Spinal manipulation

# Definition
Spinal manipulation is manipulation of synovial joints in the spinal column. The most commonly cited of these are the zygapophysial joints. However, the occipitoatlantal, sacroiliac, costotransverse and costovertebral joints are also synovial joints of the spine that may be manipulated.

# Terminology
Manipulation is known by several other names. Chiropractors refer to manipulation of a spinal joint as an 'adjustment'. Following the labelling system developed by Geoffery Maitland,  manipulation is synonymous with Grade V mobilization. Because of its distinct biomechanics (see section below), the term high velocity low amplitude (HVLA) thrust is often used interchangably with manipulation.

# Biomechanics of spinal manipulation
Spinal manipulation can be distinguished from from other manual therapy interventions such as  mobilization by its biomechanics, both kinetics and kinematics.

## Kinetics
Until recently, force-time histories measured during spinal manipulation were described as consisting of three distinct phases: the preload (or prethrust) phase, the thrust phase, and the resolution phase. Evans and Breen  added a fourth orientation phase to describe the period during which the patient is orientated into the appropriate position in preparation for the prethrust phase

## Kinematics
Section on spine motion segment kinematics only - needs expanding.
The kinematics of a complete spinal motion segment, when one of its constituent spinal joints is manipulated, are much more complex than the kinematics that occur during manipulation of an independent peripheral synovial joint.

# Practice of spinal manipulation
In the context of healthcare, spinal manipulation is performed by several professional groups. In North America, it is most commonly performed by chiropractors, osteopaths, and physical therapists.

# Mechanisms of action and clinical effects
The effects of spinal manipulation have been shown to include:
- Temporary relief of musculoskeletal pain.
- Shortened time to recover from acute back pain (RAND).
- Temporary increase in passive range of motion (ROM).
- Physiological effects on the central nervous system, probably at the segmental level.
- No alteration of the position of the sacroiliac joint.

# Effectiveness
Spinal manipulation may help lumbalgia according to a systematic review of studies
More recent trails have conflicting results with one trial showing some benefit and a second trial suggesting a placebo response."The results of this study indicate attenuation of pain sensitivity is greater in response to SMT than the expectation of receiving an SMT". 

# Safety issues
As with all interventions, there are risks associated with spinal manipulation. Common side effects of spinal manipulation are characterized as mild to moderate and may include: local discomfort, headache, tiredness, or radiating discomfort.  Infrequent, but potentially serious side effects, include: vertebrobasilar accidents (VBA), strokes, spinal disc herniation, vertebral and rib fractures, and cauda equina syndrome.
In a 1993 study, J.D. Cassidy, DC, and co-workers concluded that the treatment of lumbar intervertebral disk herniation by side posture manipulation is "both safe and effective."

## Risks of upper cervical manipulation
The degree of serious risks associated with manipulation of the cervical spine is uncertain, with widely differing results being published.
A 1996 Danish chiropractic study confirmed the risk of stroke to be low, and determined that the greatest risk is with manipulation of the first two vertebra of the cervical spine, particularly passive rotation of the neck, known as the "master cervical" or "rotary break."
Serious complications after manipulation of the cervical spine are estimated to be 1 in 4 million manipulations or fewer. A RAND Corporation extensive review estimated "one in a million." Dvorak, in a survey of 203 practitioners of manual medicine in Switzerland, found a rate of one serious complication per 400,000 cervical manipulations, without any reported deaths, among an estimated 1.5 million cervical manipulations. Jaskoviak reported approximately 5 million cervical manipulations from 1965 to 1980 at The National College of Chiropractic Clinic in Chicago, without a single case of vertebral artery stroke or serious injury. Henderson and Cassidy performed a survey at the Canadian Memorial Chiropractic College outpatient clinic where more than a half-million treatments were given over a nine-year period, again without serious incident. Eder offered a report of 168,000 cervical manipulations over a 28 year period, again without a single significant complication. After an extensive literature review performed to formulate practice guidelines, the authors concurred that "the risk of serious neurological complications (from cervical manipulation) is extremely low, and is approximately one or two per million cervical manipulations."
In comparison, there is a 3-4% rate of complications for cervical spinal surgery, and 4,000-10,000 deaths per million neck surgeries.
Understandably, vascular accidents are responsible for the major criticism of spinal manipulative therapy. However, it has been pointed out that "critics of manipulative therapy emphasize the possibility of serious injury, especially at the brain stem, due to arterial trauma after cervical manipulation. It has required only the very rare reporting of these accidents to malign a therapeutic procedure that, in experienced hands, gives beneficial results with few adverse side effects". In very rare instances, the manipulative adjustment to the cervical spine of a vulnerable patient becomes the final intrusive act which results in a very serious consequence.
Edzard Ernst has written:
In a 2007 followup report in the Journal of the Royal Society of Medicine, Ernst concluded: "Spinal manipulation, particularly when performed on the upper spine, is frequently associated with mild to moderate adverse effects. It can also result in serious complications such as vertebral artery dissection followed by stroke. Currently, the incidence of such events is not known. In the interest of patient safety we should reconsider our policy towards the routine use of spinal manipulation."

