In this study of patients who underwent internal fixation without
fusion for a burst thoracolumbar or lumbar fracture, we compared
the serial changes in the injured disc height (DH), and the fractured
vertebral body height (VBH) and kyphotic angle between patients
in whom the implants were removed and those in whom they were not. Radiological
parameters such as injured DH, fractured VBH and kyphotic angle
were measured. Functional outcomes were evaluated using the Greenough
low back outcome scale and a VAS scale for pain. Between June 1996 and May 2012, 69 patients were analysed retrospectively;
47 were included in the implant removal group and 22 in the implant
retention group. After a mean follow-up of 66 months (48 to 107),
eight patients (36.3%) in the implant retention group had screw
breakage. There was no screw breakage in the implant removal group.
All radiological and functional outcomes were similar between these
two groups. Although solid union of the fractured vertebrae was
achieved, the kyphotic angle and the anterior third of the injured
DH changed significantly with time (p <
0.05). Methods
Results
The belief that an intervertebral disc must degenerate
before it can herniate has clinical and medicolegal significance,
but lacks scientific validity. We hypothesised that tissue changes
in herniated discs differ from those in discs that degenerate without
herniation. Tissues were obtained at surgery from 21 herniated discs
and 11 non-herniated discs of similar degeneration as assessed by
the Pfirrmann grade. Thin sections were graded histologically, and
certain features were quantified using immunofluorescence combined
with confocal microscopy and image analysis. Herniated and degenerated
tissues were compared separately for each tissue type: nucleus, inner
annulus and outer annulus. Herniated tissues showed significantly greater proteoglycan loss
(outer annulus), neovascularisation (annulus), innervation (annulus),
cellularity/inflammation (annulus) and expression of matrix-degrading
enzymes (inner annulus) than degenerated discs. No significant differences
were seen in the nucleus tissue from herniated and degenerated discs.
Degenerative changes start in the nucleus, so it seems unlikely
that advanced degeneration caused herniation in 21 of these 32 discs.
On the contrary, specific changes in the annulus can be interpreted
as the consequences of herniation, when disruption allows local
swelling, proteoglycan loss, and the ingrowth of blood vessels,
nerves and inflammatory cells. In conclusion, it should not be assumed that degenerative changes
always precede disc herniation. Cite this article:
This article reviews the current knowledge of
the intervertebral disc (IVD) and its association with low back
pain (LBP). The normal IVD is a largely avascular and aneural structure
with a high water content, its nutrients mainly diffusing through
the end plates. IVD degeneration occurs when its cells die or become
dysfunctional, notably in an acidic environment. In the process
of degeneration, the IVD becomes dehydrated and vascularised, and
there is an ingrowth of nerves. Although not universally the case,
the altered physiology of the IVD is believed to precede or be associated
with many clinical symptoms or conditions including low back and/or
lower limb pain, paraesthesia, spinal stenosis and disc herniation. New treatment options have been developed in recent years. These
include biological therapies and novel surgical techniques (such
as total disc replacement), although many of these are still in
their experimental phase. Central to developing further methods
of treatment is the need for effective ways in which to assess patients
and measure their outcomes. However, significant difficulties remain
and it is therefore an appropriate time to be further investigating
the scientific basis of and treatment of LBP.
