The Back

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Chapter 8 The Back

Back pain is one of the most frequent conditions requiring medical treatment. It is also the most expensive ailment for patients between the ages of 30 and 60 years and one of the most difficult to treat. Back pain may be caused by a variety of disorders, including gynecologic, genitourinary, and gastrointestinal diseases, but the most common causes are disorders of the lumbar disc.

Anatomy

The vertebrae, discs, and ligaments of the dorsal and lumbar spine are similar in most respects to their counterparts in the cervical spine. The lumbar vertebrae are larger and thicker, however, because of their weight-bearing function (Fig. 8-1). Anterior and posterior longitudinal ligaments are applied to the respective surfaces of the vertebral bodies, and posterior stability is aided by supraspinous and interspinous ligaments and the ligamentum flavum. The discs account for more than one third of the total height of the lumbar spine and account for most of the normal lordosis.

FIG. 8-1 A typical lumbar vertebra. S, Superior articular facet; I, inferior articular facet; P, pedicle; T, transverse process; B, body.

Spinal nerves exit the canal by passing through intervertebral foramina; each foramen consists of the inferior aspect of the pedicle above and the superior aspect of the pedicle below the level of exit. In the lumbar spine, disc disease usually affects the nerve root exiting one level below, because that is the nerve that actually passes over the disc (Fig. 8-2). Thus, a herniated disc between the fourth and fifth lumbar vertebrae commonly affects the fifth nerve root and not the fourth.

FIG. 8-2 Relationship of nerve roots to discs in the lumbar spine.

History

The evaluation of the patient with back pain should first begin with the obvious questions regarding the common causes of spine disorders (trauma, disc disease, degenerative disorders, etc.). However, because low back discomfort can develop in conjunction with a variety of diseases not considered orthopedic in nature, this initial assessment should also include information developed about general medical disorders that could be causally connected with the spine complaints. This is especially true if the symptoms appear atypical (pain radiating into the groin, testicle, vulva, or inner thigh). If this cannot be done on the initial visit because of limited time, it eventually must be done if the patient’s condition does not improve and the patient returns with the same complaints.

A few simple questions should be sufficient for general system review as follow:

1 Are there any gastrointestinal (GI) symptoms (blood in stool, incontinence, etc.)?

2 Are there any genitourinary (GU) symptoms (incontinence, renal pain, etc.)?

3 Are there any general systemic complaints (fever, weight loss, peripheral joint symptoms, etc.)?

The smoking history is always critical. In addition, certain “red flags” should signal the possibility of a more serious condition underlying the low back complaints (Table 8-1).

Table 8-1 Red Flags

Fever, malaise

History of malignancy

Night pain or pain at rest (suggests spinal malignancy)

Incontinence, perianal sensory loss

Weight loss of unknown origin

Loss of strength, balance

Sudden worsening of pain level

History of substance abuse or issues of secondary gain

Night sweats

Significant morning stiffness

Examination

Valuable information can be gained by simple observation of the patient getting in and out of the chair and then moving around naturally in the examination room. The gait pattern can easily be assessed at this time as well. Then, examination of the back is performed with the patient standing, sitting on the examining table, and then lying in the supine position. The back is first inspected with the patient in the standing position. Any areas of enlargement are noted. The back is palpated for points of tenderness, and any list or excessive kyphosis or lordosis is noted. Next, the chest is measured in full inspiration and expiration. Normal expansion is greater than 5 cm but may be less than 2.5 cm in patients with ankylosing spondylitis. The iliac crests are then palpated to determine whether they are level. If they are not, footboards of varying thicknesses may be placed under the shorter extremity to assess the amount of shoe lift necessary to level the pelvis. (Up to 2 cm of leg length difference seems to be well tolerated with no apparent increase in the rate of low back pain.) The shoulders are also observed for evenness, although the dominant shoulder is frequently lower in the normal population. The spine and sacroiliac joints are palpated and percussed for tenderness. Any varicosities in the lower extremities are also noted.

The range of motion is then slowly tested. With the patient bending forward as far as possible, flexion is measured as the distance between the fingertips and the floor. This calculation represents a combination of lumbar spine mobility and hamstring flexibility. While the patient is flexed forward, the back is viewed from behind to detect any scoliosis and from the side to detect any persistence of the normal lumbar lordosis that might be present secondary to protective muscle guarding. Extension and right and left bending are then measured. Pain on bending toward the affected side frequently signifies disc disease, whereas pain on bending away from the affected side frequently denotes muscle strain. The gait pattern is again observed, and the ability to walk on the heels (L5 root) and balls of the feet (S1 root) is tested (“toe and heel walking”).

With the patient in the sitting position, a complete neurologic examination of the lower extremities is performed. Reflexes, motor strength, and sensation are tested. The thighs and calves are measured to detect any muscular atrophy. Discrepancies of greater than ½ inch in the thigh and ¼ inch in the calf are significant. Straight leg raising in the sitting position is also tested and compared with straight leg raising tests that will be performed in the supine position. The peripheral pulses are palpated and any abnormalities in the vascular status of the extremity noted, especially dependent rubor.

