Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6011_Библиотеки_им_академика_М_И_Перельмана.pdf
C H A P T E R 2 8 Occipital-Cervical and Upper Cervical Spine Fractures
165
The Vertebral Artery
Knowledge of the vertebral artery (VA) anatomy at the craniocervical junction is extremely important for understanding the mechanisms and consequences of injury to this region. Injury to the vertebral artery in this region
can occur as a result of blunt or penetrating trauma, C1 or C2 fractures
(especially those traversing the foramen transversarium), and iatrogenic
injuries caused by aggressive manipulation of the cervical spine, for example.
The paired VAs usually arise from each subclavian artery. They ascend
posteriorly and superiorly between the longus colli and scalenus anterior and
enter the foramen transversarium of the upper six cervical vertebrae. The
foramen transversarium pierces the transverse processes of each of these
cervical vertebrae. The VA travels superiorly through the lower five cervical
vertebrae and then curves laterally and superiorly to enter the foramen transversarium of the atlas. The artery then curves anteriorly and superiorly to
enter the foramen magnum, traveling along the lateral aspect of the medulla.
INJURIES OF THE CRANIOCERVICAL JUNCTION
Overview
As with any trauma patient, priority in management begins with the
primary and secondary survey including craniospinal immobilization,
hemodynamic stabilization, and radiographic evaluation. High-resolution
computed tomography (CT) scans are indicated for any patients with
clinical suspicion for cervical spine injury, including patients with altered
sensorium or clinical evidence of head injury. Once identified, traumatic
injuries of the craniocervical junction are triaged based on the clinical evidence of neural injury, vascular injury, and/or mechanical instability, and
supplemental imaging such as angiography and magnetic resonance should
be utilized liberally when indicated.
Occipitocervical Instability
OC instability is one of the most dangerous conditions affecting the cervical
spine. True OC instability is a clinical emergency. The pathophysiology of
OC instability ranges from trauma to inflammatory/neoplastic conditions,
but trauma is the most common reason for operative intervention.
Occipitoatlantal Dislocation
Among traumatic injuries to the cervical spine and causes for OC instability,
occipitoatlantal dislocation (OAD) is one of the most severe types of injuries. It is a hyperflexion-distraction injury which results in the ligamentous
disconnection of the skull from the cervical spine. OAD is often immediately fatal because of associated neurological and vascular injuries. The first
clue in the diagnosis of OAD is the mechanism of injury. High-impact injuries should always arouse the suspicion of OAD. Plain radiographs of the
cervical spine reveal prevertebral soft tissue swelling and an increase in the
basion-dens interval, which should measure 12 mm or less. More definitive
diagnosis is made with reconstructed CT images of the craniocervical junction. MRI and CT of the craniocervical junction are comparable in terms of
identifying OAD, but MRI can often identify the specific ligaments injured.
OAD injuries can be identified into three broad categories. Type I injuries are characterized by anterior displacement of the occipital condyles on
the C1 lateral masses; type II injuries are characterized by displacement of
the occiput and C1 in the vertical plane; and finally, type III injuries are
marked by posterior displacement of occipital condyles compared to C1.
C1 Fractures and Transverse Ligament Injuries
Fractures of the atlas are usually defined in relation to the lateral mass
and extent of arch involvement.
in isolation or in combination, ranging from single unilateral fractures
to burst-type fractures involving all four aspects, which is known as
a Jefferson fracture. Since isolated atlas fractures without ligamentous injury are stable and heal with simple immobilization, the clinical importance of fractures of the atlas is to understand the possible
involvement of the transverse ligament, the vertebral artery, and other
associated spinal fractures. The most commonly cited radiographic criteria indicating unstable disruption of the transverse ligament include
the Rule of Spence
4
(lateral displacement of C1 lateral masses over C2
greater than 6.9 mm) and the atlantodental interval being greater than
3mm. However, when feasible, this author prefers MRI evaluation of all
atlas fractures to assess for concomitant ligamentous injury. Transverse
ligament disruption, as with other cases of atlantoaxial instability, is an
indication for surgical fixation.
Nontraumatic disruption of the atlantoaxial ligaments can also lead to
gross atlantoaxial instability. C1-2 rotatory subluxation is a rare condition
usually seen after inflammatory and/or infectious conditions of the pharynx
and tonsils in the pediatric population. In the elderly, rheumatoid arthritis
(discussed later) can lead to atlantoaxial instability requiring surgical
stabilization.
3
They can involve any parts of the ring
C2 Fractures
Odontoid process fractures affect the elderly far more often than younger
people and are, unfortunately, relatively common. The most common classification scheme for fractures of C2, the Anderson and D’Alonzo scheme,
relies on the location of the fracture line within the odontoid process or
body of C2. In this scheme, type I fractures involve the tip of the dens, type
II fractures run through the junction of the dens and the body of C2, and
type III fractures course through the vertebral body of C2.
Type I fractures are an avulsion of the alar ligament and are usually
stable. Cervical collar immobilization for symptomatic management is usually sufficient.
