Reading

Tests, Procedures, and Techniques

1B Bone Grafting Bone grafting generally consists of taking a piece of bone, along with its periosteum and nutrient artery, from one part of the body to replace missing bone in another part of the body. The transplanted bone restores the blood supply to the transplanted site, and healing occui"s··as'fo a frac­ ture. The fibula is a common source of bone for grafting because even after a piece of the fibula has been removed, walking, running, and jumping can be normal. Recall that the tibia is the weight-bearing bone of the leg.

1/11 Bone Scan A bone scan is a diagnostic procedure that takes advantage of the fact that bone is living tissue. A small amount of a radioactive tracer compound that is readily absorbed by bone is injected intravenously. The degree of uptake of the tracer is related to the amount of blood flow to. the bone. A scanning device (gamma camera) measures the radiation emitted from the bones, and the information is translated into a photograph that can be read like an x-ray on a monitor. Normal bone tissue is identified by a consistent gray color throughout because of its uniform uptake of the radioactive tracer. Darker or lighter areas may indicate bone abnormalities. Darker areas called "hot spots" are areas of increased metabolism that absorb more of the radioactive tracer due to increased blood flow. Hot spots may indicate bone cancer, abnormal healing of fractures, or abnormal bone growth. Lighter areas called "cold spots" are areas of decreased metabolism that absorb less of the radioactive tracer due to decreased blood flow. Cold spots may indicate problems such as degenerative bone disease, decalcified bone, fractures, bone infections, Paget's disease, and rheumatoid arthritis. A bone scan

Hot spot (white area) in a'C~ll(?~i"qU~:-~ertetira ·

Disorders Affecting the Skeletal System 23

detects abnormalities 3 to 6 months sooner than standard x-ray procedures and exposes the patient to less radiation. A bone scan is the standard test for bone density screen­ ing, particularly important in screening for osteoporosis in females.

CJ Caudal Anesthesia Anesthetic agents that act on the sacral and coccygeal .nerves are s01netimes injected through the sacral hiatus, a procedure called caudal anesthesia or epidural block. The procedure is used most often to relieve pain dur­ ing labor and to provide anesthesia to the perinea! area. Because the sacral hiatus is between the sacral cornua, the cornua are important bony landmarks for locating the hiatus. Anesthetic agents may also be injected through the posterior sacral foramina. Since the injection site is infe­ rior to the lowest portion of the spinal cord, there is little danger in damaging tl1e cord.

~ Pelvimetry Pelvimetry is the measurement of the size of the inlet and outlet of tl1e birth canal, which may be done by ulttaso­ nography or physical examination. Measurement of tl1e pelvic cavity in pregnant females is important because the fetus must pass through the narrower opening of the pelvis at birth. A cesarean section is usually planned if it is determined that the pelvic cavity is too small to permit passage of the baby.

Iii! Treatments for Fractures Treatments for fractures vary according to age, type of fracture, and the bone involved. The ultimate goals of fracture treatment are realignment of the bone fragments, immobilization to maintain realignment, and restoration of function. For bones to unite properly, the fractured ends must be brought into alignment, a process called reduc­ tion, commonly referred to as setting a fracture. In closed reduction, the fractured ends of a bone are brought into alignment by manual manipulation, and the skin remains intact. In open reduction, the fractured ends of a bone are brought into alignment by a surgical procedure in which internal fixation devices such as screws, plates, pins, rods, and wires are used. Following reduction, a fractured bone may be kept immobilized by a cast, sling, splint, elastic bandage, external fixation device, or a combination of these devices. •

Disorders Affecting the Skeletal System

• Abnormal Curves of the Vertebral Column Various conditions may exaggerate the normal curves of the vertebral column, or the column may acquire a lateral bend, resulting in abnor-mal curves of the vertebral column.

24 4 The Skeletal System

Scoliosis

Scoliosis (sko-le-0-sis; sco/io =- crooked), the most com­ mon of the abnormal curves, is a lateral bending of the ver­ tebral column, usually in the thoracic region. It may result from congenitally (present at birth) malformed vertebrae, chronic sciatica, paralysis of muscles on one side of the ver­ tebral column, poor posture, or one leg being shorter than the other.

