OSMIA is now a
imparted an average radiation dose of 2.6Gycm
2
for 30 seconds of screening at
five frames per second
52
. However, this protocol resulted in poor image quality
fully operational
and failure of the automated tracking algorithms. As a result, the protocol was
changed to 15 frames per second with an associated increase in radiation dose
clinical and
to 14.9Gycm
2
. This computes to 2.05mSv which is less than the quoted average
for a year’s natural background radiation in the UK
62
. By comparison, a 5 series
research tool
lumbar spine radiographic examination (AP/PA, Lateral, L5-S1 junction, Flexion
and Extension) would impart an average dose of 1.17mSv (data from Hart 2005
63
converted with NRPB conversion factors
64
). The extra information obtained from
video-fluoroscopy justifies the increase in radiation exposure.
Applications of OSMIA
To date, the majority of OSMIA examinations have been in the recumbent
lumbar position for both clinical and research purposes. An initial research study
undertaken in 1996 compared inter-vertebral motion in asymptomatic males pre
and post chiropractic manipulation. Although there was no overall difference in
the rotational range of motion after manipulation, this study produced a set of
normative data in the coronal plane which has since been used for comparisons of
Figure 5. Continuous inter-vertebral rotation from an asymptomatic participant at L2/L3
motion signatures with symptomatic patients. The appearance of, and explanations for, laxity and irregular motion in vivo may be
linked back to the NZ theory, whereas stiffness may be linked to the end stage of
OSMIA has also been used to detect the presence of pseudarthosis (failed fusion), the degenerative process in the spine
69
. Consequently, focus has turned once more
defined as movement greater than 5 degrees
65
. OSMIA is less invasive than the to the biomechanical model in an attempt to identify sub groups of sufferers with
current gold standard of re-operation and it is more accurate than plain flexion CNSLBP.
extension radiographs which only detect 68 per cent of pseudarthosis
66
. It is
known that radiographic and clinical signs of pseudarthrosis are poorly correlated The future of video-fluoroscopy of the spine
with symptoms, however
67
; hence, further research is needed to establish the Before conclusions can be drawn from the quality of inter-vertebral motion and
relationship between the quality of motion and symptomatic pseudarthrosis. CNSLBP, more normative data from weight-bearing, recumbent, sagittal and
coronal planes are needed. Previous researchers have demonstrated a lower range
Between 2004 and 2006, a feasibility trial sponsored by Zimmer Ltd, used OSMIA to of motion in the weight-bearing position
34,70-73
which may be due to the stabilising
compare one method of dynamic stabilisation (DYNESIS) with a standard postero- activity of surrounding musculature, whereas d’Andrea
74
demonstrated greater
lateral fusion. Baseline pre-surgical data was collected from 10 patients; this allowed translationary movement in the recumbent plane.
interesting comparisons with the asymptomatic data referred to previously. The
symptomatic patients appeared to have a higher incidence of unusual motion OSMIA comprises a practical investigation to determine the physiology of new and
patterns which were classified as: stiffness (less than 3 degrees ROM), irregular existing treatments for back pain, including the ability of total disc replacements
motion (low correlation to trunk motion), paradoxical motion, (inter-vertebral motion (TDRs) to mimic physiological movement, as well as the presence or absence of
in the opposite direction to the trunk bend), and laxity (intervertebral segment adjacent segment disease following spinal fusion. Finally, OSMIA could be used to
reaches its maximum end of range before the trunk motion). With the exception of determine whether the presence of certain motion patterns is linked to pain, so
paradoxical motion, first reported on flex-extension radiographs by Kirkaldy-Willis
68
, providing data for a new biomechanical approach to CNSLBP.
these motion patterns are undetectable with static imaging methods. Figure 5
demonstrates an intervertebral motion pattern from an asymptomatic participant Conclusion
and shows a regular sine wave for inter-vertebral rotation throughout the trunk There is a high rate of failure for current treatments for CNSLBP and a major reason
bend. However, figure 6 demonstrates other inter-vertebral motion patterns including for this is the heterogeneity of sufferers. Better diagnosis of the cause of their pain
irregularity, paradoxical motion, and laxity. would better help selection of appropriate treatments for the various sub-groups
38
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