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Safety Update: Spinal Manipulation and Injury Risk

Four Recent Studies, Using Unique Assessment Approaches, Assess the Safety of Spinal Manipulation for the Treatment of Musculoskeletal Conditions


William H. Kirkaldy-Willis, MD, (1914-2006) was a pioneer in the understanding and treatment of spinal problems. In his life, he published 73 articles that are in the United States National Library of Medicine, and he authored four editions of the medical text Managing Low Back Pain. His other noted accomplishments include:

Dr. Kirkaldy-Willis’ greatest contribution to spine care was advancing the understanding of the “degenerative cascade,” including the pathology and pathogenesis of lumbar spondylosis and stenosis, instability of the lumbar spine, and lateral recess spinal nerve entrapment. In addition, he recognized and advocated for the inclusion of chiropractic spinal manipulation and exercise in the management of low back pain (1).

Thirty years ago, in 1985, Dr. Kirkaldy-Willis was the lead author of a study published in the journal Canadian Family Physician (2), titled:

“Spinal Manipulation in the Treatment of Low back Pain”

In this study, Dr. Kirkaldy-Willis notes that spinal manipulation is one of the oldest forms of therapy for back pain, and that it has mostly been practiced outside of the medical profession. He further notes that there has been an escalation of clinical and basic science research on manipulative therapy, which has shown that there is a scientific basis for the treatment of back pain by manipulation.

Dr. Kirkaldy-Willis discusses how the key to successfully managing chronic low back pain is through the utilization of applied motion. He categorizes applied motion into three groups:

1) Active Range of Motion

This range is achieved through active exercise.

2) Passive Range of Motion

Beyond the end of the Active Range of Motion of any synovial joint, there is a small passive range of mobility. A joint can only move into this zone with passive assistance. Going into this Passive Range of Motion constitutes mobilization, not manipulation.

3) Paraphysiological Range of Motion

At the end of the Passive Range of Motion, an elastic barrier of resistance is encountered. This barrier has a “spring-like end-feel.” When motion separates the articular surfaces of a synovial joint beyond this elastic barrier, the joint surfaces suddenly move apart with a cracking noise. This additional motion can only be achieved after “cracking” the joint and has been labeled the Paraphysiological Range of Motion. This constitutes manipulation. Spinal manipulation is an assisted passive motion applied to the spinal facet joints that creates motion into the Paraphysiological Range. Dr. Kirkaldy-Willis states:

“Spinal manipulation is essentially an assisted passive motion applied to the spinal apophyseal and sacroiliac joints.”

At the end of the Paraphysiological Range of Motion, the limit of anatomical integrity is encountered. The facet joint capsular ligaments create the limit of anatomical integrity.


In his 1985 study, Dr. Kirkaldy-Willis presents the results of a prospective observational study of spinal manipulation in 283 patients with chronic low back and leg pain. All 283 patients in this study had failed prior conservative and/or operative treatment, and they were all totally disabled (“Constant severe pain; disability unaffected by treatment.”) These patients were given a two or three week regimen of daily spinal manipulations by an experienced chiropractor. No patients were made worse by the manipulation, yet many experienced an increase in pain during the first week of treatment. Even with this initial increase in pain, Dr. Kirkaldy-Willis emphasized the importance of continuing with manipulative treatment and not stopping treatment. He states:

“In most cases of chronic low back pain, there is an initial increase in symptoms after the first few manipulations. In almost all cases, however, this increase in pain is temporary and can be easily controlled by local application of ice.”

“Patients undergoing manipulative treatment must therefore be reassured that the initial discomfort is only temporary.”

These outcomes and words imply that chiropractic spinal manipulation is safe and it does not cause any injury. The studies presented below quantify these safety issues surrounding chiropractic spinal manipulation for musculoskeletal syndromes.

Dr. Kirkaldy-Willis notes that when applying spinal manipulation, there is, as a rule, an initial increase in local symptoms. He explains this finding by noting that in chronic low back pain cases, there is a shortening of the periarticular connective tissues and intra-articular adhesions may form; spinal manipulations can stretch or break these adhesions, causing the symptoms. He states:

“In most cases of chronic low back pain, there is an initial increase in symptoms after the first few manipulations [probably as a result of breaking adhesions]. In almost all cases, however, this increase in pain is temporary and can be easily controlled by local application of ice.”

