Chapter 18 Special Topics

Reflex Sympathetic Dystrophy

Reflex sympathetic dystrophy (RSD), now commonly referred to as complex regional pain syndrome 1 (CRPS), is a common disorder of unknown cause that often follows a relatively minor injury. It has been called by several names: Sudeck’s atrophy, causalgia, shoulder–hand syndrome, posttraumatic dystrophy, and others. The pathogenesis of the disorder is unclear, but a disturbance in the sympathetic nervous system apparently develops that leads to the characteristic symptoms and signs of intense pain (allodynia) and vasomotor disturbances. The condition usually affects the extremity rather than the torso. Early recognition is difficult. CRPS is divided into two types with similar clinical features, but type 2 is associated with more significant nerve injury, including causalgia and traumatic neuralgias.

CLINICAL FEATURES

The diagnosis of RSD can be difficult to make and is based primarily on history and examination. Clinical manifestations can be variable, but persistent burning pain that develops after an injury is the characteristic feature. Three stages (acute, dystrophic, and atrophic) are often described. The acute stage lasts up to 6 to 12 weeks and is characterized by the development of persistent burning pain. The injury is often trivial, but the pain is characteristically severe and out of proportion to the amount of trauma. Initially, the pain is localized to the area of the injury, but gradually it spreads throughout the extremity. Hypersensitivity to light touch is a frequent symptom. The extremity appears swollen and warm, and excessive perspiration may be present. In the later dystrophic and atrophic stages, motion in the affected joints becomes restricted, and the involved area becomes cool. Skin and muscle atrophy develop, and the skin appears dry, shiny, and glossy. Stiffness and intractable pain may persist for several weeks or months. RSD is commonly associated with anxiety and depression.

Although no imaging studies are diagnostic, plain roentgenograms may eventually reveal patchy osteoporosis (Fig. 18-1). The bone scan may be positive, showing regional uptake that is diagnostic and reflects increased blood flow.

FIG. 18-1 Roentgenogram of the ankle several weeks after a relatively minor sprain. Severe osteoporosis (Sudeck’s bone atrophy) of the lower portions of the tibia and fibula are present.

TREATMENT

RSD is best treated by prevention. All injuries should have immediate attention, and pain and swelling should be controlled. Early use of the extremity is also important. Once RSD develops, it is very difficult to treat. The most important aspect of therapy is restoration of motion by exercise. Active use of the extremity should be encouraged despite the pain. The edema may be controlled by elevation. Physical therapy in the form of passive range-of-motion exercises may be helpful but should not replace active home exercise by the patient. Smoking should be discouraged. Among the pharmacologic agents sometimes effective are antidepressants, corticosteroids, and calcium channel blockers. Repeated sympathetic blocks are sometimes helpful. The treatment is often prolonged, but most patients eventually improve.

Rotational Deformities of the Legs in Children

Developmental abnormalities of the lower extremities are common and are frequently a source of concern to parents. The cause of these deformities is unknown, but hereditary and persistent postnatal malpositioning play important roles. Most correct themselves spontaneously.

IN-TOEING

The in-toeing gait pattern seen in young children is the most common rotational deformity and is usually secondary to one or more of the following causes: (1) internal rotation deformity of the hip secondary to contracture or excessive femoral anteversion, (2) internal (medial) torsion of the tibia, or (3) metatarsus varus (adductus) of the foot. In-toeing is usually the result of metatarsus adductus in the infant, internal tibial torsion in the toddler, and increased femoral torsion in the child over the age of 10.

All three of these deformities are aggravated by positions or postures that are frequently assumed by the child or infant. Lying in the prone position with the legs extended and the feet internally rotated is often associated with in-toeing deformity. Sitting in the “reverse-tailor” position with the feet internally rotated beneath the buttocks is directly related to persistent tibial rotation and adduction of the forefoot (Fig. 18-2). Children may assume these positions for extended periods of time while sleeping, playing, or watching television.

FIG. 18-2 The reverse-tailor position.

Children with internal rotation deformities have a high incidence of bowing of the lower extremities. This is frequently more apparent than actual, because the lower limb is never visualized in the true anteroposterior plane but rather in the oblique plane. The gait is occasionally clumsy, and the appearance may be unsightly.

