Chapter 41 Orthopaedics
Principles of Surgery Companion Handbook
|Manifestations of Musculoskeletal Disorders|
|Disorders of Muscle|
|Muscle Paralysis and Spasticity|
|Intrinsic Diseases of Muscle|
|Requirements for Efficient Locomotion|
|Foot and Ankle Deformities|
|Epiphyseal Disorders (Osteochondritis or Osteochondrosis)|
|Congenital Orthopaedic Deformities|
|Generalized Bone Disorders|
|Developmental Disorders of Bone|
|Diseases of Joints|
|Tumors of the Musculoskeletal System|
MANIFESTATIONS OF MUSCULOSKELETAL DISORDERS
Pain is the most common symptom of musculoskeletal disorders. Stimulation of peripheral receptors by noxious agents produces a spatiotemporal pattern of nervous impulses that is interpreted as pain within the higher cerebral centers. Neural pain activity is modulated by analgesics, as well as by neurohormones called endorphins, which function as endogenous pain-inhibiting substances.
Pain may be described as localized, diffuse, radicular, or referred. Local pain occurs at the site of the pathologic process, whereas diffuse pain appears to be more characteristic of deep tissues. Radicular pain involves the anatomic distribution of a peripheral nerve and is generally due to pathology involving the nerve or nerve root, as in sciatica. Pain is referred when manifested at a location remote from the site of pathology. Examples of referred pain include knee pain as a manifestation of hip joint pathology or pain in the flank or gluteal area secondary to a spinal problem. Muscle pain may result from direct injury or from muscle spasm, a sustained reflexive contraction of muscle. Peripheral nerve pain can be caused from external pressure (neuralgia) or internal compression of a nerve between anatomic structures (compression neuropathies), ischemia, infection (e.g., herpes zoster), metabolic disturbances, or toxins such as lead or arsenic.
Bone lesions in the vertebrae such as metastatic carcinoma, multiple myeloma, infections, or osteoporotic compression fractures can also cause persistent local and occasionally radicular pain.
UPPER EXTREMITY PAIN
Shoulder pain can result from cervical disc protrusions or tumors, rotator cuff tears or impingement syndrome, or arthritis of the shoulder joint or can be referred to the shoulder from the heart, lungs, or pleura. The rotator cuff consists of the common tendinous insertions of the supraspinatus, infraspinatus, teres minor, and subscapularis. Tendinitis and bursitis are common and usually result from an impingement of the rotator cuff on the coracromial ligament (impingement syndrome). Rotator cuff tears present with acute pain and difficulty with active shoulder abduction. Diagnosis can be made with arthrography, magnetic resonance imaging (MRI), or ultrasound. Elbow pain can result from epicondylitis (such as tennis elbow), ulnar nerve compression at the elbow, arthritis of the elbow, or radicular pain from a compressed nerve root. Pain in the hand or wrist can result from tendinitis (such as trigger finger or deQuervain's disease), arthritis, or median nerve compression (carpal tunnel syndrome).
Cervical Disc Disease Cervical disc herniation can cause neck or radicular pain, neurologic symptoms, and compression of either the spinal cord or nerve roots. Thus motor weakness or sensory abnormalities can occur either in a nerve root distribution or diffusely below the level of the lesion. Myelography or MRI can demonstrate the lesion. The C4C6 levels are most commonly involved, and patients usually present with relatively acute pain, with neurologic findings depending on the level and extent of the herniation. Cord compression will cause motor weakness and hyperreflexia in the lower extremities and occasionally incontinence. Treatment consists of cervical traction, followed by anti-inflammatory medication and a cervical collar. If neurologic deficit does not respond promptly to traction, surgical discectomy and fusion of the involved level may be necessary.
LOWER EXTREMITY PAIN
The most common causes of foot pain are metatarsalgia and plantar fasciitis, which result from repetitive loading of the metatarsal heads or of the attachment of the plantar ligament to the calcaneus. Additional causes of foot and ankle pain include arthritis, peroneal tendon subluxation, stress fractures, and tarsal tunnel syndrome. Repetitive loading of the tibia can lead to shin splints, or activity-related pain and tenderness over the tibia, as well as to stress fracture. Muscle cramps, deep venous thrombosis, ischemia, and lumbar nerve root impingement from disc herniation or spinal stenosis are other causes of leg pain. Knee pain can result from internal derangements such as meniscal tears, arthritis, chondromalacia of the patella, and patellar tendinitis or can be referred from hip pathology. Hip pain generally manifests in the inguinal area and can be due to arthritis, osteonecrosis, synovitis, tumors, or infections. Lateral hip pain commonly results from trochanteric bursitis. Posterior hip pain must be differentiated from sciatica due to lumbar spine pathology.
LOW BACK PAIN
Low back syndrome refers to a disease or injury of the lumbosacral spine that may be acute or chronic in nature. Table 41-1 lists causes of low back pain. Clinically, low back pain may be activity-related, aggravated by sneezing or coughing, or associated with muscle spasm. Referred pain may occur in the buttocks or leg, and nerve root compression can cause radicular pain and/or sensory and motor symptoms in a given nerve root distribution.
TABLE 41-1 CAUSES OF BACK PAIN
Examination of the patient should include assessment of spinal range of motion, the straight-leg-raising test (for sciatic irritability; produces radicular pain if positive), and a complete neurologic examination. Most often low back syndrome is due to traumatic or mechanical causes, and usually it will respond to conservative treatment of bed rest, anti-inflammatories, local heat, and occasionally antispasmodics for muscle spasm. With subsequent mobilization, isometric back and abdominal exercises, and occasionally a corset or back brace, are helpful.
Spondylolisthesis Spondylolisthesis is a forward subluxation of one vertebral body on another and can be caused by (1) spondylolysis (a defect in the pars interarticularis), (2) fracture of posterior elements, (3) facet deficiency (congenital), (4) facet deficiency due to degenerative disc disease, or (5) elongation of the pars (isthmic). Clinically, spondylolisthesis may be asymptomatic, although back pain may be present along with variable degrees of hamstring tightness, sciatica, and rarely, neurologic symptoms. Lateral radiographs will best demonstrate the displacement, and oblique views will show any defect in the pars (spondylolysis). Treatment is conservative, with rest and abdominal exercises, unless progression of the subluxation or of symptoms occurs, in which case a posterolateral fusion usually is done. There has been recent interest in reduction of severely displaced spondylolisthesis and in direct repair of pars defects.
Sciatica Sciatica is a symptom and not a disease, and the term is used to describe radicular-type pain. Sciatica can be caused by nerve root compression by a herniated disc, tumor, abscess, or foraminal narrowing due to degenerative arthritis with facet hypertrophy. Occasionally, an intrapelvic or gluteal tumor or abscess can cause sciatica, as can inflammatory or toxic processes. Disc herniations and degenerative arthritis are by far the most common causes. Disc herniations occur most commonly at the L5S1 and L4L5 levels, when a tear in the annulus fibrosus allows herniation of the soft, gelatinous interior nucleus pulposus posteriorly into the spinal canal. The herniated disc then impinges on nerve roots, causing back and radicular pain (sciatica) and sometimes neurologic symptoms. Disc herniations are uncommon in children and older adults and occur most often in middle-aged individuals. Pain is usually aggravated by sitting, coughing, and sneezing, and forward flexion. Symptoms also will be elicited by straight-leg raising, particularly with additional dorsiflexion of the foot (Lasegue's sign). The lesion can be demonstrated by computed tomographic (CT) scan, although generally visualization is better with myelography or MRI. Treatment is generally conservative initially, with 8090 percent of patients improving spontaneously and not requiring surgery. Surgical excision of the extruded portion of the disc or digestion by percutaneous injection of chymopapain or collagenase into the disc can be effective invasive treatments. Recent approaches of microdiscectomy and percutaneous suction discectomy remain controversial.
