Bone is living connective tissue that constantly changes. The bone marrow, where blood cells are produced, is surrounded by cancellous (spongy) bone that fills the medullary canal. Cortical bone, which is made up of the protein collagen infused with minerals, encircles the medullary canal and contains the cells that maintain bone tissue. The thin outer covering of bone is a membrane called the periosteum, which contains nerves and blood vessels and is essential for the formation and growth of new bone. Bone tissue produces its own cartilage to absorb shock and provide a tough, elastic surface between adjoining bones.

Osteoporosis
Osteoporosis is a disease in which the bones become thin, porous, weak, and more susceptible to fractures. Although osteoporosis is generally regarded as a women’s health concern, the disease also can develop in men. Because men have larger, denser skeletons, they usually experience bone loss later in life than women. However, older men are at increased risk for hip fracture and other joint fractures as a result of osteoporosis. Men and women lose bone mass at an increased rate after age 65, and calcium absorption decreases with age in both sexes. About a third of men over age 75 have been diagnosed with osteoporosis, and one of every eight men over age 50 will experience a bone fracture as a result of osteoporosis. Therefore all men need to take steps to prevent osteoporosis.

Bone mass increases throughout childhood and young adulthood, reaching its peak at about age 20. After age 35, bone tissue breaks down faster than new bone is formed. Bone becomes more porous and structurally weaker. Dense, cortical bone tissue is replaced by spongy, cancellous bone. In many cases, osteoporosis is detected only after a fracture occurs. Men who are older, small-framed, or white or Asian are at increased risk for osteoporosis. The following factors can increase your risk of developing osteoporosis:

• long-term use of certain medications (including corticosteroids, heparin, anticonvulsants, aluminum-containing antacids, and some cancer drugs)
• low testosterone level
• excess thyroid hormone
• smoking
• chronic or heavy alcohol consumption
• high intake of caffeine, protein, or sodium (salt)
• insufficient intake of calcium
• vitamin D deficiency
• sedentary lifestyle
• family history of osteoporosis
• disorders that affect absorption of calcium, such as lactose intolerance, peptic ulcers, or celiac disease

To detect bone loss, your doctor will perform urine and blood tests. He or she also will recommend that you undergo a bone density test, which is an imaging technique used to assess bone density and structure. In some cases a bone biopsy (removal of a small piece of bone tissue for microscopic examination) may be required to rule out other possible bone disorders, such as osteomalacia.

You can take steps to reduce your risk of developing osteoporosis. Lifestyle changes that focus on your risk factors will help prevent osteoporosis. If some bone loss has already occurred, lifestyle changes and treatment with medications such as calcitonin or alendronate can reduce the risk of fractures.

Here are some steps you can take to help prevent osteoporosis:

• Take in plenty of calcium every day (search “How Much Calcium Do I Need?” Post).
• Get an adequate supply of vitamin D. Fat-free milk fortified with vitamin D is an excellent source of this essential nutrient.
• Exercise regularly (especially weight-bearing exercise such as brisk walking, jogging, and stair climbing).
• Stop smoking.
• Drink alcohol only in moderation.
• Cut back on caffeine.
• Limit your intake of sodium.

Bone Cancer
Primary bone cancer—that is, cancer that begins in the bone versus cancer that spreads to the bone from another part of the body—is rare but occurs most frequently in children and young men. Osteosarcoma is the most common form of primary bone cancer. Osteosarcoma and Ewing’s sarcoma (another type of primary bone cancer) usually occur between ages 10 and 25. Other primary bone cancers include chondrosarcoma, fibrosarcoma, malignant giant cell tumor, and chordoma. These cancers occur mainly in adults over age 30.

Symptoms of bone cancer tend to develop slowly. Pain is the most frequent symptom, although in most cases, a firm lump or swelling on the bone can be felt through the skin. Bone cancer is often detected when a bone breaks without obvious cause or fails to repair itself after a fracture.

Tests for bone cancer include blood tests, bone scans, and X rays. If a tumor is detected, additional examinations will be performed to determine whether it is benign (noncancerous) or malignant (cancerous). These procedures include radionuclide scanning (a radioactive substance is injected into the bloodstream to produce images that show where the cancer is growing), computed tomography (CT) scanning or magnetic resonance imaging, and angiography (X rays of the blood vessels taken after a special dye is injected into the bloodstream). A bone biopsy (removal of a small piece of bone tissue for microscopic examination) is performed to identify the type of tumor and to help plan a course of treatment.

Bone cancer is treated with surgery, chemotherapy (treatment with powerful anticancer drugs), and radiation therapy. Most bone tumors are removed surgically, even if they are benign. In many cases, primary bone cancer is successfully treated with a bone graft (replacement of the diseased section of the bone with healthy human bone from a bone bank) and chemotherapy. In some cases, if a tumor is large or has begun to spread throughout the bone, amputation may be performed, followed by chemotherapy. Radiation therapy often is used if the cancer has spread to other tissues.

Fractures

A fracture—a break in bone or cartilage—usually results from injury or an underlying bone disease, such as osteoporosis. Fractures are categorized as either simple (closed), in which the broken bone does not break the skin, or compound (open), in which the broken bone punctures the skin. When the two ends of a fractured bone have not separated, it is called a nondisplaced fracture. When the two ends have separated, it is a displaced fracture. Within the categories of simple and compound are other types of fractures, including transverse fracture, spiral fracture, comminuted fracture, and greenstick fracture. The type of fracture determines the choice of treatment.

In general, fractured bones are painful and limit use of the injured limb or body part. Often the injured area appears misshapen. Bruising may occur, and the limb below the fracture may tingle or become numb, cold, or pale. However, sometimes it is possible to walk on a fractured leg or continue to use a fractured arm without realizing it is broken.

After any serious injury, you should seek medical attention to rule out fractures or detect them before they become worse. If you think you may have a fracture, take immediate steps to immobilize the injured bone to prevent further damage to the bone and surrounding blood vessels and nerves, and elevate the affected body part to reduce swelling. With an open fracture, be sure to place a clean cloth or a bandage gently over the wound to reduce the risk of infection.

Fractured bones must first be restored to their normal position and alignment. This process is referred to as “reduction.” A cast or a splint may be sufficient to hold a broken bone in place for healing. If you fracture a large bone or experience a complicated break, you may need surgery. Sometimes bones must be screwed together or rejoined using metal plates or rods. Pins or screws also may be inserted to hold an external frame in place that immobilizes the bone while it heals. You will need to rest the affected limb and avoid overuse until the bone heals.

A stress fracture refers to a condition in which a tiny crack (or cracks) occurs in a bone that has been exposed to repeated injury or overuse. Your lower leg and foot are especially prone to stress fractures. Early symptoms include sharp pain and swelling in the affected area. If the cracks are too small to see on an X ray, the doctor may perform a computed tomography (CT) scan to determine the location and extent of the fracture. Treatment consists of resting the affected area long enough to allow healing to take place.