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East and Central African Journal of Surgery
Association of Surgeons of East Africa and College of Surgeons of East Central and Southern Africa
ISSN: 1024-297X EISSN: 2073-9990
Vol. 14, Num. 2, 2009, pp. 9-12
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Untitled Document
East and Central African Journal of Surgery, Vol. 14, No. 2, July-Aug, 2009, pp. 9-12
Tear-drop
Fractures of the Cervical Spine
N.S.
Motsitsi, L.N. Bomela.
Department
of Orthopaedic Surgery, University of Pretoria, Kalafong Hospital,
Pretoria, S. Africa.
Correspondence
to:Dr.N.S. Motsitsi, Fax : + 27 12 373 9031, E-mail:
silas.motsitsi@up.ac.za.
Code Number: js09027
Tear-drop
fractures of the cervical spine are relatively rare injuries. Those
involving the upper cervical spine commonly occur in older patients
following minor trauma. However, they may occur following major
trauma like car accidents, falling from heights and diving into
shallow water. They are stable injuries and are treated
conservatively with relatively good outcome. They are usually not
associated with neurological deficits unless they are associated with
injuries at other levels. The cause of neurological fallout is
commonly due to associated injuries.
Tear-drop
fractures of the lower cervical spine are usually caused by severe
trauma including sports. About 83% - 87% of tear-drop fractures due
to sports are accompanied by neurological fallout. Tear-drop fractures
of the lower cervical spine are regarded as unstable. The management
of tear-drop fractures of the lower cervical spine is very
controversial. The controversies are: should all these fractures be
managed surgically? If so, what is the best surgical approach?
Unfortunately, available literature does not offer convincing answers.
Current surgical techniques provide acceptable stability, at least
according to biomechanical studies. It is still to be established
whether these biomechanical findings are confirmed clinically.
Introduction
Tear-drop
fractures of the cervical spine are defined as fractures involving
the antero-inferior angle of the cervical vertebral body, with the
vertical dimension of the triangular fragment being equal to, or
greater than the transverse dimension1. They are relatively
rare injuries. There are two major groups of tear-drop fractures of
the cervical spine: those involving the upper (C1-C2) cervical spine
and those involving the lower (C3-C7) cervical spine. These two
groups also differ with respect to mechanism of injury, the
incidence of neurological deficits, management principles and outcome. The
purpose of this article is to review the Pathophysiology of
tear-drop fractures of the cervical spine, their clinical
presentation, radiological features, principles of management and
outcome.
Pathophysiology
The
management of any clinical pathology is predicated on knowing its
Pathophysiology. The Pathophysiology of the two categories of
tear-drop fractures is different. It is their Pathophysiology that
forms the bases of management approach.
The Upper Cervical Spine.
The
vertebra that is commonly fractured is the axis (C2). Tear-drop fractures
of the axis forms 3% of the cervical spine trauma2. The
incidence may be as high as 26%3. Hyperextension dislocation of
the axis constitutes about 32% of the axis fractures4.
Fractures of the axis commonly occur in the elderly following minor
trauma and tend to be stable1. However, they may follow
severe trauma: car accidents, falls and diving into shallow water2.
The mechanism of injury is hyperextension. The tear-drop fracture is
caused by avulsion by the anterior longitudinal ligament. The
disco-ligamental complex (supraspinous ligaments, interspinous ligament,
the joint capsule, the intervertebral disc and the posterior
longitudinal ligament) is preserved. This injury pattern makes
tear-drop fractures of the axis to be stable injuries. About half
of these injuries are associated with injuries at another level2.
Isolated tear-drop fractures of the axis are not associated with
neurological deficits, but associated fractures may cause neurological
fallout. Tear-drop fractures of the atlas (C1) are very rare; no
series of these injuries have been reported in the English
literature.
Tear-drop Fractures of the Lower Cervical Spine (C3-C7).
They
are caused by severe trauma. The incidence is fairly high: 8.8% - 23%5.
There are two forces that cause tear-drop fractures of the lower
cervical spine1:
- Tension: this causes disruption of the disco-ligamentous
complex ( DLC) and thus injury to the posterior column. The posterior
column fails in tension.
- Compression: the anterior column fails in
compression and causes tear-drop fracture.
The
upper cervical column may displace posteriorly leading to anterior
compression of the spinal cord. Tear-drop fractures of the lower
cervical spine are regarded as unstable. Complete spinal cord injury
may occur in 38% - 91% of cases6. The majority of spinal
cord injuries are incomplete. Anterior spinal cord syndrome accounts for
80% of incomplete spinal cord lesions7. Other lesions like
Brown Sequard Syndrome may occur.
There
may be an additional force in the mechanism of injury of the lower
cervical spine: lateral flexion or rotational force. This force causes
and additional injury to the vertebral body. The fracture line is orientated
in the sagittal plane. The force can cause fracture of the vertebral
body and the laminar leading to a ‘hemi vertebra’. Laminar fractures
may be bilateral. The incidence of laminar fracture may reach up to
84% . The facet can also be involved. This additional fracture pattern
further compromises the stability of the injury8,9,.
