narrowing of the spinal canal space
Fig. 1: Narrowing of the spinal canal space
(larger view)

narrowing of the spinal canal space
Fig. 2: The vest in use
(larger view)

Most people with an acute episode of low back pain or leg pain find significant pain relief within a few weeks, but for some, the pain and inability to tolerate upright, weight bearing postures persists or recurs based on activity. As many as 62% of people who have experienced an acute low back pain incident have persistent pain episodes at 1 to 2 years after onset 1. Many who have returned to normal activities suffer relapses when they do certain activities of daily living 2. These painful flare-ups can occur in intervals as frequent as 6 to 7 weeks.

The reason that the pain can occur appears to be a conspiracy of four factors:

  • The normal aging process
  • Some type of damage or injury to the tissues
  • Muscular fitness
  • The effects of weight-bearing strain acting on the tissues
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While there is little that can be done to offset aging and any effects from prior damage or injury, some people with low back pain and leg pain can influence the other two factors through exercise and, where necessary, the use of other non-surgical back care that reduces weight-bearing strain on the tissues. This article provides a review of recent information presented at the 2005 North American Spine Society conference about the effectiveness of one product designed to reduce weight-bearing strain on the tissues—the Orthotrac pneumatic vest 4.

Weight Bearing Intolerance

The term “weight bearing intolerance” is used to describe pain that is aggravated by activities or tasks in the upright positions of sitting, standing, walking, lifting and bending. People who experience this find significant and reliable low back pain relief by getting off their feet and lying down or sitting in a reclining position for 30 minutes or more. For these individuals, the need to rest for low back pain relief is not only restricting to life style but can also promote a downward spiral of inactivity that promotes further disability.

Weight bearing intolerance arises from the fact that the strain of upright postures can result in a narrowing of the disc space, increasing the pressure on the facet joints and reducing the space for the spinal nerve roots (Figure 1). Aging and injury are associated with tearing and bulging of the disc material and arthritic changes in the joints that, by themselves, are often not painful. Under increased strain, they may become symptomatic causing local low back pain or radiating pain down the leg.

This situation can arise in patients with a variety of common low back problems, including:

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New Research on the Pneumatic Vest

The vest reviewed in this article is a pneumatic vest made by Orthofix (Figure 2). It is a custom vest that uses pneumatic lifters to “unload” some of the weight from the patient’s lumbar spine onto the iliac crests (the pelvic bone). The patient wears the vest when symptoms are experienced during activity, usually during walking or standing for some period of time. While there is no required minimum wear time and the patient decides when and for how long to use the vest for best individual results, the suggested minimum to help provide low back pain relief is 20-60 minutes three times per day. The vest is not to be worn during heavy lifting. Side effects can include occasional local tenderness, or soreness when touched at bony prominences of the spine, and rarely, temporarily increased symptoms when the vest is fully inflated.

A recent biomechanical study reported in The Spine Journal 3 demonstrates that the use of the vest results in a decrease in low back disc pressure by as much as 25% of normal body weight.

According to a randomized clinical trial presented at the recent North American Spine Society 4 meeting in September 2005, patients using the Orthotrac pneumatic vest had up to twice the low back pain relief versus those who did not, even when both groups had similar improvement in activity levels and continued prescribed medication or treatment.

Study background
62 patients were enrolled in the study and were randomly assigned to either the Orthotrac Pneumatic Vest or the Orthofix EZ Brace. The EZ Brace (also made by Orthofix) is designed to protect the patient from improper posture and movements that can cause additional injury, while helping the initial soft tissue injury to heal. Each enrolled patient had to meet the following selection criteria:

Inclusion criteria summary

  • Age 21-55
  • Low back pain and/or leg pain greater than 4.0 on the Visual Analog Scale
  • Confirmed disc problems on MRI scan
  • Able to stand upright
  • Consistent low back pain relief and/or leg pain relief when recumbent (lying down or reclining)
  • Inadequate low back pain relief and/or leg pain relief after 4 weeks of conservative (nonsurgical) therapy

Exclusion criteria summary

  • Prior surgery
  • Neurologic deficit
  • Leg pain and/or low back pain for less than 4 weeks

This research was funded by Orthofix, Inc, manufacturer of both the Orthotrac Pneumatic Vest and the Orthofix EZ Brace.

Study results
The patients were followed for one year. Those patients using the Orthotrac Pneumatic Vest were found to have significantly greater low back pain relief (30% more on the Visual Analog Scale) as compared to the patients using the EZ Form Brace, when combined with other conservative therapy (e.g., exercise/physical therapy, medication). While self-reported functionality was not significantly different between the two groups (as measured by the Oswestry scale), the study shows a trend favoring the pneumatic vest. Specifically, patients who seemed to get the most low back pain relief (and/or leg pain relief) from unloading the disc while weight bearing were those who did not have significant emotional distress and tended to lead more active life styles (10 point better energy/fatigue and mental health profiles as measured on the SF-36).

Prior research showed that patients most likely to get pain relief from the Orthotrac pneumatic vest typically have had discogenic pain, mechanical low back pain or radicular pain for more than 8 weeks, and experience:

  • Increased low back pain and/or leg pain when standing or walking
  • Significant decrease of low back pain or leg pain after lying down for 20 to 30 minutes
  • Ability to stand up straight
  • Approximately 24 inches to 57 inches waist measurement


  1. VonKorff M, Saunders K. The course of back pain in primary care. Spine 1996; 21:2833-2837.
  2. Carey TS, Garrett J, Jackman A. The Outcomes and Costs of Care for Acute Low Back Pain Among Patients Seen by Primary Care Practitioners Chiropractors, and Orthopedic Surgeons. New Engl J Med 1995; 333(14):913-917.
  3. Ferrara L, Triano JJ, Sohn M, Song E, Lee DD. A Biomechanical Assessment of Disc Pressures in the Lumbosacral Spine in Response to External Unloading Forces. The Spine Journal 2005; 5(5):548-553.
  4. Triano JJ, Roger C, Diederich, J, Gonzalez C, Hochschuler S. Discopathy with leg pain: An RCT of Orthotrac vest unloading vs. EZ brace—one year outcomes. Proceedings of the North American Spine Society annual meeting, Philadelphia, September, 2005. This research was funded by Orthofix, Inc.