With the patient in the supine position, the hip is placed through a full range of motion and thoroughly tested to rule out primary hip abnormality. The straight-leg–raising tests are then performed, and the leg lengths are measured (Fig. 8-3). Next, with the patient on the side, manual pressure is applied to the iliac crest (pelvic compression test). Reproduction of pain in the sacroiliac joints or symphysis pubis with this maneuver may suggest disorders of these areas. The presence or absence of clonus can be determined at this time, and Babinski testing can be performed (Fig. 8-4).

FIG. 8-3 The lower extremities are measured between the anterior superior iliac spines and the medial malleoli with the leg in neutral alignment. Discrepancies less than 1 cm are probably not significant.

FIG. 8-4 Babinski test. A sharp instrument is lightly scraped along the plantar aspect of the foot from the calcaneus along the outer border. The leg should be relaxed. If the ankle dorsiflexes or the foot withdraws, reduce the intensity of the stimulus. A, In a negative response the toes bunch together or do not move. B, An abnormal response includes extension of the great toe, while the other toes may splay and flex. The Babinski test is normally positive in the newborn but disappears soon after birth. An abnormal response indicates an upper motor neuron lesion. However, the response may be absent if there is damage to the reflex arc at the nerve or root level.

At this time, if it is indicated, a more complete general examination focusing on a particular system or area can be performed if an underlying medical disorder is suspected as the cause of the back pain.

Roentgenographic Anatomy

An evaluation of disorders of the lumbar spine should include a standard roentgenographic examination. The roentgenographic features are well visualized by the following: anteroposterior view (Fig. 8-5, A), lateral view (Fig. 8-5, B), and oblique views in both directions (Fig. 8-6). In addition, a spot lateral view of the lumbosacral space may be necessary.

FIG. 8-5 Anteroposterior (A) and lateral (B) view of the lumbar spine. S, Spinous process; P, pedicle; T, transverse process; L, lamina; A, articular facet joint; B, body; I, intervertebral foramen.

FIG. 8-6 Oblique view. A, Articular facet joint; I, isthmus or pars interarticularis; T, transverse process; L, lamina; P, pedicle. The oblique view visualizes the so-called Scottie dog. Spondylolysis occurs through the isthmus (arrow).

Lumbar Disc Syndromes

The intervertebral disc is probably the major source of most back pain, and the pattern of disc deterioration in the lumbar spine is similar to what occurs in the cervical spine. The majority (95%) of disc lesions in the lumbar spine occur at the fourth and fifth spaces, with most of the remainder occurring at the third space. With normal aging, biochemical and mechanical changes occur in the nucleus pulposus. Eventually, disc material may begin to protrude or even herniate into the neural canal. This most often occurs in the area of greatest weakness of the anulus fibrosus at the posterolateral aspect of the disc (Fig. 8-7). Herniation is most common in the third and fourth decades and is rare before the age of 15. Chronic disc deterioration (spondylosis) may also develop over time and result in osteophyte formation, disc space narrowing, and degenerative changes in the facet joints and between adjacent vertebral bodies. (NOTE: In addition to mechanical causes, chemical and inflammatory factors may also play some role in the development of back pain. Although the mechanical causes may be the easiest to visually understand, a precise diagnosis as to the etiology of back pain in many patients simply cannot be established with any certainty.)

FIG. 8-7 Lumbar disc protrusion. Note that the herniation affects the root that exits one level below.

A rare but serious complication of lumbar disc disease is the cauda equina syndrome. This results from a massive central disc herniation and may produce variable degrees of permanent paralysis in the lower extremities. Bladder and bowel function may also be severely impaired. This condition is a true emergency and usually demands immediate evaluation and surgery.

CLINICAL FEATURES

Disc disease (herniation and/or degeneration) may result in several overlapping clinical syndromes: (1) mild herniation without nerve root compression; (2) herniation with nerve root compression; (3) cauda equina syndrome; (4) chronic degenerative disease with or without leg symptoms; and (5) spinal stenosis.

The onset of symptoms from disc herniation is variable. One specific traumatic episode may produce symptoms, but because of the progressive nature of the disease process in the disc, the symptoms usually develop gradually as the disc slowly changes. (How much herniation is required to produce symptoms is unknown, but “bulging” of the disc commonly reported on magnetic resonance imaging [MRI] studies is probably not sufficient.) The most common complaint is low back pain, which is often deep and aching in nature. This pain, which is sometimes referred to as axial, is usually one sided and may be aggravated by activity and relieved by rest. Coughing, sneezing, or other actions that increase the stress on the disc tend to intensify the pain. The back pain is often localized near the disc and may be referred to the iliac crest or buttock. It is may be the result of stretching of the anulus by the expanding, protruding disc. Radicular pain occurs when the disc protrudes far enough to press on the adjacent nerve root. Nerve root pain is usually quite intense. Often, if the disc herniates completely (extrudes), the low back pain may be relieved because the tension on the anulus is gone, but the leg pain intensifies.

Axial low back pain may occur in combination with radiating pain, or the two pain patterns may occur separately. Radicular pain characteristically spreads over the buttock and passes down the posterior or posterolateral aspect of the thigh and calf and may even spread onto the foot. Both types of pain usually improve with bed rest. If little or no relief of pain occurs with rest, inorganic causes should be considered. Relentless pain that is not relieved or may even be aggravated by recumbency suggests a spinal cord tumor.

