Spinal Disorders: Fundamentals of Diagnosis and Treatment Part 87 potx

Patients treated with anterior odontoid screw fixation had a fusion rate of 20 % and patients managed with external immobilization alone had a fusion rate of 20 %.. Surgical stabilizatio

is an anterior atlantoaxial screw fixation ( Fig 16e, f).

In cases with remote dens fractures, dens non-union, os odontoideum or elderly patients with osteoporosis, a posterior approach is more likely to be

suc-cessful The classical treatment is a posterior instrumented fusion according to

d

Case Study 1

This 51-year-old male patient fell from his mountain bike and complained

about neck pain On admission, the patient was neurologically intact (ASIA E).

Standard anteroposterior and lateral (a) radiographs demonstrated a Type II

odontoid fracture The sagittal CT reconstruction confirmed the diagnosis of

the fracture at the base of the odontoid process (b) Repositioning and anterior

stabilization with a single screw was performed Follow-up radiographs (c,d)

demonstrated an anatomical reduction of the fracture and bony healing.

a b

Figure 17 Posterior atlantoaxial stabilization techniques

Posterior C1/2 fusion according toa, b Brooks and c, d Gallie e, fTransarticular atlantoaxial screw fixation according to

Magerl [113] with additional wire cerclage and fusion with a bicortical bone graft g, hAlternative screw-rod fixation

according to Harms [96].

Management in the Elderly Patient

Posterior instrumented

fusion is indicated for Type II

fractures in the elderly

The management of odontoid fractures in the elderly patient remains controver-sial Ryan and Taylor [167] described 30 patients 60 years and older with Type II odontoid fractures The fusion success rate in patients older than 60 years treated with external immobilization was only 23 % Similarly, Andersson et al [24] described 29 patients 65 years and older with odontoid fractures managed by surgical and non-surgical means In their series, six (86 %) of seven patients achieved successful fusion after posterior cervical C1–C2 arthrodesis Patients treated with anterior odontoid screw fixation had a fusion rate of 20 % and patients managed with external immobilization alone had a fusion rate of 20 % Pepin et al [152] reported their experience with 41 acute odontoid fractures and found that halo immobilization was poorly tolerated in patients 75 years and older They suggested that early C1–C2 fixation and fusion was appropriate in this group In a recent review [5], three case series argued against surgical fixa-tion in the elderly patient whereas seven other case series favor surgical fixafixa-tion

in this age group One case-control study by Lennarson et al [125] provides Class

II medical evidence for surgical treatment of elderly patients This study exam-ined 33 patients with isolated Type II odontoid fractures treated with halo vest immobilization The authors found that patients older than 50 years had a signifi-cantly increased failure rate of fusion in a halo immobilization device (21 times higher) when compared to patients younger than 50 years Other factors such as medical conditions, sex of the patient, degree of fracture displacement, direction

of fracture displacement, length of hospital stay, or length of follow-up did not influence outcome

Traumatic Spondylolisthesis of the Axis

Traumatic fractures of the posterior elements of the axis may occur after hyper-extension injuries as seen in motor vehicle accidents, diving, and falls or judicial

hangings [172, 210] Therefore, the term “hangman’s fracture” was coined by

Schneider in 1965 [172] Garber [85] described eight patients with “pedicular”

fractures of the axis after motor vehicle accidents and used the term “traumatic

spondylolisthesis” of the axis.

Classification

The classification scheme of Effendi [70] has gained widespread acceptance for the classification of these injuries Effendi et al [70] described three types of frac-tures which are mechanism based (Fig 18)

Figure 18 Traumatic spondylolisthesis (hangman’s fracture)

Type I: isolated hairline fractures of the ring of the axis with minimal displacement of the body of C2 These injuries are

caused by axial loading and hyperextension Type II: displacement of the anterior fragment with disruption of the disc

space below the axis These injuries are a result of hyperextension and rebound flexion Type IIA: displacement of the

anterior fragment with the body of the axis in a flexed position without C2–C3 facet dislocation Type III: displacement

of the anterior fragment with the body of the axis in a flexed position in conjunction with C2–C3 facet dislocation These

injuries are caused by primary flexion and rebound extension.

