Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Spondylolisthesis


Related Terms

  • Anterolisthesis
  • Retrolisthesis
  • Vertebral Subluxation

Specialists

  • Neurosurgeon
  • Orthopedic (Orthopaedic) Surgeon
  • Physiatrist (Physical Medicine and Rehabilitation Specialist)
  • Physical Therapist

Comorbid Conditions

Factors Influencing Duration

Factors that may influence the length of disability include the severity of neurological problems such as nerve root compression or sciatica, the frequency and severity of the pain or weakness, and the individual’s ability to modify aggravating activities.

Medical Codes

ICD-9-CM:
738.4 - Acquired Spondylolisthesis; Degenerative Spondylolisthesis; Spondylolysis, Acquired
756.12 - Spondylolisthesis; Congenital

Overview

© Reed Group
Spondylolisthesis describes a condition of a forward slippage of one vertebra over another, which may or may not be associated with demonstrable instability. The vertebrae of the spine are stacked one on top of the other and held in place by ligaments, muscles, joints, and discs. The healthy spine is flexible and moves in many planes, including flexion, extension, and rotation.

There are five types of spondylolisthesis (congenital/dysplastic, isthmic, degenerative, traumatic, and pathological). Congenital or dysplastic spondylolisthesis is a defect in the posterior part of L5 or S1, and the abnormal orientation of the bones permits forward slippage of one vertebra on another. It is a rare condition and is frequently associated with neurologic involvement. The severity of subluxation is graded as follows: Grade I is 0% to 25%, Grade II is 26% to 50%, Grade III is 51% to 75%, and Grade IV is more than 75% of vertebral slippage as evidenced on x-ray (Devereaux).

The most common type of spondylolisthesis is isthmic or spondylolytic spondylolisthesis. Spondylolysis, which is generally a stress fracture in the posterior part of the vertebra, called the pars interarticularis, is present in this type of spondylolisthesis. Spondylolysis is the most common cause of spondylolisthesis. Isthmic spondylolisthesis most commonly occurs in the lumbar region, at the level between the fifth lumbar vertebra and the first sacral vertebra (L5-S1 level).

Degenerative spondylolisthesis is an acquired condition related to chronic degenerative disc disease and the associated changes that may lead to segmental instability The pars interarticularis is not affected in degenerative spondylolisthesis. The degeneration of intervertebral discs (degenerative disc disease) results in narrowing of the disc space, which allows the supporting structures to become lax and can lead to segmental instability, most common at L4-L5. The facet joints are also affected: the result is persistent slippage (subluxation) of the facet joints with decreased resistance to forward slippage of one vertebra on another. The slippage is limited by the structures at the back of the spine that are still intact. Degenerative spondylolisthesis is more common in women and occurs most often at L4-5.

Spondylolisthesis can also be caused by a traumatic fracture (traumatic spondylolisthesis) of the posterior elements of the vertebra, by destruction of the posterior aspect of the spine through tumor, infection, or osteoporosis (pathological spondylolisthesis), and by spinal surgery (postsurgical spondylolisthesis).

Incidence and Prevalence: In the US, the incidence of isthmic spondylolysis is 6% to 7%, with 11.3% of cases occurring at the L4-L5 level, and 82% occurring at the L5-S1 level (Froese).

The prevalence of degenerative spondylolisthesis is 5.8% in men and 9.1% in women (Vokshoor).

The prevalence of spondylolisthesis in osteoporotic women is 28.4%, with 12% occurring at the L3-L4 level, 73% occurring at the L4-L5 level, and 28% occurring at the L5-S1 level (Nizard).

The incidence of postoperative spondylolisthesis is 11% to 14% at the vertebral level above the fused segments (Nizard).

Source: Medical Disability Advisor



Causation and Known Risk Factors

Individuals at risk for spondylolisthesis include those who have spondylolysis and those with an abnormal forward curvature of the lumbar spine (lordosis). The risk is increased in individuals who engage in contact sports (football, volleyball, or soccer), certain kinds of gymnastics, or weight lifting. Individuals with radiographic osteoarthritis and postmenopausal women with osteoporosis are also at greater risk of developing spondylolisthesis.

