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Background
Traction is a widely used treatment for low back pain and it is often provided in combination with other treatment modalities. Types of traction include mechanical traction, manual traction (unspecific or segmental traction), autotraction, gravity-dependent ("(anti-)gravity") traction, pneumatic traction, continuous traction, and intermittent traction.
The most commonly used traction techniques are manual traction (i.e., the traction is exerted by the therapist, using arms and/or legs of the patient), inverted suspension (i.e., the traction is exerted by gravitational forces, through the body weight of the patient), bed rest traction (i.e., the traction is exerted by a pulley and weights) and motorized traction (i.e., the traction is exerted by a motorized pulley). Lumbar traction uses a harness (with Velcro strapping) that is put around the lower rib cage and around the iliac crest. Duration and level of force exerted through this harness can be varied in a continuous or intermittent mode.
The exact mechanism through which traction might be effective is still unclear. It has been suggested that spinal elongation, through decreasing lordosis and increasing intervertebral space, inhibits pain (nociceptive) impulses, improves mobility, decreases mechanical stress, reduces muscle spasm or spinal nerve root compression (due to osteophytes), releases luxation of a disc or capsule from the zygapophyseal joint, and releases adhesions around the zygapophyseal joint and the annulus fibrosus. So far, the proposed mechanisms have not been supported by sufficient empirical information.
Little is known about the adverse effects of traction. Only a few case reports are available, which suggest that there is some danger for nerve impingement in heavy traction, i.e., lumbar traction forces exceeding 50% of the total body weight. Other risks described for lumbar traction are respiratory constraints due to the traction harness or increased blood pressure during inverted positional traction. Lumbar traction forces below 25% of the total body weight do not seem to increase intervertebral distances, and can therefore be regarded as a placebo (sham or low dose) traction. Placebo traction can only be expected to produce relaxation of spinal muscles and modification of the spinal curve.
van der Heijden, et al. (1995) published a systematic review of twenty-one papers reporting on 24 randomized controlled trials of traction. The authors concluded that the information of these studies did not allow for clear conclusions about the effectiveness of traction due to methodological flaws in study designs. Most studies were considered to be of poor methodological quality. As this previous review was based on literature published up to and including 1992 and several new randomized controlled trials have been published since, the lead author of the 1995 study is preparing an update for the Cochrane Collaboration.
Traction (manual or mechanical pull on extremities or spine to relieve spasm and pain), when provided by physicians or physical therapists, is typically used in conjunction with therapeutic procedures, not as an isolated treatment. Standard treatment is to provide supervised mechanical traction up to four sessions per week.
Autotraction:
Autotraction is defined as the use of one’s own weight to create the traction force (i.e., the patient determines the traction force). By utilizing positional and gravity assisted traction principles, autotraction can provide multi-plane traction. Brand names of autotraction devices include the Spinalator, Spinalign Massage, Intersegmental Traction Table and the Anatomotor. These are tables with custom-contoured rollers that deliver consistent pressure and move underneath the patient while they are lying on top of the table. A 3-motor operating system allows for roller elevation, roller travel, as well as roller rotation (clockwise or counter-clockwise).
There are only two published randomized clinical studies comparing autotraction to other forms of traction; the results of these studies are conflicting. Telso and Merlo (1993) from Italy reported on a randomized clinical trial comparing conventional passive traction to autotraction. The investigators measured subjective response concerning overall improvement, pain intensity using visual analog scale, qualitative pain severity using the McGill Pain Questionnaire, and pain-related disability using the Oswestry Low Back Pain Disability Score. The favorable response to autotraction was 75% (30 of the 40 patients) versus the 22% (6 of 27 patients) to conventional passive traction (p < 0.001).
A study by Ljunggren et al. (1984), however, found no differences in effectiveness between autotraction and manual traction. Forty-nine patients with lumbago-sciatica and prolapsed lumbar intervertebral discs, comparable concerning anamnestical and clinical data were randomized for autotraction and manual traction given by the same therapist for a period of one week while strict bed rest was prescribed. A blind overall assessment performed immediately after the traction period, after two weeks follow-up training and three months after hospitalization showed that the two traction modalities are equally efficient. The author concluded that, as treatment for hospitalized patients with lumbar intervertebral disc prolapses, the relatively simple manual traction variety should be preferred, if any.
