1
BACKGROUND
A thoracic and lumbar spinal injuries account for the
majority, about 90% of spinal injuries. In which, thoracolumbar
spine hinge vertebra (T11 - L2) and lower lumbar (L3 - L5)
account for about 84%, mainly with the indirect mechanism.
Classification emphasizes on: the form of injury, integrity of the
posterior ligamentous complex and nerve damage. The role of
the posterior ligamentous system in the stable spinal structure is
confirmed and appreciated by many authors. This is an issue
that needs to be paid more attention to in the diagnosis and
treatment of spinal injury in Vietnam when no previous research
has specifically and fully mentioned before. For surgical
indication,the authors based on the loss of steadiness of the
injured spinal vertebra on the basis of the morphologic damage,
nerve damage, and posterior ligamentous complex. However,
each indication has its own advantages and disadvantages.
Recent studies have been made on the validity and
reliability of Vaccaro AR’s TLICS (thoracolumbar injury
classification and severity score) and indicate cases where
scores of 1 to 4 had to undergo surgery late after a
conservative treatment period, or narrow scope of application
in the multiple vertebral fracture group under the indication
of McCormack and Wood KB. Posterior approaches for
treatment of thoracic spinal injury is becoming more and
more popular, effective and dominant. The efficiency of
multiple vertebral fracture surgery has been enhanced, and
demonstrated in studies by Smith JS, Ataka H., Kaminski A..
The findings of Greenberg MS about degenerative
joint diseaserequired for early surgery after 3 years in long
band fixations (≥ 4 bands) after 8 to 9 years in short band
fixations (2 to 3 bands). Therefore, from these issues, we
carry out the topic: “Study on surgical injury characteristics
and results of surgery for treatment of the lower thoracic and
2
lumbar spinal fractures due to traumatic injury by splints and
screws” with two goals:
1. Description of surgical injury characteristics and
deformation on the image diagnosis, survey of TLICS
and LSC values in lower thoracic and lumbar spinal
injury.
2. Evaluate the results of surgery for the treatment of
lower thoracic and lumbar spinal fractures with
posterior splints and screws.
CHAPTER 1. OVERVIEW
1.1. Surgery
The lower thoracic and lumbar spine consists of a relatively
straight, vulnerable thoraco- lumbar spine hinge vertebra (T11 -
L2) by a longitudinal compression and a lower lumbar vertebra
(L3 – L5) with a physiological curve opening backward to
absorb force in the spring type so that it causes less injury.
Vertebral body has weak structure in from column, stable structure
in middle and back columns. Thus, injury often occurs in the front
column under the vertical compression mechanism. According to
Benzel E.C., the proportion of periosteum and bone marrow affects
the bearing capacity and the anti-screw loosening strength. This rate
is higher in the spinal stalk than in vertebral body and higher in the
thoracic - lumbar spine hinge vertebra than in lower lumbar
vertebra. Therefore, spinal stalkis the strongest part of the vertebrae
and the T11 - L2 segment is stronger than the L3 - L5 segment. The
joint system between vertebrae is composed of two main types of
joints: Cartilaginous (semi-moveable) joint and the Synovial (freely
moveable) joint. Of which, the Synovial (freely moveable) joint
and ligament joint (rear ligament system) play an important role in
steadiness, flexibility and maintaining the amplitude for movement
of the spinal column.The vascular system nourishing the thoracic
and lumbar marrow, including the root vascular system, spinal
marrow vascular system and coronary artery network. Accordingly,
Adam kiewiczcung artery provides mainly for 4/5 marrow in cross
section from T8 to conus medullaris.
3
1.2. Biological mechanisms behind injury and nerve damage
in spinal injury
1.2.1. Biological mechanisms behind injury
According to Benzel E.C., the force acting on the spinal
column, in terms of the three-dimensional space system on each
coordinate axis, has two axial sliding motions and two
reciprocating rotating movements that produce 12 movements
around the instantaneous axis of rotation (IAR), forming up to
six levels of free movement around the IAR axis in association
with each other to creating forces: press – compression, cutting
– shearing, twisting, stretching – tearing resulting in different
forms of damages in a trauma. Instantaneous rotation axis is the
imaginary point in or around the vertebrae where the spinal
segment rotates under the impact force. When the impact force is
non-coaxial with IAR, it generates a bending moment (M) of
magnitude equal to the magnitude of the force (F) multiplying
by the distance from the point of impact to the instantaneous
rotation axis (D). The bending moment (M) is defined as the
product of the force (F) applied to the lever arm and the length
of the lever arm (D) : M = F x D.
