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Spinal Disorders in the Elderly

Jeong, Gerard, K*; Bendo, John, A

Section Editor(s): Strauss, Elton MD

Clinical Orthopaedics and Related Research: August 2004 - Volume 425 - Issue - p 110-125
doi: 10.1097/01.blo.0000131640.89143.1d
SECTION I: SYMPOSIUM: Geriatrics in Orthopaedics
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As life expectancies increase, the geriatric population will increase, and the treatment of spinal diseases in the elderly will become even more commonplace. Treatment of spinal disorders in the geriatric patient population is a difficult challenge and involves numerous surgical, medical, and social issues. This review will provide an overview of the various spinal disorders particular to the geriatric patient population and will highlight certain concepts critical in the treatment of the spine in the geriatric population. Multiple factors, including poor tolerance of immobilization, medical comorbidities, use of multiple chronic medications, poor nutritional status, inadequate bone stock, and poor bone quality limit rigorous adherence to one treatment algorithm. These issues should be taken into consideration when formulating an individualized treatment plan that emphasizes early mobilization and functional rehabilitation. Goals, expectations, and surgical indications should be realistic and often will differ from those for a younger, healthier population. The use of a multidisciplinary approach will increase the likelihood of a successful treatment outcome and decrease the likelihood of potential complications.

From the *NYU-Hospital for Joint Diseases; and the †Hospital for Joint Diseases Spine Center, NYU-Hospital for Joint Diseases, New York, NY.

Correspondence to: John A. Bendo, MD, Hospital for Joint Diseases Spine Center, 301 East 17th Street, 4th Floor, New York, NY 10003. Phone: 212-598-6625; Fax: 212-598-6723; E-mail: John.Bendo@med.nyu.edu.

Guest Editor

The number of elderly patients is increasing dramatically as the Baby Boom Generation ages and as advances in medical care continue to be made. As average life expectancies continue to increase, spinal disorders in the elderly will become an increasing concern for orthopaedic surgeons.

Spinal disorders in the geriatric patient population are much more challenging to treat than those in younger patients. The review attempts to provide an overview of the vast array of spinal disorders particular to the geriatric patient population. Geriatric-related spinal disorders are categorized into degenerative disc disease, degenerative deformities, traumatic disorders, spinal tumors, infections, and inflammatory disorders (Table 1). The orthopaedic surgeon must recognize the various spinal disorders particular to the elderly and develop a broad differential diagnosis. A comprehensive and detailed discussion of each disorder is beyond the scope of this review. However, key features in the evaluation and treatment of each disorder will be emphasized.

Table 1

Table 1

We also will highlight certain concepts critical in the treatment of the spine in the geriatric patient and will include a discussion of the characteristics and the special considerations in the treatment of the spine in the aging patient (Table 2). Recognition that elderly patients poorly tolerate immobilization and prolonged recumbency is an important concept in this review. Nonoperative techniques such as adequate pain management and physical therapy are recommended to promote early mobilization and functional rehabilitation in this population. Operative techniques such as spinal instrumentation, kyphoplasty, vertebroplasty, and minimally invasive techniques are emerging and designed to promote similar goals. The orthopaedic surgeon must recognize not only poor bone quality and difficulty in achieving stable fixation, but also concomitant medical disorders, polypharmacy, malnutrition, life expectancy, and decreased activity levels in this patient population. Treatment involves numerous medical and social issues, and requires a multidisciplinary approach to provide comprehensive care. A multidisciplinary approach from various specialties such as internal medicine, geriatrics, oncology, pain management, and nutrition will provide the spinal surgeon a careful and thorough assessment of the risks and benefits of various treatment modalities. Consequently, the treatment goals and the surgical indications in the geriatric population may be different than that in a younger, healthier population. The importance of individualizing treatment of each elderly patient cannot be overemphasized.

Table 2

Table 2

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The Spine in Elderly Patients

The pathophysiology, pathoanatomy, and pathomechanics of the spine in the aging patient form the basis for the discussion of the spinal disorders seen in the elderly. Spondylosis, metabolic bone disease (specifically, osteoporosis), and tumor are seen much more commonly in the geriatric population. Spondylosis is a degenerative local process specifically affecting the spine, whereas osteoporosis and other metabolic bone diseases are systemic processes that preferentially affect the spine because it contains the largest quantity of metabolically active trabecular bone. Malignant spinal neoplasms may be categorized as either primary or secondary. Also, they may be either local or metastatic.

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Spondylosis

By the completion of the third decade of life, degenerative changes already have begun to take place in the spine. The degenerative cascade is hypothesized to begin at the disc level where the water content of the nucleus pulposus begins to diminish and the collagen content increases.48 Radial and circumferential tears then are seen in the annulus fibrosis as the nucleus pulposus is less capable of load sharing. Biochemical alterations of the disc lead to mechanical insufficiency as the height of the entire disc complex progressively diminishes. As the intervertebral discs collapse, there may be bulging of the annulus and buckling of the ligamentum flavum into the spinal canal that may produce cord compression in the cervical and thoracic spine or thecal sac compression in the lumbar spine. With disc collapse, the neural foramina decrease in height, potentially leading to nerve root compression. Alterations in load transmission then are seen at the endplates and posterior facet joints, forming vertebral body osteophytes and facet osteophytes, respectively, which also become possible sites of neural compression7,93 (Fig 1).

Fig 1.

Fig 1.

The degenerative process may affect adjacent motion segments leading to either stiffness or instability.47,48 Stiffened levels often are characterized by diminished disc height, ligament calcification, and osteophyte formation. Hypermobile or unstable segments are characterized by spinal deformity such as degenerative spondylolisthesis or degenerative kyphoscoliosis (Fig 2). Advanced disease also may lead to alterations in coronal or sagittal balance. Neural compression then can result from either static deformity as seen in nerve root impingement in the concavity of the scoliotic curve or dynamic instability as seen in thecal sac impingement in degenerative spondylolisthesis.

