surgeon must pay meticulous attention to detailand maintain a high level of awareness andanticipation during the procedure to prevent

iatrogenic deformity. In this article, we reviewsome of the common causes of iatrogenic mala-lignment of the cervical spine and outline tech-

niques to avoid postoperative deformity.

spinous processes abutting one another. If theerror in positioning is not recognized before

fusing the patient in this position, he or she oftenhas severe interscapular and posterior cervicalpain, especially if an extensive foraminotomy is

not performed at the time of the procedure.Extension of the neck narrows the posteriorneural foramen and may result in nerve root

compression. To avoid this complication, weroutinely inspect the position with the patientsupine to ensure that the neck is in a relativelyneutral or slightly lordotic position. In addition,

we examine the localizing radiograph to verifythat the neck is in an acceptable amount of

The opinions or assertions contained herein are the

private views of the authors and are not to be con-

strued as ocial or as reecting the views of the

United States Army or the Department of Defense.

One of the authors is an employee of the United StatesIatrogenic CerviRonald A. Lehman Jr, MDa, P

Seung-Chul Rhim, MDc,aDepartment of Orthopaedic Surgery and Rehab

Washington, DCbDepartment of Neurosurgery, Columbia Univ

New York, NYcDepartment of Neurosurgery, Asan Medical Center, Un

dDepartment of Orthopaedic Surgery, Barnes-Jewish Hos

616 Euclid Avenue, Suite 11300

Even the most careful and experienced cervicalspine surgeon can inadvertently create an iatro-genic cervical deformity. Deformity can result in

simple or complex cases occurring during any stepof a cervical spine operation. Errors in patientpositioning, distractor placement, amount or

extent of decompression, type of instrumentation,selection or placement of bone graft, and use ofpostoperative immobilization may all result inpostoperative cervical deformity. Malalignment

may occur after single- or multiple-level surgery,anterior or posterior operations, and decompres-sion procedures with or without stabilization. The

Neurosurg Clin N Amgovernment. This work was prepared as part of his of-

cial duties and as such, there is no copyright to be

transferred.

* Corresponding author.

E-mail address: riewd@wustl.edu (K.D. Riew).

1042-3680/06/$ - see front matter 2006 Elsevier Inc. All ridoi:10.1016/j.nec.2006.05.001cal Deformityeter Angevine, MD, MPHb,K. Daniel Riew, MDd,*ilitation, Walter Reed Army Medical Center,

20307, USA

ersity College of Physicians and Surgeons,

10032, USA

iversity of Ulsan, College of Medicine, Seoul, Korea

pital and Washington University School of Medicine,

, St. Louis, MO 63110, USA

Preventing iatrogenic cervical malalignment

during anterior surgery

Positioning

The most common error during the positioning

of the patient for an anterior cervical operationresults from hyperlordosing the patients neck. Afolded towel or sheet is placed underneath the

patients shoulders to obtain proper sagittalalignment before performing the operation. Al-though moderate cervical lordosis is desirable, ifthe bump is excessive, it can lead to hyper-

lordosis of the cervical spine, resulting in the

17 (2006) 247261lordosis before beginning our fusion operation.

If the patients neck is hyperlordotic on thisradiograph, we place Caspar distractor pins withthe tips converging. When the converging Caspar

pins are distracted evenly, the amount of lordosis

ghts reserved.

neurosurgery.theclinics.com

fusion performed with the patient improperly

aligned, however, may result in a postoperativedeformity with clinical imbalance.

Finally, the surgeon must conrm that the

patient is positioned in neutral axial rotation.Axial malalignment may occur as a result of slightrotation of the head. During the dissection and

retraction of the soft tissues, it is common for thesurgeon inadvertently to push the head away fromthe side of the approach. Some surgeons do thisroutinely to facilitate the exposure. If the surgeon

is not aware that the head is rotated toward thecontralateral side and plates the construct in thatposition, the segment is fused in a rotated

Fig. 1. (A) In this intraoperative radiograph, the Caspar di

the caudal end plate. Note the hyperlordosis at C6 to C7

placed into C7 parallel to its rostral end plate. The tips of

over the pins, it brings them into parallel alignment and rewith distraction during multilevel operations.

When one is performing high cervical approachesto C2 to C3 or C3 to C4, it is sometimes advanta-geous to rotate the neck to the contralateral side

so as to gain better access to the spine. Underthose circumstances, it is a good idea to write a re-minder on the sterile drape to turn the head back

into neutral alignment before grafting and platingthe patient.