Spinal Stenosis Spinal stenosis is a narrowing of the spinal canal or neuroforamina and can be either acquired, as with degenerative disc disease, or congenital, as in achondroplasia. Currently, the disorder is most readily diagnosed with MRI or CT scans. Patients present with back or leg pain, generally exacerbated by standing and walking and relieved by sitting, in contradistinction to discogenic back pain. Neurologic signs and symptoms may be present, including hyporeflexia. Treatment is conservative, with flexion exercises and bracing, anti-inflammatories, or epidural steroids. Refractory cases are treated by wide posterior surgical decompression, with or without fusion.
Pyogenic Osteomyelitis of the Spine The most common organism responsible for this condition is Staphylococcus aureus, which spreads hematogenously from other sites of infection. Patients have back pain, radiographic destruction of the disc space, and sometimes neurologic deficit. They may or may not have fever or other systemic symptoms of infection. Usually leukocytosis and an elevated erythrocyte sedimentation rate (ESR) are present. Treatment usually involves intravenous antibiotics, immobilization, and frequently surgical debridement, often with anterior bone grafting.
DISORDERS OF MUSCLE
Muscle Paralysis and Spasticity
Motor paralysis is loss of voluntary control of muscular contraction. Normally, muscle has some resting tone, which is absent with lower motor neuron lesions, causing flaccid paralysis. Tendon reflexes are also abolished with interruption of the lower motor neuron pathway. Spasticity refers to abnormal increases in muscle tone with passive stretch and is seen with upper motor neuron lesions. Loss of inhibitory control of tendon reflexes with upper motor neuron lesions also causes hyperreflexia. Electrical diagnosis of disorders of nerve and muscle is assisted by electromyography (fine needles inserted into muscles record intrinsic electrical activity of the muscles) and by nerve conduction velocity studies (electrical stimulation of a peripheral nerve with recording of the distally induced muscle action potentials). The clinical grading of muscle strength is shown in Table 41-2.
TABLE 41-2 CLINICAL GRADING OF MUSCLE STRENGTH
Intrinsic Diseases of Muscle
Muscular Dystrophies These are hereditary disorders of muscle with progressive degeneration. Types: Duchenne (fatal), fascioscapulohumeral (benign), and limb girdle.
Myotonias These are hereditary progressive disorders, including myotonic dystrophy and myotonia congenita (Thomsen's disease).
Myositis This is an inflammation of muscles that may be caused by a virus, parasite, or spirochete, as well as occurring in association with the various collagen vascular diseases such as dermatomyositis, systemic lupus erythematosus, scleroderma, and rheumatoid arthritis.
Poliomyelitis This is an acute viral disease that invades the central nervous system, causing destruction of the anterior horn cells in the spinal cord, which results in flaccid paralysis. In the acute phase, patients have a febrile illness with malaise and headache, and they may recover or go on to a paralytic phase within a few days. The convalescent phase follows, and some motor improvement may occur for up to 2 years. Treatment is with physical therapy to maintain joint range of motion and prevent contractures. In the final residual stage, surgical procedures may be needed to stabilize flaccid joints by arthrodesis, correct leg-length inequalities, and transfer tendons to restore lost functions. In tendon transfers, a loss of one grade of muscle strength will occur, so only muscles of grade 4 or 5 are suitable. Foot deformities are common and can be corrected by bracing initially and by combinations of tendon transfers and, near skeletal maturity, arthrodesis.
Cerebral Palsy Cerebral palsy occurs in about 3 births per 100,000. It can be caused by head injury or birth trauma, anoxia, or viral diseases (such as measles or cytomegalovirus). Fifty percent of patients are spastic, 25 percent are athetoid, 5 percent are ataxic, 5 percent are rigid, and 15 percent have a mixed clinical picture. Sixty percent of spastic patients have hemiplegia (ipsilateral upper and lower extremity involvement). The next most common form is diplegia (lower extremities), with quadriplegia (all extremities involved) the final form. Treatment is directed toward prevention of contractures, gait training, and surgical correction of deformities that develop from muscle imbalance. Bracing may help prevent equinus deformities of the ankle, adduction and flexion contractures of the hip, and flexion contractures of the knees. Adductor spasticity of the hip can cause painful hip subluxation or dislocation and may require treatment with adductor tenotomies, obturator neurectomies, or varus/derotation osteotomies of the proximal femur. Recently, transfer of the rectus femoris to the hamstring has been used to improve the swing phase of gait. Hamstring releases and Achilles tendon lengthening may be necessary to correct contractures; occasionally, spinal fusion is needed to control progressive neuromuscular scoliosis.
Myelodysplasia (Spinal Dysraphism) Myelodysplasia describes a developmental defect in the vertebral column associated with a neurologic lesion. Failure of midline fusion of vertebral elements may occur without cord involvement (spina bifida occulta) or with a myelomeningocele, a neural tube defect at the level of the lesion. Antenatal screening for alpha-fetoprotein can aid in the diagnosis. New evidence suggests that folate supplementation during the first trimester of pregnancy may markedly decrease the incidence of meningomyelocoele. Eighty percent of patients have associated hydrocephalus. Patients with myelomeningocele generally have paralysis below the level of the defect and are treated shortly after birth by surgical closure of the cystic defect and shunting for hydrocephalus. Functional prognosis varies with the level; with lesions below the L4 level, patients usually will be ambulatory, although lower extremity deformities such as talipes equinovarus and hip subluxation may occur, requiring surgical correction. Additionally, lack of sensory function makes pressure sores a common recurring problem.
Degenerative Diseases of the Nervous System with Skeletal Deformity Peroneal muscle atrophy (Charcot-Marie-Tooth disease) is an inherited progressive process usually beginning in the first or second decade and involving initially the peroneal nerve, with foot drop, cavovarus foot deformities, claw toes, and later intrinsic atrophy in the hands. Treatment involves surgical correction of deformities. Friedreich's cerebellar ataxia is a familial disease that begins in childhood; it involves the spinocerebellar tracts, corticospinal tracts, and posterior columns. Patients have progressive gait disturbance, speech disturbance, and also scoliosis and foot deformities, with a steady downhill course. Finally, syringomyelia is a degenerative condition of the spinal cord with neuronal destruction centrally resulting in a cavity or syrinx, usually in the cervical area. Onset is usually in the second or third decade and involves intrinsic muscles of the hand initially, followed by progressive loss of both motor and sensory function in the upper and lower extremities. Orthopaedic treatment is directed at bracing for prevention of contractures and deformities or arthrodesis of neuropathic joints.