The treatment of metatarsus varus depends on whether the deformity is fixed. If the foot is flexible and the deformity easily overcorrectable, passive stretching exercises and a straight or reverse-last shoe are sometimes tried, although their effectiveness is unknown (Fig. 18-6). If the forefoot is rigid and passive correction of the deformity is not possible, early treatment with corrective casts may be indicated. The correction should begin shortly after birth. When the disorder is seen after the age of 1 or 2 years, operative intervention is occasionally necessary. Early diagnosis is therefore important.

FIG. 18-6 Stretching exercises for metatarsus varus (arrows). The heel is firmly grasped. The forefoot is then passively manipulated into the corrected position and held for 10 seconds. The exercise is repeated two to three times at regular intervals during the day.

OUT-TOEING

External rotation deformity of the lower extremities is usually caused by the following: (1) external rotation of the hip secondary to soft tissue contracture or femoral retroversion (external femoral torsion), (2) external tibial torsion, or (3) pes calcaneovalgus, or flatfeet. Out-toeing is often associated with a genu valgum deformity and may be aggravated by sleeping in the prone position (Fig. 18-7). The use of wide diapers or a children’s “walker” with a wide pad may potentiate an externally rotated gait.

FIG. 18-7 The prone sleeping position, which frequently potentiates external rotation deformities.

If femoral retroversion is the cause, examination reveals that external rotation of the hips is significantly greater than internal rotation. External tibial torsion is diagnosed by the marked posterior position of the lateral malleolus compared with the medial. The flatfoot deformity is frequently associated with eversion of the heels (see Chapter 12).

TREATMENT

Observation and reassurance are all that is indicated. Improper postural habits should be corrected. Wide diapers and walkers with wide canvas slings are avoided. Stretching exercises are begun for any hip deformity. Any additional treatment is not helpful, and surgery is rarely necessary.

Angular Deformities of the Legs in Children

GENU VARUM (BOWED LEGS)

Genu varum with mild internal tibial torsion is a common, almost normal finding in early childhood. With growth and weight bearing, this developmental bowing spontaneously corrects itself in more than 95% of patients. There is even a normal physiologic “swing” to a knock-knee deformity between the ages of 18 months and 3 years in many cases. The knock-knee deformity then usually corrects itself between the ages of 4 and 7 years.

The child is commonly brought to the doctor because of the wide space between the knees and the mild in-toeing gait. Other possible causes of bowing (such as rickets and Blount’s disease) can generally be ruled out by the child’s history. Roentgenograms may be necessary. There is usually no evidence of any intrinsic bone disease. The amount of genu varum can be determined by measuring the distance between the medial femoral condyles with the child standing and the medial malleoli touching.

Developmental genu varum is usually not severe and rarely requires any treatment. The family can be reassured that spontaneous correction usually occurs by the age of 3 years. Any associated metatarsus varus should be appropriately treated, however. Severe cases should be referred at a young age to rule out Blount’s disease.

This is an uncommon pathologic, developmental bowing that results from altered growth of the upper medial tibial epiphysis (Fig. 18-8). The cause is unknown, but abnormal pressure may play a role. Blount’s disease is more common in obese early walkers and children of short stature. It is also more common in blacks. It may be unilateral, in contrast to physiologic bowing, which is almost always bilateral. Two forms of Blount’s disease are described: an infantile type, which begins before age 3; and an adolescent form, which starts after age 8. Before the age of 2, the infantile form may be difficult to differentiate from physiologic bowing, especially if it is bilateral. Although physiologic bowing resolves with growth, Blount’s disease progressively worsens. A strong family history and severe bowing are indications for roentgenographic evaluation.

FIG. 18-8 Diagram of Blount’s disease, showing disturbance of the growth of the medial tibial epiphysis.

Early recognition (before age 2) and differentiation from physiologic bowing are important. Early referral is indicated for all children suspected of having the disorder. Bracing before age 3 may be effective. Otherwise, surgical correction is usually necessary.

