types [3]. In conclusion, the authors state that 1) there is
a high utilization of health care for chronic LBP
patients, including a high rate of advanced imaging, narcotic
prescription and physical therapy; 2) most of the
tests and treatments performed did not meet the criteria
of evidence-based practice; and 3) there is an over-utilization
of treatment types. In addition to conventional
medical treatments such as analgesics and physical therapy,
LBP patients are also utilizing integrative health
care such as spinal manipulation (SM) delivered by a
doctor of chiropractic [4].
There is an increasing body of evidence suggesting
that SM provides important benefit to patients with LBP
[5,6]. Not much is known, however, about the mechanism
of action of these treatments. This study looks closely
at the biomechanical and neural effects of SM
treatment.
In its broadest definition, SM involves the therapeutic
application of a load (i.e. force) to specific body tissues
or structures (usually vertebral joints). There are many
variations of SM in terms of their velocity, amplitude,
loading frequency, choice of lever, location and direction
of load, and treatment frequency [7,8]. Based on SM
force-time profiles, they can be divided into two broad
categories: SM with a high-velocity low-amplitude load,
or an impulse “thrust”, to body tissues (HVLA-SM) and
SM with a low-velocity variable-amplitude load (LVVASM)
[8-12]. LVVA-SM is often referred to as “mobilization
[13],” where HVLA-SM is referred to as “adjustments
[14]“ by chiropractors or “manipulation [13]“ by
other providers. HVLA-SM is typically associated with a
cavitation sound produced when the synovial joint linings
are quickly separated. In LVVA-SM the loads are
applied slowly, cyclically, and the amplitude of each load
may vary.
The general theory is that the mechanism of action of
SM may be related to the impact that manipulative
forces have on tissues surrounding the low back. At the
same time, this study is considering the nature of LBP
itself. Could SM produce its beneficial effects by altering
some deficit in the spinal structure or function?