Spondylolytic (isthmic) spondylolisthesis is most common in white males (Froese). Women are more likely to progress to a higher degree of slippage than men (Froese).

Degenerative spondylolisthesis is three times more common in blacks than whites and usually occurs after the age of 40 (Irani). It is more common in females than males by 5 to 1 (Froese).

Congenital spondylolisthesis is twice as common in females as in males, and symptom onset is usually during adolescence (Irani).

Source: Medical Disability Advisor



Diagnosis

History: Low back pain is the most common presenting symptom. Individuals with spondylolisthesis may also present with lordosis, localized tenderness over the spine just above the pelvis, pain in the thighs or buttocks, tightness in the hamstrings, and back stiffness. Isthmic spondylolisthesis may be an incidental finding on imaging studies that becomes apparent during the evaluation of low back pain in adults, and must be evaluated in the context of degenerative disc disease or other causes of low back pain.

Individuals with severe grades of slippage may not be able to walk normally, and stumble or drag their feet instead. Neurologic signs often correlate with the degree of slippage. In describing pain, individuals may report that it is aggravated when they rise out of a sitting position, walk up stairs or inclines, get in and out of cars, and lean backward (extension). The pain is relieved at rest when lying flat with the knees bent, or leaning forward (flexion).

Degenerative spondylolisthesis is generally seen in older patients, who may present with low back pain, symptoms of neurogenic claudication (heaviness in the legs with walking that is alleviated by sitting), radiculopathy, or a combination of those symptoms.

Physical exam: A complete examination of the lumbar spine, including musculoskeletal and neurological components, is performed to rule out any other underlying pathology and to determine the extent of nerve involvement. Findings of the exam may reveal decreased sensation and tendon reflexes and weakness of lower leg muscles. Examination of the spine by manual touching and massaging of the areas of concern (palpation) may reveal a step-off in higher-grade slippage. Findings are also likely to reveal a limited range of motion of the spine; increased pain when leaning backward; relief of pain when leaning forward; clumsy, swayed walking (waddling gait); and tight hamstrings.

Tests: Spondylolisthesis is usually identified by plain x-rays (radiographs). Additional studies such as MRI and CT scans will routinely be performed to evaluate for nerve involvement, degenerative disc disease, disk herniation, spondylosis, and spinal stenosis. The amount and percentage of slippage should be measured on a standing lateral x-ray. A change in the percentage of slippage when the individual bends forward or leans backward is an indication of dynamic instability. This means that the amount of vertebral slippage changes with spinal motion.

In cases of spondylolysis, the diagnosis may not be evident in plain x-rays. Oblique plain films may be helpful. Both CT and MRI can define damage to the pars interarticularis (pars defect) and nerve root impingement, although CT may be better for the purposes of identifying the bony defect, and MRI may reveal more detail about neurologic involvement. MRI also helps define the status of the disc at the impaired level and the level adjacent to the slip.

If the spondylolysis is believed to be recent, a bone scan may be useful to confirm or exclude an acute fracture. Electromyography (EMG) and nerve conduction studies check nerve function.

Source: Medical Disability Advisor



Treatment

Conservative treatment for spondylolisthesis includes rest (not excessive), activity modification (to minimize offending activity), physical therapy (to strengthen trunk muscles, especially the abdominals, and to stretch the hamstrings), and analgesics. Corsets or braces are also prescribed when necessary to minimize motion across the area of the slippage and to decrease pain.

Surgical intervention is considered when conservative therapy fails, pain becomes disabling, or a progressive neurological deficit occurs. Age is not a contraindication to surgery. Many elderly individuals seem to benefit a great deal from surgical intervention. The primary surgical procedure for treating spondylolisthesis is spinal fusion, in which 2 or more vertebrae are united by bone graft (with or without instrumentation) that heals to prevent further slippage of the vertebrae. Internal fixation devices, usually pedicle screws with or without an underbody fusion cage, may be used to enhance stability and thus the chances of successful fusion. Posterior lumbar interbody fusion (PLIF) enjoys a high success rate for Grades I and II spondylolisthesis, with nearly 100% of individuals experiencing a solid fusion (Brislin; Vokshoor). More severe grades of slippage may require both anterior and posterior fusion. If there is neurologic deficit, a decompression may be performed in addition to the fusion. In decompression for spondylolisthesis, the surgeon removes bone and ligamentous tissue compressing the lumbar nerve roots.