Signs of scoliosis include uneven shoulders and waist, one shoulder blade more prominent than the other, one hip higher than the other, and leaning to one side. In severe scoliosis (a curve greater than 70 degrees), breathing is more difficult and the pumping action of the heart is less efficient. Chronic back pain and arthritis of the vertebral column may also develop. Treatment options include wearing a back brace, physiotherapy, chiropractic care, and surgery (fusion of vertebrae and insertion of metal rods, hooks, arid wires to reinforce the surgery).

Kyphosis '(ki-FO-sis; kyphoss- = hump; -osis = condi­ tion) is an increase in the thoracic curve of the vertebral column (Figure 4.3b). In tuberculosis of the spine, verte­ bral bodies may partially collapse, causing an acute angular bending of the vertebral column. In the elderly," degenera­ tion of the intervertebral discs leads to kyphosis. Kyphosis may also be caused by rickets and poor posture. It is also common in females with advanced osteoporosis. The term round-shouldered is an expression for mild kyphosis.

Lordosis (!or-DO-sis; lord- = bent backward),

Kyphosis Lordosis

called a herniated (slipped) disc. Because the lumbar region bears much of the weight of the body, and is the region of the most flexing and bending, herniated discs most often occur in the lumbar area.

Frequently, the nucleus pulposus slips posteriorly toward the spinal cord and spinal nerves. This movement exerts pressure on the spinal nerves, causing local weak­ ness and acute pain. If the roots of tl1e sciatic nerve, which passes from the spinal cord to the foot, are compressed, the pain radiates down the posterior tl1igh, through the calf, and occasionally into tl1e foot. If pressure is exerted on the spinal cord itself, some of its neurons may be destroyed. Treatment options include bed rest, medica­ tions for pain, physical therapy and exercises, and trac­ tion. A person with a herniated disc may also uudergo a laminectomy, a procedure in which parts of the laminae of tl1e vertebra and intervertebral disc are removed to relieve pressure on the nerves.

001 Osteoporosis Osteoporosis (os' -te-6-po-RO-sis; por- = passageway; -osis = condition) is literally a condition of porous bones that affects 10 million people in the United States each year. In addition, about 18 million people have osteopenia (low bone mass), which puts them at risk for osteoporosis. The basic problem is that bone resorption outpaces bone

sometimes called hollow back, is an increase in the !um- POSTERIOR bar curve of the vertebral colunm. It may result from ,.__ _______ Spinous process

increased weight of the abdomen as in pregnancy or extreme obesity, poor posture, rickets, osteoporosis, or tuberculosis of the spine.

• Herniated (Slipped) Disc In their function as shock absorbers, interver- Spinal cord --­

tebral discs are constantly being compressed. If the anterior and posterior ligaments of the discs become injured or weakened, the pressure devel­ oped in the nucleus pulposus may be great enough to rupture the surrounding fibrocartilage (annu­ lus fibrosus ). If this occurs, the nucleus pulposus may herniate (protrude) posteriorly or into one ANTERIOR of the adjacent vertebral bodies. This condition is

Superior view Herniated disc

of vertebra

Herniation =~--- Nucleus pulposus

Normal bone a3ox

Osteoporotic bone

deposition. In large part this is due to depletion of calcium from the body-more calcium is lost in urine, feces, and sweat than is absorbed from the diet. Bone mass becomes so depleted that bones fracture, often spontaneously, under the mechanical stresses of evetyday living. For example, a hip fracture might resnlt from simply sitting down too quickly. In the United States, osteoporosis results in more than one and a half million fractures a year, mainly in the hip, wrist, and vertebrae. Osteoporosis afflicts the entire skeletal system. In addition to fractures, osteoporosis causes shrinkage of vertebrae, height loss, hnnched backs, and bone pain.