“No patients were made worse by the manipulation, yet many experienced an increase in pain during the first week of treatment. Patients undergoing manipulative treatment must therefore be reassured that the initial discomfort is only temporary.”

Safety of Chiropractic Manipulation of the Cervical Spine

A Prospective National Survey


Volume 32(21), October 2007, pp. 2375-2378

Thiel, Haymo W. DC, PhD; Bolton, Jennifer E. PhD; Docherty, Sharon PhD; Portlock, Jane C. PhD (reference #3)

This study is a prospective national survey whose objective is to estimate the risk of serious and relatively minor adverse events following chiropractic manipulation of the cervical spine by a sample from the United Kingdom of chiropractors.

The authors confess that the injury rate for chiropractic cervical spine manipulation is unknown, but is estimated that the injury ranges from 1 in 200,000 to 1 in several million cervical spine manipulations. In order to assess the injury issue, the authors studied 377 chiropractors, 19,722 patients and 50,276 cervical manipulations. This study is the first, large-scale prospective study designed to record serious and minor adverse events following chiropractic manipulation of the neck.

In this study, manipulation was defined as the application of a high-velocity/low-amplitude or mechanically assisted thrust to the cervical spine. Serious adverse events were defined as referred to hospital and/or severe onset/worsening of symptoms immediately after treatment and/or resulted in persistent or significant disability/incapacity. Minor adverse events reported by patients as a worsening of presenting symptoms or onset of new symptoms, were recorded immediately, and up to 7 days, after treatment.

“There were no reports of serious adverse events.”

In agreement with the article by Dr. Kirkaldy-Willis above (2), minor side effects following chiropractic spinal manipulation were more common. The authors state:

“Relatively minor side effects of cervical spinal manipulation, such as neck pain, stiffness and soreness, headache, and tiredness are common in clinical practice.”

“Although minor side effects following cervical spine manipulation were relatively common, the risk of a serious adverse event, immediately or up to 7 days after treatment, was low to very low.”

“Safety of treatment interventions is best established with prospective surveys, and this study is unique in that it is the only prospective survey on such a large scale specifically estimating serious adverse events following cervical spine manipulation.”

“Although minor side effects were found to be relatively common, the risk of a serious adverse event, immediately and up to 7 days after treatment, was estimated to be low to very low in these consultations.”

“On this basis, this survey provides evidence that cervical spine manipulation is a relatively safe procedure when administered by registered U.K. chiropractors.”

“Based on treatment outcomes obtained from 19,722 patients, the risk of a serious adverse event following cervical spine manipulation was estimated to be low to very low; risks of minor side effects, on the other hand, were relatively common.”

Outcomes of Usual Chiropractic:

The OUCH Randomized Controlled Trial of Adverse Events


September 2013; Vol. 38, No. 20, pp. 1723 – 1729

Bruce F. Walker, DC, MPH, DrPH; Jeffrey J. Hebert, DC, PhD; Norman J. Stomski, BHSc (hons), PhD, Brenton R. Clarke, PhD; Ross S. Bowden, M. Mathematics; Barrett Losco, M. Chiropractic; Simon D. French, MPH, BAppSc (Chiro), PhD (reference #4)

These authors note that “Chiropractic therapy is commonly used to manage musculoskeletal conditions in high-income countries.”

This study is a blinded randomized controlled clinical trial. It’s objective was to establish the frequency and severity of adverse effects from short-term usual chiropractic treatment of the spine when compared with a sham treatment group. The authors used 183 adult subjects with spinal pain, aged 20 to 85 years of age:

92 received usual chiropractic treatment

91 received a sham treatment and were told it was chiropractic.

Each participant received 2 chiropractic treatments: 98% had spinal pain for more than 3 months; 75% had spinal pain for more than 5 years. This means that the study participants were chronic spine pain sufferers.