Decompression

We routinely use Caspar distractor pins toopen the disc space during anterior cervical

straction pin has been placed into the body of C5 parallel to

with the spinous processes touching. A Caspar pin is then

the pins converge. (B) When the Caspar distractor is placed

duces the lordosis.is reduced (Fig. 1). At the end of the procedure,the goal is to have the neck in a normal lordoticconguration.

Coronal malalignment of the cervical spinemay also occur as a result of malpositioning. Weroutinely tape both shoulders to pull them down,allowing for better visualization of the spine. An

iatrogenic coronal deformity can occur, however,if one shoulder is taped lower than the other.Before preparing and draping, it is important to

inspect the patients head and shoulder positionsto conrm that the cervical spine is alignedproperly and that the shoulders are level. One

person should ensure that the shoulders are level,whereas another tapes the shoulders. If a coronaldeformity is introduced into the cervical spine ata single level, the adjacent levels generally com-

pensate for the malalignment with little eect onthe overall balance. A multilevel instrumented

position. The rotational malalignment is furthercompounded if multiple segments are fused andinstrumented.

The surgeon can avoid creating a rotationaldeformity by using one of several techniques. Therst is to ask the anesthesiologist and othermembers of the operative team to conrm that

the nose is pointed straight up before placing anygrafts and putting on the instrumentation. This,however, still requires that the surgeon remembers

to ask, introducing another possible point oferror. We prefer to place a tape across theforehead routinely to prevent inadvertent rotation

of the head during the operation (Fig. 2). Anothervariation on this technique is to use commerciallyavailable head holders with an elastic chinstrap tostabilize the head. Additionally, the surgeon may

use Gardner-Wells tongs to ensure neutral rota-tion during instrumentation. This may also aid

248 LEHMAN et al

surgery. As stated previously, pins can be used to

correct a malpositioned neck. Although the dis-tractor is quite useful in exposing the disc space,one must be careful to place the pins properly. If

both pins are placed o-center to one side, the discspace opens asymmetrically, causing segmentalcoronal angulation. If the pins are placed in an

oblique position, the disc space opens asymmetri-cally with relative lateral translation of the verte-bral bodies. If the pins are placed in dierent

planes, a rotational malalignment of the vertebracan occur (Fig. 3A). Finally, in the sagittal plane,one can overlordose or create kyphosis withpoorly positioned pins (Fig. 3B).

Failure to expose the entire disc space mayincrease the likelihood of performing an asym-metric discectomy or corpectomy. Additionally,

failure to expose the anterior and lateral marginsof the disc space adequately (by taking downthe anterior osteophytes) out to the level of the

transverse processes may result in placing thegraft asymmetrically on one side, causing a coro-nal plane deformity (Fig. 4). One can avoid this byexposing the intervertebral disc to the uncoverte-

bral joints bilaterally before starting the decom-pression. These lateral structures provide a xedreference for the surgeon and assist in performing

a symmetric decompression and reconstruction.

Fig. 2. Tape is placed across the patients forehead (A)

and secured to the operating table (B) to maintain the

cervical spine in neutral alignment.

IATROGENIC CERVThe type of decompression one performs canalso have a signicant inuence on the position ofthe fusions. Corpectomies reconstructed witha straight allograft can only be placed into

a neutral position. Because the graft is straight,it is impossible to produce lordosis, especially withlong constructs. With short constructs, one can

tilt the cranial and caudal vertebral segments toproduce some lordosis. As the graft subsides intothe end plates at the cranial and caudal margins,

kyphosis typically develops as the graft subsides(Fig. 5). To avoid this, we routinely use segmentaldecompression combining corpectomies at the

levels that have retrovertebral compression withdiscectomies at levels that only have retrodiscalneural compromise (Fig. 6). For patients whohave retrovertebral compression at more than

one level, we perform a skip corpectomy, perform-ing corpectomy at one level and skipping the nextlevel, followed by a corpectomy at the third level

(Fig. 7). This type of segmental decompressionand xation using several small grafts ratherthan one long strut graft allows for better preser-

vation of cervical lordosis.

Noninstrumented fusion

A multilevel uninstrumented arthrodesis of thecervical spine can result in kyphosis as the grafts

collapse or resorb (Fig. 8). Although the use ofa plate does not absolutely guarantee the avoid-ance of kyphosis, most surgeons would agree

that anterior cervical plates decrease the likeli-hood of postoperative kyphosis, especially ina multilevel scenario [1,2].