The disorder primarily affects middle-aged and elderly people, 80% of them women. Older women suffer from osteoporosis more often than men for two reasons: (I) Women's bones are less massive than men's bones, and (2) production .of estrogens in women declines dramati­ cally at menopause, but production of the main andro­ gen, testosterone, wanes gradually and only slightly in older men. Estrogens and testosterone stimulate osteo­ blast activity and synthesis of bone extracellular matrix. Besides gender, risk factors for developing osteoporosis include a family history of the disease, European or Asian ancestry, thin or small body build, an inactive lifestyle, cigarette smoking, a diet low in calcium and vitamin D, more than two alcoholic drinks a day, and the use of cer­ tain 1nedications.

Osteoporosis is diagnosed by taking a· family history and undergoing a bone mineral density (BMD) test. BMD tests are performed like x-rays and measure bone density. They can also be used to confirm a diagnosis of osteoporo­ sis, determine the rate of bone loss, and monitor the effects of treatment.

Treatment options for osteoporosis are varied. With regard to nutrition, a diet high in calcium is important to reduce the risk of fractures. Vitamin D is necessary for the body to utilize calcium. In terms of exercise, regularly performing weight-bearing exercises has been shown to maintain and build bone mass. Among these exercises are walking, jogging, hiking, climbing stairs, playing tennis, and dancing. Resistance exercises, such as weight lifting, build bone strength and muscle mass.

Medications used to treat osteoporosis are generally of two types: (1) Antiresorptive drugs that slow down the

Disorders Affecting the Skeletal System 25

progression of bone loss and (2) bone-building drngs that promote increasing bone mass. Among the antiresorp­ tive drugs are (1) bisphosphonates, which inhibit osteoclasts (Fosamax®, Actonel®, Boniva®, and calcitonin); (2) selec­ tive estrogen receptor modulators, which mimic the effects of estrogens without unwanted side effects (Raloxifene®, Evista®); and (3) estrogen replacement tl1erapy (ERT), ,rhfcl1 replaces estrogens lost during and after menopause (Premarin®), and hormone replacement tl1erapy (HRT), which replaces estrogens and progesterone lost during and after menopause (Prempro®). HRT helps maintain and increase bone mass after menopause. Women on HRT have a slightly increased risk of stroke and blood clots. I-IRT also helps maintain and increase bone mass, and women on HRT have an increased risk of heart disease, breast cancer, stroke, blood clots, and dementia. Among the bone-forming drugs is parathyroid hormone (PTH), which stimulates osteoblasts to produce new bone (Fortes®). Otl1ers are under development.

i.D Patellofemoral Stress Syndrome Patellofemoral stress syndrome ("runner's knee") is one of tl1e most common problems runners experience. During normal flexion and extension of the knee, the patella tracks (glides) superiorly and inferiorly in tl1e groove between the femoral condyles. In patellofemoral stress syndrome, nor­ mal tracking does not occur; instead, tl1e patella tracks lat­ erally as well as superiorly and inferiorly, and the increased pressure on the joint causes aching or tenderness around or under the patella. The pain typically occurs after a per­ son has been sitting for awhile, especially after exercise. It is worsened by squatting or walking down stairs. One cause of runner's knee _is constantly walking, running, or jogging on the same side of the road. Because roads slope down on the sides, the knee that is closer to the center of the road endures greater mechanical stress because it does not fully extend during a stride. Other predisposing factors include running on hills, running long distances, and an anatomical deformity called knock-knee.

r!!il Rickets and Osteomalacia Rickets and osteomalacia (os- te-6-ma-LA-she-a; nzala­ cia = softness) are two forms of the same disease that result from inadequate calcification of the extracellular bone matrix, usually caused by a vitamin D deficiency. Rickets is a disease of children in which the growing bones become "soft" or rubbery and are easily deformed. Because new bone formed at the epiphyseal (growth) plates fails to ossify, bowed legs and deformities of the skull, rib cage, and pelvis are common. Osteomalacia is the adult counterpart of rickets, sometimes called adult rickets. New bone formed during remodeling fails to calcify, and the person experiences varying degrees of pain and tenderness in bones, especially the hip and legs. Bone fractures also result from minor trauma. Prevention and treatment for rickets and osteomalacia consists of the administration of adequate vitamin D.