In the series reported by Effendi [70], Type I fractures were the most prevalent

(65 %) while Type II (28 %) and Type III fractures (7 %) were less common In

1985, Levine and Edwards [127] modified Effendi’s classification scheme by

add-ing a subtype Type IIA (flexion/distraction injury) However, not all axis

frac-tures can be classified according to this scheme [39] Fujimura et al [83] used

radiological criteria to classify axis body fractures into: avulsion, transverse,

burst, or sagittal fracture

Treatment

Most fractures heal within

12 weeks of external immobilization

Most patients with traumatic spondylolisthesis reported in the literature were

treated with cervical immobilization with good results [5] Importantly, there is

no Class I or Class II evidence that addresses the management of traumatic

spon-dylolisthesis of the axis [5] Fractures of the axis body can mostly be treated

non-operatively [5, 91] Most traumatic spondylolisthesis heals with 12 weeks of

cer-vical immobilization with either a rigid cercer-vical collar or a halo immobilization

device

Surgical stabilization is an option in Type II and III fractures

Surgical stabilization is a preferred treatment option in cases with:

) severe angulation (Effendi Type II)

) disruption of the C2–C3 disc space (Effendi Type II and III)

) inability to establish or maintain fracture alignment with external

immobili-zation

Axis body fractures are usually treated conservatively

Surgical options for unstable traumatic spondylolisthesis include anterior C2/3

interbody fusion with anterior plate fixation (Case Introduction) and posterior

techniques such as direct screw fixation of the posterior arch [117] In the series

by Effendi et al [70], 42 of 131 patients with hangman’s fractures were treated

surgically (10 anterior C2–C3 fusion and 32 posterior fusion) All were

success-fully stabilized at latest follow-up In the study by Francis et al [78], only 7 of 123

patients with hangman’s fractures were treated surgically (4 anterior C2–C3

fusion, 2 posterior C1–C3 fusion, and 1 posterior C2–C4 fusion) The authors

report that 6 of the 7 patients demonstrated a C2–C3 angulation of more than

a b c

Case Study 2

This 47-year-old male patient fell from a

donkey at the age of 12 years

Neurologi-cal symptoms started at the age of

26 years He recently presented with signs

of chronic central cord compression,

spasticity and gait difficulties (ASIA D).

The sagittal CT reconstruction (a)

dem-onstrates a pseudarthrosis of the

odonto-id process The MRI (b) shows the

com-pression of the spinal cord at the level of

the pseudarthrosis Flexion/extension

ra-diographs (c,d) were taken during the

operation and demonstrate the

impor-tant atlantoaxial instability Dorsal fusion

of C1/C2 was performed according to the

technique of Harms [96]; in addition

lami-nectomy of C1 was performed The

intra-operative radiographs (e,f) show the

re-position and the re-position of the hardware

as well as the needles used for the intraoperative neurological monitoring (e) The postoperative CT scan demonstrates the reposition of the odontoid process in the anteroposterior view (g) and lateral view (h), the position of the pedicle screw in C1 (i) and C2 (j), as well as the laminectomy of C1 (i).

11 degrees All seven patients achieved bony stability A number of case series of

hangman’s fractures offer similar experiences with surgical management [5]

Combined Atlas/Axis Fractures

The occurrence of the fractures in combination often implies a more significant

structural and mechanical injury Combination fractures of the C1–C2 complex

are relatively common [7] In reports focusing primarily on odontoid fractures,

the occurrence of a concurrent C1 fracture in the presence of a Type II or Type III

odontoid fracture has been reported in 5 – 53 % of cases Odontoid fractures have

been identified in 24 – 53 % of patients with atlas fractures In the presence of a

hangman’s fracture, the reported incidence of a C1 fracture ranges from 6 % to

26 % [7]

A higher incidence of neurological deficit is associated with combined atlas

and axis fractures The atlas–Type II odontoid combination fracture seems to

be the most common combination injury subtype, followed by

atlas–miscella-neous axis, atlas-Type III odontoid, and atlas–traumatic spondylolisthesis

frac-tures

Treatment

The axis fracture characteristics commonly dictate the management

Reports of combined atlas/axis fractures are relatively rare and no treatment

guidelines but only recommendations can be derived from the literature [7]

Treatment of combined atlas-axis fractures is based primarily on the specific

characteristics of the axis fracture External immobilization is recommended for

most combined atlas/axis fractures Combined atlas–Type II odontoid fractures

with an atlantodental interval of more than 4 mm and atlas–traumatic

spondylo-listhesis injuries with angulation of more than 10 degrees should be considered

for surgical stabilization and fusion The surgical technique must in some cases

be modified as a result of loss of the integrity of the ring of the atlas In most

cir-cumstances, the specifics of the axis fracture will dictate the most appropriate

management of the combination fracture injury The integrity of the ring of the

atlas must often be taken into account when planning a specific surgical strategy

using instrumentation and fusion techniques In cases where the posterior arch

of C1 is not intact, both incorporation of the occiput into the fusion construct

(occipitocervical fusion) and posterior C1–C2 transarticular screw fixation and

fusion have been successful [7]

Classification and Treatment of Subaxial Injuries

In contrast to atlas and axis, the vertebrae and articulations of the subaxial

cervi-cal spine (C3–C7) have similar morphologicervi-cal and kinematic characteristics