Type II fractures (Figure 28-1) are the most common type of dens fracture and are more often subject to nonunion, especially in patients older
than 50 years of age when displacement is greater than 5 mm. When choosing treatment strategies for type II odontoid fractures, the surgeon must
consider the integrity of the transverse ligament, age and orientation of
the fracture, displacement and/or angulation of the fractured process, and
5
Occipital Condyle Fractures
Occipital condyle fractures can be classified into three main types according
to the Anderson and Montesano scheme.
3% of cases of blunt trauma to the craniocervical region. Type 1 fractures
usually result from axial loading injuries and are comminuted. Type II fractures are linear fractures that originate in the squama of the occipital bone
and extend into the condyle. Type III fractures are avulsion fractures of the
condyles; these fractures are most prone to instability and atlanto-occipital
dislocation.
2
These fractures are seen in 1% to
F IG UR E 2 8- 1 Type II dens fracture.
166
P A R T I V Surgical Treatment Modalities: Cervical Spine
patient-specific factors such as medical comorbidities, and body habitus. For
example, certain body habitus features, such as a barrel chest, can make anterior odontoid screw placement impossible.
Type III fractures extend into the C2 vertebral body. This fracture type
can be mechanically unstable but usually heals well with immobilization.
As such, treatment usually entails cervical immobilization in either a rigid
cervical orthosis or a halovest for 12 weeks, and the majority of patients heal
by bony union.
Fractures of the C2 pedicles (also known as traumatic spondylolisthesis or hangman’s fractures) are often classified based on the mechanism
of injury,
6,7
where flexion (type III) and flexion-distraction (type IIa) are
often unstable and require surgical fixation, especially type IIa injuries with
greater than 4 mm distraction and/or greater than 11 degrees of angulation.
Other fractures of the axis can include isolated fractures of the C2 vertebral
body or fractures of the C2 spinous process or lamina, which are usually
stable and can achieve good union with nonoperative immobilization.
Craniocervical Manifestations of Rheumatoid Arthritis
Between 10% and 85% of patients with rheumatoid arthritis (RA) have
neck pain and 10% to 60% have neurological deficits.
manifestations of RA are most often seen at the craniocervical junction.
This is usually a late finding in the disease course; therefore, a significant
proportion of RA patients with craniocervical abnormalities are elderly.
RA of the upper cervical spine, similar to RA in peripheral joints, is an
inflammatory condition that results in degenerative synovitis, ligament laxity,
pannus formation, and bony erosion. These pathological changes can lead to
atlantoaxial subluxation and are present in up to 86% of patients with RA.
RA can also lead to degeneration of the occipital condyle-C1 joints, leading to cranial settling. Degeneration of the C1-2 and O-C1 joints can also
lead to vertical migration of the odontoid process into the foramen magnum
(basilar invagination), resulting in myelopathy from odontoid compression
of the lower brainstem. Myelopathy can also be caused by pannus formation
around the dens and consequent narrowing of the spinal canal.
Management of craniocervical abnormalities in patients with rheumatoid
arthritis depends on the severity of clinical symptoms and the extent of craniocervical instability. Similar to craniocervical and atlantoaxial instability
induced by traumatic events, measurement of the Powers ratio and the
atlantodental interval can be used to assess occipitoatlantal and atlantoaxial
instability, respectively. C2 vertical subluxation can be assessed by a number
of radiographic lines (Chamberlain’s, McRae’s and McGregor’s lines). Frank
craniocervical instability requires surgical stabilization.
8
Spinal column
SURGICAL APPROACHES AND TECHNIQUES
Ventral vs. Dorsal Approaches
Isolated odontoid fractures, any large C2 pannus with ventral compression
of the spinal cord, and bony tumors of C1 or C2 (especially those located
in the midline and anterior to the spinal cord) can be approached ventrally.
Ventral approaches to the high cervical spine can be accomplished through
the neck, the posterior pharyngeal wall, the maxilla, or the mandible. The
ventral retropharyngeal approach gains access to the ventral aspects of C1
and C2. With this approach, care must be taken to preserve the cervical
branches of the facial nerve and the hypoglossal nerve as these structures
traverse the neck. The transoral approach utilizes an incision in the dorsal
pharyngeal wall and provides excellent access to the ventral midline cervical
spine. It can be used for odontoid resection and for resection of clival lesions.
Transoral approaches may be associated with relatively higher complication
rates, including CSF leak, wound dehiscence, retropharyngeal abscess, and
lingual edema. Extended maxillary approaches (described by Crockard and
colleagues) and mandibular approaches can be utilized in cases where wider
surgical corridors are required.
Dorsal approaches to the occipitocervical region are used far more
frequently than ventral approaches. The patient is positioned in the standard
prone position and common surgical principles such as dissection along the
avascular midline plane and subperiosteal dissection are employed.
Occipitocervical Fusion
8
The instrumented technique for achieving rigid fixation across the occipitocervical junction was popularized by Ransford and colleagues in 1986.
