KEY TERMS

articulation: a joint between two bones of the skeleton; also called an “arthrosis”

bursa: a connective tissue sac filled with fluid that reduces friction at joints

collagen: a fibrous protein found in skin, bone, ligaments, tendons, and cartilage

inflammation: the reaction of tissue to injury, with its corresponding redness, heat, swelling, and pain

ligament: a structure of tough connective tissue that attaches one bone to another bone

synovial: referring to the lubricating fluid in the joints or the membrane surrounding the joints

tendon: a structure of tough connective tissue that attaches a muscle to a bone

SCIENCE AND PROFESSION

Orthopedics is the branch of medicine primarily concerned with the movement of the human body and its parts and disorders that affect its function. Such activities as maintaining posture, walking, doing manual work, and exercising involve a complex relationship between the nervous, muscular, and skeletal systems. While orthopedists must be familiar with the nervous system, they focus primarily on preventing and treating disorders of the skeleton and muscles. They also have expertise in properly developing these systems in childhood and the changes that occur because of aging.

The brain sends signals to the muscles when a person decides to move. The muscles contract by pulling on the bones to which they are attached, causing that body part to move. The anchor point for the muscle is the origin, and the attachment point to the bone being moved is the insertion. Muscles work in groups to perform a movement. The principal muscle involved is the prime mover or agonist. The muscles that help the prime mover are called “synergists.” When a prime mover contracts, the muscle on the opposite side of the bone, termed the antagonist, must relax. An illustration of this would be the muscle and bone interaction involved in arm flexing. The biceps muscle, anchored to the bone in the shoulder, contracts, pulling on the bone in the lower arm to which it is attached by a tendon. Its synergist, the brachialis, also contracts. On the back of the upper arm, its antagonist, the triceps muscle, relaxes to allow the arm to bend. When the arm is extended, the triceps becomes the prime mover for that action, and the biceps is the antagonist.

The skeletal system is made of bone and cartilage. Bone cells, called “osteocytes,” take in nutrients from the blood and constantly renew the bony matrix. The chemical composition of bone includes calcium and phosphorus salts, which provide stiffness. The fibrous protein collagen gives bones some flexibility. Cartilage cells, called “chondrocytes,” manufacture cartilage, a mass of collagen and elastic fibers embedded in a gelatin-like substance. The nature of this structure gives cartilage more flexibility than bone, making it an ideal substitute for bone in certain areas. The ribs, for example, are attached by cartilage to the sternum or breastbone. This arrangement allows for the expansion of the chest during breathing.

Tendons, ligaments, and bursas are also part of the skeletal and muscular systems. Tendons attach muscles to bones. They are made of fibrous tissue so strong that, under stress, the muscle will tear or the bone will break before the tendon is damaged. Ligaments, also made of fibrous tissue, attach bones to other bones and provide stability at the joints. Bursas are fluid-filled connective tissue sacs between muscle and bone, tendon and bone, or other areas around joints. They reduce the damage to the softer tissue as it rubs against the bone with each movement. Because of their close interdependence, the skeleton, attached muscles, and other associated structures are often referred to as the musculoskeletal system.

The health of the musculoskeletal system during childhood is of primary importance to an individual in attaining full growth and physical function as an adult. A cartilage skeleton is formed in the early developmental stages of the embryo and fetus. This structure is replaced with bone in an ossification process that continues for years after birth. Good nutrition is vital to this process. In particular, the body requires adequate amounts of protein, calcium, and vitamin D. The ends of a long bone are separated from the shaft of the bone by cartilage until the child reaches full growth. Care should be taken when participating in sports since damage to these areas could affect the growth of that limb. Hormonal production influences the development of the skeleton. Adequate amounts of growth hormone are needed to ensure proper growth. At puberty, sex hormones, especially testosterone, stimulate the adult skeleton’s final growth spurts and completion.

A woman of childbearing age must eat a healthy diet if she is to nourish a fetus that, in turn, is developing its skeleton.