Fig 2.

Fig 2.

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Osteoporosis

Osteoporosis is a systemic, age-related metabolic disorder affecting the axial and appendicular skeleton. Osteoporosis is characterized by a decrease in bone mass resulting in an increased susceptibility to fractures.60 Because osteoporosis only is a quantitative deficiency in bone mass in contrast to osteomalacia, patients with osteoporosis have normal calcium content and normal bone matrix. Two types of primary osteoporosis, Type I (postmenopausal and osteoclast-mediated) and Type II (senile and osteoblast-mediated), have been described with both forms of diseases affecting women more than men.24,53

Osteoporosis and other metabolic bone diseases often are manifested as spinal disorders because the spine is a major portion of the body’s bone mass and contains the largest quantity of metabolically active trabecular bone. There is a preferential decrease in the horizontal trabeculae of the vertebral body seen in osteoporosis, dramatically reducing the ability of the spinal column to withstand compressive loads.64 Therefore, there must be a high index of suspicion for compression/fragility fractures in the elderly, even in the setting of minor, incidental trauma. Furthermore, special considerations with respect to spinal instrumentation must be given if the decision to proceed with surgical treatment is made.

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Miscellaneous Conditions

Because the incidence of malignant spinal tumors is much higher in elderly patients compared with young patients, the diagnosis of malignant tumor always must be considered. Other conditions such as ankylosing spondylitis and Paget’s disease also have a greater prevalence in the elderly and also must be considered in the differential diagnosis of any elderly patient with recalcitrant spinal pain.

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Special Considerations in the Elderly

As mentioned previously, the treatment of the elderly patient with a spinal disorder is challenging and involves numerous issues not relevant in younger patients (Table 1). Treatment goals and expectations may be different in this population. The realization that complete pain relief and cure may not be possible is frustrating for the patient and the physician. However, an understanding of these special considerations and the use of a multidisciplinary approach may prevent potential complications and may maximize the likelihood of a successful result.

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Considerations in Nonoperative Treatment

Elderly patients generally will have medical comorbidities and may take numerous chronic medications that may complicate treatment. An important consideration in nonoperative treatment is polypharmacy and side-effect profiles of pain medications. Medical disorders such as chronic liver disease may preclude the use of acetaminophen. Likewise, nonsteroidal antiinflammatory drugs (NSAIDs) should be used cautiously in elderly patients with a history of renal insufficiency, gastritis, or peptic ulcer disease.23,98 Many patients with diabetes should understand the inherent risk of elevating blood glucose levels after a steroid injection. Medications that produce minimal drug interactions and provide a safer side-effect profile should be considered. In some cases, this requires consultation with pain management specialists for the appropriate selection of medications.

Another important consideration is adequate pain management. There should be a greater concern for patient satisfaction than for narcotic addiction in the appropriate geriatric patient. Narcotic addiction may be overestimated, and true addiction is less frequent in this population.45 Chronic opiate medications should be considered a reasonable option in any elderly patient who has pain refractory to all treatment modalities and are not surgical candidates.30,81

A special consideration in nonoperative treatment is the fact that the elderly poorly tolerate prolonged periods of immobilization. The geriatric patient is more susceptible to muscle deconditioning and disuse osteopenia, which can occur when analgesia is not adequate and physical therapy is not implemented.68 The role of a well-organized physical therapy program is not only to provide symptomatic relief, but also to encourage overall fitness and general health which are important particularly in the elderly patient. Treatment modalities that encourage early mobilization are encouraged, whereas those modalities that require a prolonged period of immobilization such as traction or external orthoses should be used cautiously.12,55,82

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Considerations in Operative Treatment

When surgery is considered, a thorough assessment of the risks and benefits of nonoperative and operative treatments is mandatory and frequently requires consultation from various specialists. The patient’s age, and more importantly, medical comorbidities must be considered. The medical specialist plays an important role in optimizing the patient’s medical condition preoperatively. It is important for the spinal surgeon to communicate the nature of the planned surgical procedure, including length of surgery, expected blood loss, anatomic location, and anticipated postoperative morbidity to the medical specialist.

Poor nutritional status is another important preoperative consideration that commonly occurs in the elderly and can complicate the surgical outcome. It is associated with an increased risk of poor wound healing and infection after surgery.49,58 Serologic markers of nutritional status include prealbumin, albumin, total protein, and total lymphocyte count and should be done in any geriatric patient who is suspected to have nutritional compromise. The nutrition department plays an important role in optimizing the patient’s nutritional status preoperatively.

Unfortunately, some elderly patients are not candidates for elective spinal surgery. Surgical indications can be different compared with those in a younger, healthier population, and so surgical treatment must be individualized. The surgical goals of pain relief and restoration of function may not be possible if surgery poses a significant risk in morbidity and mortality to the patient.13,73

An important consideration in surgical treatment is the altered anatomy of affected spinal elements secondary to advanced spondylosis. Elderly patients who are surgical candidates often have long-standing spinal disease causing a distortion in spinal anatomy. For example, hypertrophic facet joints from long-standing lumbar spondylosis can obscure important surgical landmarks for pedicle screw placement. In some cases, additional preoperative imaging studies such as computed tomography (CT) scanning for pedicle screw positioning may provide assistance in surgical planning and may minimize intraoperative error. Intraoperatively, it is important to identify normal surgical landmarks and then proceed from known to unknown regions.