They described the use of a contoured steel loop and sublaminar wiring to
establish a fairly rigid fixation across the OC junction. Although the use of
sublaminar wires increases the risk of injury to neural structures when compared to uninstrumented, onlay fusion procedures, the vast improvement in
fusion rates after sublaminar wiring popularized its use. However, in spite of
the improved level of fixation after sublaminar wiring, patients still required
the use of halo vests before complete solid fusion could be established. The
desire for fixation techniques that obviate the need for halo vests led to the
techniques being used today. The most common surgical treatment for OC
instability today involves the use of a contoured occipital plate that is connected by a rod to cervical screws (Figure 28-2).
CONSERVATIVE MANAGEMENT OF OCCIPITOCERVICAL INJURIES IN THE AGING SPINE
Once evidence of occipitocervical injuries is discovered in the aging spine,
the treating clinician has to decide whether to pursue surgical or nonsurgical management of these conditions. The initial step in the management
of all craniocervical region injuries is to determine whether the injury is
stable or unstable. Some instances of craniocervical abnormalities, like
occipitoatlantal dislocation, result in evidence of clear instability and
aretherefore surgical emergencies. However, stable injuries such as type
I odontoid fractures can be managed with cervical orthoses while bony
union is achieved.
Conservative management of upper cervical injuries is usually achieved
with rigid immobilization of the cervical spine either with rigid cervical
collars, such as the Philadelphia collar or Miami J collar, or with halo vests.
Cervical collars provide good sagittal motion restriction in the upper cervical
and subaxial spine. However, they are easy to remove and thus have variable
rates of user adherence.
Halo vests provide good upper cervical and subaxial sagittal motion
restriction. They also provide superior axial plane motion restriction compared to cervical collars. In addition, halo vests are secured to the skull and
cannot be easily removed by users. Halo vests are associated with a higher
morbidity and mortality rate, especially for elderly patients. For these
reasons, halo vest use in the aging population, while sometimes unavoidable,
should be approached with caution.
F IG UR E 2 8- 2 Occipital-cervical fixation.
C H A P T E R 2 8 Occipital-Cervical and Upper Cervical Spine Fractures
167
Patients undergoing occipitocervical fusion are usually placed in a Mayfield clamp and secured in a prone position, taking care to avoid excessive
motion at the craniocervical junction during positioning. Since fixation of
the occiput to the cervical spine eliminates the natural range of motion at
the OC-C1 joint, care must be taken to maintain the spine in a neutral
position in order to prevent patients from assuming a permanent flexed or
extended position after surgery. An incision is usually made from the external occipital protuberance down to C3 or C4 and a subperiosteal muscular dissection is performed at all levels where screws are to be placed. The
occipital bone is thickest in the midline and thins out laterally, so the length
of the occipital screws must be chosen carefully and in accordance with the
shape of the bone. Depending on the integrity of the bony structures in the
atlas and axis, lateral mass screws can be placed at C1 and translaminar or
pedicle/pars screws may be used at C2. Transarticular C1-C2 screws are
also an option. The cervical spine screws are then secured via a rod to the
occipital plate.
Odontoid Screw
When feasible, an excellent option for treatment of type 2 odontoid fractures is direct fixation of the fracture with an anterior odontoid screw
(Figure 28-3). Preoperative considerations include intact transverse ligament, fracture line orientation, and acuity of injury (given concern for
nonunion with sclerotic fracture edges). Depending on displacement of the
fractured odontoid process, reduction can be first achieved with external
immobilization prior to, or at the time of, surgery.
Practical preoperative considerations include patient anatomy and
operative positioning to allow proper screw trajectory. Limiting factors can
include barrel chest, short craniocaudal neck dimension, or rigid cervical
spine preventing extension to achieve necessary trajectory. When discussing the operative plans and obtaining patient consent, possible plans for
aborting screw placement and proceeding with C1-2 posterior fusion can
be helpful.
Operative planning, positioning, and set-up are critical for appropriate
odontoid screw placement. Patients are positioned and C-arm biplanar fluoroscopy is utilized to achieve adequate working views in the AP and lateral
planes and optimal fracture reduction prior to incision.
F IG UR E 2 8- 3 Anterior odontoid screw with C4-6 lateral mass fixation.
Skin incision is planned based on necessary screw trajectory and cosmesis, often centered around C5, and neck dissection should proceed with
standard attention to developing a safe corridor between the carotid sheath
and trachea/esophagus to access the anterior cervical spine. Placement of the
screw is performed over a K-wire under fluoroscopic guidance and an appropriate entry point is chosen at the anterior-inferior body of C2, depending
upon the planned screw trajectory. Optimal placement can be facilitated by
drilling a recess into the body of C3 and removing a piece of the C2-3 disc
to allow for the screw trajectory and entry point at C2. A single lag screw is
utilized for fracture fixation and reduction, and an attempt should be made
to achieve bicortical purchase through the odontoid fragment to maximize
biomechanical stability of the construct. Great care is taken at the time of
K-wire and screw placement to avoid injury to the vertebral-basilar complex
and cervical cord/brainstem dorsal to the fracture fragment. Advantages of
odontoid fracture fixation with an odontoid screw include direct fracture
reduction/stabilization, preservation of some C1-2 motion, decreased time
of immobilization, and decreased morbidity associated with halo placement
or posterior surgical approach.