Paresthesias in the form of numbness and tingling are common and are usually more marked in the distal portion of the extremity. They may follow a specific dermatome pattern (Fig. 8-8).

FIG. 8-8 Dermatomes of the lower extremity.

Examination often reveals restriction of low back motion. Bending toward the affected side frequently exacerbates the pain. Variable degrees of local tenderness and muscle guarding are present. In an attempt to relieve pressure or tension on the nerve root, the patient may list or bend away from the painful side and stand with the affected hip and knee slightly flexed. A characteristic clinical picture may be present, depending on the level of nerve root involvement (Table 8-2). The sensory examination may reveal diminished sensation along the affected dermatome, although the sensory examination is usually not very helpful. The various tests measuring sciatic nerve root tension are frequently positive if herniation is causing nerve compression (Fig. 8-9).

Table 8-2 Clinical Features of Common Lumbar Disc Syndromes

FIG. 8-9 Testing for nerve root tension. The foot is slowly raised, keeping the knee straight, until sciatic pain is produced. A positive test includes the following: (1) pain produced before 70 degrees is reached, (2) aggravation of the pain by dorsiflexion of the ankle, and (3) relief of the pain by flexion of the knee. If the patient can extend the leg to 90 degrees while sitting but the same test is impossible in the supine position, pain magnification should be suspected. If raising the leg on the contralateral side reproduces pain in the affected leg, disc herniation should be strongly suspected.

SPECIAL STUDIES

The diagnosis usually becomes apparent on the basis of the history and physical examination. Early disc herniation may be difficult to differentiate from other causes of back pain, however.

1 Plain roentgenograms are usually not required before 2 to 4 weeks unless trauma is involved or there is the possibility of some serious underlying condition.

2 Electromyography (EMG), computed tomography (CT), MRI, or myelography is used to confirm the diagnosis (Fig. 8-10). They are not usually indicated for at least 4 to 6 weeks. The myelogram is not a procedure without some morbidity, and all of these tests are costly. They are indicated under the following circumstances: (1) if surgical intervention is being contemplated or (2) if other, more serious spinal pathology is suspected. Myelography is gradually being replaced by the other imaging studies. If it is performed, spinal fluid analysis may show a slight increase in protein content if disc herniation is present.

3 Provocative discography has popularity among some spine surgeons but is considered to be controversial by others.

FIG. 8-10 Abnormal lumbar myelogram revealing a large extradural defect (arrow) in the dye column that is consistent with disc herniation.

NOTE: The number of symptomatic conditions discovered by special studies but not suspected clinically is very small. Tests such as MRI and EMG should only be performed as adjuncts to the clinical assessment.

TREATMENT

The initial treatment is always conservative, and the majority of patients respond well. Treatment is based on the symptoms of the patient and not on any imaging study. Extended periods of inactivity are no longer recommended for most low back disorders, but a short period of bed rest (5 to 10 days) may be very helpful in the treatment of acute disc herniation, mainly if radicular leg pain caused by nerve root compression is present. This is followed by a careful exercise program. While the patient is in bed, the hips and knees are kept moderately flexed. Lying on the abdomen, which increases the lumbar lordosis, is avoided. Hip flexion and pelvic tilt exercises are begun within the limits of pain (Fig. 8-11). Nonsteroidal anti-inflammatory drugs (NSAIDs), analgesics, and moist heat are used as necessary. Narcotics may even be required in cases of nerve root compression and intense leg pain. If improvement occurs, which it does in the majority of cases, gradual resumption of activity is allowed, and the exercise program is expanded. Physical therapy is often useful, mainly for the exercise program. Modalities such as deep heat and massage can be added for their “hands-on” appeal. A lumbosacral corset may be temporarily used. (There is no evidence that continued use of any brace promotes back weakness, however, especially if the patient adheres to an exercise program.) Recurrences are prevented by a proper exercise program and the avoidance of stress to the lower part of the back (Fig. 8-12).

FIG. 8-11 Low back exercises. A, Pelvic tilt performed to decrease the lumbar lordosis and raise the anterior aspect of the pelvis. The small of the back is pressed to the floor, and the abdominal and buttock muscles are tightened. B, Hip flexion, performed to stretch the tight posterior spinal musculature and unload the posterior disc. Each knee is drawn up and pulled firmly to the chest several times and held for 10 to 20 seconds. The exercise is then repeated with both knees. After the acute pain has subsided, the remainder of the exercises are performed. C, Hamstring stretching exercises. D, Hip flexor stretching exercises. E, Quadriceps strengthening and heel cord stretching exercise. F, Abdominal strengthening exercise (sit-ups, which may be partial). All exercises are performed on a carpeted floor and should be repeated in sets of 5 to 10 at least three times daily.

FIG. 8-12 General postural instructions. Patients should be instructed to do the following. A, Bend the knees and hips, and keep the back straight when lifting. B, Hold objects close to the body when carrying. C, Place one foot on a stool when standing. D, Keep the knees higher than the hips when sitting, and keep the back straight when standing by “tucking in” the abdomen and tightening the buttocks to decrease swayback. In addition, patients should avoid high-heeled shoes and sleeping on the abdomen, activities that increase lordosis.