Another important intraoperative consideration in the elderly is the poor bone stock and/or poor bone quality, which decreases bony purchase and adversely affects the quality of implant fixation.26,41,42,69 The intraoperative decision to use instrumentation must weigh the benefits of immediate stability and early mobilization with the risks of possible screw pull-out, increased likelihood of hardware failure, prolonged operative time, and increased blood loss. In elderly patients with low physical demands, the decision to do an in situ fusion without instrumentation may be a preferable option. When the decision is made to proceed with instrumentation, various techniques may be used to augment fixation. Pedicle screws can be placed deeper into the vertebral body to increase purchase and inserted in a more converging orientation to increase pull-out resistance. Sublaminar wires and hooks also can be used to provide good fixation in osteoporotic bone.32,39 Polymethylmethacrylate (PMMA) also can be added during primary or salvage pedicle screw placement to augment fixation and increase pull-out strength.61,84,100

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Degenerative Disorders

Degenerative disorders of the spine typically involve the cervical and lumbar spine. As mentioned previously, the degenerative cascade represents a spectrum of injury beginning at the nucleus pulposus and affecting other elements of the involved motion segment, adjacent motion segments, and neural structures. Degenerative lumbar disorders can cause axial symptoms (back pain) resulting from lumbar spondylosis, segmental instability, and spinal deformity or can cause lower extremity symptoms (neurogenic claudication in central stenosis or lumbar radiculopathy in lateral stenosis) resulting from lumbar spinal stenosis. Similarly, degenerative cervical disorders can cause axial symptoms (neck pain) and/or can cause appendicular symptoms (myelopathy in central stenosis or radiculopathy in lateral stenosis).

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Lumbar Degenerative Disease

Degenerative disc disease, lumbar spondylosis, and lumbar spinal stenosis are common findings in the elderly. It is critical to distinguish axial symptoms from appendicular symptoms. Depending on the stage of the disease process, lower back or lower extremity symptoms may dominate the clinical findings. Often a long history of intermittent low back pain is given. In the evaluation of the elderly patient with axial back pain, the sitting position may be less tolerated than standing or laying supine because more load is placed on the motion segments in this position.

In the evaluation of the elderly patient with lower extremity symptoms, neurogenic claudication resulting from lumbar spinal stenosis is among the most common causes. Neurogenic claudication is caused by significant central spinal stenosis. Appendicular symptoms such as pain or paresthesias radiating to the lower extremities commonly are not reported below the knee as found in a lumbar radiculopathy caused by a herniated nucleus pulposus. The symptoms of neurogenic claudication often are characterized by a deep, aching pain beginning in the buttocks and radiating down the thighs, which is exacerbated during ambulation. The pain follows a sclerotomal distribution, rather than a dermatomal distribution seen in an acute lumbar radiculopathy, and often is relieved by positions of lumbar flexion. Because comorbidities such as peripheral vascular disease and diabetic neuropathy are seen commonly in this patient population, it is important that the diagnosis of neurogenic claudication be distinguished from vascular claudication and peripheral neuropathy.

The examination of the patient often reveals a normal neurologic examination. Diminished motor strength and atrophy usually are seen only in patients with severe or long-standing disease. Deep tendon reflexes may be absent, but tension signs commonly are negative. Plain radiographs taken with the patient standing often show nonspecific degenerative changes, but are important in ruling out any deformity or any instability. Magnetic resonance imaging (MRI) is ordered routinely in patients with long-standing lumbar spinal stenosis and provides additional information and anatomic detail; however, the importance of correlating the findings on MRI scans with the clinical presentation cannot be overemphasized.4

Most patients with degenerative lumbar disease can be treated successfully by nonoperative modalities, which include oral NSAIDs, opiates, physical therapy, and injections. Fluoroscopically assisted local injections can be used diagnostically and therapeutically and are useful in the treatment of patients with lumbar degenerative disease. Lidocaine and/or steroids can be injected into the facet joints, near nerve roots, or into the epidural space to provide diagnostic information and therapeutic gain. Diagnostic nerve root blocks often help to localize the source of leg pain.36,92 Therapeutic epidural steroid injections often can provide transient, but significant symptomatic relief.77,94,95

Surgical treatment is indicated in only a small percentage of patients with lumbar degenerative disease. Surgical treatment must address the underlying disorder, and therefore, the use of various diagnostic modalities such as MRI, CT, myelography, injections, or provocative discography may be needed to identify the pain source accurately. The goals of surgical treatment are to provide pain relief, to halt or reverse any neurologic deficit, and ultimately, to restore function. Posterior lumbar decompression (laminectomy, laminotomy, or laminoplasty) is done for any neural compression producing disabling appendicular symptoms.27,46,86 Good-to-acceptable results after posterior lumbar decompression have been reported in 85% of patients 80 years or older.43 Spinal stabilization with anterior fusion, posterior fusion, or both is done for severe degenerative disc disease producing incapacitating axial symptoms, spinal instability, or spinal deformity.2,38,54 Newer surgical techniques, including disc arthroplasty, currently are being investigated.

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Cervical Degenerative Disease

Patients with cervical degenerative disc disease can present with axial neck pain, radiculopathy, and/or myelopathy. Symptoms usually are the result of multilevel disease in the elderly population. Patients commonly report a long-standing history of discogenic neck pain. Chronic cervical spondylosis may cause spinal cord compression resulting in myelopathy. Unlike discogenic neck pain and cervical radiculopathy, the clinical presentation of cervical spondylotic myelopathy often may be subtle, requiring a high index of suspicion. The most common complaint and often earliest finding in myelopathy is a gait disturbance from lower extremity weakness and loss of proprioception. Therefore, a comprehensive neurologic examination including the evaluation of long tract signs and deep tendon reflexes is mandatory in the assessment of any patient with cervical disc disease. In patients suspected to have neurologic deficits, it is important that cervical spondylotic myelopathy (CSM) is distinguished from other nervous system disorders such as multiple sclerosis and amyotrophic lateral sclerosis.

