalnews.com/z010528.html (August 6, 2005).

ORGANIZATIONS

National Osteoporosis Foundation, 1232 22nd Street N.W., Washington, D.C., 20037-1202, (202) 223-2226, (800) 231-4222, http://www.nof.org.

NIH Osteoporosis and Related Bone Diseases, National Resource Center, 2 AMS Circle, Bethesda, MD, 20892-3676, (202) 223-0344, (800) 624-BONE, (202) 466-4315, NIAMSBoneInfo@mail.nih.gov,http://www.niams.nih.gov/Health_Info/bone/default.asp.

Genevieve Slomski Ph.D.