Another two randomized clinical studies compared protocols that included autotraction with conservative management by a primary care physician; the results of these studies are conflicting. Moreover, since these latter two studies did not compare autotraction to other forms of manipulation, no conclusions about the comparative efficacy of autotraction can be drawn from them. Blomberg, et al. (1993, 1994) reported on the results of a controlled, multicenter clinical trial comparing outpatients with acute or subacute low-back pain who were randomly allocated to either standardized but optimized conventional activating treatment by primary health care teams (n = 53) or specific manual treatment such as manipulation, specific mobilization, muscle stretching, autotraction and cortisone injections (n = 48). The treatment effect was evaluated by standardized telephone interviews 3, 7, 14, 21 and 90 days after the start of treatment. The authors reported that, in the early phase of treatment as well as at the 90 days' follow-up, the group receiving manual treatment had significantly less pain, less disability, faster rate of recovery and lower drug consumption than patients receiving conventional treatment, indicating that this type of treatment is superior to conventional treatment.
Seferlis (1998) also compared a program that included autotraction to conventional management, but unlike Blomberg, found no differences in effectiveness. One hundred eighty patients sick-listed less than 2 weeks for low back pain with or without sciatica, 95 men and 85 women aged 19-64 years, were randomized to three groups: an intensive training program (I), a manual therapy program that included autotraction (R1), or standard treatment by a general practitioner (R2). The intensive training program (I) (n = 60) consisted of small groups, muscle training and general condition training, strength and co-ordination, abdominal, gluteal, paraspinal, shoulder and lower extremity muscles, 3 times per week, for 8 weeks. The manual therapy program (R1) (n = 60) consisted of autotraction, manipulation of lumbar facet joint and sacroiliac joint, mobilization, muscle energy technique, stretching, and coordination training, with number of sessions decided by the physiotherapist. The general practitioner program (R2) (n = 60) included standard treatment, rest, sick leave, drug prescription, postural advice, and back school or physiotherapy for patients failing to recover. No significant differences were found between the 3 groups in pain intensity, functional status after 1, 3 and 12 months. No significant differences were found between the 3 groups in number of days off of work due to back pain; median (range) number of days off work due to back pain after 1 year was: (I) 23 (5-365), (R1) 28 (4-365), (R2) 30 (4-365). Subjective satisfaction with treatment was significantly better with intensive training (I) and manual therapy (R1) than with standard treatment (R2); mean (SD) satisfaction on a 5 point scale after 1, 3, and 12 months was: (I) 4.3 (0.8), 4.4 (0.6), 4.1 (1.1); (R1) 4.4 (0.8), 4.5 (0.6), 4.3 (0.9); (R2) 3.4 (1.2), 3.5 (1.1), 3.6 (1.2). However, mean number of treatment sessions was least for standard treatment; mean number of treatment sessions for each of the groups was: (I) 18, (R1) 10, (R2) 4.
Because the clinical evidence is limited and conflicting, no conclusions can be drawn about the efficacy of autotraction, or about its effectiveness in comparison to other forms of traction.
Home Traction:
The Norwegian Centre for Health Technology Assessment (2001) completed an assessment, "Treatment of Lumbar Disc Herniation", that concluded that traction of patients with lumbar disc herniation has "no effect." The Swedish Council on Technology Assessment reviewed the literature on treatments of back pain and concluded that there is in fact, "moderate evidence against" the use of traction in back pain (Nachemson A, et al., 2000). Birkmeyer and Weinstein (1999) concluded that lumbar traction for back pain is an outmoded technology that has "fallen out of favor".
van der Heijden, et al (1995) reviewed the literature on traction for back pain, and concluded that "the available RCTs do not allow clear conclusions to be drawn about the effectiveness of cervical or lumbar traction." A Prodigy Clinical Practice Recommendation (SCHIN, 2001) states, based on the literature, that "[t]raction does not appear to be effective for low back pain or radiculopathy."