Plain radiographs often show nonspecific degenerative changes such as disc space narrowing, vertebral osteophytes, and uncovertebral and facet joint hypertrophy. The radiographic evaluation of sagittal alignment of the cervical spine also has important surgical treatment implications. An MRI should be ordered in any patient with clinical evidence of chronic, long-standing neural compression. Magnetic resonance imaging is noninvasive, provides excellent observation of the cervical disc and neural elements, and provides no radiation exposure. Computed tomography with myelography can provide excellent observation of the entire spinal canal including lateral disorders and can reveal evidence of dynamic stenosis. The imaging findings must be correlated with the clinical scenario because disease may be present in approximately 20% of asymptomatic patients.6

In a similar fashion to lumbar degenerative disease, most elderly patients with discogenic neck pain or cervical radiculopathy can be treated successfully by nonoperative means. Nonsteroidal antiinflammatory drugs, opiate pain medications, and physical therapy form the mainstay of nonoperative treatment. Cervical epidural injections and selective nerve root blocks are proven to be diagnostic and therapeutic.11

Surgical treatment is reserved for only a small percentage of patients with cervical degenerative disease. Surgical indications include persistent, disabling axial or radicular symptoms refractory to multiple trials of conservative treatment, progressive neurologic deficit, and cervical myelopathy. Natural history studies of cervical spondylotic myelopathy have shown that many patients follow a course of progressive deterioration and disability; therefore, early surgical decompression of the spinal cord is recommended to halt disease progression before the onset of irreversible neurologic changes.67 Surgical options for cervical spondylotic myelopathy include anterior procedures, posterior procedures, or both. Anterior procedures include multilevel anterior cervical discectomies and fusion or anterior cervical corpectomy with fusion. Posterior procedures include cervical laminatomy and foraminotomy, laminectomy and fusion, or laminoplasty. Posterior cervical laminotomy and foraminotomy often are helpful in treating intractable arm pain secondary to lateral compression when trying to avoid fusion in the elderly.20 Hasegawa et al35 reported comparable outcomes between patients who were 60 years or younger and patients who were 70 years or older after surgical treatment for cervical spondylotic myelopathy.

Anterior procedures are preferred in patients with one-level or two-level disease with significant loss of the normal cervical lordosis.17,18,78,85 However, anterior procedures may lead to problems such as prolonged dysphagia in the elderly.3 Posterior procedures generally are reserved for patients with multilevel (three or more levels involved) disease in a lordotic cervical spine.40,102 Spinal stabilization with anterior fusion, posterior fusion, or both is done for patients with severe degenerative disc disease producing incapacitating axial symptoms or for prevention of iatrogenic instability after concomitant surgical decompression.

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Deformity

Spinal deformity in the elderly population typically results from late-stage, advanced degenerative disc disease and should be differentiated from other causes (congenital, posttraumatic, idiopathic) of deformity seen in younger patients. Two of the more common deformities in adults are degenerative spondylolisthesis and degenerative scoliosis and predominantly are seen in the lumbar spine.

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Degenerative Spondylolisthesis

Degenerative spondylolisthesis is one of the most common spinal deformities in the elderly population. It typically involves the L4–L5 level, in contrast to isthmic spondylolisthesis which involves the L5–S1 level. Progressive disc and facet degeneration from spondylosis coupled with the sagittal orientation of the lumbar facet joints in insufficiency of the posterior elements to resist the anteriorly directed force of the body’s center of gravity. Consequently, anterolisthesis of the superior vertebra on the inferior vertebra occurs. Unlike isthmic or dysplastic spondylolistheses, the posterior elements in degenerative spondylolisthesis remain relatively intact, and slippage is mild, usually less than 33%.

Patients with degenerative spondylolisthesis frequently have advanced degenerative disc disease and will report back pain, buttock and leg pain, or both. An important component in patient evaluation is to assess whether back pain or leg pain is the predominant symptom. Dynamic instability may exacerbate neurologic symptoms, and positions that relieve symptoms such as lumbar flexion, which increase the spinal canal and foraminal dimensions, should be elucidated. Plain radiographs and dynamic flexion and extension radiographs are mandatory in any patient with spondylolisthesis. Magnetic resonance imaging is indicated for any patient with significant neurologic symptoms; additionally, dynamic flexion and extension MRI may elucidate neural compression that may not be seen on static MRI scans (Fig 3).

Fig 3.

Fig 3.

Most patients with degenerative spondylolisthesis will benefit from standard nonoperative treatment. Symptoms usually are controlled with a combination of NSAIDs, physical therapy, and epidural steroid injections. Surgical treatment is reserved for elderly patients with neurologic deterioration and/or patients who are unresponsive to a lengthy course of nonsurgical treatment.

When the clinical symptoms correspond to the findings on imaging studies and are refractory to nonoperative treatment, a posterior lumbar decompression and an in situ posterolateral fusion will benefit most patients. Posterior decompression alone will increase the instability at the level of the spondylolisthesis.57 An in situ posterolateral fusion serves to relieve preoperative axial symptoms and will stabilize any inherent and iatrogenic instability.37,57 Reduction usually is not necessary in degenerative spondylolisthesis because the deformity generally is mild. Increased fusion rates have been observed with pedicle screw instrumentation although the risks and benefits of instrumentation, longer operative times, and increased blood loss should be contemplated in an elderly patient who has low physical demands.22,90,103 The benefits of instrumentation to provide immediate stability and to permit early mobilization without bracing outweigh the risks in most healthy older patients (Fig 4). A concomitant interbody fusion can restore and maintain normal spinal alignment, improve the likelihood of spinal fusion, and indirectly decompress neural elements.56,87 It is indicated in rare cases in which there is a significant listhesis or loss of lordosis, severe disc collapse with foraminal compromise, profound bone loss, or previous posterior decompressive surgery.

Fig 4.

Fig 4.

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Degenerative Scoliosis

Degenerative scoliosis often may be associated with degenerative spondylolisthesis. Degenerative scoliosis, often termed de novo scoliosis, is secondary to long-standing spondylotic disease and as a result, often is painful. It is differentiated from an adult with adolescent idiopathic scoliosis by the age of onset of the spinal deformity. It occurs predominantly in the lumbar spine as opposed to idiopathic scoliosis, which usually occurs in the thoracic spine. Also, degenerative curves generally involve fewer levels and are smaller in magnitude than idiopathic curves (Fig 5).