REQUIREMENTS FOR EFFICIENT LOCOMOTION
- Stability of joints, normal bone length, normal skeletal relationships
- Normal joint range of movement and normal muscle power
- Cortical control of voluntary muscle action
- Normal muscle tone, including coordination as well as postural tone
- Normal sensory modalities
- Cerebellar control of muscle action and intact ocular and auditory balance mechanism
Gait disturbances can result from neurologic disorders such as ataxia (from cerebellar lesion, posterior column lesion, Guillain-Barré syndrome, or Friedreich's ataxia) or from spastic paraplegia (upper motor neuron lesion, stroke, or cerebral palsy). Mechanical causes include limb-length discrepancy, hip joint pathology (congenital dysplasia or dislocation, slipped femoral capital epiphysis, Legg-Calvé-Perthes disease, arthritis), or knee joint problems (arthritis, osteochondritis dissecans, genu valgum or varus, etc.). A new method of correcting limb-length discrepancies is called distraction osteogenesis (Ilizarov technique), in which a cortical osteotomy is performed after gradual lengthening of the bone in an external fixation apparatus.
Kyphosis refers to an increase in the normal posterior convexity of the thoracic spine involving a number of vertebral bodies. A gibbus deformity is an acute kyphotic angular deformity and can be congenital, traumatic, or due to infection such as tuberculosis. In adolescence, kyphosis can be the muscular or postural type (benign, and treated with exercise) or discogenic (Scheuermann's disease). Scheuermann's disease tends to be progressive and is associated with abnormalities of the vertebral end plates with disc herniations into the vertebrae (Schmorl's nodes). It is treated with exercises and occasionally with bracing or spinal fusion in refractory cases with severe deformities. Senile kyphosis occurs most commonly with osteoporosis, where multiple compression fractures cause wedging of the vertebrae.
Scoliosis refers to any lateral deviation of the spine from its usually straight form. Congenital scoliosis is associated with vertebral anomalies such as hemivertebrae or complete or partial fusions of vertebral bodies. Progression of these types of scoliosis is treated by early limited fusion. Paralytic or neuromuscular scoliosis usually is associated with a long C-shaped thoracolumbar curve and often requires instrumentation and fusion if bracing does not prevent progression. Idiopathic scoliosis progresses during adolescence, and important factors are the age of onset and site of the curve. Thoracic curves starting before age 10 have a poorer prognosis. After skeletal maturity, progression is minimal. The most common curve is the right thoracic curve, usually seen in girls. Generally, rotation of the vertebral bodies occurs in addition to lateral curvature. The rotational component is accentuated with forward flexion, causing an obvious asymmetry or prominence of the ribs or transverse processes on the convex side of the curve. Lateral bending radiographs help to determine the flexibility of the curve. Treatment consists of regular follow-up to determine progression radiographically and postural exercises. With progression, bracing is used, such as a Milwaukee brace or plastic thoracolumbar sacral orthosis (TLSO). Alternatively, electrical muscle stimulators on the convex side of the curve also have been used but remain controversial. For progressing curves greater than 40 degrees, surgical correction with Harrington rods or Luque instrumentation (sublaminar wiring) and posterior fusion is generally indicated. Use of segmental fixation may obviate the need for postoperative cast immobilization. Also, the recent use of more rigid Cotrel-Dubosset fixation allows better correction of both sagittal and lateral curvatures. For rigid thoracolumbar curves or adult degenerative scoliosis, anterior fusion with Zielke instrumentation may be used.
FOOT AND ANKLE DEFORMITIES
Pes planus (flatfoot) can be flexible or rigid. Congenital flexible flatfoot is the most common type and is usually painless and benign. Rigid flatfoot (peroneal spastic flatfoot) is usually due to a tarsal coalition or congenital fusion between the calcaneus and the navicular, talus, or cuboid and is frequently painful and treated by insoles or often resection of the coalition bar. Acquired flatfoot may result from trauma with rupture of midfoot ligaments, posterior tibialis tendon rupture, or muscle imbalance from a neurologic disorder such as poliomyelitis.
Contracture refers to a permanent shortening and rigidity of muscles, joints, and fascial structures and may be congenital or acquired. Congenital examples include clubfoot and arthrogryposis multiplex congenita. Acquired contractures of joints can result from periarticular trauma, muscle imbalance (as previously discussed with cerebral palsy), burns, or idiopathic conditions such as Dupuytren's contracture of the palmar fascia. Volkmann's ischemic contracture results from a compartment syndrome of the forearm muscles following trauma. Swelling within muscle compartments bounded by fascia leads to ischemia with permanent muscle necrosis and later fibrosis. A similar problem can occur in the lower extremities. Clinical signs include diminished perfusion or pulses, pain with passive stretch of involved muscles, paresthesias, and motor weakness. Diagnosis is made by measurements of muscle compartment pressures using a special catheter and monitor, and treatment consists of prompt surgical decompression of involved compartments.
EPIPHYSEAL DISORDERS (OSTEOCHONDRITIS OR OSTEOCHONDROSIS)
The term osteochondritis refers to an abnormality of the secondary ossification centers of the long bones. Generally, the pathologic changes are most consistent with avascular necrosis of the epiphysis. The most common locations of osteochondritis are the lunate (Kienböck), scaphoid (Preoser), tarsal navicular (Köhler), vertebral epiphyses (Scheuermann), capitellum (Panner), femoral head (Legg-Calvé-Perthes), patella (Sinding-Larsen), tibial tubercle (Osgood-Schlatter), calcaneus (Sever), and metatarsal heads (Freiberg). Patients usually present with pain and radiographic abnormalities in the associated epiphysis.
Legg-Calvé-Perthes disease of the hip usually occurs in males between 5 and 9 years of age and is bilateral in 10 percent of patients. Patients present with hip or knee pain and limping in the initial or prodromal stage. This becomes associated with loss of motion in the hip and flattening of the femoral head (coxa plana). Later, with revascularization of the epiphysis, symptoms and signs diminish, although limitation of motion and deformity of the femoral head may be permanent. The key to treatment is containment of the femoral head within the acetabulum, usually with ambulatory abduction bracing, until the restoration or revascularization stage is completed (about 12 years). In some patients with severe involvement, varus osteotomy for containment is necessary.
Osgood-Schlatter disease of the tibial tubercle presents in patients in the 1315-year age range, sometimes with a history of antecedent injury. Pain, tenderness, and enlargement of the tibial tubercle occur, with a fragmented appearance radiographically. Treatment is symptomatic, with restriction of activities, and for more severe cases a plaster cylinder cast or knee immobilizer for 6 weeks. The disease is self-limited, although prominence of the tibial tubercle is permanent.
Köhler's disease involves the tarsal navicular in young children between the ages of 3 and 6 years. Symptoms consist of pain and swelling, and diagnosis is made by radiographs demonstrating sclerosis of the navicular. Treatment consists of a plaster cast for a few weeks and a molded arch support subsequently.
CONGENITAL ORTHOPAEDIC DEFORMITIES
Deformities Present at Birth Metatarsus adductus, valgus hindfoot, unilateral externally rotated leg, internal tibial torsion, and an adducted thigh with external rotation of the leg are thought to result from in utero position, and this also may be a contributing factor to talipes equinovarus (clubfoot) deformity. These conditions generally respond to passive stretching exercises, with corrective casts occasionally being used in refractory cases.