According to the AHCPR Clinical Practice Guideline on Acute Low Back Pain in Adults (Bigos, et al., 1994), the evidence does not demonstrate traction to be effective in treatment of patients with acute low back pain.
Several additional systematic evidence reviews have been published more recently that have reached these same conclusions about the lack of adequate evidence of lumbar traction for back pain (see, e.g., Harte, et al., 2003; Vroomen, et al., 2000; Philadelphia Panel, 2001; van Tulder & Koes, 2004).
Spinal Unloading Devices:
Spinal unloading devices provide a traction-like effect in an effort to shift weight-bearing off the lower back and onto the hips. The method used to shift weight-bearing varies from device to device. Some devices (e.g., LTX 3000) utilize gravitational force provided by the body mass of the individual. Other devices (e.g., Orthotrac Pneumatic Vest, STx -- Saunders Lumbar Traction Device, Saunders Lumbar Hometrac Deluxe) utilize applied pneumatic pressure in an effort to shift weight-bearing.
Falkenberg and associates (2001) examined the surface electromyographic (EMG) changes during axial spinal unloading using the LTX 3000 in normal subjects to determine the optimal time for effective traction. Hales, et al. (2002) reported on the short-term effect of LTX3000 on spinal curvature. Janke, et al. (1997) and Podien & Iaizzo (1998) have reported on the biomechanical and physiologic changes during axial spinal unloading the LTX 3000. However, there is a lack of evidence regarding the clinical value of LTX 3000 in improving clinical outcomes (reduction in pain and disability, improvements in function) in patients with low back pain.
There are a lack of published peer-reviewed studies that have specifically evaluated the safety and effectiveness of the Saunders Lumbar HomeTrac or Saunders STx (The Saunders Group, Chaska, MN) home pneumatic traction devices for back pain. In addition, there is a lack of well-designed studies comparing the safety and effectiveness of the Saunders Lumbar HomeTrac or Saunders STx with lumbar traction provided by a physical therapist. Well designed controlled clinical studies demonstrating reductions in pain and disability and improvements in function are especially important in evaluating pain interventions because of the susceptibility of this symptom to placebo effects. One is unable to determine from uncontrolled observations whether any noted improvements are due to the application of home lumbar traction, the impact of any other interventions that the patient was concurrently receiving, or the waxing and waning natural history of chronic back pain.
The Orthotrac™ Pneumatic Vest (Orthofix, Inc., McKinney, TX) is an inflatable pneumatic vest that has been promoted for use in relieving back pain from a variety of causes (e.g., herniated disc, spinal stenosis, facet syndrome, spondylolysthesis, etc). The Orthotrac was evaluated in a study of 41 patients with radicular pain due to degenerative discopathy (Dallolio, 2005). The investigator reported that, after five weeks, 32 patients (78%) have showed improvements on a SF-36 inventory, and all patients referred a decrease or disappearance of radicular pain. The investigator concluded, however, that “further multicenter and interdisciplinary studies on a greater number of patients are obviously needed to confirm these preliminary results.” The primary limitations of this study was the uncontrolled nature of this study, its short duration, and the subjective endpoints,
These devices were cleared by the FDA based on a 510(k) premarket notification, so that the manufacturer was not required to submit the evidence of effectiveness that would be required to support a premarket approval application (PMA).
A Cochrane review on traction for low back pain with or without sciatica (Clarke et al, 2007) noted that various types of traction are used in the treatment of patients with low-back pain, often in conjunction with other treatments. These investigators concluded that that traction is probably not effective. Neither continuous nor intermittent traction by itself was more effective in improving pain, disability or work absence than placebo, sham, or other treatments for patients with a mixed duration of low back pain, with or without sciatica. They also noted that while there was moderate evidence that autotraction was more effective than mechanical traction for global improvement in patients with sciatica, these studies had methodological limitations and inconsistent results.
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