Fig 5.

Fig 5.

Patients commonly will report neurogenic claudication or radicular symptoms, which often will overshadow the chronic back pain. A thorough neurologic evaluation is mandatory, and nerve root findings usually are observed on the concave side of the lumbar curve. Truncal balance is assessed, and any findings of coronal or sagittal decompensation are noted. Full-length scoliosis series radiographs should be taken with the patient standing to evaluate any compensatory curves above the usual lumbar curve and to assess coronal and sagittal balance. Lateral radiographs often will show a loss of lordosis or a kyphotic thoracolumbar junction. Because most degenerative curves are mild, MRI often is adequate to observe the neural elements, disc degeneration, and sites of neural compression. Computed tomographic-myelography can provide more useful diagnostic information in larger deformities. Bending and flexion and extension radiographs taken with the patient supine are used to assess curve flexibility in the coronal and sagittal planes and to identify fusion levels in any patient indicated for surgical intervention. Most degenerative curves are rigid and stiff.

The standard nonoperative treatment including NSAIDs, opiate analgesics, physical therapy, and epidural steroid injections may provide some symptomatic relief. Accommodative, not corrective, flexion bracing also may help alleviate symptoms. Unlike idiopathic scoliosis, the surgical indication is based less on curve magnitude and more on symptoms. The main indication for surgical intervention is incapacitiating back or leg pain or progressive neurologic deficit refractory to nonoperative treatment. The goals of surgical treatment are neural decompression, spinal balance, and spinal stabilization.

In the setting of degenerative scoliosis, any posterior decompression usually requires additional spinal stabilization. A posterolateral arthrodesis is sufficient in most patients.28,105 However, additional interbody fusion produces greater correction of sagittal alignment, improves the likelihood of fusion, and provides indirect compression of neural elements.59 Similar to degenerative spondylolisthesis, interbody fusion is indicated in patients in whom there is significant sagittal plane deformity, severe disc collapse with foraminal compromise, deficient posterior bone stock, and previous posterior decompressive surgery. When long fusions are done to the sacrum, interbody fusion also is recommended to augment posterior fixation and reduce the stress on instrumentation at the lumbosacral junction.51 Infrequently, patients present with large, rigid, stiff curves and with severe truncal decompensation that cannot be corrected with standard anterior and posterior techniques. In these patients, osteotomies and vertebral column resections are indicated to obtain appropriate correction.9

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Trauma

Unlike spinal trauma in younger patients, traumatic disorders in elderly patients usually are the result of low-energy trauma such as a fall. Two important traumatic disorders specific to the geriatric population are compression fractures and central cord syndrome. Compression fractures in elderly patients also are known as fragility or insufficiency fractures and are the result of a decrease in bone mass. Central cord syndrome is an incomplete spinal cord lesion that occurs in the setting of cervical spondylosis and stenosis.

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Compression Fracture

Compression fractures are a common source of morbidity in the elderly population. Prevalence rates vary from 2.9–27% in women 65 years or older. Insufficiency fractures are attributable to the preferential loss of horizontal trabeculae in the vertebral body seen in osteoporosis and the resultant decrease in the compressive stiffness of each spinal segment. Compression fractures are the result of a failure in axial load. Most compression fractures occur in the thoracic and thoracolumbar spine. Because the center of gravity often is anterior to the thoracic spine, most compression fractures truly are flexion-compression injuries, rather than direct axial compression injuries as the name implies. Compression fractures frequently involve multiple levels and may cause a secondary, kyphotic deformity, which frequently is associated with chronic, disabling pain.

The clinical presentation is variable, and the patient may present with an acute onset of well-localized pain after an episode of minor trauma or a rather subacute or chronic history of long-standing, low-grade back pain with no recollection of a traumatic episode. There is a fourfold increased risk for subsequent fractures if there is a history of a prior insufficiency fracture.50 Pathologic fracture secondary to tumor must be ruled out in the evaluation. The neurologic examination typically is normal. High-quality plain radiographs in orthogonal planes are essential in the evaluation. The amount of compression (loss of height) and amount of angulation are evaluated and quantified. Compression fractures, especially in the upper thoracic spine, can be difficult to see on plain radiographs because of adjacent mediastinal structures. Computed tomography scanning may be necessary to better observe the fracture personality. An MRI scan is indicated if there is an accompanying neurologic deficit or if there is any suspicion of a pathologic fracture.

Treatment goals are pain relief, early mobilization, preservation of spinal balance, and prevention of late neurologic complications. The long-standing treatment of patients with acute compression fractures has been opiate analgesic medication and an hyperextension orthosis or cast for pain relief. Often, the cumbersome nature of bracewear reported by patients and patients’ body habitus preclude the effective use of external orthoses. Moreover, prolonged periods of immobilization often lead to muscle deconditioning and are tolerated poorly in the elderly.

In efforts to mobilize elderly patients faster, surgical treatment options such as percutaneous vertebroplasty and kyphoplasty are emerging and have become used more commonly. The indications for surgical treatment are continuing to evolve. Surgical treatment typically is done for patients with acute or subacute fractures. Both techniques are minimally invasive and are done under fluoroscopic guidance. Vertebroplasty involves the injection of PMMA into the fracture site through a percutaneous posterior transpedic (unipedic or bipedic) or extrapedic approach.91 As the PMMA polymerizes and hardens, the fracture site is stabilized and pain is reduced. Kyphoplasty is a similar technique, but attempts to restore vertebral body height with an inflatable balloon tamp before fracture stabilization with PMMA. The early results of vertebroplasty and kyphoplasty are encouraging, and these new surgical techniques offer a promising alternative to the 6- to 12-week period of pain medication, fracture healing, and brace wear found in standard nonoperative care.44,52,65,89

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Central Cord Syndrome

Central cord syndrome is the most common incomplete cord syndrome in the elderly. It usually is the result of a hematoma located in the center of the spinal cord after a hyperextension injury in the setting of preexisting cervical spondylosis and cervical spinal stenosis. Clinically, the patients have greater loss of motor function in the upper extremities compared with the lower extremities. The preferential loss in the upper extremities is secondary to the somatotopic organization of the corticospinal tract with the upper extremity fibers located centrally. Sensory loss is variable. Perianal sensation usually is preserved because of sacral sparing.