Source: Medical Disability Advisor



ACOEM

ACOEM's Practice Guidelines, the gold standard in effective medical treatment of occupational injuries and illnesses, are provided in this section to complement the disability duration guidelines.*
 
Low Back Disorders
 
* The relationship between the MDGuidelines (MDA) content and ACOEM's guidelines is approximate and does not always link identical diagnoses. The user should consult the diagnostic codes in both guidelines, as well as the clinical descriptions, before assuming an equivalence.

Source: ACOEM Practice Guidelines



Prognosis

In young patients with spondylolisthesis, surgical fusion with or without decompression may be curative, and no further intervention may be required. Individuals who have sustained an acute fracture with minimal slippage may completely recover if the fracture heals. Individuals with progressive degenerative changes may continue to have intermittent symptoms. Surgery (fusion, decompression) can be curative, but some individuals may experience only partial or intermittent relief.

The risk of degenerative spondylolisthesis increases with age, and progression of vertebral slippage occurs in 30% of individuals (Nizard). If vertebral slippage progresses, the neural foramen may narrow, causing nerve compression or sciatica that may require surgical decompression. Surgical outcomes are improved when fusion is performed in addition to decompression (Sengupta).

Source: Medical Disability Advisor



Rehabilitation

Rehabilitation for spondylolisthesis varies depending on the severity of the disease and the symptoms. If the spinal cord is compromised, see Spinal Cord Injury. If surgery is considered, the literature suggests that a 6-week period of rehabilitation treatment should be undertaken prior to surgical intervention.

Rehabilitation includes modalities such as heat and cold to control pain (Braddom). Once pain is controlled, general stretching and strengthening exercises of the trunk are indicated and progressed as tolerated. Therapists teach a home exercise program to complement the supervised rehabilitation. Individuals should be advised to continue these exercises on a regular basis, including after discharge from therapy, regardless of symptoms (Matsunaga). Instruction in proper posture and body mechanics for all activities of daily living should be reviewed.

If pain is severe see Low Back Pain for additional guidelines.

If surgery is indicated for severe and progressive spondylolisthesis, a postoperative protocol must be followed (Moller). This will include ambulation and transfer training, possibly with an orthosis to stabilize the trunk. Following surgery, some individuals may benefit from occupational therapy to assess the need for devices to promote independence in daily activities. After several weeks, general low back stretching, strengthening and stabilization exercises can be initiated and progressed as indicated by the treating physician.

Whether managed operatively or nonoperatively, an ergonomic assessment may be beneficial prior to return to work.

FREQUENCY OF REHABILITATION VISITS
Nonsurgical
SpecialistSpondylolisthesis
Physical TherapistUp to 15 visits within 6 weeks
Surgical
SpecialistSpondylolisthesis
Physical TherapistUp to 6 visits within 6 weeks
Note on Surgical Guidelines: Rehab usually begins after tissue healing, about 6 to 8 weeks after surgery.
The table above represents a range of the usual acceptable number of visits for uncomplicated cases. It provides a framework based on the duration of tissue healing time and standard clinical practice.

Source: Medical Disability Advisor



Complications

Progression of the slippage with increased pressure or traction on the spinal nerve roots may complicate treatment.

For individuals requiring surgery to stabilize the spondylolisthesis, complications include nerve root injury (less than 1%), cerebrospinal fluid leak (2% to 10%), fusion failure (5% to 25%), and infection and hemorrhage from surgery (1% to 5%). Among individuals who smoke, the nonunion rate of lumbar fusion is up to 50% (Vokshoor).

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Work restrictions may include the elimination of overhead work that involves hyperextension of the back. The individual may also be restricted in performing unassisted heavy lifting, repetitive bending, or pushing heavy objects. Some individuals may not be able to perform activities that require twisting at the waist. Use of a rigid corset (orthotic) may be needed to limit motion of the spine. Safety issues should be evaluated, as well as drug-testing policies, since individuals may need to take pain medication.