However, important differences in lateral mass anatomy and in the course of the

vertebral artery exist between the mid and lower cervical spine Approximately

Eighty percent of all cervical injuries affect the subaxial spine

80 % of all cervical spine injuries affect the lower cervical spine and these injuries

are often associated with neurological deficits [17, 22, 32, 182] The variety and

heterogeneity of subaxial cervical spinal injuries require accurate

characteriza-tion of the mechanism and types of injury to enable a comparison of the efficacy

of operative and non-operative treatment strategies

Table 8 AO Fracture Classification of lower injuries Type A: compression

injuries

Type B: anterior and posterior element injury with distraction

Type C: anterior and posterior element injury with rotation

impaction of the endplate with transverse disc disruption rotational wedge fracture

wedge impaction with Type A vertebral body

fracture

rotational split fracture

vertebral body collapse anterior subluxation rotational burst fracture

sagittal split fracture transverse bicolumn fracture B1 injury with rotation

coronal split fracture transverse disruption of the disc B2 injury with rotation

pincer fracture with Type A vertebral body

fracture

B3 injury with rotation

incomplete burst fracture hyperextension subluxation slice fracture

burst-split hyperextension spondylolysis oblique fracture

complete burst fracture posterior dislocation complete separation of

the adjacent vertebrae Types, groups, and subgroups allow for a morphology-based classification of cervical fractures according to Aebi and Nazarian [13] and modified by Blauth et al [30]

The fracture types are related to specific injury pattern, i.e.:

) injuries of the anterior elements induced by compression (Type A)

) injuries of the posterior and anterior elements induced by distraction (Type B)

) injuries of the anterior and posterior elements induced by rotation (Type C)

Types B and C are the most

common fractures

Types B and C are the most common fracture types (Table 9)

Subaxial fracture-dislocation is frequently associated with neurological injury

Figure 19 AO Fracture Classification of subaxial injuries

According to the classification of AOSPINE (Blauth et al [30], redrawn and modified).

Table 9 Frequency of fracture types in subaxial injuries

n = 448 Total percentage Percentage within the types

Based on an analysis of 448 cases by Blauth et al [30]

C3 1 100 %

Based on an analysis of 448 cases by Blauth et al [30]

Treatment Non-operative Management

Most subaxial cervical

injuries can be treated

conservatively

Most subaxial spine injuries can be successfully treated by conservative means (Philadelphia collar, Minerva cast or halo vest fixation) Treatment with traction and prolonged bedrest has been associated with increased morbidity and mor-tality and has widely been abandoned today After reduction of dislocated frac-tures, more rigid fixation techniques (halo vest fixation, Minerva cast) appear to have better success rates than less rigid orthoses (collars, traction only)

Operative Management

Operative stabilization of unstable fractures (especially for Type B and Type C injuries) is gaining increasing acceptance because it facilitates aftertreatment

without disturbing external supports Indications for surgical treatment include

Table 11 Surgical indications for subaxial injuries

) irreducible spinal cord compression ) vertebral subluxation of 20 % or more ) ligamentous injury with facet instability ) failure to achieve anatomical reduction

(irreducible injury) ) spinal kyphotic deformity more than 15° ) persistent instability with failure to

maintain reduction ) vertebral body fracture compression of

40 % or more

) ligamentous injury with facet instability

Most subaxial spine injuries

can be treated by

an anterior approach

Both posterior (Fig 20) and anterior (Fig 21) cervical fusion techniques usually result in spinal stability for most patients with subaxial injuries The outcome of

anterior vs posterior fracture fixation has been addressed in various recent

publications [14, 77, 97, 119, 133, 162, 192] The studies include only small case series (21 patients [77] to 35 patients [119]) and the methodology allows the clas-sification of the studies using only Class III and Class IV [97, 192] evidence Aebi

et al [14] were one of the first groups to suggest that most lower cervical spine fractures can successfully be treated by an anterior approach even in the case of distraction and rotation injuries with posterior element involvement Today, lit-erature reviews indicate that anterior fixation of fractures of the lower cervical

a b

Figure 20 Posterior fracture stabilization

a, bLateral mass screw fixation according to the technique of Magerl [113] The screw is directed from the medial upper

quadrant of the facet joint 20 – 25° laterally and 30 – 40° cranially Polyaxial top-loading screws facilitate rod placement.

c, dAfter decortication of the posterior elements, a posterior fusion is added and a cross-connector used (when

appro-priate) to increase construct stability.

spine is now the preferred treatment approach Failures of this technique which

may result in reoperations are rare (0 – 6 %) [119, 133]

Anterior fusion should not

be performed without plate fixation

Anterior fusion should not be performed without plate fixation (Fig 21),

because it is associated with an increased likelihood of graft displacement and

the development of late kyphosis, particularly in patients with distractive Type B

and Type C injuries [11]

Similarly, posterior fusion that uses wiring techniques is more likely to result

in late displacements with kyphotic angulation when compared to posterior