Young adults have attained full growth, but the skeleton must continually renew itself to remain strong and maintain its ability to repair an injury. Both men and women must take care to exercise since the stress of activity builds muscle and sends messages to the bone to maintain its strength. Calcium and vitamin D intake must continue, or the bones may begin to dissolve some of their calcium matrices. Automobile accidents, work injuries, and sports injuries are more likely to occur at this stage of life.

As adults age, metabolic and other cellular processes become less efficient. Care must be taken to maintain functions and prevent further losses. At one time, disorders such as osteoarthritis and osteoporosis were considered an inevitable part of the aging process. While heredity is certainly a risk factor in these conditions, substantial evidence has been accumulated showing that some degenerative processes can be traced to lifestyle and diet. Osteoarthritis is the type of joint tissue degeneration associated with wear and tear on the joints. A person who is obese puts excessive pressure on the skeletal system, especially the hips, knees, and ankles. This pressure increases the damage to the joints. A person who fails to exercise begins to lose flexibility in the joints, and muscles become weaker.

Osteoporosis occurs as bones become porous and brittle. As osteocytes age, they become less efficient at calcium absorption and renewal of the bony matrix. At a time in life when more calcium is needed to make up for this inefficiency, most people consume fewer dairy products, either because of lactose intolerance or because of the ingestion of other beverages. Older women are at particular risk because their bones are lighter than men’s. After menopause, women lose some of the protection that estrogen provides by stimulating the absorption of calcium and thus bone renewal. Suppose older people lose the ability to move as surely as before, and their reflexes slow down. In that case, injuries are more likely to occur due to falls. These injuries are much more serious if the bones are brittle. Even if osteoporosis is not a factor, fractures and other injuries in an older individual do not heal as quickly as in a younger person.

This fracture of the lower cervical vertebrae is one of the conditions treated by orthopedic surgeons and neurosurgeons.

Photo by Moquito 17 at the English-language Wikipedia, via Wikimedia Commons.

Because of their knowledge of developmental processes, orthopedists and pediatricians can advise parents concerned about their growing children and the appropriate precautions for sports activities. Orthopedists make recommendations about the design and utilization of safety equipment to prevent or reduce injury. Physicians may also advise on nutrition and exercise for adults to reduce the incidence of problems as a person ages, allowing the continuation of an active, independent life.

DIAGNOSTIC AND TREATMENT TECHNIQUES

In nonemergency situations, patients with some pain or disorder of the muscles, bones, or joints are usually referred to an orthopedic surgeon. The first office visit begins with a review of the condition. The physician will take a general medical history and obtain a history of the current complaint. This history will include the time frame from the onset, any action that may have initiated the condition, and a description of any movement difficulty the patient has. A physician will then perform a physical examination to determine the areas affected and observe range-of-motion exercises to determine if function has been lost.

X-rays or other imaging methods are ordered to see whether any structural defect can be seen. The physician may order blood tests if a disease process is suspected. Once a diagnosis has been made, a physician may prescribe medication, order physical therapy or home exercises, schedule surgery, or take other therapeutic measures to correct the condition. The abnormalities treated by orthopedists generally fall into one of three categories: injuries caused by accidents, repetitive motion disorders, and diseases affecting the skeleton, skeletal muscles, or joints.

The most common situation in which a patient sees an orthopedist is after an accidental injury. The patient may be transported to a hospital emergency room if the injury is severe. Care is taken to keep the injury site immobilized until a physician can see the patient. The type of treatment needed will be determined by the type and severity of the injury. In a closed or simple fracture, the skin is unbroken; the bones are manipulated back in line and then immobilized with a plaster cast or brace. An open or compound fracture occurs when the ends or fragments of the bone protrude through the skin. In this case, or if surgery is needed to align the bones properly, there is a higher risk of infection. Sometimes, the orthopedic surgeon must use pins or wires to hold the bone in position. Fractures of the skull or vertebrae are of special concern because of the possibility of permanent damage to the brain or spinal cord; a neurologist (a physician with specialty training in the nervous system) is usually called to assist an orthopedic surgeon.

