Definition/Description
Lumbar traction is the process of applying a stretching force to the lumbar vertebrae through body weight, weights, and/or pulleys to distract individual joints of the lumbar spine. The word traction is a derivative of the Latin word "tractico", which means "a process of drawing or pulling, and various forms of spinal traction have been described, since the time of Hippocrates, for the relief of pain.
James Cyriax popularized lumbar traction during the 1950s and 1960s as a treatment for disc protrusions, and until today, it is still a common modality for treating patients with back pain and leg pain. Although its effectiveness is still being questioned by a few clinical trials, there are three benefits of lumbar traction described by James Cyriax: distraction to increase the intervertebral space, tensing of the posterior longitudinal vertebral ligament to exert centripetal force at the back of the joint and suction to draw the disc protrusion towards the center of the joint. Some other effects attributed to traction include widening of the intervertebral foramen and distraction of the apophyseal joints.
Clinically Relevant Anatomy
The lumbar spine is made up of five individual vertebrae which are numbered L1 to L5 and together they create the concave lumbar curvature in the lower back. Found along the body’s midline in the lumbar (lower back) region, the lumbar vertebrae make up the region of the spine inferior to the thoracic vertebrae in the thorax and superior to the sacrum and coccyx in the pelvis.These vertebrae carry all of the upper body’s weight while providing flexibility and movement to the trunk region. They also protect the delicate spinal cord and nerves within their vertebral canal.
Connecting each vertebra to its neighboring vertebra is an intervertebral disk made of tough fibrocartilage with a jelly-like center. The outer layer of the intervertebral disk, the annulus fibrosus, holds the vertebrae together and provides strength and flexibility to the back during movement. The jelly-like nucleus pulposus acts as a shock absorber to resist the strain and pressure exerted on the lower back.
The lumbar vertebrae are the some of the largest and heaviest vertebrae in the spine, second in size only to the sacrum. A cylinder of bone known as the vertebral body makes up the majority of the lumbar vertebrae’s mass and bears most of the body’s weight. Posteriorly the body is connected to a thin ring of bone known as the arch. The arch surrounds the hollow vertebral foramen and connects the body to the bony processes on the posterior of the vertebra. The vertebral foramen is a large, triangular opening in the center of the vertebra that provides space for the spinal cord, cauda equina, and meninges as they pass through the lower back.
Extending from the vertebral arch are several bony processes that are involved in muscle attachment and movement of the lower back. The spinous process extends from the posterior end of the arch as a thin rectangle of bone. It serves as a connection point for the muscles of the back and pelvis, such as the psoas major and interspinales. On the left and right lateral sides of each vertebra are the short, triangular transverse processes. The transverse processes form important connection points for many muscles, including the rotatores and multifidus muscles that extend and rotate the trunk.
Unlike the cervical vertebrae in the neck, the lumbar vertebrae lack the transverse foramina in the transverse processes, and also lack facets to either side of the body. The fifth lumbar vertebra is distinct from the L1-4 vertebrae in being much larger on its front side than in the back. Its spinous process, on the other hand, is smaller than in the other lumbar vertebrae with a wide, four-sided shape that comes to a rough edge and a thick notch.
Types of Lumbar Traction
Several types of lumbar traction are described in literature but the most used include:
Continuous Traction
Continuous or bed traction uses low weights for extended periods of time (up to several hours at a time). This long duration requires that only small amounts of weight be used. It is generally believed that this type of traction is ineffective in actually separating the spinal structures. In other words, the patient cannot tolerate weights great enough to cause separation of the vertebrae for that length of time.
Sustained Traction
This type of traction involves heavier weights applied steadily for short periods of time (for periods from a few minutes up to 1 hr). Sustained traction is sometimes referred to as static traction.
Intermittent Mechanical Traction
Intermittent traction is similar to sustained traction in intensity and duration but utilizes a mechanical unit to alternately apply and release the traction force at preset intervals
Manual Traction
Manual traction is applied as the clinician's hands and/or a belt are used to pull on the patient's legs. It is usually applied for a few seconds duration or can be applied as a sudden, quick thrust.
Autotraction
Autotraction utilizes a specially designed table that is divided into two sections that can be individually tilted and rotated. The patient provides the traction force by pulling with the arms and/or pushing with the feet. Investigations of autotraction have reported favorable clinical results but no change in size or location of lumbar disc herniation
Positional Traction
This form of traction is applied by placing the patient in various positions using pillows, blocks, or sandbags to effect a longitudinal pull on the spinal structures. It usually incorporates lateral bending and is only affected to one side of the spinal segment
Gravity lumbar traction
This involves using a chest harness to secure the patient as the treatment table is tilted to a vertical position, thereby using the weight of the lower half of the body to provide a traction force.
Mechanism of Action
Several theories have been proposed to explain the possible clinical benefit of traction therapy. Distracting the motion segment is thought to change the position of the nucleus pulposus relative to the posterior annulus fibrosus or change the disc-nerve interface. These effects are plausible based on studies examining the kinematics of the lumbar spine during traction therapies. In addition to separating the vertebrae, traction has been shown to reduce nucleus pulposus pressure and increase foraminal area.
However, it is unlikely that mechanical changes observed in a prone position will be sustained after a patient resumes an upright, weight bearing posture. Any lasting clinical response to traction therapy would more likely be because of the effect of traction on the mechanobiology of the motion segment or neural tissues. Complicating the issue further is that not all traction therapies exert the same force on the spine and animal studies have found the mechanobiology of the disc to be sensitive to the amount, frequency, and duration of loading.
It is possible that some forms of traction stimulate disc or joint repair whereas others promote tissue degradation. Although these variables have not been systematically examined, even in animal models, what is known regarding disc mechanobiology should alert us to the possibility that not all traction therapies are equal. If distracting the spine can influence disc and joint mechanobiology, different modes of traction may result in different clinical results. Systematic reviews of lumbar traction therapy have typically not considered that different effects may exist based on force and time parameters. Traction trials have most often included patients with a mix of clinical presentations including back-dominant low back pain (LBP), leg-dominant LBP, or both. However, a patient with only dominant LBP and no radiculopathy is likely experiencing pain from a sclerotomal source, such as facet joints or disc, whereas sciatic pain, even if caused by disc herniation, may be predominately of neural origin. Although it is reasonable to suspect that traction therapies may affect these conditions differently, there is insufficient evidence to support this hypothesis.
Distraction-manipulation and positional distraction are mechanically different than traditional traction (intermittent or sustained). Rather than allowing forces to be dispersed throughout the lumbar tissues, these treatments attempt to concentrate them in a smaller area. AT, for example, allows the patient to concentrate the force by finding the position that most relieves their pain and applying distraction in that position. Distraction-manipulation, most often used by chiropractors and physical therapists, is performed on treatment tables that allow the operator to determine the moment-to-moment vector and timing of the distractive force. These techniques include FD (Cox technique), Leander technique, and Saunders Active Trac method, among others.
Article Source: Physiopedia
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