Caudal or epidural cortisone injections are often very helpful. They may help relieve residual radicular pain. They tend not to relieve axial spine pain and may have no effect on acute leg pain if there is persistent nerve root compression from herniated or extruded disc material.

The prognosis for full recovery is excellent, and the majority of patients with disc herniation will improve with conservative treatment. Mild axial spine pain may recur on a sporadic basis indefinitely, however. Most of the time, this can be managed with mild analgesics and physical therapy. Motivation and reassurance are important. Keeping the patient active and comfortable can be difficult and challenging. What happens to the disc material that has herniated is unknown. It is theorized that it may act as a foreign body and be invaded by granulation tissue. Ultimately, the material may be absorbed or transformed into scar tissue. Larger herniations may actually regress the most.

Disc removal is reserved for those patients with major or progressing neurologic deficits or those with intractable leg pain who fail to respond to conservative management for at least 6 weeks. Of those patients with radicular leg pain documented by radiographic studies, fewer than 5% require surgery to relieve their symptoms. The patient must understand that disc removal is performed to relieve leg pain and that it has no effect on axial spine pain.

There are several ways of removing disc tissue, but the results of surgery are influenced more by patient selection that by the manner that the disc is removed. With a positive history, physical findings, myelography (or similar study), and EMG, there is a 90% to 95% success rate for surgery. In the absence of one or more of these, the cure rate for disc removal by any means declines considerably. Patients must also be cautioned that although their leg pain will usually disappear postoperatively, some mild intermittent low back pain may persist.

SUMMARY

Surgery is effective in most cases, but selection is the key. When advising treatment, the following well-known facts should always be kept in mind:

1 There is no long-term difference in the outcome of most patients treated conservatively (by nature) and those treated surgically. The major benefit to surgery is that the intense pain in the leg is relieved sooner.

2 Disc removal by any means does not cure back pain, only leg pain.

3 Having sciatic nerve root pain does not assume surgery.

4 Before any procedure is contemplated, radicular symptoms should have been present for at least 6 weeks and should have failed to improve with at least 2 weeks of complete bed rest. If this rule is strictly followed, the majority of patients will get better on their own without surgery.

5 Cauda equina syndrome (back pain, bilateral sciatica, saddle anesthesia, and motor weakness sometimes with incontinence) is the only absolute indication for disc removal and is often performed on an emergency basis.

CHRONIC LUMBAR DISC DISEASE

A high percentage of adults older than 40 years of age have degenerative disc disease at one or more levels on roentgenographic examination (Fig. 8-13). Significant thinning of the disc accompanied by osteophyte formation is often present. And MRI studies commonly reveal “bulging” disc abnormalities in patients, many of whom are without symptoms. These roentgenographic changes are common in the general population and are present in 30% to 40% of normal individuals. They are so common, in fact, that some question whether or not lumbar disc disease should be considered a “disease” or simply a change which occurs with age. Disc degeneration and the accompanying changes in the adjacent facet joints with soft tissue inflammation can, however, lead to intermittent low back pain and even nerve root irritation or compression with leg pain. The severity of the symptoms often bears no relation to the severity of the radiographic findings, however.

FIG. 8-13 Chronic degenerative disc disease in an adult with only minimal symptoms.

Pain of this nature usually responds to conservative management. NSAIDs, analgesics, rest, moist heat, and the use of a lumbosacral corset may be the only treatment necessary. Exercises, education, and postural training are important. Risk factors associated with chronic back pain should be addressed, such as smoking and poor physical conditioning. A physical therapist can be helpful in this regard. When signs of nerve root irritation with radicular pain are present, compression or irritation of the root by a small, acute, soft disc herniation or degenerative osteophyte should be suspected. The leg pain often responds well to epidural pain blocks. Surgical intervention is occasionally indicated to relieve nerve pressure. Arthrodesis of the adjacent vertebrae may rarely be indicated to relieve chronic low back pain by stabilizing the degenerated painful disc segment but the procedure is highly controversial (see Chapter 18). Conservative treatment is usually successful in most cases. Recurrences are not uncommon and generally respond to medical management.

LUMBAR SPINE STENOSIS

Lumbar spinal stenosis is a syndrome in which narrowing of the spinal canal and nerve root foramina occurs, thus decreasing the space available for the neural elements; this may lead to vague and unusual symptoms. The disorder occurs secondary to a combination of disc degeneration, facet joint arthritis, and subluxation and occasionally to a congenitally small spinal canal. These changes can lead to abnormal pressure on spinal nerve roots.

