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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


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Overview

Image Description:
Spondylolisthesis - A profile of the trunk and spine highlights the thoracic spine of the upper back. A close up of the thoracic vertebrae reveals defects in the pars interarticularis between the vertebrae; one vertebra is depicted as having slipped forward, compressing the spinal nerve.
Click to see Image

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