August 2010 Newsletter from Malik Slosberg, DC, MS

Article #1 Hinton PM, DC, FCCRS(C) et al. Outcome Measures and Their Everyday Use in Chiropractic Practice. Journal of the Canadian Chiropractic Association 2010; 54(2):118–131.

Article #2: Hezog, Walter, PhD. The Biomechanics of Spinal Manipulation. Journal of Bodywork & Movement Therapies. 2010; 14: 280-286. INVITED REVIEW.
It's mid-August and here are two valuable studies. The first is a survey of Canadian chiropractors asking about the use of quantifiable outcomes used in practice. The article has a good review of the types, purpose, benefits, and demand for the use of objective outcomes. The second study is an invited review of the biomechanics of spinal manipulation. It reviews forces, variability of forces, the audible release, internal stresses on the vertebral artery, and more. The papers reviewed are very recent publications to understand and support what we do. Hope you find this update of interest.


Article #1 Hinton PM, DC, FCCRS(C) et al. Outcome Measures and Their Everyday Use in Chiropractic Practice. Journal of the Canadian Chiropractic Association 2010; 54(2):118–131.


This study looks at the frequency of use of common outcome measures by chiropractors in the Saskatchewan, Canada. The paper notes that there is an ever increasing demand for health care providers (HCPs) to provide quantifiable evidence of physical & psychosocial dysfunction and proof that these factors improve with care. In addition, the authors emphasize that the use of outcome assessments has become essential in modern health care to assess the quality of care & to contain costs. A favorable change in outcomes reassures patients and provides diagnosis & treatment justification for the HCP & third party payers. Functional outcomes provide an objective quantifiable baseline that influences treatment decisions & provides a meaningful end point of care. HCPs should focus on assessing physical function that identifies movement difficulties related to activities of daily living. The Canadian Chiropractic Association has promoted the utilization of outcome measures by providing its membership with specific guidelines.

There are 2 general types of outcome measures used in chiropractic: (1) patient self-reporting instruments, & (2) objective functional assessment methods. Standardized performance tests provide normative values which allow health care providers to accurately assess patients’ function. The combined use of patient self-reports & objective functional capacity tests, the authors suggest, should be viewed as the expected standard of care as this protects the patient from ill-defined treatment goals & needless costs, particularly when there is no established end point of care.

Methods: A cross-sectional mailed survey to DCs in order to describe the use of various standardized quantifiable outcome instruments: pain scales, pain drawings, general health, disability, & psychosocial indices and clinical measures: posture, ROM, & neurological tests used in practice to measure Pt’s baseline health status & responses to treatment. The study determined the extent to which a range of relatively common outcome instruments applicable to chiropractic practice were used by DCs.

Results: Of 164 DCs, 62 (38%) completed questionnaires. A pain diagram was the most commonly used subjective outcome measure administered “always” or “commonly” by 75% of DCs. Numerical rating scale (NRS) & visual analogue scale (VAS) were used: 59% always & 42% commonly. 80% “occasionally” or “never” used spine specific disability indices: Oswestry, Neck Disability Index or the Roland-Morris. DCs didn’t use psychosocial instruments: Fear Avoidance beliefs questionnaire, Depression Index, or general health assessments: SF- 36 or SF-12. Neurological testing was the most commonly used objective outcome measure. 84% to 95% indicated that they continually monitored neurological status thru dermatomal, manual muscle strength & DTRs. ROM was routinely measured by 95%, but usually only visually (96%) rather than goniometrically or by other more precise device. DCs use visual estimation of ROM despite the fact that this method has poor reliability & validity. The Canadian Chiropractic Association recommends the use of measurement devices and states that they are required to accurately assess ROM to reliably document improvement, rate impairment or determine a plateau in healing. 75% of respondents indicated that they never use any of the listed psycho-social outcome measures such as the Fear-Avoidance Beliefs Questionnaire (FABQ). Patients’ fears about pain with physical activity & work, as a single factor, appear to best predict the patient’s willingness to partake in any form of active care. This instrument can be very useful in identifying, monitoring, & managing workers with non-physical return-to-work barriers. The Oswestry Disability, Roland Morris, & Neck Disability Indices aren’t routinely performed by DCs. Greater use of back pain disability indices is recommended to improve monitoring & documentation of Pts’ response to care.

