Optimization of Spinal Manipulative Therapy Protocols

Research on spinal manipulative therapy for individuals with low back pain has been hampered by a lack of understanding of which of the physiologic effects produced by spinal manipulation are related to clinical benefit, and how these effects can be used to optimize treatment outcomes. Prior research has identified physiologic effects that relate to the clinical benefits from spinal manipulation treatment. The goal of this project is to examine strategies to use these effects to identify optimized treatment protocols. The results of this project will provide critical information for future clinical trials related to spinal manipulation.

Low back pain (LBP) is a common and costly condition. Spinal manipulative therapy (SMT) is a common mind body intervention for individuals with LBP. Although SMT for LBP has been examined in numerous clinical studies, the literature on SMT remains unclear and even contradictory as to the effectiveness of this treatment. Studies that have supported SMT have generally found relatively small treatment effects. Many reasons have been offered for the inconsistent research literature and small effect sizes of SMT. A primary rationale offered is that the SMT protocols used in clinical research are not optimal, primarily due to a lack of understanding of the underlying mechanisms explaining the clinical benefits of SMT realized by some patients with LBP. The prior work of this research team has identified two mechanisms explaining the therapeutic effects of SMT. These effects are a reduction in spinal stiffness and improved activation of the lumbar multifidus muscle. This research has also developed accurate, non-invasive methods to measure these effects and their response to SMT. The model identifying these two mechanisms has been validated in a second patient sample. The overall goal of this proposal is to optimize SMT treatment protocols for patients with LBP. The optimization strategy in this study will evaluate SMT combined with other treatments known to modulate the same signals that underlie the clinical effects of SMT assessing both mechanistic (stiffness, lumbar multifidus activation) and patient-centered (function and pain) outcomes. This project will use innovative methodology to efficiently evaluate the effects of various individual treatment components towards an overall effect; identifying which components are contributing to the target outcomes and which, if any, may be discarded. All participants will be provided 2 sessions of SMT, and then will be randomized to a treatment group for an additional 3 weeks using a factorial design and stratified by responder status in order to evaluate different combinations of intervention components (muscle activation exercise, spinal mobilizing exercise, additional SMT) that work on the same pathways that modulate the same effects (spinal stiffness and muscle activation). Outcomes will include spinal stiffness and muscle activation measures as well as patient-reported outcomes assessed at baseline, and after 1 week, 4 weeks and 3 months. Results of this project will provide optimized SMT protocols that will be ready for application in future randomized controlled trials examining the efficacy and effectiveness of SMT.

2 sessions of SMT during week 1 and 6 additional sessions of lumbar multifidus activating exercises during weeks 2-4.

2 sessions of SMT during week 1; 6 sessions of lumbar multifidus activating exercises and spinal mobilizing exercises during weeks 2-4.

2 sessions of SMT during week 1; 6 sessions of SMT and lumbar multifidus activating exercises during weeks 2-4.

2 sessions of SMT during week 1; 6 sessions of SMT, multifidus activating and spinal mobilizing exercises during weeks 2-4.

All patients receive 2 SMT sessions in the first week. The subject is supine. The clinician stands opposite the side to be manipulated and side-bends the subject away from the side to manipulate. The side to be manipulated is the more painful. If the subject cannot identify a more painful side the clinician selects a side. The clinician rotates the subject, and delivers a high-velocity, low-amplitude (HVLA) thrust to the pelvis in a posterior/inferior direction. The clinician notes if a cavitation (ie, a "pop") occurred. If it does, SMT treatment is complete. If no cavitation occurs, the subject is repositioned and SMT is performed again. If no cavitation occurs on the second attempt, the clinician manipulates the opposite side. A maximum of 2 attempts per side is permitted. If no cavitation is noted by that time, SMT treatment is complete. Substitution with a side-posture HVLA technique is allowed if the preferred technique is not possible due to subject preference or comfort.