C1-2 Harms
Multiple options exist for posterior C1-2 fixation. In cases of fractures involving both the atlas and odontoid, consideration must be given to the stability
of the atlantal arch in immobilizing the C1-2 complex, and, when necessary,
fixation can be extended to the occiput. Otherwise, posterior C1-2 fixation
techniques are useful in cases of atlantoaxial instability including type II
odontoid fractures, degenerative disease of the C1-2 complex, osteoinvasive
malignancy of the C1-2 complex, and nonunion of odontoid fracture.
C1 lateral mass-C2 pars/pedicle screw fixation, known as the Harms
construct
selected patients, and, unlike an odontoid screw, it can be utilized in patients
with a disrupted transverse ligament. Advantages include direct visualization
of fusion surfaces, flexibility in timing of surgery (can be utilized in acute and
chronic treatment of instability), and, as a polyaxial screw and rod construct,
it can easily be extended to the occiput or subaxial spine, if necessary.
include a preoperative cervical spine CT scan to delineate the bony anatomy; when necessary, this can be supplemented with vascular imaging to
define vertebral artery anatomy. Patients are positioned prone with the head
immobilized in a halo or Mayfield pins that are secured to the table. The
neck is maintained in a neutral position, and C-arm fluoroscopy or other
navigation tools are utilized.
ing the patient should be modified accordingly. Incision and dissection is
carried through the midline ligamentum nuchae to expose the caudal edge
of the occipital bone and the cephalad edge of the C3 lamina, and subperiosteal lateral dissection is extended to the C1-2 joint and the lateral aspect
of C2 (while preserving the C2-3 facet capsule). Great care must be taken to
avoid injuring the vertebral artery, including limiting lateral dissection to the
medial one third of the cephalad atlantal arch and, when present, recognizing the ponticulus posticus identified on preoperative CT scan.
C1, which requires identification, and often retraction of, the C2 (greater
occipital) nerve, along with meticulous hemostasis, as there is often significant bleeding from a venous plexus. The middle of the C1 lateral mass
at the junction with posterior atlantal arch is a reliable entry point for the
C1 lateral mass screw. The screw is inserted with a slight medial trajectory as the medial wall of C1 is palpated to ensure maintenance of its
integrity. Lateral fluoroscopy (or other navigation tool) should be utilized
and the tip of the screw should be aimed at the anteriormost part of the
anterior arch.
entry point for a C2 pedicle screw. The screw is placed with a medial and
cephalad trajectory (about 30 degrees in each plane). A C2 pars screw is an
alternative to the pedicle screw; it is very similar but has a more inferior and
medial entry point and thus has a steeper cephalad trajectory and less medial
trajectory. It is essential that preoperative CT scans be studied carefully, as
there is a high variability in the position and course of the vertebral arteries
in this area.
9
, is an effective posterior fusion construct for appropriately
Operative planning is critical to safe and effective treatment and should
If use of iliac crest autograft is planned, positioning, prepping, and drap-
Screw placement requires adequate exposure of the lateral mass of
The superolateral quadrant of the C2 lateral mass is the approximate
168
P A R T I V Surgical Treatment Modalities: Cervical Spine
Placement of rods is performed in a standard fashion. Use of autograft and/or allograft is done at the preference of the surgeon, and careful
attention is directed to decortication and preparation of the fusion surfaces
including the C1-2 articulating surfaces.
C1-2 Transarticular Screws
An alternative method for posterior atlantoaxial fixation is a C1-2 transarticular screw construct (Figure 28-4), where an appropriatelysized lag screw
traverses the pars interarticularis of C2, the atlantoaxial joint, and the lateral
mass of C1. The indications for its use and its biomechanical stability are
similar to C1-2 posterior fixation screw-rod constructs.
Preoperative planning is similar to that for C1-2 posterior screw-rod
fixation techniques, with an emphasis on the importance of vertebral artery
anatomy. The patient should be positioned in Mayfield or halo pins rigidly
fixed to the operating room table. C-arm fluoroscope should be positioned
for AP and lateral imaging, and sterile prep and drape should include the
caudal extension of the sterile field to the upper thoracic spine for possible
percutaneous placement of the transarticular screws. Careful analysis of
fluoroscopic visualization of atlantoaxial spine and ability to achieve appropriate alignment of C1-2 for screw placement should be performed prior to
incision. Sublaminar wiring can augment the transarticular screw fixation
construct, and may be employed at the surgeon’s discretion.
The appropriate trajectory of the transarticular screw requires a steep
cephalad angle that, depending upon individual patient anatomy, may not
be technically feasible in the wound utilized for dissection of the atlantoaxial
spine. Therefore, use of a percutaneous tunneling device through a separate
stab incision over the lower cervical or upper thoracic spine may be necessary to achieve the optimal angle, under fluoroscopic guidance.
Beginning with a K-wire under fluoroscopic guidance, the entry point
for the transarticular screw is approximately 3 mm lateral to the medial
edge, and 3 mm superior to the inferior edge of the C2 inferior articular
process. The trajectory proceeds in a steep cephalic and slightly medial angle
across the pars of C2. After traversing the pars, the screw can be visualized
in the surgical field prior to entering the lateral mass of C1, where attention
should be directed toward retracting/protecting the C2 nerve and ganglion.