Conclusions: Findings suggest that most DCs don’t use psychosocial questionnaires or condition-specific disability indices to document baseline or subsequent changes in health status. DCs rely more on medical history & pain drawings at initial intake and neurological & visually estimated ROM. The results suggest that DCs may not be doing a particularly exemplary job of incorporating objective outcome assessment measures into everyday practice.

Commentary: This new study confirms the results of previous work which has demonstrated the failure of many chiropractors to keep objective documentation of a patient's severity of chief complaint at presentation, benefit of care to date, and need for additional care. The outcome tools necessary to quantify these parameters are readily available, have reams of documentation/publications to confirm their value, are very inexpensive, and easy to administer and grade. They are valuable tools to evaluate progress for the patient, the clinician, and for third-party payers. These outcome assessments eliminate any uncertainty or dispute about whether the care provided is necessary, effective, and reimbursable. Furthermore, this documentation enhances the credibility of the treating chiropractor and the profession as a whole, as well as, improves and accelerates reimbursement for care .


Article #2: Hezog, Walter, PhD. The Biomechanics of Spinal Manipulation. Journal of Bodywork & Movement Therapies. 2010; 14: 280-286. INVITED REVIEW.

This is an excellent review article on the biomechanics of spinal manipulation (SM).

Basics: Clinicians using high-velocity, low-amplitude (HVLA) SM exert a force of specific magnitude in a controlled direction to a target site causing deformations of the spine & surrounding soft tissues often eliciting a cracking sound/audible release, identified as cavitation of spinal facet joints. The external forces applied during HVLA SM vary dramatically depending on the treatment site & across clinicians. All clinicians apply substantially less force for SM of the cervical spine (~100 N) vs the thoracic, lumbar & sacroiliac regions (~400 N). To determine the amount of force applied to patients, researchers use a thin, flexible pressure pad placed under the thrusting hand of the clinician. The studies find that clinicians, who tend to adjust with great force, and clinicians who use little force, do so consistently. Some “soft” adjusting clinicians will not even reach the preload forces of some of the “hard” adjusting clinicians. The thrust times (duration of forces applied manually) were approximately 100 ms for cervical and 150 ms for thoracic and lumbar spine SM. The authors found that treatment forces vary dramatically between clinicians. In their lab they have measured peak forces ranging from 200N to 1600N, an eightfold difference. However, in a study of a random sample of 10 female & 10 male DCs performing SM on subjects, the average forces between males & females were about the same, and so were the average forces between novice & experienced DCs .

Selected effects of HVLA spinal manipulative treatments: The number of studies investigating mechanical, physiological or neurological effects of HVLA SM is small, & a direct link between treatment forces, the effects produced by these forces, and the beneficial effects created are almost completely missing.

Relative movements of the target segment: A premise of HVLA SM is that the target joint (typically a facet joint) is brought to its end ROM by the application of a preload force. Following the preload force, a HVLA thrust is applied, which is the actual treatment, and this HVLA thrust takes the joint beyond its limited end ROM back toward its full ROM. To test this, researchers inserted bone pins into 3 adjacent vertebral bodies of the thoracic spine in human cadavers, and calculated the relative movements of the vertebral bodies during the preload & thrust phase of HVLA P-A thrusts to the TP of a thoracic vertebra. There was substantial relative movement of the target & adjacent vertebrae during the preload phase, and substantially further relative movement of target & adjacent vertebrae during the thrust phase of HVLA SM.

Reflex responses associated with HVLA SM: SM, in addition to restoring joint mobility & function, is thought to produce reflex responses in the muscles underlying the treatment area. Researchers measured the surface EMG of back muscles at the treatment site. Typically, a muscle reflex response was measured within 200 to 400 ms following the onset of the SM thrust. Muscle activity wasn’t observed during preload phase & disappeared after the HVLA thrust, suggesting that the muscle activity observed was a reflex response, and was associated with the speed of force application. When applying a very short, precisely focused HVLA force (ie Activator instrument), a reflex response was elicited after a delay from the onset of force application of 50-100 ms, suggesting a muscle spindle reflex pathway & was always restricted to the vicinity of force application. For manual HVLA SMs, reflex responses were not restricted to the immediate treatment area, but formed wider spread activation patterns that depended on the site of force application. In patients with spastic muscles, EMG activity in the muscles in the area of the HVLA thrust relaxed and EMG activity was abolished in some but not all patients. It’s not known why HVLA SM produced relief of muscle spasticity in some patients but not in others. Herzog concludes that HVLA SM elicits reflex response that is not necessarily localized, and may affect locations that are remote from the actual treatment site.