Graft selection

Discectomies without fusion result in loss ofnormal lordosis or even kyphosis. Because thedisc provides 5 to 6 mm of height, removal of thedisc without putting a spacer in its place results in

collapse (Fig. 9).The type of graft material that one uses can

also inuence the likelihood of postoperative

kyphosis. Generally, the likelihood of graft col-lapse increases in the following order: irradiatedfreeze-dried bone, freeze-dried bone, and then

fresh-frozen allografts [3,4]. If a surgeon ndsa piece of allograft to be fragile, it is advisableto use another specimen rather than implanting

an inferior allograft. We most commonly use cor-tical allografts harvested from the bula, the ulna,the radius, the humerus, and, occasionally, the

249ICAL DEFORMITY

Fig. 3. (A) Misplacement of Caspar distraction pins may result in segmental deformity. Placing the pins o-center may

cause a coronal malalignment. Pins that are placed obliquely o the midline create a coronal deformity and a lateral

listhesis when distraction is applied. Distracting on pins that are o-plane creates a rotational deformity. (B) If the

tips of the pins are placed divergently, the parallel arms of the distractor force the segments into lordosis. Conversely,

if the pins are placed convergently, kyphosis results.

250 LEHMAN et al

Fig. 5. Long corpectomies reconstructed with a straight

bula are at best in neutral alignment.

Fig. 4. Asymmetric corpectomy can lead to scoliosis if

an oversized graft is placed into the trough.

IATROGENIC CERVFig. 6. Performing a corpectomy at one level and an ad-

jacent discectomy (corpectomy-discectomy) provides

more sites for xation and allows the maintenance or es-

tablishment of lordosis.

Fig. 7. This patient underwent a C4 and C6 skip corpec-

tomy (corpectomy-corpectomy) procedure 7 years previ-

ously. Note that the plate is placed too proximal to the

C2 to C3 disc space, resulting in adjacent level ossica-

tion development.

251ICAL DEFORMITY

tibia. We also use dense cancellous allograft from

the patella (Fig. 10).The size of the graft also inuences the pro-

pensity to develop postoperative kyphosis. Thegrafts should be large enough to allow for 1 or

2 mm of subsidence without creating kyphosis. Inaddition, the more graft one uses per level, the lesslikely it is to collapse. For this reason, we routinely

ll the disc space with as much graft as possible,often placing two allografts side by side (Fig. 11).

Anterior instrumentation

Although judicious and careful use of anteriorcervical plates can help to avoid postoperativekyphosis, poor attention to detail can result in

plate-induced malalignment. If a screw inadver-tently perforates an adjacent disc space, it canresult in rapid degeneration and collapse of that

disc space. When performing anterior cervicalfusions on a patient with preoperative cervicalscoliosis, the surgeon must pay close attention to

the overall alignment of the head, neck, and torso

(Fig. 12). Often, even in a patient with severe sco-liosis, the spine rebalances itself such that the pa-tient can hold his or her head in a neutral position.If the surgeon corrects the cervical scoliosis in

a patient with a severe thoracic curve, the headis tilted to one side. This is analogous to correct-ing only the thoracic curve in a patient with a bal-

anced and oppositely directed thoracolumbarcurve, thereby causing shoulder asymmetry.

Patients undergoing multilevel fusions or those

having long corpectomies are prone to graftextrusion, with the reported incidence as high as9% in the literature [5]. Unfortunately, plates do

not help to prevent such complications (Fig. 13)[6]. With static plates, extension of the neck loadsthe graft, because the plate acts as an anterior ten-sion band but may result in the inferior screws

pulling out. In exion, the graft is unloaded, be-cause the anterior cervical plate acts as the centerof rotation and the inferior screws can be driven

into the next disc space, resulting in graft collapse

Fig. 8. (A) MRI and CT scans of a patient who had been treated with an uninstrumented fusion from C5 to C7. The

graft appears to have resorbed or collapsed, resulting in segmental kyphosis. (B) In the plain lm on the right, an un-

instrumented single-level corpectomy has settled into a mild kyphosis. Unplated multilevel reconstructions can lose their

lordotic angle or even collapse into kyphosis.252 LEHMAN et al

or extrusion. To avoid these complications, weroutinely perform circumferential stabilization inpatients who undergo corpectomies at two or

more levels. We also prefer a circumferential ap-proach in patients with poor-quality bone whoundergo single-level corpectomies, including

Fig. 9. This patient had a discectomy without a fusion.