CLINICAL FEATURES

The history is highly suggestive. Neurogenic claudication is a hallmark symptom. Low back pain, motor weakness, leg cramping (pseudoclaudication), and a sensation of “poor circulation” in the extremities are typical. The patient is usually older than 50 years of age. The symptoms are characteristically aggravated by walking and by extension of the lumbar spine. Improvement usually occurs with rest or flexion of the back. While grocery shopping, the patient often leans forward onto the cart to relieve the leg pain. These symptoms are often misinterpreted as being vascular in origin. Vascular symptoms will improve with rest, however, whether the patient is standing or sitting, but the patient with neurogenic claudication usually requires sitting because the forward flexed position increases the cross-sectional area of the bony canal, thereby relieving the symptoms. Sphincter disturbances and muscle atrophy rarely may be present. Physical findings typical of disc herniation are usually absent. Neurologic findings are also frequently minimal, and results of a straight-leg–raising test are usually normal. Pain on extension of the lumbar spine may be severe. The vascular examination is usually normal, but because vascular disease and stenosis occur in similar age groups and can produce similar symptoms, vascular studies may be necessary in some cases to differentiate the two conditions.

Roentgenographic examination of the lumbar spine usually reveals degenerative changes throughout the lower part of the back. EMG and myelography may help localize the disorder, and CT scanning is frequently diagnostic (Fig. 8-14). MRI is also helpful.

FIG. 8-14 Normal (A) and abnormal (B) computed tomographic scans of the lumbar spine. Marked narrowing (arrow) is present in B because of hypertrophic spurring.

TREATMENT

Nonsurgical treatment is the mainstay of care for the patient with degenerative stenosis. Treatment is directed at reducing the lumbar lordosis and promoting lumbosacral flexion. A light corset is sometimes beneficial. Anti-inflammatory medication may be prescribed, but unfortunately, the older patient who develops this conditon often cannot tolerate NSAIDs, and simple analgesics may be more suitable. Hip flexion and abdominal strengthening exercises may also be helpful. Periodic epidural pain blocks can relieve the leg symptoms.

The long-term prognosis is generally good. Serious neurologic sequelae are unusual. Patients who fail to improve with nonsurgical care may need to be referred to a surgeon who specializes in spine disorders.

THE FACET SYNDROME

The small articular facet joints of the spine have occasionally been implicated as a cause of chronic low back pain. They may become affected secondary to disc thinning and frequently develop arthritis. And even though arthropathy is a common finding in these joints, the relationship of this abnormality to back pain has been difficult to prove. As a result, many doubt the existence of this disorder. The patient is often one who has a long history of chronic spine pain that has not responded to the traditional methods of management. Clinically, there may be local facet tenderness and pain on side bending. To alleviate the symptoms, injection and even denervation of these joints have occasionally been performed. The results of these treatments are only modestly successful.

Lumbar Strain

Acute muscular or ligamentous injury is a common cause of low back pain. Incomplete muscular tears or ligament sprains occur and lead to pain and tenderness over the affected area. The simple acute injury usually heals quickly and should respond well to brief rest and symptomatic treatment. When the injury is superimposed on a chronic pattern of low back pain or lumbar disc disease, the course is often more protracted, however. When there is a delay in the normal recovery time of the simple soft tissue injury, other problems may have to be considered, particularly those related to the disc. And because of the common findings of incidental disc abnormalities in the normal population, the relevance of these radiographic findings in cases of low back strain is difficult to establish.

Many patients who sustain what appear to be seemingly minor low back strains fail to improve. A variety of factors are probably involved. Obesity, poor muscular tone, smoking, faulty work habits, the wearing of high-heeled shoes, and the lack of a daily exercise program are among the contributing factors. The center of gravity of the body may become shifted forward, which leads to an increase in the lumbar lordosis. This may place an added strain on the discs, ligaments, and muscles to maintain an upright posture. Chronic back pain is also frequently seen in teenagers who are vigorous weightlifters.

Smoking has a clear connection with low back pain. Smokers have a higher incidence of chronic back problems and recover more slowly from injuries. Microcirculatory factors are probably involved.

Obesity contributes to chronic low back pain in other ways. First, it is known that intraabdominal pressure aids the erector spinae muscles in keeping the lumbar spine erect and decreases intradiscal pressure. Obese patients have poor abdominal muscular tone. Obese patients also typically have an increase in their lumbar lordosis, which further adds stress to the lower part of the back.

With a daily program of proper postural exercises, weight loss, and a general exercise program, most patients who develop chronic back pain will be able to rehabilitate the lower part of the back. The use of modalities (hot packs, massage, etc.) in physical therapy is discouraged, although short-term use may allow the exercise program to be more easily implemented. Full cooperation is necessary.

NOTE: The term lumbar strain is often used as a “wastebasket” diagnosis. An exact diagnosis of low back pain in many cases of this nature may be difficult. Muscle strain, ligament sprain, and mild early disc herniation or degeneration may all present with similar clinical findings. Regardless of the cause, the initial treatment is the same. A short period of rest (1 to 2 days) and mild analgesics followed by a gradual return to activities may be all that is needed. Early return to normal activities is important. Walking or other similar aerobic exercise is started promptly to prevent deconditioning (generalized cardiovascular and musculoskeletal deterioration). Patients with chronic back pain benefit from postural back exercises and correction of obesity. Relaxation techniques are sometimes helpful. Active participation by the patient is most important. Passive care (massage, manipulation, etc.) has very little long-term benefit. Proper lifting and bending habits are stressed.