Congenital dislocation of the hip (CDH) consists of partial or complete displacement of the femoral head from the acetabulum, with an incidence of 0.67 per 1000 births. Treatment is most successful if undertaken early, and all babies must be examined carefully for CDH. On examination, a hip click (Ortolani's sign) can be elicited as the hip reduces in abduction and flexion. Also, limitation of abduction to 75 degrees or less, apparent shortening of one thigh (Galeazzi's sign), and asymmetric gluteal creases may be present. If undetected in infancy, the child will have a noticeable limp or waddle when beginning to walk. Radiographically, delay in ossification of the epiphysis will occur, and the acetabular index (angle of the acetabulum from horizontal) will be greater than normal (22 degrees). Arthrography of the hip, MRI, or ultrasonography also will demonstrate the dislocation. Treatment of subluxation in the neonate usually can be accomplished with a Pavlik harness worn for 36 months. If the hip does not reduce in abduction or in older infants, a period of skin traction followed by closed reduction in an abduction spica cast may be needed. Open reduction is generally unnecessary in children under 1 year of age but may be needed in cases of late diagnosis. In the older child, femoral shortening and innominate osteotomies may be necessary to ensure a stable concentric reduction with containment of the femoral head by the acetabulum.
Congenital talipes equinovarus (clubfoot) is a deformity involving flexion of the ankle, inversion of the foot, adduction of the forefoot, and medial rotation of the tibia. Incidence is about 4 per 1000 births. Without treatment, the deformity is permanent and ambulation difficult. Treatment begins immediately after birth, with passive stretching exercises followed by application of serial corrective plaster casts. The forefoot adduction is corrected first, then the hindfoot varus, and only then the equinus. If the deformity recurs or correction is incomplete, surgical release of the hindfoot must be done with open reduction of the deformity and subsequent casting. In the older child, mild degrees of recurrence can be treated by lateral transfer of the tibialis anterior and/or Achilles tendon lengthening.
Congenital convex pes valgus (vertical talus) involves a dislocation of the talonavicular joint, with the talus in a vertical position and the navicular articulating with the dorsum of the talus. The sole of the foot has a rocker-bottom flatfoot deformity and is rigid. Early manipulation with plaster casting may be successful, but most patients will require operative reduction and pinning with Achilles tendon lengthening. Triple arthrodesis may be indicated in the older child.
Arthrogryposis multiplex congenita, or amyoplasia, is associated with fibrous tissue replacement of muscles at birth causing loss of joint mobility and associated deformities such as CDH, clubfoot, and knee dislocation, which are treated as previously described.
Sprengel's deformity (congenital high scapula) is caused by embryonic failure of the scapula to migrate to its normal position. Occasionally, the scapula is attached to the vertebral column by an abnormal band of fibrous tissue or cartilage called the omovertebral mass. Mild cases need no treatment, but in more severe cases, surgical correction may be undertaken, although it is generally delayed until age 36 years.
Klippel-Feil syndrome, or congenital short neck, is caused by multiple fusions of cervical vertebrae and generally is not treatable. Congenital wryneck (torticollis) is caused by unilateral contracture of the sternocleidomastoid muscle causing a lateral inclination of the head and is thought to be posttraumatic, with a tender swelling in the muscle preceding the deformity. Treatment consists of stretching exercises and, in refractory or late-diagnosed patients, surgical release of the muscle.
Other congenital deformities include radioulnar synostosis (fusion of the proximal radius and ulna), Madelung's deformity (bowing of the distal radius with subluxation of the radioulnar joint), and congenital aplasia or dysplasia of long bones (most commonly, absence of the radius with radial clubhand, fibula, or proximal femoral focal deficiency).
GENERALIZED BONE DISORDERS
Bone Composition Organic components: 90 percent type I collagen; the remaining constituents include phosphoproteins, bone-specific proteoglycan, sialoprotein, osteonectin, osteocalcin, and growth factors such as transforming growth factor-beta, fibroblast growth factor, and bone morphogenetic proteins.
Inorganic components: calcium phosphate in the crystalline form of hydroxyapatite and 89 percent water. Bone cell enzymes: Osteoclasts contain acid hydrolases, collagenase, and acid phosphatase, whereas osteoblasts contain alkaline phosphatase and collagenase activity.
There are two primary forms of ossification or mineral deposition within skeletal tissues. The long bones form developmentally by mineralization of cartilage initially, with subsequent conversion of this mineralized tissue to bone. This process is called endochondral ossification, and in addition to embryonic bone formation, it gives rise to the growth plates of long bones, secondary ossification centers of the epiphyses, and callus formation in fracture healing. The other form of ossification is called intramembranous ossification and involves mineralization of osteoid by osteoblasts directly without a cartilage phase. Bone remodeling occurs when osteoclasts resorb bone, which is followed by a tightly coupled formation of bone by osteoblasts and occurs constantly throughout the skeleton.
Because of the content of growth factors in the matrix of bone, it can be readily transplanted, and as it is resorbed, it stimulates local bone formation (osteoinduction). In addition, osteoblasts deposit new bone directly on graft surfaces (osteoconduction), which act as a scaffold supporting bone replacement. Bone grafts are used in nonunion of fractures, to stimulate arthrodeses, and to replace segmental loss of bone resulting from trauma, infections, or tumors. Bone allografts are almost as effective as autografts, given the negligible amount of antigenic cellular material. Recent advances also include the use of vascularized bone grafts, where microvascular anastomosis of the bone blood supply allows rapid incorporation of a living segment of bone, and use of synthetic bone graft substitutes such as hydroxyapatite, demineralized bone matrix, or growth factors such as the bone morphogenetic proteins (BMPs).
Developmental Disorders of Bone
Achondroplasia This is the most common form of dwarfism, and it is associated with relatively normal trunk height but shortened extremities; it is autosomal dominant in inheritance.
Ollier's Disease (Dyschondroplasia) Multiple abnormal rests of cartilage in the metaphyses lead to deformities of the long bones. Malignant degeneration into chondrosarcoma occurs in 1525 percent of patients.
Multiple Exostoses This autosomal dominant hereditary disorder is characterized by numerous cartilaginous outgrowths from the metaphyses of the pelvis and long bones. These require surgical excision only when symptomatic or occasionally when malignant degeneration into a chondrosarcoma occurs.
Polyostotic Fibrous Dysplasia This disease usually appears in childhood and results in dysplastic bone formation by fibroblastic-like cells in the metaphyses and diaphyses of long bones. Pathologic fractures or bowing of the bones can occur and may require surgical treatment.
Osteogenesis Imperfecta This is a familial disorder of the type I collagen gene with several subtypes. Patients may have blue sclera and deafness, and all have fragile bones that fracture easily. The fetal form is severe and lethal. The infantile form is less severe, and the adolescent form, called osteogenesis imperfecta tarda, is the least severe. In children, intramedullary rodding and osteotomies are often used to prevent long bone fractures.