GENU VALGUM (KNOCK-KNEE)

Knock-knee may be caused by a variety of disorders, including injury and metabolic disease. However, most genu valgum is present as one stage in the normal physiologic “swing” between developmental genu varum and normal alignment. It is usually bilateral and is most common between the ages of 2 and 4 years. The severity of the deformity can be determined by measuring between the medial malleoli or Achilles tendons with the child standing, the medial femoral condyles touching, and the patellae facing forward (Fig. 18-9). Similar measurements can be taken on return visits to confirm spontaneous correction if reassurance is needed.

FIG. 18-9 Measuring genu valgum.

Most patients need only reassurance and follow-up. The rare case that persists beyond the age of 7 years may require brace correction. If the deformity is excessive or unequal, a thorough search should be made for the underlying abnormality.

Leg Length Inequality

Limb length discrepancies in the lower extremities may result from several causes. The most common are fractures, osteomyelitis, neuromuscular disease, and vascular anomalies. Usually, the affected limb is shorter, but occasionally the inequality is the result of overgrowth because of epiphyseal stimulation by inflammation or injury. Frequently, no cause is found. The inequality may cause a mild limp and compensatory scoliosis.

In children, a thorough search should be made to determine the cause. If any is found, the appropriate treatment is instituted. If no cause is noted and the difference is less than 1 cm, the child is followed by repeated careful measurements until mature to determine whether the inequality is static or increasing. Both types of inequality require specialized care, and surgical correction of the asymmetry may be indicated. In children with growth remaining, equalization of the discrepancy may be accomplished either by lengthening the shortened extremity or by partially stopping epiphyseal growth on the longer extremity.

In the adult, the amount of leg length discrepancy that is clinically significant is controversial, but it appears that up to 2.0 cm of shortening is well tolerated. However, chronic low back pain that may be accompanied by a leg length discrepancy can be empirically treated with a shoe lift to compensate for some of the difference (1- to 1.5-cm correction for a 2-cm difference, for example). There are no scientific studies that correlate leg length discrepancy with low back pain, but occasionally patients experience some improvement with a shoe lift to equalize length.

Primary Bone Tumors

Primary bone tumors are relatively uncommon in comparison to metastatic or secondary neoplasms. Because such a great variety of tissues comprise bone, classification of neoplastic processes arising in the skeleton is often difficult. Most bone tumors or tumor-like conditions are benign, but some of these, such as giant cell tumor and osteoblastoma, often recur after local resection and can even metastasize. Sometimes, this type of tumor is classified as “intermediate” in nature between benign and malignant. These neoplasms are occasionally fatal, but normally, metastatases from this group are not life threatening. True malignant tumors of bone, on the other hand, are often difficult to eradicate.

BENIGN BONE TUMORS

Most common benign bony neoplasms are either fibrous or cartilaginous. Cystic lesions such the simple bone cyst (see Chapter 5) occur with some frequency but may not be true neoplasms. The benign lesions that occur with any frequency are as follows: (1) fibrous cortical defect; (2), nonossifying fibroma; (3) fibrous dysplasia; (4) enchondroma; and (5) osteochondroma. Most of these lesions are diagnosed by a specific clinical and radiographic presentation, often related to the age of the patient and the bone involved. And although the radiographic appearance may not always be pathognomonic in all cases, certain characteristics are highly suggestive of specific lesions. Radiologic or orthopedic referral is valuable to determine the significance of such lesions.

Enchondromas are benign tumors of cartilage usually located centrally in bone. The most common sites are the small bones of the hand and feet (Fig. 18-10). The enchondroma is the most common tumor of the bones of the hand. It most often occurs in patients between the ages of 10 and 50 years. Symptoms are nonspecific. The lesion is usually discovered incidentally or is identified after a pathologic fracture. Treatment is simple observation if the diagnosis is obvious. If enough bone weakness is present, leading to recurrent fracture, or if the diagnosis is uncertain, surgical intervention is indicated.

FIG. 18-10 Enchondroma of the phalanx. The lesion is well circumscribed. A pathologic fracture is present.