Isthmic Spondylolisthesis

Spondylolisthesis is a disorder, usually in the lumbar spine, in which one vertebra gradually slips on another. Several types have been described (congenital, degenerative, pathologic, traumatic, and spondylolytic). However, most spondylolisthesis is secondary to spondylolysis, which represents a fibrous defect in the pars interarticularis or isthmus of the vertebra (Fig. 8-15). The disorder is therefore probably acquired and not congenital. The development of this defect has a hereditary predisposition and usually becomes manifested as the result of impact loading and extension stresses to the lower part of the back. These cause the development of an overuse fatigue fracture, usually bilateral, at the isthmus that fails to heal, resulting in a fibrous nonunion. It is most common at L5-S1. It develops in the teenage years, but may not become symptomatic until years later, if at all. It is often associated with lumbosacral anomalies such as transitional vertebrae and spina bifida occulta. There is an increased incidence in football players and gymnasts, possibly from hyperextension and chronic overload. If the defect is bilateral, forward displacement (spondylolisthesis) can occur. Spondylolisthesis is classified according to the amount of forward slippage of the affected vertebra (Fig. 8-16). An increase in slippage often occurs during the adolescent growth spurt but is rare after maturity.

FIG. 8-15 Bony defect (arrow) in the isthmus or neck of the “Scottie dog” present in spondylolysis (oblique view).

FIG. 8-16 Meyerding’s classification of spondylolisthesis. The amount of slippage is graded 1 to 4. Grade 1 represents 25 % forward displacement; grade 2, 25% to 50%; grade 3, 50% to 75%; and grade 4, greater than 75%.

CLINICAL FEATURES

Spondylolysis may be symptomatic even without spondylolisthesis, and both conditions may be associated with lumbar disc herniation. The disorder is often asymptomatic, however, and is frequently discovered incidentally in adults on roentgenograms taken for other purposes. When it is seen on roentgenograms taken as a part of a routine evaluation for back pain, it is often difficult to determine whether or not it is playing any role in the patient’s complaints.

Symptoms from spondylolisthesis may begin gradually in the second or third decade. Low back pain, sometimes radiating into the buttocks, occurs with activity and is relieved by rest. If the lesion is acute, symptoms of nerve root irritation may also be present, along with radiation of the pain into the extremities. These symptoms often progress in severity, especially in the teenager.

Examination may reveal guarding of the lower part of the back and “spasm” of the paraspinal muscles, especially in the adolescent. Many children have no pain, however, but present with postural deformity or an abnormal gait pattern resulting from hamstring tightness. With moderate forward slippage, the lumbar lordosis appears increased, and the buttocks may appear more prominent. A palpable “step-off” in the spinous processes of the lumbar spine may be present. There may be tenderness in the affected area and hamstring tightness. Neurologic deficits are rare.

Roentgenograms reveal the typical findings of a defect in the pars interarticularis on both sides, which may be accompanied by forward slippage (Fig. 8-17). Unilateral defects are unusual. The classic findings of periosteal new bone present in stress fractures of long bones are rarely seen in the spine. A bone scan may be positive if the lesion is “acute” in the adolescent. MRI may be indicated in cases of negative bone scan to rule out other causes of pain. CT is also helpful to assess healing potential.

FIG. 8-17 Spondylolisthesis of the lumbosacral junction.

TREATMENT

In the adolescent, the goal of treatment is to achieve healing of the stress fracture and if that is not possible, to have a painless nonunion. It is helpful to determine if the lesion is simply a stress reaction that has not yet progressed to a complete fracture. It is also important to assess healing and the status of the lesion, whether acute or chronic. If the lesion is acute and no slip is present, the patient may benefit from prolonged bracing and restricted activities for several months in an attempt to encourage bony healing before nonunion can develop, which could allow slippage to occur. If the scan is cold and chronic with several millimeters of separation, then the lesion probably will never heal, especially if healing has not occurred by 6 months. In this case, such extreme limitations on the patient’s activities would not be helpful. Then, the treatment is similar to that for an adult.

Management in the adult is usually conservative and consists of rest, a careful exercise program, hamstring stretching, weight loss, anti-inflammatory medication, and the intermittent use of a lumbosacral orthosis. A change in occupation or work habits is sometimes indicated. The spondylolisthesis may increase in degree, but this is a gradual process and usually ceases by maturity. Further slippage in adulthood is rare. Progressive symptoms or intractable pain occasionally warrants surgical intervention. Decompression with spinal fusion is usually performed.

DEGENERATIVE SPONDYLOLISTHESIS

This type of spondylolisthesis results from disc degeneration and narrowing. When the process of disc “settling” is uneven, spondylolisthesis can develop (Fig. 8-18). The signs and symptoms are those of degenerative disc disease, sometimes accompanied by those of stenosis. Although many patients are pain-free, low back and occasionally radicular leg pain may develop. The treatment is the same as that for chronic degenerative disc disease and stenosis.

FIG. 8-18 Degenerative spondylolisthesis at L4–5. The disc is markedly narrowed.

Back Pain in the Workplace

A variety of terms have been used to describe this condition, including “chronic benign industrial back pain” and “chronic pain syndrome.” This terminology partly reflects the difficulty in assigning a specific diagnosis and cause for the pain. A part of this difficulty, in turn, is a result of the fact that low back pain in general, and especially back pain in the workplace may be the result of a variety of biomechanical, biochemical, behavioral, socioeconomic, and psychophysiologic factors. In addition, trying to distinguish between a work injury and a normal disease of life can have profound implications for the patient.