Kyphosis can result, because the height of the removed

disc has not been restored.

Fig. 10. Patella allograft. A large, well-tting, dense

cancellous graft with a cortical rim can be fashioned.

IATROGENIC CERVIpatients with osteomyelitis, chronic renal failure,and tumors.

Preventing iatrogenic cervical deformity

during posterior surgery

Positioning

Positioning for posterior cervical procedures isjust as critical as for anterior operations. We

routinely use the Jackson frame (OrthopedicSystems [OSI], Union City, California) to positionour patients for posterior operations. We tape the

shoulders down as for the anterior procedures.We also make sure that one shoulder is not pulledasymmetrically to prevent an iatrogenic coronal

plane deformity. We place bolsters just under-neath the clavicle and use Gardner-Wells tongswith bivector traction to allow us to position theneck in exion or extension (Fig. 14). We check

the position before surgery to ensure that we canplace the neck into an adequate amount of exionand extension. Before fusing the patient, we make

sure that the neck is in proper alignment.Although it is important to position the neck

properly for xation of the subaxial spine, it

becomes even more critical when one is perform-ing an occipitocervical or occiput-to-thoracicfusion. If the neck is improperly positioned andinstrumented, the resulting malalignment can be

quite debilitating. Phillips and colleagues [7] mea-sured the occipitocervical angle on 30 normal cer-vical spine radiographs of patients in exion,

extension, and neutral alignment. The occipitocer-vical angle was dened as the angle betweenMcRaes line (line connecting the basion and opis-

thion, which demarcates the foramen magnum ona lateral radiograph) and a line parallel to the ros-tral end plate of C3. The mean occipitocervical

angle on the neutral radiographs was 44. Phillipsand colleagues [7] recommend that when perform-ing an occipitocervical fusion, the surgeon shouldtry to replicate this value to provide the patient

with a functional head position (Fig. 15). Whenperforming occiput-to-thoracic fusions, however,we prefer to x the patient with 5 to 10 of exioncompared with normal. If these patients, who areunable to bend their necks, are xed with a hori-zontal gaze, they are not able to look down to

see their own body.

Decompression

Deformities can result from overly aggressivedecompressions of the cervical spine. Even

253CAL DEFORMITY

Fig. 11. When using cortical allografts, we prefer to use two or three grafts or to ll the disc space maximally. Double

grafts in place (A, B) and radiographic appearance (C) are shown. At C6 to C7 and below, occasionally, three bular

grafts are necessary to ll the entire disc space.

Fig. 12. (A) Preoperative anteroposterior view shows signicant cervicothoracic scoliosis of approximately 55 becauseof autofusion at T1 to T2. (B) Preoperative lateral view. (C) Anteroposterior view status post (s/p) posterior cervical

fusion (PCF) from C5 to T3 with osteotomy of convexity. (D) Postoperative lateral s/p PCF from C5 to T3.

254 LEHMAN et al

minimally invasive procedures, such as posterior laminoplasties, especially when more than one

cervical foraminotomies, can result in a postoper-ative deformity. If the procedure is performed

through a small tubular retractor by a surgeonwho is not intimately familiar with the microanat-omy of the facet joint or loses anatomic land-

marks, too much of the facet may be resected.Zdeblick and coworkers [8] demonstrated that re-section of greater than 50% of a facet can result ininstability. To prevent this, one must always iden-

tify and visualize the lateral and medial aspects ofthe facet joint and take care to resect only the me-dial half of the joint.

Laminectomies without fusions can producedeformity. Laminectomies in children have beenassociated with a high incidence of postlaminec-

tomy kyphosis [9]. Even in adults, it is dicult topredict when a patient might develop postopera-tive kyphosis. We therefore prefer to do complete

laminectomies on patients who have signicantanterior stabilizing osteophytes with minimalrange of motion of the cervical spine or single-level disease. For multilevel cases, we take care

to preserve the facet capsule and never takemore than 50% of the facets on each side.

To avoid the complications associated with

complete laminectomies, we usually prefer

level of disease is present. Laminoplasties are notwithout potential complications, however, be-

cause excessive resection of the facets whenperforming foraminotomies can result in instabil-ity and deformity. In addition, when performing

a laminoplasty of C2, care must be taken toreattach the semispinalis cervicis muscle. Thismuscle acts as the major extensor of the neck,and failure to reattach this muscle can result in

cervical kyphosis.