26 4 The Skeletal System

~ Sinusitis Sinusitis (sin-ii-SI-tis) is an inflammation of the mucous membrane of one or more paranasal sinuses. It may be caused by a microbial infection (virus, bacterium, or fun­ gus), allergic reactions, nasal polyps, or a severely deviated nasal septum. If the inflammation or an obstruction blocks the drainage of mucus)pJo the nasal cavity, fluid pressure builds up in the para;1aial sinuses, and a sinus headache may develop. Other symptoms may include nasal con­ gestion, inability to smell, fever, and cough. Treatment options include decongestant sprays or drops, oral decon­ gestants, nasal corticosteroids, antibiotics, analgesics to relieve pain, warm compresses, and surgery.

Ill Spina Bifida Spina bifida (SPI-Ina BIF-i-da) is a congenital defect of the vertebral column in which laminae of L5 and/or SI fail to develop normally and unite at the midline. The least serious form is called spina bifida occulta. It occurs in L5 or S 1 and produces no symptoms. The only evidence of its presence is a small dimple with a tuft of hair in the overlying skin. Several types of spina bifida involve protrusion of meninges (membranes) and/or spinal cord through the defect in the laminae and are collectively termed spina bifida rystica because of the presence of a cyst­ like sac protruding from the backbone. If the sac contains the meninges from the spinal cord and cerebrospinal flnid, the condition is called spina bifida with meningocele (me­ NING-g6-sel). If the spinal cord and/or its nerve roots are in the sac, the condition is called spina bifida with menin­ gomyelocele (me-ning-go-MI-e-16-sel). The larger the cyst and the number of neural structures it contains, the more serious the neurological problems. In severe cases, there may be partial or complete paralysis, partial or complete loss of urinary bladder and bowel control, and the absence of reflexes. An increased risk of spina bifida is associated with low levels of a B vitanlin called folic acid during pregnancy. Spina bifida may be diagnosed prenatally by a test of the

Cyst like sac of spina bifida

mother's blood for a substance produced by the fetus called alphafetoprotein, by sonography, or by amniocentesis (with­ drawal of amniotic fluid for analysis).

,! Temporomandibular Joint Syndrome One problem associated with the temporomandibular joint is temporomandibular joint (TMJ) syndrome. It is characterized by dull pain around the ear, tenderness of the jaw muscles, a clicking or popping noise when opening or closing the mouth, limited or abnormal opening of the mouth, headache, tooth sensitivity, and abnormal wearing of the teeth. TMJ syndrome can be caused by improperly aligned teeth, grinding or clenching the teeth, trauma to the head and neck, or arthritis. Treatments include appli­ cation of moist heat or ice, limiting the diet to soft foods, administration of pain relievers such as aspirin, muscle retraining, use of a splint or bite plate to reduce clenching and teeth grinding (especially when worn at night), adjust­ ment or reshaping of the teeth ( orthodontic treatment), and surgery. ITT

Additional Clinical Considerations

u Black Eye A black eye is a bruising around the eye, commonly due to an injury to the face, rather than an eye injury. In response to trauma, blood and other fluids accumulate in the space around the eye, causing the swelling and dark discolor­ ation. One cause might be a blow to the sharp ridge just superior to the supraorbital margin that fractures the frontal bone, resulting in bleeding. Another is a blow to the nose. Certain surgical procedures (face lift, eyelid surgery, jaw surgery, or nasal surgery) can also result in black eyes.

l',l Cleft Palate and Cleft Lip Usually the palatine processes of the maxillary bones unite during weeks 10 to 12 of embryonic development. Failure to do so can result in one type of cleft palate. The condi­ tion may also involve incomplete fusion of the horizontal plates of the palatine bones. Another form of this condi­ tion, called cleft lip, involves a split in the upper lip. Cleft lip and cleft palate often occur together. Depending on the extent and position of the cleft, speech and swallowing may be affected. In addition, children with cleft palate tend to have many ear infections, which can lead to hearing loss. Facial and oral surgeons recommend closure of cleft lip during the first few weeks following birth, and surgical results are excellent. Repair of cleft palate typically is com­ pleted between 12 and 18 months of age, ideally before the child begins to talk. Because the palate is important for pron0nneing-c0ns0nants; speech therapy may be required, and orthodontic therapy may be needed to align the teeth. Again, results are usually excellent. Supplementation with folic acid (one of the B vitamins) during pregnancy decreases the incidence of cleft palate and cleft lip.