EVALUATION

The treating physician is often required to give an opinion regarding the etiology of musculoskeletal conditions involved in workers’ compensation, so obtaining an accurate physical examination and history is especially important to determine whether an injury actually occurred or if the pain simply developed during or after an activity. If pain began some time later, it should be recorded how much time passed between the event or work activity and the onset of symptoms. The pain may be referred to one or both legs, but it is usually not truly radicular in nature. Frequently, a description of the location and nature of the pain changes slightly from visit to visit.

Physical findings are often nonspecific. There is usually generalized low back tenderness and diminished range of motion. Sometimes, the physical findings are “nonanatomic” in nature. Waddell signs are often cited when nonorganic physical findings are present (Table 8-3). There is usually no neurologic deficit, and sciatic tension tests are generally normal but may be difficult to assess.

Table 8-3 Waddell Tests

These findings should not be taken as a sign that no illness is present, but simply that this may be a way that patients can show how bad it is to them.

• Nonanatomic weakness or sensory disturbances

• Superficial or nonanatomic tenderness

• Inconsistent test findings when distracted

• Pain on simulated stress tests

• Overreaction

SPECIAL STUDIES

All of the anatomic structures of the lower part of the back (discs, ligaments, facet joints, bone, and muscle) can be the source of pain. The intervertebral disc is thought by many to be the source of most low back pain. Unfortunately, as many as 35% of asymptomatic adults will have abnormal findings on myelography, CT, or MRI that are usually related to the disc. This makes evaluation of this problem difficult, and it is felt by many that in the majority of cases, the exact underlying pathology probably cannot be determined and the condition is simply called “idiopathic.” Initially, a routine roentgenographic examination should be performed in 2 to 4 weeks if the patient does not improve, mainly to rule out any serious disorder. Further studies (EMG, CT, MRI, bone scan, myelography) should be performed only as adjuncts to the physical examination and history. The yield of clinically useful information from these studies is often poor. Subjecting patients to further extensive testing in a search for the exact etiology of their pain is likely to be futile, sometimes painful, and always costly. Diagnosing a spinal disorder solely on the basis of any of these tests should be avoided. It is rare that these special tests clearly demonstrate a source for the pain when it is not suspected clinically. In addition, any treatment (e.g., surgery) based solely on a special study will often fail. In general, myelography and other special studies should be used only under the following circumstances: (1) if surgical disc removal is contemplated for intractable leg pain or a serious neurologic deficit, or (2) if other serious spinal abnormality is suspected.

TREATMENT AND PROGNOSIS

Considerable controversy exists regarding the treatment of this problem. Historically, the disorder has always been resistant to traditional medical care. Thus, there has been a proliferation of rehabilitation services, pain centers, work-hardening programs, surgical procedures, chiropractic care, and physical therapy services. Patients often prefer this type of “hands-on” treatment, but no scientific proof exists that any of these treatments is any better than nature’s own. And although orthopedic and neurologic surgeons are commonly called on to assess and treat this condition, in fewer than 1% of these cases is surgery ever indicated (usually for leg pain associated with severe disc herniation), and not for at least 6 to 8 weeks. Surgery may even become a negative factor for returning the patient to work in that it gives validity to the injury.

Fortunately, the natural history of most back problems is that they improve and the end result of conservative management is usually good. Unfortunately, the longer the patient is away from work with benign low back pain, the less likely it is that the patient will ever return to gainful employment, and after 6 months of not working, the chance that the patient will return to any work is minimal. Thus, for a number of reasons, the trend for managing this condition has changed. There has been a de-emphasis on the initial rest period and more encouragement to early exercise and returning to work on a limited basis. This trend has developed largely because of the low success rate with prolonged bed rest and the belief that it causes a deterioration of the musculoskeletal and cardiopulmonary systems (deconditioning). It has also been shown that patients who begin exercise programs quickly after minor low back injuries have less pain and are disabled for shorter periods of time. (Only the patient with nerve root impingement because of disc herniation may require more rest.) The following approach may be helpful:

1 Reassurance and education. Instructions should be given regarding proper body mechanics and lifting habits. The patient needs to know that hurt does not mean harm and that returning to work is safe.

2 Limit activities for no more than a few days, and take mild analgesics followed by over-the-counter medication.

3 Temporarily avoid bending and lifting, and use a chair with good lumbar support and armrests when sitting.

4 Begin a walking, biking, or swimming program as soon as possible. A back rehabilitation program is gradually added as tolerated. As with any low back pain, spine stabilization exercises, stretching, and general conditioning are important.

5 Avoid the excessive use of passive treatment (massage, heat, etc.). Encourage active patient involvement, especially with the exercise program. Relaxation techniques may be helpful.

6 Encourage a return to work (work activities may initially have to be modified). Time off from work is discouraged.

It is important for the treating physician to remain the patient’s advocate but to be objective at the same time, a situation that often results in conflict. Patients should be made to understand that the pain may recur if they resume light work, but it is usually not as severe as it was initially and does not mean any damage is occurring. It should not require further time off from work. The patient should continue the exercise program and practice good body mechanics. (A formal education program may be necessary.) Active participation by the patient and compliance are extremely important.