Fig. 14. Bivector traction. The neck should be extended

to a normal alignment before instrumentation.Fig. 13. This patient has a two-level corpectomy. (A) Graft

a rigid cervical collar. (B) Lateral radiograph illustrates wha

tial fusion. The plate does not prevent subsidence and colla

IATROGENIC CERVextrusion occurred despite postoperative immobilization in

t can happen after a long corpectomy without circumferen-

pse of the graft and screw into the next disc space.

255ICAL DEFORMITY

Uninstrumented fusion

We believe that an uninstrumented fusion ofthe posterior cervical spine is rarely, if ever,indicated. With safe and eective modern instru-

mentation, including lateral mass screws, spinousprocess wires and/or cables, and polyaxial screw-rod instrumentation, it is rare for us to encounter

a situation in which we would consider anuninstrumented arthrodesis. A patient who un-dergoes an uninstrumented arthrodesis often has

pain posteriorly, resulting in the loss of normallordosis. As the spine fuses, it generally does so ina kyphotic or, at best, neutral alignment (Fig. 16).

Inadequate instrumentation

The use of inadequate instrumentation canalso result in postoperative malalignment. In

degenerative cases, wires are often insucient toprevent the loss of normal lordosis as the graftheals, even in cases of circumferential fusion.Older lateral mass plating systems had no rigid

connection between the plates and screws, essen-tially creating a dynamic plating system that couldnot prevent kyphosis (Fig. 17). In trauma cases in

which patients have signicant posterior osteoli-gamentous disruption resulting in an unstablespine, one must achieve solid xation with instru-

mentation to stabilize that segment. If the spinousprocesses or the lateral masses have been disrup-ted such that one cannot attain adequate bony

Fig. 15. It is important to position the patient properly

before an occipitocervical or occipitocervicothoracic

fusion to provide the patient with a functional position

after fusion. We place the neck in slight exion so that

the patient can see his or her own body.

256 LEHMANpurchase, the xation may have to be extendedcranially and caudally until good purchase is ob-tained. Alternatively, circumferential stabilization

can be performed. If the xation is still inade-quate, consideration should be given to immobi-lizing the patient in a halo vest. The greater the

instability, the greater is the necessity to obtainadequate bony purchase at multiple levels(Fig. 18).

When using lateral mass or pedicle screws androds, the surgeon must be aware that the relativelyexible cervical spine conforms to the shape of the

rod. If the rod is not contoured properly toproduce an acceptable sagittal alignment, thecervical spine may be xed in suboptimal align-ment. Modern polyaxial screws allow for some

medial-to-lateral oset of the screw heads. If thescrews are placed too far laterally or mediallybeyond the ability of the screw to accommodate

the placement, however, lateral listhesis of onevertebral segment may occur. If the listhesis isextreme, it may even cause nerve root compres-

sion. This can be especially troublesome whenattaching a C2 pedicle screw (directed froma lateral-to-medial direction) to a lateral massscrew at C3 (directed from a medial-to-lateral

direction). The directional change of these screwsis such that one occasionally has to bypass C3 andplace the rod from C2 down to a screw at C4. In

some circumstances, a translaminar screw at C2might align better with a screw placed at C3. A

Fig. 16. This patient has an uninstrumented posterior

fusion, resulting in overall kyphosis and nonunion at

C5 to C6.

et al

fall into kyphosis. Modern systems with polyaxial screws locked onto rods help to prevent such malalignments.Fig. 18. (A) Inadequate xation after traumatic injury to the cervical spine may lead to iatrogenic deformity. (B) This

patient is not fully reduced, and this type of sublaminar wire is inadequate to maintain proper alignment. In addition,

these wires are contraindicated in patients with neurologic decits.similar situation arises when transitioning froma lateral mass screw at C6 or C7 to a pedicle screw

at the adjacent caudal level.Even when an arthrodesis is performed with

the neck in lordotic alignment with adequate

xation, postoperative malalignment may occur.Patients with a preoperative kyphotic alignmentattributable to degenerative disc disease fused in

extension are at risk for developing postoperativekyphosis. The screws may loosen or the rods maybend as the spine settles back into its preoperative

kyphotic alignment. Patients who have severeFig. 17. (A) Although wires work well, they can lose reduction and leave the patient with a loss of normal lordosis. (B)

Lateral mass plates with independent screws are essentially dynamic systems that make it possible for the construct to

257IATROGENIC CERVICAL DEFORMITY

Fig. 20. This patient had a previous laminectomy of C3 to C7. (A) We performed an anterior-only operation to decom-

press all the levels with a combination of a corpectomy with multiple discectomies. (B) We used four points of xation

above and six below.The stability of a spinal segment is critically

dependent on the integrity of the ring of bone thatsurrounds the spinal cord. Although a singlehalves of the spine are connected only by soft

tissues (Fig. 19). This markedly decreases the tor-sional and axial loading stability of the segmentpreoperative kyphosis or who have poor muscle

control are often best treated with a circumferen-tial procedure.

