The Underlying Mechanism of Spinal Manipulative Therapy and the Effect of Pain on Physical Outcome Measures
Condition: Low Back Pain; Degeneration of Lumbosacral Intervertebral Disc; Muscle Weakness; Spine Stiffness
MeSH terms: Muscle Weakness; Back Pain; Low Back Pain
Study type: Interventional

Summary: 
      The purpose of this study is to compare changes in spinal stiffness and back muscle activity
      between spinal manipulative therapy (SMT) responders, non-responders and asymptomatic
      participants. Additionally, the investigators wanted to compare the amount of lumbar
      degeneration between SMT responders, non-responders and asymptomatic participants. This study
      also determines if the presence of pain modifies post-SMT spinal stiffness and back muscle
      activity.
    

Detailed description: 
      SMT is a common manual therapy for treating patients with mechanical low back pain (LBP). SMT
      is defined as a high velocity, low amplitude thrust technique. Specifically, the clinician
      stands beside a supine patient. The patient is passively side-bent towards the side to be
      manipulated. The clinician passively rotates the patient and then delivers a high velocity,
      low amplitude thrust to the anterior superior iliac spine in a posteroinferior direction. SMT
      is indicated for patients with LBP judged to have spinal hypomobility or malalignment.
      Recently, our collaborators have discovered that LBP subjects who benefit from SMT can be
      identified prior to treatment by a five-item clinical prediction rule. Compared to
      non-responders, those who respond to SMT have: 1) more than 30% decrease in the modified
      Oswestry Disability Index score, 2) a significant and immediate decrease in spinal stiffness,
      and 3) a concurrent change in lumbar multifidus muscle activity. Taken together, the physical
      changes experienced by SMT responders alone provide an unique opportunity to better
      understand the mechanisms underlying SMT.

      Since spinal stiffness is an important physical indicator of SMT response, it is important to
      understand the causal relation between pain, paraspinal/trunk muscle activity and spinal
      stiffness. Although research has shown positive correlation between pain and muscle activity,
      and between paraspinal muscle activity and spinal stiffness, the causal relation between
      pain, paraspinal/trunk muscle activity and spinal stiffness remains unknown. Given this
      background, an induction of temporary benign experimental pain to asymptomatic individuals
      can help clarify such causal relation and improve our understanding of physical responses in
      responders following pain resolution by SMT.
    

Intervention name(s): SMT for low back pain patients; Pain induction (optional); Low back pain participants without SMT
Intervention type(s): Other; Other; Other
Intervention description(s): High velocity, low amplitude spinal manipulative therapy (HVLA-SMT) will be provided to the lumbopelvic region on both sides.; A randomized crossover design is used to investigate the changes in spinal stiffness and back muscle activity of asymptomatic participants following an experimental pain induction procedure. Specifically, asymptomatic participants attend two separate sessions 5 days apart. Participants will receive 0.3 ml of 5% hypertonic saline or 0.9% isotonic saline in random order into the interspinous ligaments at L3 to L5 levels. The resulting temporal changes in pain intensity, spinal stiffness and trunk muscle activity following saline injections will be monitored. During the second session, the participants will undergo the same procedures but with the previously unused saline concentration.; No treatment
Other intervention name(s): High velocity, low amplitude spinal manipulative therapy; spinal manipulation
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: Double (Care Provider, Outcomes Assessor)
Primary purpose: Treatment
Keywords: spinal manipulative therapy; low back pain; experimental pain; spinal stiffness; lumbar multifidus; degeneration