Individuals with severe pain and hamstring spasm, individuals with Grade III or IV vertebral slippage, and individuals who have had spinal fusion are generally restricted to sedentary, light, or moderate work.

Source: Medical Disability Advisor



Failure to Recover

If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case.

Regarding diagnosis:

  • Has diagnosis been confirmed?
  • What type of spondylolisthesis does individual have?
  • Have other conditions with similar symptoms been ruled out?
  • Does individual have increased lumbar lordosis?
  • Does individual engage in contact sports, gymnastics, or weight lifting?
  • Where does individual have pain? In the lower back? In the thighs or buttocks?
  • Does individual have tenderness over the spine above the pelvis?
  • Is there a palpable step-off in the lumbar spine?
  • Does individual stumble or drag the feet?
  • Is pain relieved when lying flat with bent knees or leaning forward?

Regarding treatment:

  • Have conservative measures been effective in relieving symptoms?
  • Is pain interfering with function?
  • Is individual receiving physical therapy?
  • Is surgery indicated?
  • Did individual undergo internal fixation? If not, upon what was the decision based?

Regarding prognosis:

  • Did individual have surgery? Was it successful or did it only bring partial or intermittent relief?
  • Were there any complications that could affect recovery?
  • Does individual have an underlying chronic condition such as osteoarthritis, osteoporosis, or degenerative disc disease that may affect recovery?
  • Is individual compliant in rehabilitation?

Source: Medical Disability Advisor



References

Cited

Braddom, Randolph L. Physical Medicine and Rehabilitation. 3rd ed. Philadelphia: W.B. Saunders, 2006.

Brislin, B., and A. R. Vaccaro. "Advances in Posterior Interbody Fusion." Otolaryngologic Clinics of North America 33 2 (2002): 367-374.

Devereaux, M. W. "Low Back Pain." Primary Care: Clinics in Office Practice 31 1 (2004): 33-51. MD Consult. Elsevier, Inc. 5 Dec. 2008 <http://home.mdconsult.com/das/journal/view/40139119-2/N/14670443?sid=293080764&source=MI>.

Froese, Beth B. "Lumbar Spondylolysis and Spondylolisthesis." eMedicine. Eds. Curtis W. Slipman, et al. 15 Mar. 2006. Medscape. 24 Mar. 2009 <http://emedicine.medscape.com/article/310235-overview>.

Irani, Zubin, and Jehangir J. Patel. "Spondylolisthesis." eMedicine. Eds. David S. Levey, et al. 6 May. 2008. Medscape. 24 Mar. 2009 <http://emedicine.medscape.com/article/396016-overview>.

Matsunaga, S., K. Ijiri, and K. Hayashi. "Nonsurgically Managed Patients with Degenerative Spondylolisthesis: A 10-to-18-Year Follow-Up Study." Journal Neurosurgery Spine 93 2 (2000): 194-198. National Center for Biotechnology Information. National Library of Medicine. 5 Dec. 2008 <PMID: 11012048>.

Moller, L., R. Hedlund, and . "Surgery Versus Conservative Management in Adult Isthmic Spondylolisthesis--a Prospective Randomized Study: Part 1." Spine 25 14 (2000): 1711-1715. National Center for Biotechnology Information. National Library of Medicine. 5 Dec. 2008 <PMID: 10870148>.

Nizard, R. S., M. Wybier, and J. D. Laredo. "Radiologic Assessment of Lumbar Intervertebral Instability and Degenerative Spondylolisthesis." Radiologic Clinics of North America 39 1 (2001): 55-71.

Sengupta, D. K., H. N. Herkowitz, and . "Degenerative Spondylolisthesis: Review of Current Trends and Controversies." Spine 30 6 (2005): S71-S81.

Vokshoor, Amir, and Ali R. Jamali. "Spondylolisthesis, Spondylolysis, and Spondylosis." eMedicine. Ed. Lee H. Riley. 12 Jan. 2009. Medscape. 24 Mar. 2009 <http://emedicine.medscape.com/article/1266860-overview>.

Source: Medical Disability Advisor






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