Osteochondromas are the most common of all benign bone growths. They may not actually be neoplasms but are more likely developmental abnormalities thought to be the result of some “pinching-off” of a portion of growth cartilage. This lesion begins to grow separately, and its growth ceases when the patient reaches skeletal maturity. The typical site of formation is on the metaphysis near the growth plate of the distal femur or proximal tibia, but they can be found on other long bones (Fig. 18-11). Most lesions consist of a stalk that is directed away from the growth plate from which it originated. The lesion is covered with a cartilaginous cap. Signs and symptoms are related to the presence of the mass, but most are only minimally symptomatic. The lesion is removed if producing symptoms. These lesions commonly regress when growth ceases.

FIG. 18-11 Osteochondroma of the humerus. The lesion is contiguous with the normal cortex, and there is no bony destruction.

Fibrous lesions of bone are common benign neoplasms that are usually discovered incidentally. Fibrous cortical defects are common in growing bone and have a characteristic radiographic appearance (Fig. 18-12). They are asymptomatic and do not require further investigation or treatment. The lesions most likely resolve within 2 to 3 years.

FIG. 18-12 Fibrous cortical defect (arrow).

Nonossifying fibromas are similar lesions histologically but are much larger (Fig. 18-13). Biopsy is not usually required, but treatment may be needed in large lesions that are painful. These often regress as well.

FIG. 18-13 Nonossifying fibroma of the distal tibia. The lesion is well circumscribed.

Fibrous dysplasia is a developmental disturbance of bone formation in which fibroplastic proliferation occurs. The disorder may be monostotic or polyostotic. Endocrine abnormalities may also be present. Marked deformities may develop over time. The tibia is commonly involved, and pathologic fracture may occur (Fig. 18-14). Referral for surgery is indicated when deformity or pathologic fracture develops.

FIG. 18-14 Fibrous dysplasia of the tibia with bowing and a pathologic fracture.

MALIGNANT BONE TUMORS

Primary malignant bone tumors are invasive, anaplastic, and have the ability to metastasize. Most arise from the marrow (myeloma), but tumors may develop from bone, cartilage, fat, and fibrous tissues. Leukemia and lymphoma are excluded from this discussion. Fibrosarcoma and liposarcoma are extremely rare. They are similar to those tumors arising in soft tissue. Osteosarcoma is an uncommon primary malignant tumor of bone characterized by malignant tumor cells that produce osteoid or bone. Several variants have been described: parosteal sarcoma, periosteal sarcoma, multicentric, and telangiectatic forms. Chondrosarcoma is a malignant cartilage tumor that may develop primarily or secondarily from transformation of a benign osteocartilaginous exostosis or enchondroma. Ewing’s sarcoma is a malignant tumor of unknown histogenesis, and multiple myeloma is a neoplastic proliferation of plasma cells.

Multiple myeloma is the most common tumor in bone. The age of onset is usually over 40. It may present as a systemic process or, less commonly, as a “solitary” lesion. Early manifestations include anorexia, weight loss, and bone pain; the majority of cases present initially with back pain that often leads to the detection of a destructive skeletal lesion. Other organ systems eventually become involved, resulting in more bone pain, anemia, renal insufficiency, and/or bacterial infections, usually as a result of the dysproteinemia typical of this disorder. Secondary amyloidosis may develop, leading to cardiac failure or nephrotic syndrome.

Osteosarcoma most often develops between the ages of 10 to 20. Most lesions originate in the metaphysis, 50% to 60% around the knee. Pain and swelling may be present, but otherwise the patient is healthy. Osteosarcoma may develop in conjunction with Paget’s disease, manifested primarily as a sudden increase in bone pain.

Chondrosarcoma most often involves the pelvis, upper femur, and shoulder girdle in patients over age 40. Painful swelling may be the only finding.

Ewing’s sarcoma is typically a disorder that develops between the ages of 10 to 15. A painful soft tissue mass is often present sometimes with increased local heat The midshaft of a long bone is usually affected (in contrast to other tumors). Weight loss, fever, and lethargy are associated findings.