## Potential for incident underreporting
Statistics on the reliability of incident reporting for injuries related to manipulation of the cervical spine vary. The RAND study assumed that only 1 in 10 cases would have been reported. However, Prof Ernst surveyed neurologists in Britain for cases of serious neurological complications occurring within 24 hours of cervical spinal manipulation by various types of practitioners; 35 cases had been seen by the 24 neurologists who responded, but none of the cases had been reported. He concluded that underreporting was close to 100%, rendering estimates "nonsensical." He therefore suggested that "clinicians might tell their patients to adopt a cautious approach and avoid the type of spinal manipulation for which the risk seems greatest: forceful manipulation of the upper spine with a rotational element."  The NHS Centre for Reviews and Dissemination stated that the survey had methodological problems with data collection.  Both NHS and Ernst noted that bias is a problem with the survey method of data collection.
A 2001 study in the journal Stroke found that vertebrobasilar accidents (VBAs) were five times more likely in those aged less than 45 years who had visited a chiropractor in the preceding week, compared to controls who had not visited a chiropractor. No significant associations were found for those over 45 years. The authors concluded: "While our analysis is consistent with a positive association in young adults... The rarity of VBAs makes this association difficult to study despite high volumes of chiropractic treatment." The NHS notes that this study collected data objectively by using administrative data, involving less recall bias than survey studies, but the data were collected retrospectively and probably contained inaccuracies.
In 1996, Coulter et al. had a multidisciplinary group of 4 MDs, 4 DCs and 1 MD/DC look at 736 conditions where it was used. Their job was to evaluate the appropriateness of manipulation or mobilization of the cervical spine in those cases (including a few cases not performed by chiropractors).
"According to the report ... 57.6% of reported indications for cervical manipulation was considered inappropriate, with 31.3% uncertain. Only 11.1% could be labeled appropriate. A panel of chiropractors and medical practitioners concluded that '. . . much additional scientific data about the efficacy of cervical spine manipulation are needed.'"

## Misattribution problems
Studies of stroke and manipulation do not always clearly identify what professional has performed the manipulation. In some cases this has led to confusion and improper placement of blame. In a 1995 study, chiropractic researcher Allan Terrett, DC, pointed to this problem:
This error was taken into account in a 1999 review of the scientific literature on the risks and benefits of manipulation of the cervical spine (MCS). Special care was taken, whenever possible, to correctly identify all the professions involved, as well as the type of manipulation responsible for any injuries and/or deaths. It analyzed 177 cases that were reported in 116 articles published between 1925 and 1997, and summarized:
In Figure 1 in the review, the types of injuries attributed to manipulation of the cervical spine are shown, and Figure 2 shows the type of practitioner involved in the resulting injury.  For the purpose of comparison, the type of practitioner was adjusted according to the findings by Terrett. 
The review concluded:

# Emergency medicine
In emergency medicine joint manipulation can also refer to the process of bringing fragments of fractured bone or dislocated joints into normal anatomical alignment (otherwise known as 'reducing' the fracture or dislocation). These procedures have no relation to the HVLA thrust procedure.