Role of the audible release: Although the audible release is an indicator of a successful treatment for many DCs, so much so, that when an audible release does not occur, many clinicians will immediately apply a second or even third treatment thrust, there are a variety of observations that do not fit that idea. For example, every HVLA thrust we have recorded was associated with an EMG response, but not all of these caused an audible. That is, reflex responses were observed in the absence of cavitation. In one study, slow force applications were applied, and audible releases were elicited with some but not all treatments, but these releases were not associated with an EMG response, suggesting that the audible release is not responsible for the observed reflex responses during HVLA SM.

Internal stresses and strains during HVLA SM of the cervical spine: Estimates of the risk of stroke vary from 1:5000 to 1:10 million. The majority of fatal vascular accidents following SM involved the vertebrobasilar system, specifically the cephalad/distal loop of the vertebral artery, as it exits the C1 transverse foramen. It has been suggested that the vertebral artery experiences considerable stretch & tissue stress during extension & rotation of the neck which may lead to occlusion and damage to the arterial walls. It has been hypothesized that HVLA SM may lead to stretch-induced vertebral artery damage, although the author’s biomechanical evidence does not support this view. There are only two documented reports of measurements of internal stresses on the vertebral artery caused by SM (Herzog and Symons (2002), and Symons et al. (2002)). In these studies, the strains of the vertebral artery were measured for a variety of ROM & diagnostic testing, as well as for different HVLA cervical SMs. They then excised the vertebral arteries from cadavers and measured the forces experienced by the vertebral arteries for the strains (elongations) measured during diagnostic tests and SM. The research found that stretches to the vertebral artery during cervical SM (6% for the cephalad/distal segment) were much smaller than the stretches produced during ROM & diagnostic testing (13%). Importantly, they found that the elongations produced during HVLA SM did not produce any tensile forces in the vertebral artery, suggesting that the vertebral arteries were slack when the head and neck were in the neutral position and that this slack was not fully taken up during SM. Therefore, SM didn’t cause any tensile stress in the vertebral arteries during the SM.

A limitation of these studies was that measurements were only made for the cephalad to C1 and caudad to C6 in vertebral arteries of unembalmed cadavers devoid of fluid, possibly affecting their shape. To overcome these limitations, a pilot study was performed to measure the strains in the vertebral artery segments C1 through C6 with the arteries filled with gel and while measuring forces applied by 2 DCs. The forces applied by the DCs during SM were similar to those administered to patients, thus mechanics were similar. The peak strain (elongation from neutral) that was measured for any of the 176 SM was 2.1% while strains for diagnostic procedures were in excess of 10% (flexion 10.1%, rotation 13.0% and Houle’s test 9.4%), suggesting, that strains during HVLA SM were much smaller than those produced during diagnostic procedure. The results suggest that SM produces stretches of the vertebral artery that are much smaller than those that are produced during normal everyday movements, and thus they appear harmless.

Commentary: This article is a concise review of the past several decades of research concerning the biomechanics of spinal manipulation. It identifies and discusses key areas of concern related to HVLA SM. It explains the research on the variability of forces and duration of forces delivered with an HVLA SM. It discusses the movement/displacement of the target and adjacent vertebrae in response to an HVLA SM, as well as, motor reflexive responses to the forces delivered, the role of the audible release, the internal stresses generated in the vertebral artery in response to cervical HVLA SM. The paper concludes that although more research is necessary, current findings indicate that cervical HVLA SMs produce stretches of the vertebral artery that are much smaller than those that are produced during normal everyday movements, and thus they appear harmless. In addition, the paper concludes that cervical HVLA SM didn’t cause any tensile stress in the vertebral arteries during the SM. Of further note, the audible does not seem to be directly related to the documented reflex motor responses.