For optimal placement, the tip of the screw should engage the cortex of the
anterior-superior lateral mass of C1. Use of a 4- to 5- cm lag screw (size can
be planned based on preoperative CT) can achieve firm bony purchase and
tight compression of the C1-2 joint for optimal fusion. Attention should be
directed toward decortication of fusion surfaces, often including placement
of a tricortical strut graft between lamina of C1 and process of C2 to augment fusion.
C2 Laminar Screws
In 2004, Wright and Leonard reported a case series of C2 fixation using
crossing laminar screws at C2 (Figures 28-5 and 28-6). Since then, the C2
laminar screw has emerged as a viable alternative to C2 pedicle/pars screws
and C1/2 transarticular screw techniques. The growth of this technique can
be attributed to ease of placement, lower incidence of vertebral artery injury,
and a similar biomechanical profile when compared to C2 pedicle/pars or
C1-2 transarticular screw placement.
The initial approach to C2 for translaminar screw placement is similar
to the techniques described before. A midline incision is carried down to the
posterior elements of C2 in the avascular midline plane. Subperiosteal dissection is used to free the muscular attachments to the lamina and spinous
process of C2. The entry point for the laminar screws are on the opposite
side of the spinous process (i.e., the left laminar screw starts on the right
side of the spinous process). One entry site should start slightly more cephalad and the other should start slightly more caudad to allow crossing in the
middle of the spinous process. A hand drill or small pedicle probe is used to
cannulate the lamina, usually to a length of 26 to 30 mm. The undersurface
of the lamina, within the cervical canal, should be palpated to ensure maintenance of the cortical wall. A 3.5 × 26-30 mm screw is placed in the predrilled
lamina. These screws can then be attached via rods to C1 lateral mass screws,
occipital plates, or subaxial screws, depending on the particular construct. If
needed, lateral extenders are available to make rod placement easier.
COMPLICATIONS
Injuries to the occipital-cervical region are associated with significant morbidity and mortality. Most often, death is due to neurologic injury or cerebrovascular insufficiency. The risk of death or serious morbidity is higher if instability
F IG UR E 2 8 -4 C1-2 transarticular screws with supplemental translami-
nar wiring.
F IG UR E 2 8 -5 C1 lateral mass–C2 laminar screw fixation of type II
dens fracture seen in Figure 28–1.
C H A P T E R 2 8 Occipital-Cervical and Upper Cervical Spine Fractures
F IG UR E 28 -6 Type II dens fracture seen in Figure 28-1 healed after
C1-C2 laminar screw fixation.
169
is missed or the diagnosis is delayed. With appropriate management, nonunion of bony injuries is uncommon, except for type II odontoid fractures.
CONCLUSIONS
The craniocervical junction is a complex region with complex biomechanics
and unique skeletal, ligamentous, and neurovascular anatomy. It is a commonly injured region with potential for significant morbidity and mortality.
Initial treatment of these spine injuries requires attention to maintenance of
airway and ventilation, cervical stabilization, diagnostic imaging, and reduction of vertebral displacement if malalignment is present. Definitive treatment is based on injury type, patient demographics such as age, and clinical
presentation such as the presence or absence of neurologic deficit.
References
1. R .S. Jackson, D.M. Banit, A.L. Rhyne, B.V. Darden, Upper cervical spine injuries, J. Am. Acad.
Orthop. Surg. 10 (4) (2002) 271–280.
2. P.A. Anderson, P.X. Montesano, Morphology and treatment of occipital condyle fractures,
Spine 13 (1988) 731–736.
3. C.D. Landells, P.K. Van Peteghem, Fractures of the atlas: classification, treatment and morbidity, Spine 13 (1988) 450–452.
4. K.F. Spence, S. Decker, K.W. Sell, Bursting atlantal fracture associated with rupture of the
transverse ligament, J. Bone Joint Surg. Am. 52 (1970) 543–549.
5. L.D. Anderson, R.T. D’Alonzo, Fractures of the odontoid process of the axis, J. Bone Joint
Surg. Am. 56 (1974) 1663–1674.
6. B. Effendi, D. Roy, B. Cornish, R.G. Dussault, C.A. Laurin, Fractures of the ring of the axis: a
classification based on the analysis of 131 cases, J. Bone Joint Surg. Br. 63 (1981) 319–327.
7. A.M. Levine, C.C. Edwards, The management of traumatic spondylolisthesis of the axis,
J. Bone Joint Surg. Am. 67 (1985) 217–226.
8. P.M. Pellicci, C.S. Ranawat, P. Tsairis, W.J. Bryan, A prospective study of the progression of
rheumatoid arthritis of the cervical spine, J. Bone Joint Surg. Am. 63 (A) (1981) 342–350.
9. J. Harms, R.P. Melcher, Posterior C1-C2 fusion with polyaxial screw and rod fixation, Spine
26 (22) (2001) 2467–2471.
Subaxial Cervical and Upper Thoracic
Spine Fractures in the Elderly
Jared T. Lee, Christopher C. Harrod, and Andrew P. White
29
k e y p o i n t s
Elderly patients are at increased risk of neurological injuries, including
central cord syndrome, due to degenerative stenosis, spondylotic stiffness, and
changes in spinal cord morphology and vasculature.