The sham chiropractic treatment used in this study included “detuned ultrasound,” and Activator adjusting device on the lowest setting applied randomly through a tongue depressor.

The authors found that the adverse event rate was essentially the same between real chiropractic treatment and sham treatment. They interpret this as meaning that there is no injury risk from real chiropractic treatment. Specifically, they note:

“Adverse events were common in both the usual chiropractic care and sham groups, but no important differences were seen between the groups and no serious adverse events were reported.”

“The rate of severe adverse events was not different between the groups.”

“No serious adverse events were reported,” such as disc injury, cauda equina syndrome, fracture, and stroke.

“Most adverse events associated with chiropractic treatment are mild, short lasting, and typical of musculoskeletal condition symptoms.”

Most adverse events attributed to chiropractic have been “benign, transient, and typically consisted of increased pain, muscle stiffness, tiredness, headache, and radiating discomfort.” “Less common events were dizziness, nausea, tinnitus, and impaired vision.”

“A substantial proportion of adverse events after chiropractic treatment may result from natural history variation and nonspecific effects.”

“A substantial proportion of adverse events experienced during chiropractic care for spinal pain may be the result of natural symptom fluctuation or from nonspecific effects.”

Most of the adverse events were benign and transitory.

“The results of our study suggest that many adverse events experienced after chiropractic treatment result from either natural history variation or nonspecific effects.”

“Some may view these results as evidence that chiropractic treatment is essentially an entirely benign intervention.”

In agreement with Dr. Kirkaldy-Willis (2) and Dr. Thiel (3) and colleagues above, chiropractic treatment is associated with minor increases in symptoms. However, this study found similar symptomology in patients receiving sham chiropractic, suggesting that the increased symptoms are probably not secondary to the chiropractic treatment, but rather due to the natural history of their condition. An important comment by the authors is:

“Some may view these results as evidence that chiropractic treatment is essentially an entirely benign intervention.”

Risk of Traumatic Injury Associated with Chiropractic Spinal Manipulation in Medicare Part B Beneficiaries Aged 66-99


December 9, 2014 [epub]

James M Whedon, DC, MS; Todd A Mackenzie, PhD; Reed B Phillips DC, PhD; Jon D Lurie, MD, MS (reference #5)

The primary authors from this study are from the Dartmouth Institute for Health Policy and Clinical Practice. This is a retrospective cohort study. The objective of this study was to compare the risk of injury to the head, neck or trunk following an office visit for chiropractic spinal manipulation for neuromusculoskeletal pain, as compared to office visits to a primary care physician. The study subjects were aged 66-99 years.

This study was quite large. It assessed:

This is the first nationwide population-based study in the United States on the risk of injury following chiropractic spinal manipulation. It is also the first study of the risks of chiropractic to focus specifically on older adults, aged 66-99 years.

The cumulative probability of injury was:

The authors state:

“Spinal Manipulation as performed by chiropractors is an effective option for the treatment of certain types of spinal pain and some headaches.”

“The adjusted risk of injury in the chiropractic cohort was lower as compared to the primary care cohort [by 76%].”

“Among Medicare beneficiaries aged 66-99 with an office visit risk for a neuromusculoskeletal problem, risk of injury to the head, neck or trunk within 7 days was 76% lower among subjects with a chiropractic office visit as compared to those who saw a primary care physician.”

“It is unlikely that chiropractic care is a significant cause of injury in older adults. The lower risk [of injury] in the chiropractic cohort may suggest to some that chiropractic care is protective against injury in older adults.”

“The risk of injury in patients with intervertebral disc disorder with myelopathy was actually reduced, suggesting that this condition is not a risk factor for injury due to chiropractic spinal manipulation.”

“In conclusion, among Medicare beneficiaries aged 66-99 with an office visit risk for a neuromusculoskeletal problem, risk of injury to the head, neck or trunk within seven days was 76% lower among subjects with a chiropractic office visit as compared to those who saw a primary care physician.”

The authors did identify factors that increased the risk of injury from chiropractic. Chiropractors are well schooled in these factors, which include:

The authors suggest that chiropractors use caution in providing spinal manipulation in older patients with these conditions.