EVALUATION

The evaluation and treatment of malignant bone tumors are complicated. Diagnostic studies and treatment should be supervised by an orthopedic cancer specialist and oncologist. The age of the patient and the initial radiographic features often determine the next appropriate diagnostic steps. Laboratory evaluation may be helpful. Alkaline phosphatase is often elevated in osteosarcoma. In Ewing’s sarcoma, the findings include: reflective of systemic reaction, symptoms include anemia, an increase in white blood cell (WBC) count, and an elevated sedimentation rate. In multiple myeloma, findings include the following: (1) Bence Jones protein in the urine; (2) anemia and elevated sedimentation rate; (3) characteristic dysproteinemia on serum protein electrophoresis; (4) the diagnostic feature of a peak in the electrophoretic pattern suggestive of a monoclonal gammopathy; (5) rouleaux formation in the peripheral blood smear; and (6) often, presence of hypercalcemia, but alkaline phosphatase levels usually normal.

Imaging studies are often diagnostic. Classic osteogenic sarcoma penetrates the cortex early in many cases. The radiographic findings may vary as follows. (1) a blastic (dense), lytic (lucent), or a mixed response may be seen in the affected bone. (2) An aggressive perpendicular sunburst pattern may be present as a result of periosteal reaction, and peripheral Codman’s triangles are often noted. (3) The margins of the tumor are poorly defined.

Speckled calcifications in a destructive radiolucent lesion are usually suggestive of chondrosarcoma. Ewing’s sarcoma is characterized radiographically by mottled, irregular destructive changes with periosteal new bone formation. The latter may be multilayered, producing the typical “onion skin” appearance.

The typical roentgenographic finding in multiple myeloma is the “punched-out” lesion with sharply demarcated edges (Fig. 18-15). Other characteristics include the following: (1) multiple lesions are usual; (2) diffuse osteoporosis may be the only finding in many cases; and (3) pathologic fractures are common.

FIG. 18-15 Multiple myeloma of a vertebral body (arrows).

TREATMENT AND DISPOSITION

In the past 20 years, dramatic improvements have been made in the treatment protocols for osteosarcoma with the use of adjuvant multidrug regimens and limb-sparing surgery.

Early diagnosis is important because most tumors have not metastasized at the time of the initial presentation. Five-year survival rates of 70% have been obtained in some series. The prognosis for multiple myeloma remains poor, despite new therapies. Complete remissions are uncommon. Survival with a solitary lesion may be long, but most patients succumb after a median of 3 years.

The prognosis for Ewing’s sarcoma has improved with a combination of chemotherapy, local resection, and radiation therapy. Chondrosarcomas are not sensitive to chemotherapy or radiation, and the prognosis depends on the grade of the tumor and the ability to obtain an adequate resection.

Spinal Cord Compression

Spinal cord compression is the neurologic loss of spinal cord function. Lesions may be complete or incomplete and develop gradually or acutely. Incomplete lesions often present as distinct syndromes, as follows: (1) central cord syndrome; (2) anterior cord syndrome; (3) Brown–Séquard syndrome; (4) conus medullaris syndrome; and (5) cauda equina syndrome.

CLINICAL FEATURES

Clinical findings reflect the amount of spinal cord involvement (Fig. 18-16): there are usually motor loss and sensory abnormalities. Babinski testing is usually positive, and clonus is commonly present. Gradual compression is often manifested by progressive difficulty walking, clonus with weight bearing, and involuntary spasm; development of sensory symptoms; bladder dysfunction is a late finding. The following list describes findings in various types of spinal cord syndromes:

1 Central cord syndrome results in a variable quadriparesis with the upper extremities more severely involved than the lower extremities; there is some sensory sparing.

2 Anterior cord syndrome results in motor, pain, and temperature loss below the lesion

3 Brown–Séquard syndrome is a spinal cord syndrome caused by injury to either half of the spinal cord and resulting in the loss of motor function, position, vibration, and light touch on the affected side. Pain and temperature sense are lost on the opposite side.

4 Conus medullaris syndrome results in variable motor loss in the lower extremities with loss of bowel and bladder function.

5 Cauda equina syndrome typically involves low back pain, weakness in both lower extremities, saddle anesthesia, and loss of voluntary bladder and bowel control (see Chapter 8).

FIG. 18-16 Spinal cord compression. A, Central cord syndrome. B, Anterior cord syndrome. C, Brown–Séquard syndrome.

