What are bone disorders?

Causes and Symptoms

Bones are usually studied in combination with their surrounding structures because many of the disorders to which bones can be subjected also involve muscular, cartilaginous, and other tissues to which they are connected. Hence, a common term for this medical category is “musculoskeletal and connective tissue disorders.”

There are 206 bones in the human body that serve three functions. Some form protective housing for body organs and structures; these include the skull, which encloses the brain, and the rib cage, which encloses the heart and lungs. Some support the body’s posture and weight, including the spine and the bones of the hips and legs. The third function is motion: Most of the bones in the body are involved in movement. These bones include those of the hands, wrists, arms, hips, legs, ankles, and feet.

Bone consists of three sections: an outer layer called the periosteum; the hard bony tissue itself, consisting of mineral compounds that form rigid skeletal structures; and the interior, a spongy mass of cancellous (chambered) tissue, where blood marrow is manufactured and some fat cells are stored. Bone is living tissue. It is a depository for calcium, phosphate, and other minerals that are vital to many body processes. Calcium and phosphate in particular are constantly being deposited in and withdrawn from bone tissue to be used throughout the body.

Bones can be attacked in many ways: They can be broken or dislocated; the processes by which they form, grow, and maintain themselves can be compromised; they can be attacked by pathogens; they can be subject to a series of degenerative diseases that impede function and even destroy bone tissue; and they can become cancerous.

Dislocations take place when the bones of a joint are forced out of alignment. They may occur in the elbows of young children whose arms are forcibly pulled. Fractures are more common. They arise from sports activities, accidents, falls, or hundreds of possible causes, including various disease conditions.

Osteoporosis
and other diseases can destroy bone structure to the point where fractures occur with minimal stress. This condition is common in elderly women. The supply of calcium within the bones is gradually drained, leaving the bones porous and brittle. Hip fractures occur often in these people. Also, compression fractures occur in the vertebrae (the bones of the spine), causing the spine to bend forward. A hump develops, and the patient may not be able to raise his or her head.

Osteomalacia is similar to osteoporosis. Called rickets
in children, this disease is caused by a deficiency in vitamin D, which impairs the absorption of calcium by the bone. In this condition, bones become soft and pliable. In children, leg bones do not develop correctly and may become bowed. The chest and stomach may protrude.

Bone infection is called
osteomyelitis; it occurs most often in children. Infection can be introduced to the bone by fracture or other exposure, or it can be carried to the bone in the blood.

By far the most prevalent long-term bone disorders are those in the general class of diseases called
arthritis.
Osteoarthritis, a common form, is sometimes called “wear-and-tear arthritis” because it usually surfaces in older people after years of work have constantly challenged certain joints. It occurs often in contact sports such as football, where its progression can be accelerated by years of rough-and-tumble activity. Joints are cushioned by pads of cartilage. Eventually, this cartilage can wear down and become rough. It cannot protect the bones of the joint, and little nodes form at the ends of the bones. Bones of the neck and back are often affected, as are the hips and knees.

Osteoarthritis is painful and debilitating, but it is rarely crippling. More painful and far more serious is rheumatoid arthritis, a progressive disease. It often starts with inflammation in the joints of the hands or feet and is usually bilateral, for example affecting both hands, both feet, or both knees. While rheumatoid arthritis may start with relatively mild inflammation, it can progress to severe deformity and even total destruction of the joint. Fingers and toes can become grossly twisted; the joint can become completely fused and immobile.

There are other relatively common forms of arthritis. People with the skin condition psoriasis can develop psoriatic arthritis. Reiter’s syndrome is a form of arthritis that can be transmitted through sexual contact. Ankylosing spondylitis is a form of arthritis that can affect any of the joints in the torso, such as the shoulders and hips, but is most often found in the neck and spine. Patients with inflammatory bowel disease (IBD) may also develop a concomitant arthritis in the joints of the hands or feet.

The bone condition called
gout can affect many joints, but it appears most often in the big toe. The body produces a substance called uric acid. If, for any reason, too much is produced, or if it is not properly eliminated, uric acid crystals can form around joints and trigger inflammation. Gout is extremely painful, and an attack may last for weeks.

The spine is subject to a wide range of disorders. One of the most common is the prolapsed (slipped) disk. The individual vertebrae of the spine are separated and cushioned by pads of cartilage called disks. For various reasons, a disk can bulge out and impinge on the nerves of the spinal column. The result can be severe pain, numbness, and loss of movement. In some individuals, the spine fails to grow correctly or becomes misaligned, or curved. This condition is called
scoliosis. The curvature of the spine can cause the ribs on one side of the body to separate as those on the other side are pushed together. Over time, this separation can cause severe heart and lung problems.

Many cases of joint pain are attributable to inflammation of the tissues surrounding the bony structures. An example is
bursitis, in which the bursa, a saclike membrane enclosing many joints, becomes inflamed. Repetitive activities, such as throwing a baseball, hitting a tennis ball, or scrubbing the floor on one’s knees, can irritate the membrane and cause inflammation.

Bone
cancers or tumors can be benign or malignant. Cancer rarely begins in the bone; it usually spreads there from a tumorous site elsewhere in the body. Of the cancers that arise directly within bone tissue, the most common are multiple myeloma, in which cancer originates in plasma (white) cells and affects the body’s ability to produce proteins and fight infection, and osteosarcoma, in which the cancerous tumor originates on the bone itself.