Ell Deviated Nasal Septum A deviated nasal septum is one that does not run along the midline of the nasal cavity. It deviates (bends) to one side. A blow to the nose can easily damage, or break, this delicate septnm of bone and displace and damage the cartilage. Often, when a broken nasal septum heals, the bones and cartilage deviate to one side or the other. This deviated sepn1m can block airflow into the constricted side of the nose, making it difficnlt to breathe through that half of the nasal cavity. The deviation usually occurs at the junction of the vomer bone with the septa! cartilage. Septa! deviations may also occur due to devel­ opmental abnormality. If the deviation is severe, it may block the nasal passageway entirely. Even a partial blockage may lead to infection. If ~;:~~~;•d inflammation occurs, it may cause nasal conges- tion, blockage of the paranasal sinus openings, chronic sinusitis, headache, and nosebleeds. The condition usually can be corrected or improved surgically.

iiiil Flatfoot and Clawfoot The bones composing the arches of the foot are held in position by ligaments and tendons. If these ligaments and tendons are weakened, the height of the medial longitudinal arch may decrease or "fall." The result is flatfoot, the causes of which include excessive weight, postural abnormalities, weakened supporting tissues, and genetic predis­ position. Fallen arches may lead to inflammation of the deep fascia of the sole (plantar fasciitis), Achilles tendinitis, shinsplints, stress fractures, bunions, and calluses. A custom-designed arch support often is prescribed to treat flatfoot.

Clawfoot is a condition in which the medial longitudinal arch is abnormally elevated. It is often caused by muscle deformities, such as may occur in diabetics whose neurological lesions lead to atrophy of muscles of the foot.

1111 Fractures The clavicle transmits mechanical force from the upper limb to the trunk. If the force transmitted to the clavicle is excessive, as when you fall on

fr d I I Fractured your outstretched arm, a acture c avic e may femur result. A fractnred clavicle may also result from a blow to the superior part of the anterior thorax. The clavicle is one of the most frequently broken bones in the body. Because the junction of the two curves of the clavicle is its weakest ·point, the clavicu­ lar midregion is the most frequent fracture site. Even in the absence of fracture, compression of the clavicle as a result of automobile accidents involving the use of shoul­ der harness seatbelts often causes damage to the median nerve, which lies between the clavicle and the second rib. A fractnred clavicle is usually treated with a regular sling to keep the arm from moving outward.

Additional Clinical Considerations 27

Although any region of the hip girdle may fracnire, the term hip fracture most commonly applies to a break in the bones associated with the hip joint-the head, neck) or trochanteric regions of the fen1ur, or the bones that form the acetabulum. In the United States, 300,000 to 500,000 people sustain hip fractures each year. The incidence of hip fractures is increasing, due in part to

longer life spans. Decreases in bone mass due to osteo­ porosis (which occurs more often in females), along with an increased tendency to fall, predispose elderly people to hip fractures.

Hip fractures often require surgical treatment, the goal of which is to repair and stabilize the fracture, increase mobility, and decrease pain. Sometimes the repair is accom­ plished by using surgical pins, screws, nails, and plates to secure the head of the femur. In severe hip fractures, the femoral head or the acetabulum of the hip bone may be replaced by prostheses (artificial devices). The procedure of replacing either the femoral head or the acetabulum is

28 4 The Skeletal System

hemiarthroplasty (hem-e-AR-thro-plas-te; henzi- = one half; arthro- = joint; -plasty = molding). Replacement of both the femoral head and acetabulum is total hip anhroplasty. The acetabular prosthesis is made of plastic, and the femoral prosthesis is metal; both are designed to withstand a high degree of stress. The prostheses are attached to healthy por­ tions of bone with acrylic cement and screws.