Osteopetrosis (Albers-Schönberg Disease, Marble Bones, Congenital Osteosclerosis) This is a rare hereditary disease with defective osteoclasts incapable of bone remodeling, characterized by dense bones radiographically, anemia, and frequent fractures and infections. Several reported cases have been cured by bone marrow transplantation.
Melorheostosis This disease involves regional asymmetric osteosclerosis of cortical bone with the radiographic appearance of candle drippings, local pain, and adjacent joint fibrosis.
Scurvy Vitamin C deficiency results in defective cross-linking of collagen and therefore weakness of vascular endothelium. Subperiosteal hemorrhages occur, as well as increased density of the calcification zone of the growth plate due to defective remodeling and bone formation. Treatment with vitamin C is rapidly curative.
Rickets Vitamin D deficiency can be caused by a number of diseases and results in inadequate absorption of calcium in the intestine. Nutritional deficiency and intestinal malabsorption syndromes cause inadequate vitamin D absorption, whereas renal or hepatic diseases result in inadequate hydroxylation of vitamin D to the active form. In children, the long bones are soft and bowed, with widening of the growth plate and enlarged and tender epiphyses. Treatment is with vitamin D repletion. Vitamin Dresistant rickets is a hereditary disease that requires massive doses of vitamin D plus phosphate to treat the bone disease.
Hypophosphatasia This rare hereditary disorder is characterized by low levels of alkaline phosphatase and urinary excretion of phosphoethanolamine.
Osteomalacia This disease is the adult equivalent of rickets and is caused by any derangement of vitamin D metabolism, as noted earlier. Pathologic fractures can occur, and treatment is with vitamin D.
Osteitis Fibrosa (Parathyroid Osteodystrophy) Multiple bony lesions and areas of bone resorption are caused by excessive secretion of parathyroid hormone. Hypercalcemia may be present in the case of primary hyperparathyroidism, and pathologic fractures or bowing of long bones can occur. Parathyroidectomy is generally the treatment of choice.
Osteoporosis This condition results from an inadequate amount of bone that is otherwise biochemically normal. It is seen in association with Cushing syndrome, thyrotoxicosis, chronic steroid therapy, and most commonly in postmenopausal women as a consequence of estrogen loss. Treatment is with calcium and physiologic doses of vitamin D (to offset any component of superimposed osteomalacia), exercise, estrogen supplementation when appropriate, and occasionally, antiresorptive agents such as calcitonin or bisphosphonates.
Pituitary Disturbances Hypopituitarism in childhood can cause dwarfism, whereas hyperpituitarism in childhood leads to gigantism. In adulthood, onset of hyperpituitarism (usually due to a pituitary adenoma) causes acromegaly, with enlargement of the skull, thorax, and digits.
Hypothyroidism (Cretinism) Delayed ossification results in short stature, and the bones are short with a thick cortex. Epiphyseal ossification is delayed and irregular, resembling osteochondroses such as Legg-Calvé-Perthes disease. Thyroid replacement is curative if begun in infancy.
Mucopolysaccharidoses A series of 12 hereditary disorders of mucopolysaccharide (glycosaminoglycan) metabolism have been identified, including Hurler, Hunter, Scheie, Sanfilippo, and Morquio syndromes. These vary in severity and are variably associated with spinal deformities, mental retardation, osseous abnormalities, corneal opacities, and joint stiffness.
Paget's Disease (Osteitis Deformans) This disorder of bone turnover is thought to be caused by a slow viral infection of osteoclasts. Early in the disease there is excessive osteoclastic resorption and vascularity, followed by abnormal bone formation and sclerosis, with trabecular and cortical thickening. In the late phase, dense sclerotic woven bone and inactive fibrous marrow replacement predominate. The disease begins between the ages of 35 and 50 years and is painful in about 30 percent of patients. Pathologic fractures occur, and bowing of long bones also occurs. Serum alkaline phosphatase and urinary hydroxyproline levels are elevated and correlate with activity of the disease. Diphosphonates or calcitonin are useful in controlling the disease by inhibiting bone resorption.
Lipoid Granulomatosis This results from any disturbance of lipid metabolism. In Gaucher's disease, a cerebroside lipoprotein accumulates; in Niemann-Pick disease, a phosphatide lipoid; in Hand-Schüller-Christian disease, cholesterol; in Tay-Sachs disease, a cerebroside protein. Radiographs show lytic skeletal lesions.
Eosinophilic Granulomatosis This may present as a solitary skeletal lesion in childhood or multiple lesions that are then referred to as Hand-Schüller-Christian disease. Hand-Schüller-Christian disease is also associated with hepatosplenomegaly, exophthalmos, and diabetes insipidus. Solitary eosinophilic granulomatosis may cause vertebrae plana or pathologic fracture in long bones and generally responds to conservative treatment, being a self-limited disorder. The most severe form of disease is Letterer-Siwe, which presents in infancy and is generally fatal. The systemic forms of eosinophilic granulomatosis respond to treatment with vinblastine and prednisone.
Hodgkin's Disease This is a form of malignant lymphoma that may present with lytic lesions in bone secondary to bone marrow involvement. Symptomatic lesions respond to radiation therapy, and the systemic disease is responsive to chemotherapy.
Leukemia Leukemia may produce bone lesions, most commonly in lymphoblastic leukemia, which can demonstrate lucencies adjacent to the growth plate in the metaphyses.
Multiple Myeloma This is a proliferation of malignant plasma cells that produces sharply demarcated, punched-out lesions in bone. The skull, ribs, and long bones are all affected, and diagnosis can be made on bone marrow biopsy or by demonstration of an abnormal monoclonal immunoglobulin on serum immunoelectrophoresis.
Hemolytic Anemia This can cause bone marrow changes in the vertebrae and skull, with a hair on end or sun ray appearance, particularly in the skull.
FRACTURES (SEE TABLE 41-3, TABLE 41-4, AND TABLE 41-5)
TABLE 41-3 FRACTURES AND JOINT INJURIES IN THE UPPER EXTREMITY
TABLE 41-4 FRACTURES AND JOINT INJURIES IN THE LOWER EXTREMITY
TABLE 41-5 FRACTURES AND JOINT INJURIES OF THE PELVIS AND SPINE
A fracture is, by definition, a deformation or discontinuity of bone produced by forces exceeding the strength of the bone. Fractures are classified according to pattern (transverse, spiral, oblique, segmental, comminuted), location (diaphyseal, metaphyseal, epiphyseal), and integrity of the surrounding skin and soft tissue (open or compound versus closed). A pathologic fracture is one through bone that is abnormally weakened by a pathologic process such as metabolic bone disease or a tumor. Clinical manifestations include pain, swelling, deformity, ecchymosis, instability, and crepitus. Diagnosis requires two orthogonal radiographs as a minimum, including views of the joint above and below the fracture site. Evaluation should include assessment for other injuries, as well as assessment of the neurologic and vascular function in the injured extremity. Open fractures represent orthopaedic emergencies, requiring immediate debridement in the operating room setting to prevent occurrence of osteomyelitis. Debridement should be carried out within 68 h, and wounds generally are not closed primarily. Any devitalized tissue is removed, and the fracture is stabilized in either an external fixator or a plaster cast.