Treatment and Therapy

In treating a fractured bone, the most important thing is to realign the segments and keep them immobile until they can fuse. Most often, the physician will X-ray the fracture, set the bones correctly, and immobilize the limb in a cast. If injury to the spinal column is suspected, the physician may also order computed tomography (CT) scanning. Surgery is sometimes required in order to set the bones, and the surgeon may join the bone segments together with pins, plates, or screws. In some cases, it is possible to cement bone fragments together with a special glue. Broken arms, legs, fingers, and toes can usually be easily immobilized with appropriate casts or splints. In cases of accidents, falls, or other trauma, if there is any suspicion of injury to the spinal column, it is critical not to move the patient. Movement can worsen the injury and even cause permanent paralysis.

Dislocations, like fractures, should be X-rayed. If the spinal column appears to be involved, CT scanning may be required. The misaligned bones are put back in their proper positions, and the joint is immobilized, often with a splint.

Osteoporosis requires both preventive and therapeutic care. If the physician recognizes that an individual, usually a postmenopausal woman, is at high risk for osteoporosis, supplementary calcium will be prescribed and, in some patients, estrogen replacement therapy. When osteoporosis has begun, supplementary calcium, vitamin D, and hormone therapy may check the progress of the disease.

A patient may suffer from acute back pain because of crushed vertebrae in the spine. Pain relievers such as aspirin may be required, and the patient may need orthopedic support. Gentle exercise is recommended to strengthen back muscles.

In
osteomalacia, vitamin D, phosphorus, and calcium supplements are the mainstays of therapy. In osteomyelitis, antibiotics will usually eradicate the infection, but in some cases, surgery is required in order to remove infected tissue. In other cases, amputation is the only option.

The first line of therapy for
osteoarthritis and
rheumatoid arthritis is the relief of pain and inflammation. The physician may recommend rest and immobilization of the joint; heating pads and hot baths may give some relief. Exercise can maintain motility in the joints and help the patient avoid stiffness. Most patients are given over-the-counter pain relievers such as aspirin, ibuprofen, or acetaminophen. In a large number of patients, however, these drugs are either not adequate to manage the pain or, as in the case of aspirin, ibuprofen, and others, may be irritating to the gastrointestinal tract. Gastrointestinal disturbances are also common with the drugs proscribed for arthritis. Gastric and duodenal ulcers are often reported and are sometimes so severe that the patient requires surgery. In a small but significant number of patients who develop such ulcers, the outcome is fatal.

Because rheumatoid arthritis is a crippling disease that worsens over the years, the physician has an additional goal: to prevent the progress of the disease, avoiding bone deterioration and degeneration. In these patients, a group of drugs called disease-modifying antirheumatic drugs (DMARDs) may be used in conjunction with pain relievers. Corticosteroids are also used to alleviate acute episodes of pain and inflammation. They can be very effective, but they cannot be used over the long term and may have severe side effects.

Surgery is often required for arthritis patients. Synovectomy is a procedure in which part or all of the synovial membrane that surrounds the diseased joint is removed. It gives temporary relief in inflammation and may help preserve joint function. When a joint has deteriorated severely, the physician may recommend joint replacement therapy. In this procedure, the degenerated bone and joint structures are surgically removed and replaced with an orthopedic device of metal and/or plastic. This procedure is most effective in hip replacement, although it is also used in the knee.

Relief of pain is the main goal of therapy in other arthritic conditions such as psoriatic arthritis and Reiter’s syndrome. In ankylosing spondylitis
, exercise is also an important facet of treatment, to help avoid stiffening of the spine.

Gout has a tendency to recur. Therefore there are medications for acute episodes, such as pain relievers, and others to control levels of uric acid and prevent attacks.

Benign bone tumors sometimes require surgery. Malignant tumors can be treated surgically and may also require radiation and chemotherapy.

Perspective and Prospects

Radical new therapies for bone disorders are evolving, with exciting possibilities: bone regeneration, bone cements, and glues to knit fractures and replace bone destroyed by disease.

Osteoarthritis, rheumatoid arthritis, and other forms of arthritis continue to afflict vast populations around the world. Current medical treatment is significantly flawed by the incidence of side effects, especially gastrointestinal effects, from the medications used. The search for safer medications is ongoing, as is the search for treatment modalities that will halt the degenerative processes of rheumatoid arthritis.

Orthopedic implants are now quite successful in the hip, sometimes successful in the knee, but otherwise not universally useful in elbows, fingers, toes, and other joints that can be destroyed by disease. This is an area that is being addressed.

Operating techniques and instrumentation improve constantly. Many procedures are now done with the aid of arthroscopic instruments. Rather than an extensive incision to reveal the joint and surrounding tissues, the surgeon works through a tiny hole, through which he or she can inspect the inflamed joint and even perform minor surgery.

Operations on prolapsed spinal disks once entailed long incisions and laborious, careful removal of disk tissue. Fusion of the involved vertebrae was often necessary, limiting spinal movement. Healing time could be extensive. Today, simpler, less painful procedures may be as successful and far less traumatic. In one procedure, an enzyme is injected into the prolapsed disk, causing it to shrink and reducing pressure on nearby nerves. In another procedure, disk material is removed with a needle inserted through the skin into the disk.

Overall, progress in the treatment of bone disorders has been significant: Many people who would have lived with deformities and disability are being helped with modern medical and surgical techniques, medications, and instrumentation.

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