Lower Back Biomechanics in Veterans With Non-Specific Low Back Pain
Condition: Chronic Low Back Pain
MeSH terms: Back Pain; Low Back Pain
Study type: Observational

Summary: 
      Low back pain (LBP) is strongly associated with opioid consumption among Veterans, and
      improved clinical management of LBP is likely to reduce reliance on opioid among Veterans. Up
      to 60% of patients with an acute episode of nonspecific LBP experience either symptom
      persistence or symptom relapse within one year. This is likely an indication of a failure in
      addressing the underlying mechanisms of pain or initiation of a new etiology; both may stem
      from a mismatch between patients and treatments. The overall goal of this research is to
      develop, validate and implement measures that are relevant to known mechanisms of LBP, which
      can then be used to holistically gauge the health status of patients' lower backs beyond
      self-reporting of symptoms. More accurate measurements will help better match of patients
      with existing treatments or development of more effective new treatments. The specific
      objective of this study is to generate evidence in support of the feasibility of the
      investigators' methods for 1) the evaluation of relative contribution of lower back tissues
      to spinal loads, and 2) the investigation of the resultant spinal loads in Veterans with
      non-specific LBP. The investigators have developed a powerful set of tools for the
      comprehensive assessment of spinal loads and lower back mechanical behavior (MB), that will
      enable the investigators to examine the existence or development of abnormalities in spinal
      loads and lower back MB in three groups of Veterans with different experiences with
      non-specific LBP. These groups will include 1) Veterans with chronic, non-specific LBP and
      high level of disability (n=18), 2) Veterans with chronic, non-specific LBP and low level of
      disability (n=18), 3) asymptomatic Veterans without a recent history of non-specific LBP
      (n=18; serving as control group). Successful completion of this feasibility project will pave
      the way for future studies (merit grant applications) that will verify the role of
      abnormalities in lower back MB and spinal loads in the clinical presentation of LBP. Such an
      understanding has the potential to help the affected Veterans with disabling non-specific
      LBP. Specifically, measures of lower back MB and spinal loads can be used not only to
      identify Veterans with mechanical abnormalities in their lower back who are likely to
      experience LBP in the future, but also to guide novel integrated physical and psychological
      preventative treatments aimed at improved lower back mechanics. Ultimately, the goal and
      resultant improvement in clinical outcomes of treatment for non-specific LBP is to diminish
      reliance on opioids for the symptom management of particularly Veterans with chronic LBP.
    

Detailed description: 
      Specific Aims

      The specific objective of this study is to generate evidence in support of the feasibility of
      the investigators' developed methods for the evaluation of 1) relative contribution of lower
      back tissues to spinal loads, and 2) the resultant spinal loads experienced during daily
      activities in Veterans with non-specific LBP. Results of this feasibility study will enable
      proper design of the investigators' future projects, wherein the investigators will
      investigate the role of spinal loads experienced in daily life activities in clinical
      presentation of LBP. The investigators have developed several innovative computational and
      experimental methods for a comprehensive and personalized assessment of spinal loads.
      Specifically, the relative mechanical contribution of active and passive lower back tissues
      to spinal loads is assessed using advanced measures of bulk lower back mechanical behavior
      (MB), whereas muscular responses to physical demands of daily activities and the resultant
      spinal loads are evaluated using the investigators' finite element model of human spine. The
      investigators have used the methods proposed in this application extensively for evaluation
      of bulk lower back MB and spinal loads in asymptomatic individuals. This project will
      demonstrate the sensitivity of the measures for capturing abnormalities in lower back MB and
      spinal loads in patients with nonspecific LBP by completing the following two aims to achieve
      the investigators' objective:

      Aim-1: Feasibility of distinguishing potential differences in lower back MB between Veterans
      with different LBP experiences. The investigators will characterize lower back MB in three
      gender-balanced groups of Veterans between 20 and 70 years old. These will include Veterans
      with 1) chronic LBP and a Roland-Morris Disability Questionnaire (RMDQ) score of >12 (n=18),
      2) chronic LBP and RMDQ score of 12 (n=18), 3) no recent history of LBP and currently
      asymptomatic (n=18), serving as control group). Participants will be recruited from the
      population served by the Lexington, KY, VA Medical Center. The investigators will determine
      passive stiffness of the lower back and its relaxation along with its active intrinsic and
      reflexive mechanical properties, using the sudden perturbation and stress-relaxations tests.
      Given the reported differences in trunk neuromuscular behavior and lumbo-pelvic coordination,
      the investigators expect to see differences in the measures between patient groups targeted
      for this project.

      Aim-2: Feasibility of distinguishing potential differences in spinal loads between Veterans
      with different LBP experiences. Trunk muscle forces and the resultant spinal loads will be
      determined in the same participant groups when they perform common activities of daily living
      like walking and manual material handling. Considering the causal role of spinal loads, and
      given the persistence of symptom in patients with chronic LBP, along with the high risk of
      LBP recurrence in patients with non-chronic LBP and those with a recent history of LBP, the
      investigators expect differences in spinal loads between patient groups.

      Research Procedures:

      Participants deemed eligible will complete one data collection session during which they will
      first be instrumented with sensors to enable measurement of kinematics and muscle activity,
      similar to procedures the investigators used in earlier studies. Specifically, wireless
      inertial measurement units (Xsens MTW, Xsens Technologies, Enschede, Netherlands) will be
      used to measure rotations of the thorax and pelvis, and surface EMG electrodes will be used
      to measure the activity of erector spinae, rectus abdominis, internal and external obliques.
      Participants will then be asked to stand on a force plate and perform a forward bending and
      backward return test. Participants will be instructed to bend from an upright standing
      posture to their maximum comfortable forward bending posture and then return to the upright
      posture at a self-selected pace. Participants will then be instructed to perform the
      following activities of daily life at a self-selected pace: walking on level and sloped
      surfaces, sit-to-stand and stand-to-sit motions, and lowering and lifting a 10 lb load to
      their knee height. These activities have been selected because they represent basic but
      repetitive activities of daily life, and the investigators have successfully used them in
      earlier investigation of spinal loads among asymptomatic non-Veterans, as well as persons
      with unilateral lower limb amputation. Finally, sudden perturbation followed by
      stress-relaxation tests will be conducted as in earlier studies and as explained below. Each
      of the above tests will take less than 5 minutes, and the investigators will provide break
      periods between each set of tests to minimize fatigue and discomfort.

      In preparation for future projects, the investigators will also administer the following
      questionnaires that are relevant to LBP experience during the data collection session: 1)
      comprehensive health status using the PROMIS-29 questionnaire (all participants), 2) survey
      of habitual physical activity (all participants), 3) the short version of Copenhagen
      Psychosocial questionnaire concerning work and non-work-related factors (all participants),
      4) the minimum data set recommended by the NIH task force on research standards for chronic
      LBP (only Veterans with LBP), 5) pain intensity using a numerical rating scale (only Veterans
      with LBP), 6) LBP-related disability using the 24-item Roland Morris Disability Questionnaire
      (only Veterans with LBP), 7) the fear-avoidance beliefs questionnaire (only Veterans with
      LBP). Total time for the entire data collection session, including the instrumentation time,
      is estimated to be less than 3 hours.
    

Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        The investigators will recruit 54 gender-balanced veterans in the following three groups:
        1) with chronic, non-specific LBP and a Roland-Morris Disability Questionnaire (RMDQ) score
        of >12 (n=18), 2) with chronic, non-specific LBP and a RMDQ score of =12 (n=18), 3)
        asymptomatic and no a recent history of non-specific LBP (n=18; serving as control group)
      
Keywords: Back pain; Lumbar spine; Biomechanics; Spinal loads