Associated vascular injuries require early recognition and treatment, since irreversible muscle ischemia will occur within 68 h. Also in the presence of ischemia, prophylactic fascial compartment releases are necessary to prevent compartment syndrome on reperfusion of the limb. Fat embolism syndrome, a form of adult respiratory distress syndrome (ARDS), occurs in some patients, particularly those with multiple long bone fractures. This syndrome occurs 23 days postinjury and is attended by hypoxemia, confusion, fever, and transient petechiae. Treatment is with respiratory support and corticosteroids.
Nerve injuries may be associated with fractures and range from neurapraxia (a transient, reversible impairment of nerve function), to axonotmesis (axons transected but nerve sheath intact; can regenerate), to the most severe, irreversible form of neurotmesis in which the entire nerve is transected. Transected nerves should be repaired primarily when possible at the time of fracture fixation or debridement.
Joint injuries are assessed radiographically to rule out intraarticular fractures, which often require surgical treatment. Physical examination is important to evaluate ligamentous instability, which may be treated by immobilization or repair depending on the particular injury. Arthroscopic examination is a useful tool in evaluation and treatment of joint injuries and is used most commonly in the knee and shoulder. Surgical arthroscopy can be used to treat meniscal tears, osteochondral fractures, cartilage degeneration, synovitis, shoulder instability due to glenoid labral tears or intraarticular loose bodies, and anterior cruciate ligament tears. Morbidity and rehabilitation time are diminished when compared with comparable open surgical procedures.
Fracture Healing The stages of fracture healing include
- Stage of impact: energy absorbed to failure
- Inflammatory stage: hematoma, necrosis of fracture edges, cytokines released, granulation tissue in gap lasts about 2 weeks
- Reparative stage: cartilage and bone differentiate from periosteal and mesenchymal cells; cartilage undergoes endochondral calcification, and membranous bone formed by osteoblasts at the periphery of the callus gradually replaces the calcified cartilage with bone lasts from one to several months
- Remodeling stage: woven bone converted to lamellar bone through coupled resorption and formation; bone tends to resume its original shape by remodeling under influence of mechanical stresses lasts months to years.
Cartilage Healing Articular cartilage has a very limited repair capacity. Injury results in loss of proteoglycans with increased mechanical stress, chondrocyte death, fibrillation, and progressive degeneration. Surgical penetration of the subchondral bone can allow repair of a defect by fibrocartilage formation.
Delayed Union and Nonunion Delayed union refers to a fracture that takes longer than average to heal and is somewhat poorly defined. Nonunion refers to a fracture that fails to progress toward healing. Causes of nonunion include excessive motion at a fracture site, excessive distraction, infection, and severe soft tissue disruption. Nonunions may be treated by bone grafting or stimulation with pulsed electromagnetic fields.
Stress Fractures Stress or fatigue fractures are a result of repeated stress to a bone that would not be injured by isolated forces of the same magnitude. They can occur on long marches, after jogging, or during other activities. Radiographic findings may be subtle but eventually show periosteal reaction. Treatment is with immobilization.
Epiphyseal Plate Injuries Longitudinal growth occurs from the growth plate adjacent to the epiphyses of the long bones. The zone of provisional calcification of the plate is a mechanically weaker area of the bone, and it is through this zone that fractures about the epiphysis usually occur. The Salter-Harris classification of growth plate injuries is in wide use:
Type III: Transverse fracture through metaphyseal side of growth plate; excellent prognosis after closed reduction.
Type II: Fracture through growth plate partially, exiting through the metaphyseal bone; also excellent prognosis with closed reduction.
Type III: Fracture longitudinally through the articular surface and epiphysis and then transversely through the metaphyseal side of the growth plate; prognosis good with anatomic reduction only.
Type IV: Longitudinal fracture through epiphysis and growth plate and exiting through metaphyseal bone; open reduction generally necessary and has higher risk of late growth disturbance.
Type V: Crush injury to the growth plate; high incidence of late growth disturbance.
Fractures in children generally heal more rapidly than those in adults, with nonunions being extremely rare. Greater capacity for remodeling also allows acceptance of greater angular deformities. However, limb-length discrepancies can occur with growth after fractures, as can progressive angular deformities, unlike the adult.
Closed treatment of fractures generally involves application of plaster casts. Complications of cast treatment include swelling, which can impair circulation and cause ischemic limb damage; pressure sores; and neurapraxias. Neurovascular compromise in a cast initially is treated by splitting the cast and underlying padding to relieve pressure. If prompt resolution does not occur, measurements of compartment pressure must be made to rule out compartment syndrome, which would necessitate emergent surgical fasciotomies. Casts should include the joint proximal and distal to the fractured bone. Body casts can be used for spinal fractures.
External fixation is used in open fractures associated with soft tissue injury or loss. Pins inserted into the bone above and below the fracture are connected to an outrigger and stabilize the fracture while allowing access to wounds. Another method of stabilizing a fracture is with traction. In children, skin traction with adhesive tapes can be used, although with older children and adults skeletal traction through a transverse percutaneous pin is necessary.
Electrical stimulation can be used through either percutaneous pins or externally applied coils to stimulate a high percentage of nonunions or delayed unions to heal without surgery.
DISEASES OF JOINTS
Joints consist of hyaline articular cartilage bounded by a fibrous capsule that has a lining of synovial cells, which secrete the synovial fluid that provides nourishment and lubrication of the articular surface. Articular cartilage matrix is composed of 40 percent type II collagen, 40 percent proteoglycan, and 20 percent glycoproteins as the organic components. Minor collagens (type IX and XI) are also found in the matrix, as well as growth factors such as transforming growth factor-beta and fibroblast growth factor. Normal synovial fluid contains hyaluronate and up to 200 nucleated cells, as well as glucose and electrolytes.
Clinical examination of a joint includes measurement of range of motion, presence of effusion, synovial thickening, warmth, erythema, and tenderness. Radiographic examination includes standard biplanar radiography and, occasionally, arthrography if meniscal or capsular pathology is suspected. Synovial fluid analysis is helpful. Normal synovial fluid is clear and straw-colored. When the cell count is increased or crystals are present, turbidity results. Viscosity is decreased as a result of the breakdown of hyaluronate when inflammation is present. A poor mucin clot is another indication of inflammation. Normal synovial fluid contains 10 mg/dL less glucose than serum, and this gradient is increased in the presence of large numbers of inflammatory cells.
Pyogenic arthritis refers to a bacterial infection, or septic arthritis, and can result in rapid and irreversible destruction of the articular cartilage. S. aureus and hemolytic streptococci are the most common organisms, but many organisms are possible agents. Patients may have fever, effusion, pain with motion of the joint, and an elevated white blood cell count and ESR. The white blood cell count in the synovial fluid is generally greater than 50,000/mm3, with 90 percent polymorphonuclear leukocytes. Organisms may be identified by Gram stain or culture of the fluid aspirated. Treatment is generally by surgical drainage of the joint in conjunction with appropriate intravenous antibiotics. Some infections may be treated with daily aspirations rather than surgery. Infections of the hip joint must all be treated by prompt surgical drainage to prevent avascular necrosis. The knee joint frequently can be drained arthroscopically. Early motion after subsidence of the acute infection is important to prevent joint stiffness, and antibiotics usually are continued for 36 weeks.