The diagnosis of central cord syndrome often is made after the initiation of pharmacologic treatment following the treatment protocol of the Third National Acute Spinal Cord Injury Study (NASCIS III).8 Magnetic resonance imaging is mandatory in the evaluation of any patient with spinal cord injury or neurologic deficit. Surgical treatment is reserved for the rare cases in which there is spinal instability. Central cord syndrome has a relatively good prognosis for recovery of ambulatory capacity and of bowel and bladder function with approximately 41% of patients having functional improvement.72,78 The surgical indications and timing of operative intervention for central cord syndrome remain a topic of controversy.

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Tumors

Primary and secondary spinal tumors present diagnostic and therapeutic challenges in the evaluation of the spine in elderly patients. A multidisciplinary approach incorporating the oncologist, pathologist, musculoskeletal radiologist, and spinal surgeon is necessary for appropriate treatment of these conditions.

Spinal tumors in the elderly are more likely to be malignant and involve the anterior column, unlike those in the younger population, which tend to be benign processes involving the posterior elements. The most common spinal tumors in the geriatric population are the result of skeletal metastases and of myeloproliferative disorders (lymphoma, myeloma). Tumors that metastasize to the spinal column are lung, breast, prostate, renal, thyroid, and occasionally colon cancer. In women, the most common primary tumor is breast cancer. In men, lung and prostate cancer are the most common primary lesions. The most common location for skeletal metastasis is in the thoracolumbar region, which accounts for approximately 70% of all lesions and was hypothesized to occur from the rich vascular network of Batson’s plexus.33,66 The route of skeletal metastasis predominantly is hematogenous; however, direct tumor invasion into the spinal column can be seen, especially in bronchogenic carcinoma.

With the exception of multiple myeloma, primary bone tumors of the spine are less common, but must be considered in the differential diagnosis of any elderly patient with a spinal mass. Primary bone tumors specific to the elderly population include chordoma, chondrosarcoma, and malignant fibrous histiocytoma.96 Malignant primary bone tumors such as osteosarcoma and Ewing’s sarcoma generally are seen in a much younger patient population.

There are three common clinical presentations in patients with spinal tumors. First, the patient may report back pain, which usually is focal and site-specific because of the symptomatic lesion. Second, the patient may present with a neurologic deficit caused by neural compression from the tumor. Third, the patient may be asymptomatic, and the diagnosis is made based on an incidental finding on radiographs or routine evaluation.

Back pain is the most common symptom and may be associated with radicular symptoms or neurologic deficit. A slow, gradual, insidious onset of back pain, persistent at night, and unrelated to mechanical stress, is the usual clinical presentation. Patients with spinal tumors are more likely to have a specific site of focal tenderness compared with patients with mechanical or discogenic back pain. Acute exacerbation or onset of pain after minor or incidental trauma often may represent a pathologic fracture. If spinal tumor is being considered, a complete physical examination including evaluation of the breasts, thyroid, abdomen, rectum, and prostate should be done. Because plain radiographs may show a lesion only after 30% of the bone mass is lost, there must be a low threshold to do technetium-99 bone scanning, which not only is more sensitive in detecting a neoplasm, but also may show other occult neoplastic foci.34,79,96 An MRI scan showing relative preservation of the disc space can differentiate a tumor from nontuberculous infection.1

The treatment of patients with spinal tumors must be individualized and must take into account numerous factors including the nature of the tumor, extent of disease, and patient’s life expectancy. The surgical indications for spinal tumors include spinal instability, neural compression, biopsy, and tumor excision. However, it is important to clearly identify the goals of medical and surgical treatments of each patient. In patients with benign lesions such as giant cell tumors, surgical excision is done to eradicate the lesion. Patients with radiosensitive malignant lesions such as myeloma, lymphoma, and metastases preferentially are treated with radiation therapy and/or chemotherapy for tumor control, whereas surgery is reserved for patients with solitary lesions, spinal instability, or bony compression of neural elements.

Surgical treatment that leads to rapid mobilization, early return to function, and avoids prolonged recumbency is critical. Tumor excision is done to produce a wide tumor resection with negative margins. Surgical decompression can be done either anteriorly, posteriorly, or combined depending on the site of the tumor. Stabilization may be done using PMMA, autograft, allograft, or cages usually accompanied by instrumentation.34

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Infection

Spinal infections deserve special mention because elderly patients with vertebral osteomyelitis particularly are challenging to treat. Elderly patients are not only at increased risk of failure of nonoperative treatment, but also at increased risk of neurologic deterioration.16,74 Spinal infections can be categorized in many ways: acute versus chronic, pyogenic versus granulomatous (tuberculous, fungal), or primary versus postsurgical. The most common location for pyogenic vertebral osteomyelitis is in the lumbar spine, whereas the most common location for tuberculous vertebral osteomyelitis is in the thoracic spine.80 Vertebral osteomyelitis usually is a secondary process from another focus of infection such as urinary tract infection, pneumonia, or skin infection and is the result of hematogenous seeding from arterial septic emboli or from retrograde flow from engorged venous channels of Batson’s plexus. Staphylococcus aureus is the most common microorganism infecting the vertebral column.80 Gram negative infections such as Escherichia coli and Pseudomonas are characteristic of spinal osteomyelitis arising from a genitourinary tract infection. Atypical fungal and tuberculous infections are characteristic in immunocompromised patients because of HIV, cancer, or organ transplantation.