Tear-drop
fractures may also occur in athletes. It is common in most sports. These
fractures show two fracture patterns and the incidence of neurology10:
- Isolated tear-drop fractures: the
incidence of neurology is 83%.
- Three - part, two plane fracture
pattern: the
incidence of neurology is 87%.
Injuries
to the vertebral and the carotid arteries (thrombosis or dissection)
must always be borne in mind in all injuries involving the upper
cervical spine and fractures or fracture-dislocation of the lower
cervical spine. Carotid artery injury is unusual and tends to be symptomatic7.
These injuries must always be excluded.
Clinical presentation
Patients
who sustain tear-drop fractures of the cervical spine do not have
specific ways of presentation. Elderly patients with tear-drop
fractures of the axis may give a history of minor trauma like
bumping their heads against a wall. Clinical examination may reveal
tenderness in the upper cervical spine. There is usually no neurological
deficits. The majority of patients will give a history of severe
trauma: motor vehicle accidents, diving into shallow water and
falling from a height. Those who sustained fractures of the axis
will have no clinical neurological deficits unless there are
associated fracture(s) at other levels. About two-thirds of patients
who sustain lower cervical spine tear-drop fractures as a results of
diving have neurological deficits on presentation6.
Radiological investigations
Radiological
investigations are the key to the diagnosis of tear-drop fractures
of the cervical spine.
1.
Standard Radiological investigations (X-rays).
These
are the first lines of investigations. Features that must be noted are:
- Soft
tissue shadow: pre-vertebral soft tissue swelling (especially in
uninitiated patients) may show either localized or diffuse
swelling 1. Diffuse soft tissue swelling is
significant if it extends to at least one level above or
below the level of injury.
- The
character of the avulsed fragment. The shape of the avulsed
fragment is triangular, with the vertical dimension being equal
to, or larger than the transverse dimension. This is a critical
concept to understand in order to distinguish it from the
fragment due to hyperextension dislocation (H D) and the
quadrangular fracture. In HD the avulsion is mediated through
intact Sharpey fibers which penetrate the former ring apophysis1.
The fragment originates from the antero-inferior endplate of the
involved vertebra. It is small, flat and wedge-like with the
vertical height being less than the transverse width1.
It is rarely found in the upper cervical spine. Patients with
this type of injury ( HD) almost always have neurological
deficits. Quadrangular fractures are due to compression fractures. They
resemble tear-drop fractures, but they respond poorly to
posterior fusion. Farero and Van Peteghem11 outline major
differences between quadrangular fractures and tear-drop fractures,
although some authors use these two terms interchangeably. They
are also different from burst fractures12.
2.
Computed Tomographic Scan (CT – SCAN).
It is an ideal method for
demonstrating sagittal fracture involving the vertebral body and
posterior elements. It is highly recommended that CT - SCAN must
always be done in patients with tear-drop fractures of the cervical
spine, especially the lower cervical spine.
3. Magnetic Resonance Imaging (MRI).
It is the best mode for
demonstrating the extend of soft tissue and spinal cord injury. The
extend of DLC disruption can be well demonstrated by this modality.
It will also exclude any possible mechanical compression to the
spinal cord. MRI-Angiography can be added to exclude possible vascular
injury.
Management Principles
Management
of tear-drop fractures of the upper cervical spine is conservative
because these fractures are stable13,3. But the management
of lower cervical tear-drop fractures is controversial. Scheider and Kahn14 emphasized that these fractures must always be management
surgically. They maintained that conservative treatment leads to late
neurological deterioration. The first controversy is whether they should all
be operated. Unfortunately, studies available in the English literature
are all retrospective, and there are no randomized controlled trials.
Fisher
et al5 reviewed 45 of their patients of whom 24 were
treated conservatively and 21 treated operatively. Five of
conservatively treated patients had to be operated because of loss of
alignment and neurological deficits in two patients. Those whose
fractures united on conservative treatment developed significant late
kyphosis. All their operated patients had 100% union rate. Cabana and
Ebersold16 treated their 8 patients surgically and had
successful outcome. Koivikko et al17 confirmed better
outcome in tear-drop fractures treated operatively compared to
conservative treatment. Korres et al15 in their latest study
maintained that not all tear-drop fractures of the lower cervical
spine need surgical intervention. They stated that there are certain
parameters that need to be taken into account before one decides
whether to operate or not which include size of the triangular
fragment, the presence or absence of sagital fracture, the presence
or absence of retrolisthesis, the magnitude of the retrolisthesis,
the presence or absence of dislocation and the presence or absence
of locked facet. They proposed a classification system that serves
as a guide whether to operate or not.
The
second controversy is the surgical approach. The currently favored
technique is anterior discectomy, grafting and anterior cervical
plating. Posterior procedures like plating and grafting are also
surgical options.. Biomechanical studies18 showed that
currently practised surgical techniques provide good or acceptable
stability. Future or prospective studies are needed to answer or
address the following pertinent clinical questions or issues:
- Comparison
between operative and non-operative treatment of tear-drop
fractures of the cervical spine using randomized controlled trials.
- Development
of classification system for these fractures or validation of
proposed classification system(s) currently available.
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