Tuberculosis is now an uncommon infection in this country, but it can cause severe destruction of bone and joints. Most commonly the spine is involved, with destruction of adjacent vertebrae, kyphosis, and abscess formation. In peripheral joints, the subchondral bone is eroded and destroyed early, whereas the articular cartilage is relatively well preserved until late in the course. The end result is fibrous ankylosis of the joint. The clinical course may be insidious, and diagnosis depends on recovery of organisms from the bone or joint by biopsy or aspiration. Synovial fluid usually contains less than 20,000 leukocytes per deciliter. Patients are treated by surgical debridement of involved joints, supportive therapy, and triple-drug therapy (isoniazid, ethambutol, and rifampin) for 6 months to 1 year. Surgical arthrodesis of destroyed joints may be necessary. Tuberculous spondylitis (Pott's disease) is treated by anterior debridement, decompression, and fusion with rib grafts in conjunction with triple-drug therapy.
Gonococcal arthritis is more common in females. Symptoms start with migratory polyarthralgia, followed by localization in one or two joints. The knee, elbow, and wrist are the most common sites of involvement. Infection may be clinically subacute or chronic, and treatment is with aspiration and penicillin.
Lyme arthritis is a tick-borne illness caused by a spirochete, Borrelia burgdorferi. A skin eruption may herald the onset of a rheumatic syndrome resembling rheumatoid arthritis with oligoarticular presentation. Cardiac and neurologic symptoms also can occur. Penicillin or tetracycline therapy will eliminate the infection.
Rheumatoid arthritis is a systemic disease affecting many organs of the body, characterized especially by proliferative synovial destruction of multiple joints. The proliferative synovium that destroys the articular cartilage is called pannus, and radiographically, periarticular osteopenia and concentric joint space narrowing occur. Ninety percent of rheumatoid patients have the antigammaglobulin factor, called rheumatoid factor, measured by latex fixation test. Radiographs show soft tissue swelling, osteoporosis, and periarticular erosions, followed by complete joint destruction.
Medical management includes anti-inflammatory drugs (both steroidal and nonsteroidal), gold salts, methotrexate, and antimalarials. Surgical treatments include synovectomies of involved joints and tenosynovectomies to prevent tendon ruptures; joint replacements for end-stage disease [hip, knee, shoulder, elbow, wrist, metacarpophalangeal (MP), and proximal interphalangeal (PIP) joints]; metatarsal head resections (Hoffman procedure) for forefoot deformity; and various procedures on the hand for correction of deformity.
Osteoarthritis, or degenerative arthritis, is a noninflammatory form of progressive joint destruction. Cartilage wear is manifested by loss of proteoglycans, which then causes fibrillation of the articular surface. Marginal osteophytes form as part of the injury and repair process, and the cartilage surface eventually becomes denuded to subchondral bone. Radiographs demonstrate asymmetric joint space narrowing, subchondral sclerosis, subchondral cysts, and osteophytes. Joints deranged by any process such as trauma, Legg-Calvé-Perthes disease, septic arthritis, gout, or hemophilia can undergo changes of osteoarthritis. Effusion tends to be minimal, and the arthritis is only slowly progressive. Treatment involves limitation of activities, anti-inflammatory medications, walking aids, osteotomy to correct deformity or realign joints, and as a last resort, joint arthrodesis or total joint replacement. Complications of total joint arthroplasty include infections, loosening, and periarticular heterotopic ossification. Recently, use of uncemented total joint implants, prompted by the long-term problems of loosening of prostheses at the bone-cement interface, has become popular, particularly in younger patients. These devices have porous metal coatings that allow ingrowth of bone to permanently anchor the prosthesis and have been demonstrated to give comparable clinical results to conventional cemented components.
Osteonecrosis of the femoral head can result from trauma, sickle cell anemia, or alterations of lipid metabolism (e.g., lipid storage diseases, alcoholism, corticosteroids). The articular surface can collapse during the revascularization phase, when bone resorption and mechanical weakness occur, and this in turn leads to rapid degenerative arthritis. MRI is the most sensitive method of early detection, and early surgical treatment by bone grafting or marrow decompression may prevent collapse.
Gout is a metabolic disease in which crystals of sodium urate are deposited in and around joints, with severe episodic arthritis, classically involving the metatarsophalangeal (MTP) joint of the great toe in males over age 30. Diagnosis can be confirmed by aspiration of the joint with demonstration of urate crystals by polarized light microscopy. Treatment is with colchicine or indomethacin acutely and chronically with allopurinol to decrease serum urate levels.
Pyrophosphate arthritis (pseudogout or chondrocalcinosis) is an episodic arthritis resembling gout and most commonly affects the knee or wrist. The diagnosis rests on finding pyrophosphate crystals in the synovial fluid; radiographs also may demonstrate calcification of menisci. Treatment is with anti-inflammatory medication.
Hemophilic arthritis results from acute recurrent bleeding into synovial joints, usually after minor injury. The knee, elbow, shoulder, and ankle may be involved. Contractures develop, with synovial thickening and hemosiderin deposition, and progressive destruction of the articular cartilage. Minimization of hemorrhages is the key to preventive treatment, along with dynamic splinting for contractures. In end-stage disease, total joint reconstruction or arthrodesis may be necessary under protection of large infusions of factor VIII.
Synovial Lesions Pigmented villonodular synovitis is a proliferative inflammatory process of synovium of unknown cause. Patients have a thickened, brownish proliferation of synovium that causes progressive joint destruction. Effusions aspirated from the affected joint will be brown because of the hemosiderin content. Treatment consists of early synovectomy, by either arthrotomy or arthroscopy.
Synovial chondromatosis is a condition of cartilaginous metaplasia of synovium that may become detached and form loose bodies within the joint. This condition, like pigmented villonodular synovitis, is monarticular and slowly progressive and is best treated by synovectomy.
Toxic or transient acute synovitis of the hip occurs in childhood and mimics septic arthritis or Legg-Calvé-Perthes disease. It frequently follows a viral illness and usually presents with a limp or refusal of the child to walk. One must exclude septic arthritis, and hip aspiration is generally necessary to accomplish this. Treatment is symptomatic with bed rest, skin traction, and protected weight bearing until the condition resolves.
Slipped Capital Femoral Epiphysis This condition affects adolescents ages 1015 years and is more common in males. It presents with hip pain and a limp and involves slippage of the epiphysis medially and posteriorly on the femoral neck. Patients have a loss of internal rotation of the hip and an antalgic gait. The condition is bilateral in 25 percent of patients. Diagnosis is by orthogonal radiographs of the hip. The condition is treated by pinning in situ (subacute or chronic slips) or by closed reduction and pinning (acute slips). Chondrolysis is a complication of this disease, more common in blacks and females. Patients can develop secondary degenerative changes later in life.
Neuropathic (Charcot) Joints A Charcot joint results from any denervating process affecting the extremities. Tabes dorsalis, syringomyelia, leprosy, diabetes, or spinal cord injury may lead to neuropathic joints. It is generally thought that joint destruction results from repeated trauma to joints with impaired sensation. The joint may undergo very rapid and severe destruction, with gross instability and swelling but minimal inflammation. Arthrodesis is difficult to achieve; usually conservative methods such as bracing are used.