Spinal ankylosis increases the risk of unstable fractures, which may not be
diagnosed on initial imaging studies such as plain radiographs.
For historical reasons, central cord syndrome has traditionally been treated
nonoperatively or operatively after a period of observation, but early surgical
treatment has been demonstrated to be advantageous for patients with
traumatic instability, ongoing cord compression, or severe neurological
deficits.
Elderly patients with subaxial cervical and upper thoracic spine fractures have
increased treatment risks as compared to young patients, related to medical
comorbidities, ankylosed segments, osteoporotic bone, and preexisting
stenosis.
Spinal reconstruction in the setting of osteoporotic fractures may require
specific operative techniques to prevent hardware failure.
INTRODUCTION
The geriatric cervical spine is prone to injury. The susceptibility to bony,
ligamentous, and neurological injury may be associated with age-related
changes including osteoporotic bone, stiffened spinal articulations, preexisting stenosis, and altered spinal cord vasculature and morphology. Because of
these factors, which influence injury susceptibility in the elderly patient, the
majority of subaxial cervical and upper thoracic spine injuries occur secondary to low-energy mechanisms. Even within the geriatric population, age is
an important predictor of injury location based on mechanism.
Although atlantoaxial fractures are more common than subaxial fractures in the elderly, there is considerable morbidity associated with subaxial
cervical and upper thoracic spine fractures. These more caudal spine injuries
are more likely to be associated with neurological deficits, in comparison
to atlantoaxial injuries, and more likely to be associated with higher-energy
mechanisms.
Apart from the nearly ubiquitous osteoarthritic spondylosis seen in geriatric patients, other etiologies of severe cervical and thoracic spine ankylosis
can alter the biomechanics of the cervical spine, causing increased susceptibility to fracture from minor traumatic events. These include ankylosing
spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH). Both
conditions result in a stiff and often osteoporotic spine. With injury, both
the anterior and posterior columns may be completely disrupted, causing
frank instability. Fractures of the ankylosed spine are associated with 50%
morbidity and 30% mortality.
required not to overlook potentially unstable fracture patterns.
The lateral cervical spine radiograph is widely used as a screening tool in
the nongeriatric trauma patient. Because of the susceptibility of injury, the
1
2
For this reason, a high level of suspicion is
170
significant consequences of injury, and the potential for occult injury in the
geriatric population, however, more extensive imaging may be warranted.
This is particularly relevant in the spondylotic or ankylotic spine, to avoid
missing injuries.
The treatment of subaxial cervical and upper thoracic spine fractures continues to be evaluated. The subaxial cervical spine injury classification system
(SLIC) has been established to provide clinicians with standardization for
making nonoperative versus operative decisions and, ultimately, how to surgically approach the injuries.
optimal timing of surgical treatment of injuries is also changing. Specifically,
there is now good evidence that early surgical treatment of central cord injuries is superior to late treatment for certain categories of patients. Geriatric
surgical techniques are also evolving; the complex and overlapping pathologies of osteoporosis and ankylosis present challenges for which meticulous
preoperative planning may prevent certain postoperative complications.
3
The traditional thinking regarding the most
BASIC SCIENCE
Cervical spine fractures occur in approximately 2% to 3% of blunt trauma
patients. Subaxial fractures account for 40% to 60% of the cervical spine
fractures. Of these, it has been found that nearly 20% involve the C7-T1
junction. Many subaxial cervical and upper thoracic spine fractures can be
overlooked in the multiply-injured trauma patient. Geriatric patients, in particular, have characteristics that may make injury recognition difficult. These
include preexisting spondylosis with or without degenerative deformities, as
well as patient factors that make the physical examination difficult, including
dementia, baseline weakness, and neuropathies. In the ankylosed spine, even
minimally displaced segments can be unstable. The failure to recognize these
sometimes subtle injuries can lead to devastating neurological consequences.
The radiographic and clinical evaluation of the cervical spine in the
patient following trauma continues to be evaluated. There are ongoing
modifications of recommendations regarding the role of radiographs, multiplanar CT, and MRI to rule out cervical spine injuries in the trauma patient.
Multiplanar CT and MRI have been shown to have very high sensitivity for
detecting cervical spine injury. Despite a high sensitivity, there are reports of
cervical spine injury in obtunded patients with an unremarkable multiplanar
4
CT.
Brandenstein and colleagues recently reported on four patients with
negative cervical CT scans and MRIs who later had evidence of cervical
instability.
cervical spine instability despite normal CT and MRI findings. Not surprisingly, three of the four patients with instability were geriatric. It is prudent
to have a high degree of suspicion for cervical spine injuries in the geriatric
patient despite seemingly normal imaging.