If no improvement has occurred after 4 to 6 weeks, referral to a specialist is indicated. Psychosocial factors and work-related conditions may also need investigation. The attitude of the patient to the job and involvement of the employer also play important roles in the length of disability. Workers who like their jobs and employers who promote a good working environment are more likely to have a mutually satisfactory relationship.

Thoracic Disc Disease

Disc degeneration in the dorsal spine is common although it rarely produces symptoms. The most serious sequela of thoracic disc disease is acute or progressive spinal cord compression from central disc herniation, leading to paralysis. Unilateral nerve root compression from lateral herniation also occurs.

CLINICAL FEATURES

Only axial dorsal spine pain occurs in most cases. With central herniation and myelopathy, however, gradually increasing motor weakness in the lower extremities becomes apparent. Sphincter control may be lost, and diffuse numbness is common. Sensory testing may help determine the level of involvement. Examination usually reveals limited motion in the dorsal spine. Major neurologic deficits may be present in the lower extremities (spasticity, clonus). Roentgenographic examination often reveals calcification, narrowing, and spondylosis in the dorsal spine. Myelography may reveal a complete block in central lesions. MRI is often needed.

TREATMENT

Treatment is symptomatic for the typical case, with thoracic pain caused by degenerative disc disease. Symptoms in most cases with no cord compression resolve without sequelae. The treatment is surgical in those with cord compression caused by disc rupture, and immediate referral is indicated. Residual neurologic deficits are not unusual, in spite of surgical decompression.

Scoliosis

Scoliosis is a general term used to describe a lateral curvature of the spine in the upright position. The lateral curvature is usually accompanied by some rotational deformity and sometimes by an increase in the normal kyphosis or lordosis. Scoliosis may be classified as either structural or nonstructural. Structural curves are fixed and nonflexible and fail to correct with side bending. Nonstructural curves, on the other hand, are flexible and readily correct with side bending. Nonstructural scoliosis is frequently seen as a compensatory mechanism secondary to a leg length discrepancy, local inflammation, or irritation from acute lumbar disc disease. This type of scoliosis tends to disappear when the offending disorder is treated, such as correcting a leg length inequality with a lift in the shoe.

Structural scoliosis may occur from a variety of causes. Congenital abnormalities in the spine with anomalous vertebral formation may lead to asymmetric growth and result in scoliosis. Neurofibromatosis and a variety of neurologic and myopathic conditions may also lead to structural scoliosis. The most common type, however, has no known cause and is usually termed “idiopathic.”

Idiopathic scoliosis accounts for approximately 90% of all scoliosis. The etiology is probably multifactorial. It appears to represent a hereditary disorder, but the exact mechanism of its production is unknown.

CLINICAL FEATURES OF IDIOPATHIC SCOLIOSIS

Genetic or idiopathic scoliosis usually appears clinically between the ages of 10 to 13 years, but may be seen at any age. By definition, the curve must be greater than 10 degrees. (This has been used historically because 10 degrees is the limit that can be detected by clinical examination.) It is six times more common in females, and serious curvatures are also more frequent in females. Right thoracic curves are the most common. In young people, the disease is usually asymptomatic, and subjective complaints are absent. (Pain should suggest tumor or other disorder.) Many cases are diagnosed by nurses in screening clinics or by other family members. Idiopathic scoliosis is sometimes classified according to age of onset (infantile, juvenile, adolescent) or by curve pattern. The adolescent type is most common. Prevalence is 1% to 3% of the general population.

The diagnosis is usually made on routine physical examination. Attention should be focused on the problem in all children, but especially in those between the ages of 10 to 14 years, when spinal growth is most rapid. For the examination, the patient should be undressed to the waist or wear a bathing suit, and a routine should be followed. The shoulders and iliac crests are inspected to determine whether they are level. The scapulae, rib cage, and flanks are then observed for symmetry. The spinous processes are palpated to determine their alignment. The patient is then asked to bend symmetrically forward at the waist with the arms hanging free (Fig. 8-19). Observation from the back or front will detect the spinal rotation in the form of a rib hump or abnormal paraspinal muscular prominence. Height measurements are taken initially and at all follow-up visits to gauge the growth rate of the patient and assess the risk of rapid progression of the curve. Additional data should be obtained regarding skeletal and sexual maturity (onset of menses, etc.).

FIG. 8-19 A, Scoliosis with rib prominence resulting from vertebral rotation is best exhibited on forward bending (the Adams position). B, Cross-section of the chest showing rib distortion caused by vertebral rotation.

The diagnosis is confirmed, and the degree of curvature is measured by a standing roentgenogram of the spine (Fig. 8-20). There is no other method of determining the severity of the curve, and a patient should never leave the office without an accurate roentgenographic measurement of the curvature. The roentgenogram may have to be repeated at intervals to determine whether or not the curve is progressive. Breasts and gonads should be shielded when films are done. The degree of skeletal maturity can be determined by assessing the status of the iliac apophysis using the Risser sign (Fig. 8-21).