Third Safety Study

Tissue Damage Markers after a Spinal Manipulation in Healthy Subjects:

A Preliminary Report of a Randomized Controlled Trial

Disease Markers

December 25, 2014

The primary author is from the Department of Medicine, Universidad Complutense de Madrid, Spain. This is the first work that focused on the study of spinal manipulation and mechanically induced tissue damage through the analysis of damage biomarkers in blood samples. All the researchers were blinded to the therapist’s intervention.

These authors note that spinal manipulation is a common form of intervention used by a wide range of practitioners used to relieve pain and disability of the musculoskeletal system. Spine manipulation “presents benefits for patients such as an anti-inflammatory effect, pain relief, and reduction of drug consumption.” However, conceptually, spinal manipulation could be associated with injury because of these factors:

“The spinal manipulation is frequently defined as a manual procedure that involves a directed impulse to move a joint past its physiologic ROM without exceeding its anatomical limit.”

“Spinal manipulation is a manual therapy technique frequently applied to treat musculoskeletal disorders because of its analgesic effects.” It involves “a directed impulse to move a joint past its physiologic range of movement (ROM).”

“In this sense, to exceed the physiologic ROM of a joint could trigger tissue damage, which might represent an adverse effect associated with spinal manipulation. The present work tries to explore the presence of tissue damage associated with spinal manipulation through the damage markers analysis.”

To assess the possibility of spinal manipulation causing tissue injury, thirty healthy subjects were randomly assigned to:

Before and after intervention, each had their blood analyzed for 7 tissue injury biomarkers. “The detection of these proteins in serum and cerebrospinal fluid is a tell-tale of cell breakage produced by tissue damage.”

Creatine phosphokinase (CPK) [muscle injury]

Lactate dehydrogenase (LDH) [general tissue damage]

C-reactive protein (CRP) [systemic marker of inflammation and tissue damage]

Troponin-I [muscle injury]

Myoglobin [muscle injury]

Neuron-specific enolase (NSE) [neuronal damage]

Aldolase [general tissue damage]

The thoracic spinal manipulation technique involved a high-velocity, end-range, anterior-posterior force through the elbows to the middle thoracic spine in a supine position with patient’s arms crossed. “There is no evidence of serious adverse events related to thoracic spinal manipulation.”

The cervical manipulation was a high-velocity, midrange left rotational force to the lower cervical spine while supine, with left rotation and right side bending.

Control participants were treated following the cervical manipulation protocol with regard to hand contact, but without intention of mobilization, nor application of tissue tension by the treating clinician.

“Our data show no changes in any of the studied damage markers.”

“After the analysis of seven tissue damage markers, our data do not show any significant differences in [their] concentrations.”

“Neither cervical manipulation nor thoracic manipulation did produce significant changes in the CPK, LDH, CRP, troponin-I, myoglobin, NSE, or aldolase blood levels.”

“Our data suggest that the mechanical strain produced by spinal manipulation seems to be innocuous to the joints and surrounding tissues in healthy subjects.”

Muscle soreness following spinal manipulation should be “regarded as a minor, and expected, consequence of treatment.”

“Most adverse events reported by manual therapy patients are thought to be benign and transient and are often unknown to the practitioner unless patients show observable signs (e.g., loss of motion or neurological deficits) or report pain or discomfort.”

“Lower cervical and thoracic manipulative techniques seem to be safe manual therapies techniques which cause no harm to the health of the subject.”


The four safety studies presented here show that chiropractic spinal manipulation is incredibly safe for the management of musculoskeletal syndromes. Each study looked at the safety issue from a unique perspective, and each reached essentially the same conclusion.

It is noteworthy that those receiving chiropractic spinal manipulation will experience minor increase in symptoms, which are not indicative of injury or harm. Patients should be told to expect such soreness, so as not to be alarmed.


“Authored by Dan Murphy, D.C.. Published by ChiroTrust® – This publication is not meant to offer treatment advice or protocols. Cited material is not necessarily the opinion of the author or publisher.”


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