Fractures of the 1netatarsals ocCtfr '\vhen a heavy object falls on the foot or when a heavy object rolls over the foot. Such fractures are also common among dancers, especially ballet dancers. If a ballet dancer is on the tip of her/his toes and loses her/his balance, the full body weight is placed on the metatarsals, causing one or more of them to fracture.

Rib fractures are the most common chest injuries. They usually result from direct blows, most often from impact with a steering wheel, falls, or crushing injuries to the chest. Ribs tend to break at the point where the great­ est force is applied, but they may also break at their weak­ est point-the site of gteatest curvature, just anterior to the costal angle. The middle ribs are the most commonly fractured. In some cases, fractured ribs may puncture the heart, great vessels of the heart, lungs, trachea, bronchi, esophagus, spleen, liver, and kidneys. Rib fractures are usually quite painful. Rib fractures are no longer bound with bandages because of the pneumonia that would result from lack of proper lung ventilation.

Dislocated ribs, which are common in body contact sports, involve displacement of a costal cartilage from the sternum, with resulting pain, especially during deep inha­ lations.

Separated ribs involve displacement of a rib and its costal cartilage; as a result, a rib may move superiorly, overriding the rib above and causing severe pain.

Fractures of the vertebral column often involve Cl, C2, C4-T7, and T12-L2. Cervical or lumbar fractures usually result from a flexion-compression type of injury such as might be sustained in landing on the feet or but­ tocks after a fall or having a weight fall on the shoulders. Cervical vertebrae may be fractured or dislodged by a fall on the head with acute flexion of the neck, as might hap­ pen on diving into shallow water, or being thrown from a horse. Spinal cord or spinal nerve damage may occur as a result of fractures of the vertebral column.

11 Hormonal Abnormalities that Affect Height Excessive or deficient secretion of hormones that nor­ mally control bone growth can cause a person to be abnormally tall or short. Oversecretion of hGH during childhood produces giantisnt, in which a person becomes much taller and heavier than normal. Undersecretion of hGH produces pituitary dwarfism, in which a person has short stature. (A dwarf has a normal-sized head and torso but small limbs; a midget has a proportioned head, torso, and limbs.) Because estrogens terminate growth at the epiphyseal (growth) plates, both men and women who lack estrogens or receptors for estrogens grow taller than

normal. Oversecretion of hGH during adulthood is called acrn11zega6, (ak'-r6-MEG-a-le). Although hGH cannot produce further lengthening of the long bones because the epiphyseal (growth) plates are already closed, the bones of the hands, feet, and jaws thicken and other tissues enlarge. In addition, the eyelids, lips, tongue, and nose enlarg·e, and the skin thickens and develops furrows, especially on the forehead and soles. hGH has been used to induce growth in short-statured children. 1. i

Medical Terminology

Chiropractic (ki-r 6-PRAK-tik; cheir = hand; pmktikos = efficient). A holistic health care discipline that focuses on nerves, muscles, and bones. A chiropractor is a health care professional who is concerned with the diagnoses, treatmenti and prevention of mechanical disorders of the musculoskeletal system and the effects of these disorders on the nervous system and health in general. Treatment involves using the hands to apply specific force to adjust joints of the body(manual adjustment), especially the vertebral column. Chiropractors may also use massage) heat therapy, ultrasound 1 electric stimula­ tion, and acupuncture. Chiropractors often provide infonnation about diet, exercise) changes in lifestyle, and stress manage1nent. Chiropractors do not prescribe drugs or perform surgery.

Clubfoot or talipes equinovarus (-pes = foot; equino- =

horse) An inherited deformity in which the foot is twisted inferiorly and medially, and the angle of the arch is increased; occurs in 1 of every 1000 births. Treatment consists of manipulating the arch to a normal curva­ ture by casts or adhesive tape, usually soon after birth. Corrective shoes or surgery may also be required.

Craniostenosis (krU-ne-6-sten- 6 -sis; cranio- = skull; -stenosis= nan-owing). Premature closure of one or more cranial sutures during the first 18 to 20 months of life, resulting in a distorted sknll. Premature closure of the sag­ itral suture produces a long narrow sknll; premature closure of the coronal suture results in a broad sknll. Premature closure of all sutures restricts brain growth and develop­ ment; surgery is necessary to prevent brain damage.