5
They estimated that 0.2% to 0.4% of their patients would have
ANKYLOSING SPONDYLITIS
Ankylosing spondylitis (AS) is a seronegative (RF-negative) spondyloarthropathy that predominantly affects the sacroiliac joints and spine. It
typically, but not exclusively, affects HLA-B27–seropositive patients. The
Text continues on p. 174
Clinical Case Examples
C H A P T E R 2 9 Subaxial Cervical and Upper oracic Spine Fractures in the Elderly
171
CASE 1
A 58-year-old male fell from standing and struck the back of his head. is
resulted in temporary loss of consciousness and neck pain. He was transferred from an outside hospital when abnormal neurological findings were
appreciated. On presentation at our institution, he was immobilized in a
rigid cervical collar and was hemodynamically stable. His exam revealed
F IG UR E 2 9- 1 Case 1: Midsagittal CT of cervical spine shows multilevel
degenerative changes without evidence of fracture.
weakness (4/5) of bilateral upper extremities muscle groups. He also had
4/5 strength in his quadriceps but other lower extremity strength was 5/5.
His past medical history was significant only for hypertension.
Imaging evaluation revealed extensive degenerative changes. Posterior
osteophytes from C3 to C7 and calcification of the posterior longitudinal ligament were demonstrated on CT scanning. ere was no fracture,
malalignment, or prevertebral edema appreciated (Figure 29-1). An MRI
revealed C3-4 disc osteophyte complex associated with spinal cord compression and T2 hyperintensity of the cord. Additional disc protrusions
were seen at more caudal cervical levels (Figure 29-2).
He was initially treated with cervical collar immobilization. His neurological examination was monitored. e patient showed no improvement
in his neurological examination. e recommendation to decompress and
stabilize the cervical spine was accepted by the patient. A posterior direct
decompression with instrumented fusion was performed from C3 to T1
(Figure 29-3).
Postoperatively, his upper extremity weakness resolved. Two weeks later,
however, he presented to the emergency department with recurrent weakness in elbow flexion bilaterally. His examination revealed 4/5 strength in
bilateral deltoids and 3/5 strength in biceps and forearm supination. Otherwise his upper and lower extremity motor strength had improved to 5/5.
He did not have any sensory deficits. Examination was consistent with C5
nerve palsy. He was treated with observation and analgesic medications. At
latest follow-up, he is ambulatory with a fluid narrow-based gait and with
resolved weakness in elbow flexion and supination.
CASE 2
A 51-year-old male with known diffuse idiopathic skeletal hyperostosis
(DISH) had a syncopal event and fell from the stands at Fenway Park,
impacting his face and forehead. He had transient paralysis of bilateral
upper extremities and severe neck pain. He was stabilized in a cervical collar at Fenway and transferred to our emergency department for evaluation.
On initial examination, he was found to have recovered motor function, and to have intact sensation to pain and light touch in bilateral upper
extremities. He had persistent severe neck pain and severe burning pain
and sensitivity to light touch in both hands, refractory to intravenous pain
medications.
C2
C3
C4
C5
C6
C7
T1
T2
T3
A
FI G U RE 2 9- 2 Case 1: MRI performed after physical examination consistent with central cord syndrome. A, Midsagittal
T2-weighted cervical spine MRI shows anterior cord compression from the C3-4 disc. B, Axial T2-weighted cervical spine
MRI at the C3-4 disc level shows cord edema and central canal stenosis.
B
172
P A R T I V Surgical Treatment Modalities: Cervical Spine
Imaging evaluation demonstrated several disc osteophyte complexes.
e largest was observed at C3/C4, where there was 50% narrowing of the
central canal. Extensive flowing nonmarginal osteophytes were also well
characterized by CT scan (Figure 29-4). While no obvious unstable injuries were appreciated on CT, a subsequent MRI revealed extension distraction fractures with three column disruption at both C3-4 and C6-7. Each
level of injury was associated with dissociation of the anterior longitudinal
ligament and osteophytes (Figure 29-5). e spinal cord was compressed
at C3-4 and C6-7.
A C3 to C7 laminectomy and C3 to T1 instrumented fusion were
performed. He tolerated the procedure well and was extubated in the
operating room (Figure 29-6). Since the patient’s body habitus limited the
adequacy of intraoperative radiographs, a CT scan was performed immediately postoperatively to evaluate the spinal alignment and instrumentation
(Figure 29-7).
Postoperatively, the patient reported an immediate decrease in his
burning hand pain. He was able to ambulate with PT and was discharged
home on postoperative day 3. At his 6-week follow-up, he complained only
of hyperesthesias of the right small and index fingers. He had no weakness and normal sensation, with resolution of his severe sensitivity to light
touch.
A
FI G U RE 2 9 -3 Case 1: C3-C7 laminectomy and C3-T1 instrumentation and fusion show hardware in correct
position and adequate laminectomy. A, Lateral postoperative x-ray. B, AP postoperative x-ray.
A
FI G U RE 2 9- 4 Case 2: Initial midsagittal and axial CT reveals many aspects of DISH. There are four continuous
ankylosed vertebrae, the osteophytes are nonmarginal, and it spares the posterior elements, Due to the degree of DISH,
it was difficult to say if there was a fracture or instability base on CT scan alone. A, Midsagittal CT scan. B, Axial CT scan
at C3 level shows central cord compression from osteophyte.