ETIOLOGY

Among the most common causes of spinal cord syndromes are trauma, tumor, infection, and degenerative disc conditions with spinal stenosis. Sometimes the central cord syndrome develops from compression of the cord from the front by a bulging or degenerative disc and from the back by a buckled ligamentum flavum. The stenotic spine may be more susceptible. Other causes of cord compression are inflammatory processes, cystic abnormalities, and severe disc herniation.

EVALUATION

Spinal cord compression requires an immediate referral for radiographic and neurologic assessment. Laboratory results are usually unremarkable unless infectious or inflammatory causes are suspected, Imaging studies depend on the suspected etiology. Magnetic resonance imaging (MRI) is usually required.

Spinal Braces

Braces are appliances that allow partial movement of a joint. They perform several functions, including protection and stabilization. They are most commonly used to temporarily support and restrict motion in the treatment of painful disorders of the spine. There is no evidence that wearing a brace “weakens” the back, but the patient should always be encouraged to exercise and maintain proper muscular tone if the brace is being used for pain management only and not for fracture stabilization.

CERVICAL COLLARS

Cervical collars extend from the head to the thorax and are usually soft, although semirigid collars are also available (Fig. 18-17). The soft collar is usually more comfortable but restricts motion less than the other collars. These appliances are all used in the treatment of degenerative disc disease and minor ligamentous or muscular injuries of the cervical spine.

FIG. 18-17 Cervical collars. A, The soft foam collar. B, The adjustable collar. C, The Philadelphia collar.

TAYLOR BRACE

This is a fundamental back brace useful in dorsal and lumbar spine disease (Fig 18-18). It is a high, semirigid brace that may be modified. Degenerative disc disease and minor fractures may be treated with this brace or one of its modifications (long Taylor, modified Taylor, and short Taylor).

FIG. 18-18 Spinal braces. A, The Taylor brace. B, The Knight spinal (chairback) brace. C, The Jewett hyperextension brace. D, The lumbosacral support. (From Camp International, Inc, Jackson, MI. Used by permission.)

These supports are usually made of canvas and may be reinforced with metal stays. They are commonly used in the treatment of lumbar disc disease and chronic low back pain syndromes. They may also function to increase the intraadominal pressure, which may aid in the support of the lower portion of the back. They are more comfortable than the Knight spinal brace but provide less support.

Disability Rating

The physician is often called on to determine the amount of disability that is present as the result of musculoskeletal disease or injury. This determination is frequently used as the basis for settlement in workers’ compensation cases, as well as in personal injury litigation. However, it is usually the “physical impairment rating” expressed as a percentage rather than “disability” that must be determined. It is not the duty of the physician to determine how this impairment affects the patient socially or economically. Often, however, it is the impairment rating that is used as the sole basis for the determination of disability by those administrators responsible for it.

Disability may be defined in various ways and is not a medical term but rather an administrative one. It does not simply mean pain that has persisted for several months. (Pain without objectively validated limitations in daily activities has no impairment.) Medically, it is physical impairment that prohibits the performance of normal physical function. For Social Security purposes, disability means the inability to do any work for at least 12 months because of a physical impairment. Legally, it means permanent bodily injury for which restitution may be judged necessary. Under workers’ compensation statutes, disability is frequently divided into (1) temporary total disability, during which period of time the patient is under care and unable to work; (2) temporary partial disability, during which time recovery is sufficient that some employment may be begun; or (3) permanent disability, which is permanent loss of function after maximum recovery.

Physical impairment can usually be measured accurately on the basis of the loss of physical function. A careful clinical history and physical examination are mandatory. Laboratory and roentgenographic analysis may also be necessary.

For the determination of specific ratings for each impairment, the following manuals are excellent: Manual for Orthopedic Surgeons in Evaluating Permanent Physical Impairment, Guide to the Evaluation of Permanent Impairment (AMA), and Disability Evaluation Under Social Security. Patients need to understand that a disability rating follows them for life. Although there may be some short-term financial benefit, an impairment rating can sometimes adversely affect future employability.

Joint Replacement Surgery

Great advances have been made in the past 25 years in the surgical treatment of degenerative and rheumatoid arthritis. These advances have been primarily caused by improvements in the techniques of joint arthroplasty. This procedure is most commonly used for conditions of the hip and knee, but devices have been developed for use in almost every joint (Fig. 18-19). The indications for surgery are the presence of arthritis and failed medical management.