TUMORS OF THE MUSCULOSKELETAL SYSTEM
Primary bone tumors are relatively rare, but a number of both benign and malignant types occur. Musculoskeletal neoplasms are characterized by initial centrifugal growth from a single focus, pseudoencapsulation, and a tendency to respect anatomic compartment boundaries during growth (bone, muscle fascia, joint capsules, neurovascular sheaths). Metastasis usually is hematogenous to lung or bone. The surgical staging system used for bone and soft tissue tumors is shown in Table 41-6. Diagnostic evaluation includes radiographs, MRI or CT scan of the lesion, bone scan, and lung CT scan, preferably before biopsy of the lesion. Biopsy incisions should be longitudinal and excisable en bloc at the time of definitive surgery, cortical bone windows oval and small, frozen sections and cultures obtained on all specimens, neurovascular structures avoided, meticulous hemostasis achieved, drains placed in line with incision, and contamination of uninvolved compartments avoided. Treatment for benign lesions involves resection or curettage and bone grafting. Malignant lesions usually are treated by a combination of surgery, radiation therapy, and chemotherapy depending on the tumor type. Technological advances in bone grafting and prosthetic devices in conjunction with better adjuvant radiation and chemotherapy regimens now allow limb salvage surgeries with tumor resection and preservation of function in the majority of cases of musculoskeletal sarcomas.
TABLE 41-6 SURGICAL STAGING SYSTEM FOR MUSCULOSKELETAL TUMORS (AFTER ENNEKING)
Primary bone-forming tumors are listed below:
- Osteoma: This is a small, benign, sessile lesion of dense bone usually occurring in the skull bones and generally asymptomatic. No treatment is necessary.
- Osteoid osteoma: A benign, sclerotic bone-forming tumor of children and young adults that is usually painful and less than 1 cm in diameter. Aspirin often relieves the pain, and adjacent bone may show sclerotic thickening. Excision must include the radiolucent central nidus of the lesion to prevent recurrence.
- Osteoblastoma: A benign, bone-forming tumor of children and young adults, common in the spine, which is histologically identical to osteoid osteoma but larger in size. Curettage and bone grafting are the treatment.
- Osteosarcoma: This is the most common aggressive malignant bone tumor, generally involving the metaphyses of long bones about the knee and predominantly found in adolescents. Pulmonary metastases are frequent, and treatment consists of amputation or radical resection with limb reconstruction, in conjunction with systemic chemotherapy. Occasionally seen in older patients as a secondary malignancy arising in Paget's disease or following radiation treatment. Parosteal osteosarcoma is a less aggressive variant arising extraosseously adjacent to the periosteum, usually near the knee in young adults.
Cartilaginous tumors include the following:
- Osteochondroma (exostosis): A benign exophytic growth from the metaphyses of long bones with a cartilage cap. Multiple form is hereditary. Secondary malignant change can occur in older adults (chondrosarcoma). Simple excision when indicated is curative.
- Enchondroma: A benign, sometimes expansile cartilaginous tumor of the metaphyses of long bones or the tubular bones of the hands that exhibits calcification radiographically. Pathologic fractures can occur, as can late secondary malignant change. Treatment, when necessary, consists of curettage and bone grafting.
- Chondroblastoma: A benign tumor of the epiphyses of children that may cause joint pain or effusion and is treated by curettage and bone grafting.
- Chondrosarcoma: A malignant tumor of cartilage, most commonly seen in the metaphyses of long bones and in the pelvis of adults age 3060 years. Wide resection or amputation is needed, and chemotherapy or radiation is of little benefit. Secondary tumors can arise in older individuals from an enchondroma or osteochondroma.
Fibrous tumors of bone include
- Nonossifying fibroma (metaphyseal fibrous cortical defect): A benign fibrous lesion of childhood that is usually an incidental radiographic finding. Large lesions may cause pathologic fractures. Lesions spontaneously regress at skeletal maturity.
- Fibrosarcoma: An aggressive malignancy, rare as a primary tumor in bone. Radical surgical removal or amputation with radiation usually needed for treatment.
Other musculoskeletal tumors include
- Giant cell tumor (osteoclastoma): An aggressive, destructive, benign epiphyseal tumor of young adults, with a high recurrence rate with local treatment. A small percentage are frankly malignant and can metastasize to the lungs. Treatment is with resection and limb reconstruction or thorough curettage and cementation with methyl methacrylate bone cement, which seems to reduce local recurrence incidence.
- Unicameral bone cyst: This is a metaphyseal, expansile, benign lesion of childhood, most commonly seen in the upper humerus or femur, consisting of a fluid-filled cavity in the bone. Pathologic fractures are common, and the lesion resolves spontaneously after skeletal maturity is reached. Steroid injections into the lesion may effect healing, and occasionally curettage and bone grafting are necessary, but the recurrence rate is 50 percent.
- Ewing's sarcoma: An aggressive malignancy of childhood affecting the diaphyses of long bones, with permeative bone destruction and periosteal reaction, which must be differentiated from solitary eosinophilic granuloma and osteomyelitis. Treatment is with systemic chemotherapy and radiation, with 5070 percent 5-year survival.
- Reticulum cell sarcoma (primary histiocytic lymphoma of bone): A malignant tumor of bone occurring in the diaphyses of long bones in patients aged 2040 years. Treated by radiation unless metastases are present, in which case chemotherapy is used.
- Aneurysmal bone cyst: An aggressive, benign, expansile lesion of the metaphyses in children or young adults. Lesion is vascular, with blood-filled cystic spaces, and is treated by curettage or resection, except for inaccessible lesions in the spine or pelvis, which may respond to intermediate-dose radiation.
- Hemangioma: A benign vascular tumor of bone that is usually asymptomatic and most commonly diagnosed as an incidental finding on spine films; generally, no treatment is needed.
- Adamantinoma: A low-grade malignancy resembling an epithelial tumor arising in the diaphyses or metaphyses of long bones (usually the tibia) in young adults. Wide resection or amputation is the usual treatment.
- Chordoma: A slow-growing malignancy derived from notochordal remnants usually occurring in the sphenooccipital or sacrococcygeal areas of middle-aged adults. Recurrence incidence is high after surgical resection.
- Soft tissue sarcomas: Include fibrosarcoma, malignant fibrous histiocytoma, rhabdomyosarcoma, liposarcoma, neurofibrosarcoma, synovial sarcoma, and epithelioid sarcoma. All are treated by aggressive surgery or amputation, often in conjunction with radiation and chemotherapy.
- Metastatic tumors of bone: A number of cancers that do not arise primarily in bone have a propensity to metastasize to bone, including breast, prostate, lung, kidney, and thyroid carcinoma and neuroblastoma. Patients may present with pain or pathologic fractures. The lesions generally are controlled by radiation treatment, and fractures are stabilized surgically with rods or plating and bone cement, followed by radiation treatment for the lesion.
For a more detailed discussion, see Rosier RN: Orthopaedics, chap. 41 in Principles of Surgery, 7th ed.
Copyright © 1998 McGraw-Hill
Seymour I. Schwartz
Principles of Surgery Companion Handbook