Because of twisting movements, injuries that affect one or more joints are common. A dislocation occurs when the bones at a joint are separated. An orthopedist must realign the bones as closely as possible to the original positions and immobilize the joint to allow healing. Joint sprains result from severe twisting of a joint without dislocation. The severity of joint injury and recovery time depend on the extent of the damage to surrounding ligaments, tendons, cartilage, and other tissues. The orthopedist may schedule an arthroscopy procedure since damage to soft tissue may not be revealed in an X-ray. An orthopedic surgeon inserts a flexible tube, called an “arthroscope,” into the injury site. This tube, combined with lights and a camera, allows the surgeon to view the joint cavity to see if any abnormality is present and, if possible, repair it.

Some damage to the musculoskeletal system is not the result of a single accident but actions repeated over a long period as a part of work duties or recreational activities. These are termed “repetitive motion disorders”. For example, bursitis, or inflammation of the bursas, may arise in a baseball pitcher’s shoulder or a tennis player’s elbow. Because the same motion is repeated over and over, the rub of the bursa and other soft tissue over bone causes irritation and inflammation, resulting in pain each time the movement is attempted. Treatment consists of reducing the inflammation by using cortisone or other similar drugs, usually by injection at the affected site, coupled with rest. Resumption of the activity may occur following recommendations from an orthopedist or therapist on a change in technique to reduce the trauma. Sometimes, the condition becomes chronic, and the patient may have to discontinue the activity altogether.

Many occupations arising in the mid-twentieth century involved small movements of the hands and wrists. A worker on an assembly line who installs a specific part and an employee who uses a computer keyboard all day are examples of people at high risk for repetitive motion disorders. An understanding of the structure of the wrist leads to a better understanding of the problem involved. The median nerve leads from the spinal cord through a tunnel in the wrist’s carpal bones and then branches out to the fingers. It is encircled, together with tendons leading to the fingers, by the transverse carpal ligament. When constant friction causes swelling of the tendons and tissues adjacent to the nerve, the nerve is pinched, resulting in pain, tingling, and weakness in the hand and fingers. This condition is termed carpal tunnel syndrome. Therapy may include changing work positions, wearing a splint to hold the wrist straight, using medications to reduce inflammation, and injecting cortisone at the injury site. If the problem continues, the patient may need surgery. In this procedure, the orthopedic surgeon makes an incision in the wrist and cuts the transverse carpal ligament, thus releasing the pressure on the nerve and tendons. If the motion or activity that initially caused carpal tunnel syndrome is not stopped, the condition is likely to recur.

Diseases can affect the bones and joints. Congenital disabilities and inheritance may result in deformities that can be treated by orthopedic devices or surgery. A physician may use hormone therapy to help a child attain full growth. Nutritional disorders, such as rickets, may cause the softening of the bones, with the corresponding bowed-leg deformity. Rickets is caused by vitamin D deficiency and must be treated with vitamin therapy and braces to keep the legs straight while the bones harden. Multiple myeloma is a form of cancer that invades the bone and bone marrow and must be treated with chemotherapy and surgery to remove the tumor. Infections such as gangrene affect the limbs and, if not treated in time, may necessitate amputation by the orthopedic surgeon.

Of all the musculoskeletal system diseases, arthritis and related disorders are the most common. “Arthritis” is a general term referring to inflammation of a joint. Osteoarthritis is a degenerative disease resulting to some extent from aging. However, it can be exacerbated by obesity, lifestyle, or injury. Arthritis can also be caused by infection or deposits of uric acid crystals; a condition called “gout.” The most serious form of joint disease is “rheumatoid arthritis.” This term is sometimes used to encompass a group of related disorders. These diseases are classified as autoimmune conditions because the body is making antibodies against itself—in this case, against the tissues associated with the joints. A specialist often treats the disease process itself called a “rheumatologist,” who tries various medications to alleviate the condition. A referring physician may call an orthopedic surgeon to help correct the deformities resulting from the disease or replace defective joints with artificial ones. Special care must be taken in cases of juvenile rheumatoid arthritis since the growth process may also be affected. Systemic lupus erythematosus (SLE), ankylosing spondylitis, and scleroderma are some other autoimmune diseases that affect the musculoskeletal system.