FIG. 18-19 A, Severe rheumatoid arthritis of the hand with dislocations of the metacarpophalangeal joints. B, Postoperative roentgenogram after metacarpophalangeal replacement. The alignment and function are markedly improved. The thumb has also been fused.

The basic purpose of these techniques is to implant a device into the joint that replaces the degenerated articular surfaces. Most joint replacement procedures use a hard plastic, high-density polyethylene for the socket (Fig. 18-20). This articulates with a metallic component, both components usually being fixed to the bone by a cementing compound, methylmethacrylate, or by an in-growth system.

FIG. 18-20 A, Degenerative arthritis of the knee. B, Postoperative roentgenogram after total knee replacement.

The goal of joint replacement surgery is to eliminate the disability that results from pain, loss of motion, and malalignment. It is suitable in patients with bilateral disease, and advanced age is no contraindication. It has been used successfully in almost every age group. Rehabilitation after a joint replacement is usually rapid. Patients older than 65 years of age can expect a 90% 15-year implant survival.

Mechanical problems with total knee replacement are slightly more common than those after total hip replacement, but the results are uniformly good in both procedures. More than 90% of patients undergoing arthroplasty have excellent relief of pain and improvement in motion. Short-term problems are those related to infection and venous thrombosis, both of which are treated prophylactically. Long-term concerns include aseptic loosening and osteolysis, a term used to describe an inflammatory response to particulate debris that can lead to bone loss and implant failure.

Compartment Syndromes of the Lower Leg

Compartment syndromes are disorders of the extremities in which increased tissue pressure compromises the circulation to the muscles and nerves within the space (see Chapter 15). These conditions are most common in the lower part of the leg, where four natural compartments exist (anterior, lateral, deep posterior, and superficial posterior). The anterior compartment is most commonly involved.

The disorder may be acute or chronic. Chronic cases may be confused with stress fractures, tendinitis, and other forms of “shin splints.” The acute case is associated with significantly greater morbidity.

CLINICAL FEATURES

The acute form of compartment syndome may follow fractures, burns, trauma, or vascular injury. Patients with peripheral vascular disease are at risk because poor tissue perfusion leads to ischemia and transudation of fluid, which increases compartment pressure. Extreme pain, numbness, and weakness are the most common complaints. The pain is often very severe because of muscle and nerve ischemia. The chronic case is usually related to exercise, and symptoms are generally mild. Weakness, hypoesthesia, and pain on passive stretch of the involved muscle are usually present. The affected area may also be swollen and tense. The peripheral pulse is often diminished. There is usually an increase in intracompartmental tissue pressure that can be measured directly.

Roentgenographic findings are usually normal (except in fractures) but should be obtained in chronic cases to rule out stress fracture.

TREATMENT

Chronic cases usually subside with rest, but fasciotomy is occasionally performed to prevent recurrence. The acute form requires immediate surgical decompression. Without treatment, necrosis of muscle and nerve may occur and result in permanent weakness, contracture, and nerve dysfunction similar to Volkmann’s ischemic contracture in the upper extremity (see Chapter 2).

Injection and Aspiration Therapy

Locally injected analgesics and steroids are frequently used in the treatment of musculoskeletal diseases. Their use in many specific disorders has been described in previous chapters. This section deals with their usage in other common conditions.

The ability of steroids to relieve pain and improve the function of inflamed joints, tendons, and bursae is unquestioned. And although a cellular inflammatory response is not always present in those disorders usually called “arthritis” and “tendinitis,” corticosteroid injections have been shown by randomized, controlled trials to provide excellent relief of pain in these conditions. The exact mechanism by which this is accomplished is unknown. It is theorized that these drugs reduce the local infiltration of those cells and compounds that mediate the inflammatory response. An increase in local blood flow and improvement in local tissue metabolism are other common explanations. A placebo effect is undoubtedly present in some cases. Systemic absorption is less after their use than it is with oral administration. However, some absorption does occur, and plasma cortisol levels can be suppressed for up to 1 week after injection. Markers of bone formation, such as osteocalcin, can also be depressed transiently but return to normal in 2 weeks after intraarticular use of a corticosteroid, while markers for bone resorption do not change, suggesting that there is no effect on bone resorption and only a temporary effect on bone formation.