Craniotomy (kra-ne-OT-6-me; cranio- = sknll; -tome = cutting) Surgical procedure in which part of the cranium is removed. It may be performed to remove a blood clot, a brain tumor, or a sample of brain tissue for biopsy.

Genu valgum (fE-noo VAL-gum; genu- = knee; valgnnt = bent outward) A deformity in which the knees are abnor­ mally close together and the space between the ankles is increased due to a lateral angulation of the tibia. Also called knock-lµiee.

Genu varum (fE-noo VAR-um; varum = bent toward the midline) A defonnity in which the knees are abnormally separated and the lower limbs are bowed medially. Also called bowleg.

Halhtx valgus (HAL-uks VAL-gus; hallux = great toe) Angulation of the great toe away from the midline of the body, typically caused by wearing tightly fitting shoes. ·when the great toe angles toward the next toe, tl1ere is a bony protrusion at the base of the great toe. Also called a bunion.

Laminectomy (lam'-i-NEK-to -me; lamina- = layer) _Surgi,cal procedure to remove a vertebral lamina. It may be performed to access ilie vertebral cavity and relieve tl1e symptoms of a herniated disc.

Lumbar spine stenosis (sten- = narrowed) Narrowing of the spinal canal in tl1e lumbar part of tl1e vertebral column, due to hypertrophy of surrounding bone or soft tissues. It may be caused by arthritic changes in the intervertebral discs and is a common cause of back and leg pain.

Orthodontics (or-tho-DON-tiks) is ilie branch of dentist:1y concerned with tl1e prevention and correction of poorly aligned teeili. The movement of teeth by braces places a stress on the bone that forms ilie sockets that anchor the teeth. In response to iliis artificial stress, osteoclasts and osteoblasts remodel the sockets so iliat ilie teetl1 align properly.

Osteoarthritis (os'-te-6-ar-THRI-tis; arthr = joint) The degeneration of articular cartilage such iliat ilie bony ends touch; the resulting friction of bone against bone worsens tl1e. condition. Usually associated with tl1e elderly.

Osteogenic sarcoma (os' -te-6-JEN-ik sar-KO-ma; sarcoma = connective tissue tumor) Bone cancer that primarily affects osteoblasts and occurs most often in teenagers during their growili spurt; the most common sites are ilie.metaphyses of ilie iliigh bone (femur), shin

Medical Terminology 29

bone (tibia), and arm bone (humerus). Metastases occur· most often in lungs; t:1·eat:1nent consists of multidrug chemotherapy and removal of tl1e malignant growtl1, or amputation of tl1e limb.

Osteomyelitis (os'-te-6-mi-e-LI-tis) An infection of bone characterized by high fever, sweating, chills, pain, nau­ sea, pus formation, edema, and warmth over the affected bone and rigid overlying muscles. It is oftel)·,caused by bacteria, usually Staphylococcus aui-ez1S. The ba~teria may reach the bone from outside the body (through open fractures, penetrating wounds, or orthopedic surgical procedures); from oilier sites of infection in the body (abscessed teeth, burn infections, urinary tract infec­ tions, or upper respiratory infections) via tl1e blood; and from adjacent soft tissue infections (as occurs in diabetes mellitus).

Osteopenia (os'-teo-PE-ne-a; penia = poverty) Reduced bone mass due to a decrease in the rate of bone syn­ thesis to a level too low to compensate for normal bone resorption; any decrease in bone mass below normal. An example is osteoporosis.

Spinal fusion (FU-zhun) Surgical procedure in which two or more vertebrae of the vertebral column are sta­ bilized witl, a bone graft or synthetic device. It may be performed to treat a fracture of a vertebra or following removal of a herniated disc.

Whiplash injury Injury to the neck region due to severe hyperextension (backward tilting) of ilie head followed by severe hyperflexion (forward tilting) of the head, usually associated witl1 a rear-end automobile collision. Symptoms are related to stretching and tearing of liga­ ments and muscles, vertebral fractures, and herniated vertebral discs.