B
B
C H A P T E R 2 9 Subaxial Cervical and Upper oracic Spine Fractures in the Elderly
173
A
FI G U RE 2 9 -5 Case 2: A, Sagittal STIR MRI with increased signal at C3-4 and C6-7 consistent with acute injury.
B, Axial T2-weighted image at C7 shows cord compression.
B
FI G U RE 29 - 6 Case 2: Postoperative AP and lateral cervical spine x-rays with good sagittal and coronal alignment.
Hardware in appropriate position without evidence of complications.
174
P A R T I V Surgical Treatment Modalities: Cervical Spine
A
FI G U RE 29 - 7 Case 2: Postoperative CT scan. A, Axial CT at C3 level with lateral mass screws. B, Sagittal CT scan
demonstrates pedicle screws within the C7 and T1 pedicles.
prevalence ranges from 0.1% in African and Eskimo populations to as high
as 6% in Haida Native Americans in northern Canada. The white populations of the USA and UK have a prevalence of 0.5% to 1.0%. AS typically
has its onset in the third decade of life, with a mean age of onset of 26. It
rarely begins after the age of 40, although the diagnosis may be made at a
later age because earlier symptoms are ignored or benign. A juvenile form of
AS is described, but it does not affect the spine.
Sacroiliitis is the most common presenting symptom, with bilateral or
unilateral buttock pain being the chief complaint. Spinal stiffness and discomfort typically progress gradually and affect all joints in the spine. Extraaxial involvement includes plantar fasciitis, insertional Achilles tendinitis,
eye lesions, enteritis, colitis, prostatitis, aortitis, and, rarely, fibrosis of the
upper lung.
The hallmark spinal pathology seen in AS is due to enthesitis. The
enthesis is the site of tendon and ligament attachment to bone. Local inflammation at the enthesis may lead to radiographic lysis of bone. AS affects the
insertions and attachments of the discovertebral, costovertebral, and costotransverse joints, as well as the other interspinal ligaments. The reactive
bone formation at the sites of inflammation and the remaining lysis result
in a stiff and osteoporotic spine. This combination results in an increased
susceptibility to spine fractures.
6
DIFFUSE IDIOPATHIC SKELETAL HYPEROSTOSIS
Diffuse idiopathic skeletal hyperostosis (DISH) was first described by Forestier and Rotes-Querol in 1950, and it is often still referred to as Forestier
disease. It has specific diagnostic criteria as outlined by Forestier. These
include at least four contiguous vertebrae involved in ossification, without
evidence of loss of disc height, and with relatively well-preserved facet joints
and SI joints. The ossification is nonmarginal and flowing along the anterolateral vertebrae. Additionally, there are extraspinal manifestations such as
increased heterotopic ossification after surgery.
DISH is not related to HLA-B27, and there has been no relationship
found with other seronegative spondyloarthropathies such as AS. DISH
has some relationship with HLA-8 and is relatively common, with prevalence as high as 28% in autopsy series. It is felt that 15% of women and
25% of men over the age of 50 have DISH, and the prevalence increases
with age. There is no difference in prevalence between blacks and
whites.
B
The thoracic spine is most commonly affected. The large syndesmophytes more often involve the right half of the vertebral body in the thoracic
spine, contralateral to the aorta, whereas involvement is symmetric in the
cervical or lumbar spine. DISH of the cervical spine usually involves the
lower segments and can become large enough to exert a mass effect on
the esophagus and cause dysphagia.
The bone morphology in DISH is different than in AS. Whereas vertebrae with inflammation-induced osteolysis adjacent to affected entheses are
commonly seen in AS, in DISH, bone quality is relatively well preserved.
Both conditions, however, are associated with increased risk of fracture
through or adjacent to ankylosed vertebral segments. These patients can
present a challenge in correctly identifying a cervical fracture.
7
BIOMECHANICS AND CLASSIFICATION OF SUBAXIAL SPINE FRACTURES
Ferguson and Allen reviewed 165 cases to develop a classification system
for subaxial spine fractures based on the mechanism of injury. They developed six mechanisms with reproducible fracture patterns. The mechanisms
described can be divided into three compression injuries (compressionflexion, compression, and compression-extension), two distraction injuries (distraction-flexion, distraction-extension), and lateral flexion. Each
mechanism has varying degrees of severity based on radiographic findings.
Although commonly used as a framework for fracture discussion, these
results have never been validated in the current literature. Additionally, witnessed compression injuries have resulted in variable fracture morphology.
This classification does not specifically grade the amount of ligamentous
injury nor does it quantify the amount of neurological injury.
In addition to classification is the question of subaxial spine instability
after injury. White and Panjabi published a biomechanic study evaluating
clinical and radiographic markers of cervical spine instability. Their work
focused on the ligamentous structures surrounding the vertebral bodies.
They developed a checklist with point values, with a score of five or more
indicating instability. The radiographic markers on plain film are sagittal
plane translation of >3.5 mm, sagittal plane rotation >11 degrees, positive
stretch test, and abnormal disc narrowing. Clinical criteria are cord damage, root damage, and if dangerous loading is anticipated. There are two
additional criteria: anterior elements unable to function and posterior elements unable to function. While this checklist, published in 1976, is a tool