PERSPECTIVE AND PROSPECTS

In the study of prehistoric humans, a major source of information is their skeletal remains. Archaeologists have found evidence of broken bones that were set and healed, indicating some rudimentary attempts at treating injuries. Examination of hieroglyphs shows that ancient Egyptians set bones and used wooden splints held in place by the same gum and bandages used to wrap mummies. There were no medical specialties and the treatment of wounds and fractures as part of the duties of any medical practitioner.

The branch of medicine known as orthopedics had its start in the eighteenth century. The term “orthopedics” is a combination of two Greek words: orthos, meaning “straight” or “correct,” and pais, meaning “child.” A physician named Jean André Venel (1740-91) opened an institute in Switzerland to correct skeletal deformities in children. Treatment of congenital deformities such as clubfoot and defects caused by rickets or injury was the primary function of this type of clinic.

In the nineteenth century, the development of quick-setting plaster for casts aided physicians in immobilizing broken bones after they were set. The development of anesthesia and antiseptic techniques to prevent infection allowed the practice of orthopedic surgery to expand. Research using the microscope added to the understanding of the structure and function of bone as living tissue.

In 1895, Wilhelm Conrad Röntgen (1845-1923) discovered that radiation from a cathode-ray tube would produce a photographic image of the bones of his hand. By the early twentieth century, the medical X-ray became widespread, providing an invaluable diagnostic tool for orthopedists. In the 1940s and 1950s, a better understanding of radioactive phenomena allowed the development of safer X-ray equipment and techniques. In the 1970s and 1980s, other imaging techniques, such as computed tomography (CT) scanning and magnetic resonance imaging (MRI), increased the ability of orthopedic surgeons to diagnose and treat musculoskeletal disorders.

One of the greatest orthopedic surgical advances has been in the ability to treat badly damaged limbs. At one time, the best the orthopedic surgeon could do for some patients was to amputate the limb to prevent the spread of infection and the development of gangrene, then help the patient cope with the amputations by using artificial limbs. More sophisticated techniques, incorporating the microscope with computer-directed surgical instruments, allow the reattachment of limbs in many cases by enabling the surgeon to connect even the smallest blood vessels and nerves.

If amputation is necessary, artificial limbs or prostheses have become more sophisticated. Artificial hands have become functional because of computer technology that enables the patient to direct the movement of the fingers by contracting and relaxing arm muscles. New plastics and other materials are being developed and used for synthetic joint replacements, increasing mobility and decreasing pain for arthritic patients.

Joints are now routinely replaced. The most common replacements are hip and knee joints, although techniques have been developed to replace other joints. The surgery is performed in a hospital. Recipients are encouraged to use their replaced joints within twenty-four to forty-eight hours after surgery. Complete rehabilitation requires several months of increasingly intense physical activity and exercise. Contemporary materials have an expected useful life of twenty or more years.

A better understanding of the natural healing process at the cellular level has also allowed advances in the treatment of fractures. It has been found that attaching a device that generates a weak electric current can increase the rate of healing in some patients. This current stimulates the multiplication of osteocytes and the growth of new bone in the area.

As the understanding of disease and degenerative processes increases, better treatments can also be devised. For example, osteoporosis is, in many cases, a preventable condition when a correct diet and sufficient physical exercise are maintained throughout life. After menopause in women, treatment with estrogen replacement therapy gives further protection against osteoporosis. New imaging devices allow osteoporosis to be detected earlier and more aggressive treatment measures to be applied. The genetic factor in diseases and conditions that trigger autoimmune disorders are other areas of research that are being pursued. While accidents will always occur, orthopedic research into the injury process can help devise methods of prevention, as well as new treatments for the orthopedic problems that arise.

Further Reading