1.2.2. Nerve damage
In spinal trauma, there are four major traumatic
mechanisms involved in nerve deformation in the long term:
extrinsic nerve compression, diffusion, arch effect on the vertical
plane, arc effect on the horizontal plane. It has two forms of lesions:
primary lesions and secondary lesions. Disorders or malfunction of
nerve cells due to the mechanism of: cell destruction leads to nerve
cell death and cell deformation, metabolic disorders leading to
temporary or permanent malfunction. Surgery removing the
compression factors can prevent, overcome cell deformation and
metabolic disorders. Secondary nerve damage may be prevented
partially at least by medicine interventions: anticoagulant medicine
therapy and corticoide therapy are recommended to use as soon as
possible within the first 8 to 72 hours after injury.
1.3. Classification of injuries
4
1.3.2. Classification of Denis (1983)
In 1983, Denis introduced the three column concept of spinal
fractures: anterior column (the anterior vertebral body, ½
anterior annulus fibrosus, and anterior longitudinal ligament),
middle column ( posterior longitudinal ligament, ½ posterior
annulus fibrosus, and posterior wall of the vertebral body), the
posterior column (spinal canal vein, marrow, posterior ligament
system, posterior arch).
Denis divides the vertebral body injury into four types:
compression fracture (anterior column damage, no injury to the
middle column, possible injury to the posterior column), burst
fracture (injury to the middle and posterior column by the
mechanism of vertical compression in combination with
bending, turning, and the posterior fracture piece may press the
spinal canal), distraction fracture (the fracture lies at the same
level in the vertical plane, the fracture lies in two levels in the
vertical plane causing injury to bones, ligaments and annulus
fibrosus), dislocation fracture (severe damage to all three
columns causing instability).
Denis introduced the concept of “stable and unstable spinal
injuries” as the basis for indications for treatment in spinal
injuries. The term “stability fracture” includes mild or moderate
subsidence, no injury to the middle and posterior columns,
indicating conservative therapy, early movement practice.
There are three types of instability based on the relationship
between morphological and neurological damages: mechanical
instability, neurological instability, mechanical - neurological
instability, and surgical indication.
1.3.3.Classification after Denis
McCormack classified fractures based on three factors: the
breaking degree of the vertebral body, the cohesion of fractured
pieces, the kyphosis being quantified on a scale of 1 to 3 points
on each factor by severity status. The higher the point, the more
severe the injury. Indication for surgery in case of 6 – 9 points.
VaccaroA.R., gave the TLICS classification based on three
important traumatic features: injury morphology, integrity of
5
the posterior ligament system, and nerve damage. Indication: 5-
10 points => surgery, 1 - 3 points => conservative treatment
and 4 points => priority for surgery.
1.4. Medical imaging methods
3 main methods: conventional x – ray imaging, computerized
tomography and MRI.
1.4.1. Conventional x – ray imaging
Conventional X-ray imaging has diagnostic value: position;
discontinuity of three lines: inter- posterior spinal cord, inter-joint
block, inter- horizontal spinal cord; vertebral traumas, angular
bending of the traumatic area and the distance between joint
blocks and posterior spinal cord. The advantage of conventional
x-ray compared to computerized tomography and magnetic
resonance imaging (MRI) is that it can be investigated in a
dynamic state to diagnose suspected cases of semi-dislocation.
1.4.2 Computerized tomography (CT scan) of of spine
CT scan have a accuracy rate (sensitivity) of over 98% with
bone damage, which is of high value in the classification of
spinal fractures. Determination of bone loss: reduction of the
height of the anterior column, fracture line, separate fracture
piece and compression position, joint block lesions, spinal
canal, plates, bending angular deformations or dislocation,
spinal canal narrow levels. However, it is difficult to assess soft
tissue lesions such as ligaments, nerves.
1.4.3. MRI of spine
Magnetic resonance imaging may determine the damage in
marrow, soft tissue, posterior ligament complex. Marrow
edema and marrow contusion without blood bleeding have
same signal image or low signal on T1, high signal on T2.
Acute or semi-acute bleeding has low signal image on T2, in
chronic phase it is a high signal image on T1 and T2. For
marrow breaking, the image shows a persistent breaking of
the injured segment and the marrow edema, accompanied by
haemorrhage. Image of ligament injury: sudden loss of signal
in a signal decreasing region on T1, increasing signal in the