Mobilizing exercises will include a program of repeated movements progressing into end-ranges of spinal flexion and/or extension shown in past studies to improve ROM and reduce spinal stiffness. Patients will be instructed in mid-range exercises and will be further assessed for a directional preference. A directional preference is present if movement in a particular direction decreases LBP intensity or causes symptoms to centralize towards the midline. If a subject has a directional preference he or she will be prescribed exercises specifically in that direction along with mid-range exercise. Otherwise the subject will be assigned exercises moving into either flexion or extension based on the clinician's discretion. Subjects will perform their prescribed exercises at treatment sessions and will be instructed to perform the exercises daily on other days.

Activation exercises are designed to facilitate use of the lumbar multifidus muscle. Exercises will begin with isometric multifidus contractions in different positions with clinician feedback and exercises to isometrically co-contract the multifidus and deep abdominal muscles. Subjects will also perform lumbar extensor strengthening exercises shown to produce 20%-50% of multifidus maximum voluntary contraction. Subjects will continue to perform isometric exercises throughout treatment. Subjects will perform their prescribed exercises at treatment sessions and will be instructed to perform the exercises daily on other days.

This treatment involves 6 additional SMT sessions. Each SMT session is conducted as described previously.

Spinal stiffness is assessed with the VerteTrack device that applies a vertical load along the lumbar spine of a prone participant. The indenter houses a sensor to provide continuous, real-time quantification of spinal deformation in response to a defined load. Stiffness was determined as the ratio of the maximum applied force to the resultant displacement in N/mm. Higher numbers indicate greater amounts of stiffness.

Assessed at Phase II Baseline, 4 weeks, 12 weeks. 4 weeks and 12 weeks reported. Phase II baseline values were constrained to be equal to a common overall mean for analyses.

Multifidus activation was measured with brightness-mode ultrasound images using a 60mm, 2-5 MHz curvilinear array. Images are acquired with the multifidus at rest and during submaximal contraction. Three images in each state are acquired and averaged. Muscle activation is calculated as the change in thickness at rest and submaximal contraction and expressed as a percentage change. Greater numbers indicate higher muscle activation.

Assessed at Phase II Baseline, 4 weeks, 12 weeks. 4 weeks and 12 weeks reported. Phase II baseline values were constrained to be equal to a common overall mean for analyses.

The Oswestry Disability Index measures back pain-related disability. The scale contains 10 items with a minimum score of zero and maximum score of 100. Higher numbers indicate more disability. There are no subscales.

Assessed at Phase II Baseline, 4 weeks, 12 weeks. 4 weeks and 12 weeks reported. Phase II baseline values were constrained to be equal to a common overall mean for analyses.

A 0-10 numeric pain rating is used to assess pain intensity. The minimum score is zero, maximum score is 10. Higher numbers indicate greater pain intensity. There are no subscales.

Assessed at Phase II Baseline, 4 weeks, 12 weeks. 4 weeks and 12 weeks reported. Phase II baseline values were constrained to be equal to a common overall mean for analyses.

Inclusion Criteria: I. Pain between the 12th rib and buttocks with or without symptoms into one or both legs, which, in the opinion of the examiner, originate from the lumbar region. II. Age 18 - 60 years III. Oswestry disability score > 20% Exclusion Criteria: I. Prior surgery to the lumbosacral spine II. Currently pregnant III. Currently receiving mind-body or exercise treatment for LBP from a healthcare provider (e.g., chiropractic, physical therapy, massage therapy, etc.) IV. Neurogenic signs including any of the following: positive ipsi- or contra-lateral straight leg raise test; reflex, sensory, or strength deficit in a pattern consistent with lumbar nerve root compression

Fritz JM, Sharpe JA, Lane E, Santillo D, Greene T, Kawchuk G. Optimizing treatment protocols for spinal manipulative therapy: study protocol for a randomized trial. Trials. 2018 Jun 4;19(1):306. doi: 10.1186/s13063-018-2692-6.