The clinical manifestation of spinal osteomyelitis is highly variable and dependent on host resistance and organism virulence. Because of the variability of presentation, spinal infection and spinal neoplasm should be considered in the differential diagnosis of any elderly patient with relentless, unremitting back pain. It usually is associated with a significant delay in diagnosis (usually greater than 3 months) and therefore, requires a high index of suspicion for prompt diagnosis and treatment.80 As mentioned previously, elderly patients especially are vulnerable to the complications of vertebral osteomyelitis. Along with advanced age, other risk factors that place the patient at increased risk of neurologic deficit because of spinal osteomyelitis include diabetes mellitus, rheumatoid arthritis (RA), Staphylococcus aureus infection, and more cephalad levels of infection.16

The typical presentation of spinal osteomyelitis in an elderly patient is an insidious onset of unremitting back pain that is constant, may awaken the patient from sleep, and is unrelated to activity.80 Constitutional symptoms of fever, chills, and weight loss frequently are absent. Patients with acute infections are more likely to have the classic signs of infection than patients with more indolent infections found in subacute or chronic disease. The physical examination often is nonspecific. Paravertebral spasm and tenderness may be elicited especially in patients with the acute stage of infection. The presence of neurologic deficit and structural deformity should be actively sought in the examination.

Laboratory studies including a leukocyte count with differential, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and blood cultures comprise the initial diagnostic workup. Plain radiographs often will show relatively normal findings at the acute phase of the infection.15 Disc space narrowing may be evident at 2 weeks.80 Rarefaction may be present at 6 weeks, and new bone formation may be evident at 12 weeks from the onset of infection. Technetium-99 bone scanning when used in conjunction with gallium scanning is a sensitive and specific study that will show an infectious process long before any radiographic findings.63 Magnetic resonance imaging is the diagnostic modality of choice to observe the inflammatory process. It provides excellent soft tissue detail and permits observation of disc involvement, abcess formation, or neural compression. Magnetic resonance imaging can distinguish a pyogenic infection from a tuberculous infection or a spinal neoplasm. In pyogenic vertebral osteomyelitis, the vertebral body and affected disc will produce a dark signal on the T1-weighted sequence and a bright signal on the T2-weighted sequence. In a tuberculous infection and in a spinal tumor, the disc remains relatively unaffected1 (Fig 6).

Fig 6.

Fig 6.

The initial treatment of vertebral osteomyelitis in the elderly patient is intravenous antibiotics and immobilization with an orthosis. Consultation with an infectious disease specialist is recommended for appropriate antibiotic selection after the microorganism has been isolated from blood cultures and/or percutaneous needle biopsy specimens. The ESR and CRP can be used to monitor the response to antibiotic therapy.

Surgical intervention is indicated when (1) a tissue diagnosis cannot be made through percutaneous biopsy; (2) systemic signs remain despite antibiotic therapy; (3) abcess formation is present; (4) there is a progressive or evolving neurologic deficit; and (5) there is evidence of spinal instability in the form of significant vertebral collapse and deformity. The operative sequence and surgical principles of vertebral osteomyelitis are similar to those of locally aggressive spinal neoplasms. An open biopsy generally is done. An aggressive surgical debridement of any infected tissue or abcess collection is done leaving clean margins and a well-vascularized bed. A neural decompression is done if necessary. The route of decompression is dependent on the site of disease. An anterior decompression generally is done because the underlying disease usually originates from the vertebral body. Reconstruction is done using autograft or allograft.19,25,99 Stabilization with the use of instrumentation is controversial although excellent results have been reported with the use of anterior or posterior instrumentation after debridement and reconstruction.14,29,74,101

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Inflammatory Disorders

Two inflammatory disorders, RA and ankylosing spondylitis, deserve special mention. The two disorders cover both ends of the spectrum in spinal treatment. The treatment of RA considers its predisposition toward spinal instability, whereas the treatment of ankylosing spondylitis considers its predisposition toward spinal rigidity. In the geriatric population, RA and ankylosing spondylitis are challenging to treat because both will present as severe, advanced, late-stage disease. A multidisciplinary approach with the rheumatologist and geriatrician is crucial to optimizing patient treatment.

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Rheumatoid Arthritis

Rheumatoid arthritis is a progressive seropositive polyarthropathy predominantly affecting females and can present at any age. For reasons not completely understood, rheumatoid involvement is almost always restricted to the cervical spine. Significant involvement in the thoracolumbar spine is exceedingly rare. Three clinical manifestations of rheumatoid disease are evident in the cervical spine: atlantoaxial instability, basilar invagination, and subaxial instability. Usually, there is a sequential progression of cervical involvement beginning with atlantoaxial instability progressing to basilar invagination and then to subaxial subluxation. Most patients will present with advanced disease, when all three findings are commonly present.

Presenting complaints of axial or appendicular pain or subtle findings of myelopathy often are masked by the peripheral deformities from late-stage rheumatoid disease. Overlooking subtle symptoms and missing cervical spinal disease in the patient with RA can lead to disastrous complications such as quadriparesis and sudden death. Therefore, every elderly patient with RA should be assumed to have cervical disease until proven otherwise. Radiographic evaluation of atlantoaxial instability is determined best by measuring the posterior atlantodens interval (PADI), which should be greater than 14 mm in healthy subjects.5 The decreased PADI often is observed on the lateral film taken with the spine in flexion. Measurement of the atlantodens interval (ADI) (normal < 3.5 mm) is less reliable because accompanying basilar invagination may produce a falsely normal ADI. Numerous radiographic measurements to evaluate basilar invagination have been introduced. However, the combination of the Clark station, Redlund-Johnell line, and Ranawat line has been reported to yield the highest diagnostic accuracy.76

The radiographic evaluation of subaxial instability is determined best by measuring the space available for the cord (SAC), which is greater than 14 mm in healthy subjects, and by measuring translation and angulation of motion segments on the lateral radiographs taken with the spine in flexion and extension. An increase of greater than 3.5 mm translation or 10° angulation between motion segments is a radiographic sign of subaxial instability.97

The natural history of the rheumatoid cervical spine is a steadily progressive disability and loss of ambulation caused by myelopathy with sudden death in approximately 10% of patients.62,71,88,104 Goals of surgical treatment are neural decompression if needed, spinal stabilization, and early mobilization. Early aggressive surgical decompression and stabilization before permanent neurologic deficit are crucial to improve the functional recovery in these patients. Surgical stabilization with or without decompression is indicated for patients with any clinical evidence of myelopathy. Indications for surgical stabilization irrespective of the presence of neurologic deficit include patients who have atlantoaxial instability with a PADI less than 14 mm, patients who have atlantoaxial instability and greater than 5 mm basilar invagination, and patients who have subaxial subluxation and SAC less than 14 mm.