Greater systemic absorption occurs when a given dose is divided equally and instilled into two joints than when administered into one joint. Although not well documented, subtle adverse effects of cortisone use may also be seen. (For example, joint injections may temporarily help other conditions such as hay fever and allegies.) It is known that absorption causes insomnia in some patients the first night after injection. Diabetes control may also be temporarily altered by the use of intraarticular cortisone. Diabetic patients should be made aware of the potential for transient hyperglycemia and the need to monitor themselves more closely for a few days. Because of the systemic absorption, 3 to 4 weeks should pass before reinjecting large joints.

There are very few negative effects associated with steroid injections, and the benefits far outweigh any potential risks. They are highly cost effective compared with other intraarticular injectable agents and are not associated with the side effects so commonly seen with nonsteroidal anti-inflammatory drugs (NSAIDs). There is, however, individual variability regarding the response to these drugs. Many of the concerns expressed by patients (and physicians) are often based on myth and misinformation. Among the causes of apprehension are (1) a general patient fear of needles, and (2) the belief that that steroid shots are painful. In general, they are no more or less painful than most intramuscular injections, depending on the volume of material injected and site of the injection. The experience of the physician also plays some role, as does the size of needle and speed of injection. (3) Fears of “steroids.” These fears are often related to the well-known side effects associated with long-term oral prednisone use. (4) Fear of infection or damage from the needle. These complications are rare, but may occur if proper preparation and technique are not followed. (5) That once started, injections are needed forever. Injections are not expected to “cure” arthritis but may help cure tendonitis, which often heals on its own eventually. (6) The belief that steroids make joints worse. There is no evidence that steroids accelerate degenerative changes in joints compared with control groups.

There is little to be gained by a “series” of shots or by repeating an injection to relieve a small amount of residual pain after a successful first shot. There is also nothing gained by giving a shot too early, and nothing is lost by trying other treatments first.

A variety of materials are available, but the most commonly used is 1% plain lidocaine, usually mixed with 1 mL of one of the various corticosteroids, either short- or long-acting. Many steroids are offered in different strengths, although the more concentrated solutions may offer no advantage over the less concentrated ones. The duration of action varies inversely with the degree of solubility. The stronger, less soluble forms should be avoided in superficial injections, because they are more likely to cause subcutaneous atrophy and depigmentation. (Dark skin depigmentation effects may be more apparent.) The more water-soluble compounds may cause less lipoatrophy but have a shorter duration of action. (Atrophy often reverts to normal when the steroid is absorbed. This may take up to a year.)

The lidocaine and steroid may be injected separately but are usually mixed together. The use of a small amount of lidocaine alone for skin and soft tissue infiltration may be necessary in the apprehensive patient. If a joint with a thick capsule is to be entered, the capsule may also need to be infiltrated because passing a larger needle through the capsule may be uncomfortable for the patient. Do not use the steroid mixture to anesthetize the site; use only the anesthetic. Otherwise, atrophy may occur. The anesthetic is best injected with a 25-gauge needle (⅝-inch or 1 ½-inch). This needle size may also be used to inject the steroid–lidocaine mixture, especially if the injection is superficial. A 22-gauge, 1 ½-inch needle is sometimes necessary in deeper injections. A “giving” sensation usually occurs as the needle penetrates the tough, fibrous capsule, especially in the knee. The needle should not be advanced once the joint has been entered to avoid joint trauma. Aspirating the syringe while withdrawing the needle may prevent residual drops of the mixture from contaminating the skin and subcutaneous tissue.

The dose of cortisone is usually based on volume; 1 to 2 mL is used for larger joints and lesser amounts for smaller joints (Table 18-1). Tendons, except the quadriceps and elbow epicondyles, usually are not directly injected. Instead, it is usually a space (joint, tendon sheath or subacromial space) that is injected. There should be little resistance when injecting a space. If resistance occurs, the needle tip is probably incorrectly placed in some soft tissue, and its position should be changed. The volume of fluid injected depends on the size of the joint or soft tissue area.

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