Integrity of the spinal ring: corpectomyafter previous laminectomy

discontinuity in the ring seems to be well tolerated

in most cases, two disconnections seem to increasethe likelihood of deformity signicantly.

The most common example of a double dis-continuity in the spinal ring is in the patient who

undergoes a corpectomy after a previous laminec-tomy. Until the anterior bone heals, the two

Fig. 19. Patients who have had previous laminectomies and then undergo a corpectomy have two halves of the spine that

are only connected by soft tissues. These are thus quite unstable.

258 LEHMAN et al

and predisposes the construct to graft extrusion or

collapse. With torsional forces, the two halvesmove independently, and with axial load theysplay apart. Even with halo vest immobilization

after surgery, these patients are at high risk forgraft extrusion, collapse, and recurrent kyphosis[10]. In these cases, we generally recommend a cir-

cumferential operation with an anterior corpec-tomy, followed by posterior stabilization withlateral mass instrumentation.

In patients who have excellent bone quality

and who only require a single-level corpectomy,a plated corpectomy seems to work without

complications [11]. If there is no retrovertebral

compression, multiple discectomies are prefera-ble to corpectomies, because the spinal ring re-mains intact with the discectomies. In some

cases, a single-level corpectomy at the level ofretrovertebral compression and discectomies atthe levels with only retrodiscal compression

may be performed. If one can place four screwsproximal to the level of the corpectomy andfour to six screws distally and if a rigid collaris used after surgery, the construct is generally

quite stable with an anterior-only operation(Fig. 20). For most patients who have signicant

Fig. 21. Anterior atlas arch resection in a patient with a posterior arch fracture. (A, B) This patient had an os odontoi-

deum and cord compression. (C) The surgeon performed an odontoid resection, followed by posterior C1 to C2 fusion.

(D) There was a fracture in the posterior arch of C1, however, as seen on the postoperative CT scan. (E) This created two

breaks in the ring of C1, predisposing the construct to failure. (F) C1 ring splayed apart, and cranial settling resulted.IATROGENIC CERV 259ICAL DEFORMITY

kyphosis and persistent stenosis requiring a cervi-cal corpectomy, circumferential instrumentationis indicated. Because these patients often haveunstable cervical spines, even the use of lateral

mass instrumentation alone may result in

failure, because the xation points may be tenu-ous, especially in patients with osteoporosis. Forthis reason, we typically instrument these pa-tients circumferentially (illustrative cases are

shown in Figs. 21 and 22).

Fig. 22. (A) This patient had what appears to be minimal degenerative changes on preoperative radiographs. He under-

went a three-level anterior cervical discectomy and fusion with plate xation. (B) The plate is too long, and the screws

have perforated into the end plate of C4. (C) The surgeon then revised by removing the plate, whereupon the grafts

collapsed and pseudarthrosis resulted. (D) He then revised with a cage without correcting the kyphotic alignment. (E)

When this failed, the anterior plate was removed and some type of posterior plate with cables was used, again, without

correction of kyphosis. (F) When this failed, the nal revision was performed by removing the anterior cage and

reconstructing with allografts and a plate, which also failed. The result was a patient who was incapacitated by pain

and deformity. This case illustrates the need to approach all cases with caution. If a revision surgery is performed, it

is preferable to correct residual deformities whenever possible.260 LEHMAN et al

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[2] Wang JC, McDonough PW, Endow KK, et al. In-

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261IATROGENIC CERVICAL DEFORMITY

Iatrogenic Cervical DeformityPreventing iatrogenic cervical malalignment during anterior surgeryPositioningDecompressionNoninstrumented fusionGraft selectionAnterior instrumentation

Preventing iatrogenic cervical deformity during posterior surgeryPositioningDecompressionUninstrumented fusionInadequate instrumentationIntegrity of the spinal ring: corpectomy after previous laminectomy

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