The surgical treatment chosen must address the underlying disease. C1-C2 fusion is indicated for patients with isolated atlantoaxial instability. The fusion should be extended to the occiput if there is any evidence of accompanying basilar invagination. The fusion should be extend caudad (an occiput-to-upper thoracic fusion) in patients with advanced disease in whom there also is additional subaxial subluxation or instability.

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Ankylosing Spondylitis

Although the typical onset of ankylosing spondylitis is approximately 40 years, it is a slowly progressive deformity with late-stage disease being difficult to treat. Because ankylosing spondylitis affects the elderly most severely, it deserves special consideration. Ankylosing spondylitis is an HLA-B27 seronegative spondyloarthropathy more commonly affecting males. It begins as an enthesopathy affecting the sacroiliac joints and as the disease progresses, ossification and ankylosis occur in an ascending manner. Multisystem involvement does occur, and associated conditions include uveitis, prostatitis, carditis, and pneumonitis.

As the fusion progresses cephalad, it results in the development of a long rigid spinal column making it vulnerable to fracture, even in the setting of minor or incidental trauma. A high suspicion for acute fracture is required for any patient with ankylosing spondylitis complaining of neck or back pain despite the history of minor or no trauma. Loss of lordosis usually is seen in the lumbar spine; progressive kyphotic deformity especially in advanced disease are seen in the thoracic and cervical spine. The thoracic and cervical deformity can progress to the point that the chin abuts the chest, making it difficult for the patient to look forward or to eat. Extension osteotomies are reserved for progressive and severe kyphotic deformities that interfere with vision and eating.31,83 The procedure is technically demanding, and because it is associated with significant neurologic compromise, spinal cord monitoring is mandatory.

Because of extensive ankylosis and kyphotic deformity, acute fracture in patients with ankylosing spondylitis is associated with a high incidence of profound neurologic deficit.10,21,70 There is a significant risk of epidural hemorrhage, ascending paralysis, and death in these patients. Because the spinal ankylosis results in longer lever arms, stresses are concentrated at the fracture site predisposing it to pseudarthrosis. Prompt rigid immobilization by halo immobilization, surgical instrumentation, or both must be used to prevent additional fracture displacement, which could lead to epidural hematoma.10,21

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DISCUSSION

As life expectancies increase, the geriatric population will increase, and the treatment of spinal diseases in the elderly will become even more commonplace. There is a broad spectrum of spinal disorders in this patient population. Disorders may be age-specific or may represent end-stage disease from an earlier adult or childhood onset. Multiple factors, including medical comorbidities, use of multiple chronic medications, poor nutritional status, inadequate bone stock, and poor bone quality limit rigorous adherence to one treatment algorithm. These issues should be considered when formulating an individualized treatment plan. Goals, expectations, and surgical indications should be realistic and often will differ from that in a younger, healthier population. The use of a multidisciplinary approach will increase the likelihood of a successful treatment outcome and decrease the likelihood of potential complications.

The goals of early mobilization and pain relief while optimizing functional outcome and maximizing patient satisfaction are challenging especially in the geriatric population. Recognition that elderly patients poorly tolerate prolonged immobilization and recumbency is paramount in treatment. Nonoperative techniques such as adequate pain management and physical therapy are recommended to promote early mobilization and functional rehabilitation in this population. Operative techniques such as spinal instrumentation, kyphoplasty, vertebroplasty, and minimally invasive techniques are emerging and are designed to promote similar goals in this patient population. The clinical efficacy of many of these newer techniques remains to be proven.

Some questions have been answered. There is good evidence to do posterolateral fusions to stabilize deformities such as degenerative spondylolisthesis and degenerative scoliosis.37,57 Various techniques to augment screw fixation in osteoporotic bone have been proven in biomechanical studies.32,39,61,84,100 Based on the studies available, early cervical spinal stabilization in patients with RA is recommended.62,71,88,104 Radiographic parameters to provide the best method of detection of basilar invagination have been identified.75 There is evidence to promote early decompression in patients with cervical spondylotic myelopathy based on studies reporting the natural history of the disease.18,17,40,67

However, many questions remain unanswered. The indications for posterolateral fusion with instrumentation versus in situ posterolateral fusion in the treatment of patients with degenerative disc disease and deformity remain controversial in this patient population. The role of bone graft substitutes versus autograft in spinal fusions has yet to be defined. The efficacy of plate fixation over no instrumentation in one-level anterior cervical interbody fusions has not been shown clearly. The clinical efficacy of kyphoplasty or vertebroplasty versus nonoperative treatment in the treatment of acute compression fractures remains unproven in any prospective, randomized trials. The role of instrumentation in the surgical treatment of spinal infections remains controversial.

Most treatment decisions in the elderly patient with a spinal disorder are based on inferences from natural history studies or on the results of retrospective studies with cohort samples. There also is a paucity of studies with the effects of various treatments on general health and on functional outcome. Prospective, randomized clinical trials are lacking and are needed to provide the spinal surgeon with evidence-based treatment strategies in elderly patients with spinal disorders.

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