Effect of Lumbar Bracing on Spinal Function
Condition: Low Back Pain
MeSH terms: Low Back Pain
Study type: Interventional

Summary: 
      A recent province-wide survey (Alberta, Canada) suggests that clinicians' beliefs about soft
      lumbar bracing for low back pain (LBP) vary substantially. Approximately 50% of clinicians
      (MDs, DCs, PTs) find back braces "useful" for acute back pain while the remaining half report
      that bracing causes muscle atrophy. While previous studies suggest bracing for acute low back
      conditions can reduce pain and does not cause atrophy, no prior study has assessed back
      function after bracing using self-reported and objective measures within the same cohort.

      PURPOSE:

      To assess both self-reported and objective measures of spine function before, and after, use
      of an inelastic lumbar brace over a two week period.

      STUDY DESIGN:

      Before-After Design

      OUTCOME MEASURES:

      Self-reported spine function, spinal stiffness and muscle endurance.

      METHODS:

      Three groups were studied: asymptomatics who did not wear a brace (-LBP/-Brace),
      asymptomatics who were braced (-LBP/+Brace) and acute LBP subjects who were braced
      (+LBP/+Brace). Both groups of braced subjects (-LBP/+Brace; +LBP/+Brace) were instructed to
      wear the brace continually for 2 weeks with the exception of bedroom & bathroom activities.
      Before and after the 2 week period, 3 measures of spine function were performed: spinal
      stiffness via motorized indentation of the L3 spinous process, a modified Sorensen test
      (timed lumbar extension against gravity), and the Oswestry Disability Index (ODI). Unbraced
      (-LBP/-Brace) subjects were studied over the same time with the same measures. Repeated
      measures analyses of variance were conducted for all three outcomes with a significance level
      of 0.05.
    

Detailed description: 
      Background: While various treatments for low back pain (LBP) are prescribed, one in
      particular appears to be frequently self-prescribed: external lumbar bracing (i.e. elastic
      corsets and other similar devices). Given that the mechanical function of the back is to bear
      static and dynamic loads and that most LBP is thought to be mechanical in nature, there is a
      biological plausibility that underlies bracing as a treatment for LBP Indeed, several reports
      suggest lumbar bracing may be effective for some LBP patients.

      The high frequency of self-prescribed bracing may be the result of the clinical community's
      reluctance to prescribe these devices. Approximately half of Alberta spine clinicians believe
      that spine bracing results in muscle atrophy and/or future dependency on braces. Conversely,
      recent work from our laboratory has shown that after two weeks of brace wearing, the volume
      of spinal muscles remains unchanged in asymptomatic subjects (i.e. no brace-induced atrophy
      was caused)

      Objective and hypothesis: While bracing for 14 days does not result in decreased muscle
      volume in asymptomatic subjects, there is a need to understand if bracing preserves muscle
      volume while muscle function declines. This information would allow us to understand the
      effects of bracing on spinal function independent of changes in muscle volume. Therefore, we
      hypothesize that that brace-wearing will result in an insignificant alteration in spinal
      function.

      Future Relevance: Results from this pilot study will allow us to construct future
      investigations to reveal the underlying mechanisms of bracing with respect to the alleviation
      of LBP.

      Subjects: Subjects of both genders between the ages of 18 and 65 will be recruited from the
      University of Alberta and surrounding area. The target recruitment populations are 1)
      asymptomatic subjects and 2) those with low back pain. Subjects excluded from the study will
      have a history of back pain with red flags, those who are pregnant (or believe they may be
      pregnant) or other contraindications described in the full protocol.

      Methods: Potential subjects will complete a survey to obtain demographic data as well as a
      focused medical history and physical examination performed by one of the research team. If a
      subject meets the inclusion/exclusion criteria and provides written, informed consent, they
      will be enrolled in the study. Those not able to be enrolled will be thanked and dismissed.

      Asymptomatic subjects will be assigned randomly into a brace and non-brace cohort. From the
      recruited subjects, three cohorts will be created: 1) Asymptomatic subjects who will wear a
      brace (-LBP/Brace+), 2) asymptomatic subjects who will not wear a brace (-LBP/-Brace) and 3)
      low back pain subjects who will wear a brace (+LBP/+Brace). Because this experiment is not
      designed to assess brace efficacy, there is no need to include a cohort of symptomatic
      subjects who do not wear a brace. Each subject who will wear a brace will be fitted and sized
      for an elastic brace supplied at no charge to the subject. Subjects will be instructed on how
      to don and remove the brace as well as the circumstances when they are permitted to remove
      the brace (washroom, shower, sleep). The subject will also be informed that the brace has a
      monitoring feature to determine brace compliance as well as their activity level.

      As soon as possible after brace fitting, a battery of tests will be conducted to determine
      each subject's spinal function. These tests are as follows:

        1. The Oswestry Disability Index (OWDI). The OWDI is a self-reported measure of function.
           The OWDI has established reliability and validity and has been used extensively in low
           back pain research.

        2. Spinal Stiffness testing. This test uses a blunt probe to push into the back of a
           resting subject to measure the stiffness of the spine. It was developed in our lab and
           has been used in many prior studies both at the Universities of Alberta, Hong Kong and
           Utah.

        3. Rehabilitation Ultrasound Imaging (RUSI). This test uses ultrasound to image spine
           muscles during simple tasks (e.g. arm raising) to quantify the ability of the back
           muscles to contract with the desired magnitude and timing. This test is well-described
           in the literature and has been approved for use previously in our laboratory.

        4. Modified Sorensen test. This is a timed test of spine function where subjects are asked
           to straighten their backs from a semi-inclined position until pain onset and/or failure
           to maintain the target position. The test, and its variants, has been well-studied since
           it was first described in 1984. The modified version of the test to be used here has
           been shown to be safe to perform in acute back pain subjects.

      The subject will now be released to their usual activities of daily living for a period of 14
      days.

      To determine if there are any problems in subjects wearing braces, those subjects will be
      contacted by the PI or research team within the first 24 hours following brace fitting and
      then approximately every three days after that time. If a correction to the brace cannot be
      made that is satisfactory to the research team and the subject, the subject will thanked and
      dismissed.

      Following the two week experiment period, subjects will attend the laboratory. Usage data
      will then be extracted from the data logger of those wearing braces. If the subject has worn
      the brace for less than 75% of the requested time, the subject will be dismissed and thanked
      for their participation. If subjects have worn the brace for more than 75% of the requested
      time, the spinal function tests will be performed for a second time.

      Change scores of each of the 5 spine function tests will be calculated and then compared
      between the three cohort using an analysis of variance (alpha = 0.05).

      Expected results: Given our prior data that muscle volume does not changes after 14 days of
      bed rest, it is expected that brace-wearing will not reduce spinal function in symptomatic or
      asymptomatic populations.
    

Intervention name(s): Lumbar corset (Quickdraw, Aspen Medical Products)
Intervention type(s): Device
Intervention description(s): The corset (a.k.a. brace) is made of webbing and elastic. It is wrapped around the trunk and tightened with Velcro and a series of cords (like tying shoes).
Other intervention name(s): Soft lumbar brace
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Basic Science