REVIEW ARTICLE

Osteotomy of the spine for multifocal deformities

Ibrahim Obeid • Louis Boissiere • Jean-Marc Vital •

Anouar Bourghli

Received: 1 October 2014 / Revised: 1 November 2014 / Accepted: 1 November 2014

� Springer-Verlag Berlin Heidelberg 2014

Abstract

Introduction When a deformity involves more than one

area of the spine, it becomes a multifocal deformity; such a

deformity could either be extending on two adjacent seg-

ments, or be two separated deformities on two non-adjacent

segments.

Materials and methods The surgical management of

multifocal spinal deformities is challenging and must be

done through a thorough preoperative planning where

spinal and pelvic parameters should accurately be deter-

mined. Different strategies should be applied depending on

the type of the multifocal deformity, the area involved, the

angulation and stiffness of the spine in that area, and the

presence of either a pure sagittal malalignment or a com-

bined coronal and sagittal malalignment. This paper dis-

cusses these strategies and gives guidelines regarding the

use of the different osteotomy techniques depending on

each different situation that the deformity spine surgeon

may encounter. For instance, where is the ideal level to

perform a pedicle subtraction osteotomy (PSO) in a mul-

tifocal deformity? How does one take advantage of the

remaining high discs to increase the correction without the

need for a second PSO? When and where does one perform

an asymmetrical PSO? When and where does one perform

two PSOs? How does navigation help the spine surgeon to

push the surgical limits further in these complex cases?

Conclusion All these questions about the management of

multifocal deformities will be discussed and answered with

technical details and concrete examples of the different

situations that may be encountered.

Keywords Multifocal deformity Pedicle subtraction

osteotomy Adjacent osteotomies Thoracic osteotomy

Asymmetrical osteotomy Coronal malalignment Sagittal

malalignment Navigation

Introduction

Accurate assessment of the sagittal balance on full spine

X-rays is mandatory nowadays to better understand spinal

pathologies and especially spinal deformities, where com-

pensatory mechanisms should be detected at any level,

from the cervical spine to the lower extremities [1]; this

enables the surgeon to choose the best procedure for the

patient and to target the best area in case an aggressive

treatment is required, such as a pedicle subtraction oste-

otomy (PSO) [2, 3].

PSO is a very efficient technique for the treatment of

fixed sagittal imbalance and is nowadays widely used by

the spine surgeon community. It can be applied at the

different levels of the spine depending on the pathology,

with special precautions that are related to the area where it

is performed (lumbar, thoracic, or cervical spine) and to the

type of pathology involved especially in a patient that had

multiple previous surgeries.

The ideal indication for a simple PSO is a pure sagittal

imbalance, in a patient with a stiff spine due to ankylosing

spondylitis, postoperative flat back, posttraumatic kypho-

sis, or pure arthrosis. But when the imbalance is in the

coronal plane, or when it is an association of coronal and

sagittal imbalance, the situation becomes more compli-

cated, with different rules that need to be applied. Also

when the degree of the imbalance is very important, or

when there is more than one area involved in the deformity,

i.e., a multifocal deformity, performing a single PSO at one

I. Obeid (&) � L. Boissiere � J.-M. Vital � A. Bourghli

Spine Unit, Bordeaux University Hospital, Place Amelie Raba

Leon, 33000 Bordeaux, France

e-mail: ibrahim.obeid@gmail.com

123

Eur Spine J

DOI 10.1007/s00586-014-3660-9

location may not be enough to obtain a satisfactory result;

in such a case, the solution would be to perform either

multiple Ponte osteotomies associated with a PSO, or to

perform two adjacent or non-adjacent PSOs, or to perform

a vertebral column resection (VCR) [4] or its variation, the

vertebral column decancellation (VCD) [5]. The last two

techniques are the most aggressive techniques where

removal or weakening of a complete vertebral body is

performed, the procedure is usually done at a single level,

or more, and enables a correction in the different planes

simultaneously even in long rigid deformity; however,

VCR is a very complex surgery and should be done in very

specific indications.

In this paper, we focus on the different types and

management of multifocal deformities, i.e., a deformity

extending on two adjacent segments (the thoracolumbar

junction being considered as a segment, in addition to the

cervical, thoracic, lumbar, and sacral segments), or two

separated deformities on two non-adjacent segments.

Adjacent deformities

Performing complex surgeries such as PSOs should take

into account their two major risks that have been widely

described in the literature [6–8], namely the bleeding [9]

and the neurological risk [10]; that is why, in the case of a

multifocal deformity on adjacent segments, when multiple

PSOs must be performed at one site or at two different

sites, many factors should come into play to decide the best

strategy for the patient and whether the surgery will require

one or two sessions.

One or two PSOs?

The first parameter to deal with is whether two PSOs are

really needed or would it be possible to achieve a satis-

factory result with a single PSO, associated with multiple

Ponte osteotomies at the adjacent levels? This should be

decided through a thorough preoperative planning, on

standing full spine X-rays (AP and lateral), sagittal

dynamic views in flexion and extension, and supine sagittal

view with a bolster underneath the major deformity to

assess its stiffness; the pelvic parameters should be accu-

rately calculated in correlation with the spinal parameters.

When there is an important kyphosis in the lumbar area,

with several high discs, a single Ponte osteotomy at one level

with an anteriorly placed cage is expected to bring the spine

back more than the same procedure performed at the same

level on a flat spine, because the number of degrees that will

change the concerned level from kyphotic to neutral will be

added to the usual 8–10� that we reach per level with this

technique. This could lead to a 20–25� correction at a single

level in the case of kyphosis with a high disc, and this

strategy should be taken into consideration to avoid per-

forming any additional PSO where it could be replaced by

one or two Ponte osteotomies, which would significantly

decrease the neurological risk and bleeding rate [7].

Location of the PSO

Another parameter to deal with is the location of the PSO.

Usually for a classical postoperative flat back deformity, it

is generally accepted that either L3 or L4 PSO is suitable

[11]; but for the other etiologies of sagittal imbalance, no

clear guidelines exist. The best way of choosing the optimal

level for a PSO would be to look for the level mostly

affected by the deformity, mainly its apex in the sagittal

plane; this would be the logical solution to achieve the best

physiological contour and avoid the creation of new com-

pensatory mechanisms. The latter situation happens when

the shape of the pelvis is not taken into account; thus we

should always remember that any surgery should be adapted

to the patient’s pelvis. For instance performing a lumbar

osteotomy for a major thoracic deformity may partially or

completely correct the imbalance, but instead of having a

harmonious sagittal contour, there will be an important

kyphosis associated with an important lordosis. This shape

could be accepted for a patient with a type 4 lumbar lordosis

according to the Roussouly classification [12], where the

angles of lumbar lordosis and thoracic kyphosis are physi-

ologically important, in relation to a high pelvic incidence;

but in the case of a patient with a type 1 lumbar lordosis

with a small pelvic incidence, this type of correction strat-

egy may have a major impact, given the small ‘‘hip exten-

sion reserve’’ [13], and limited ability to compensate such

important curves, especially in case of a failure.

This latter strategy could be only used in a very specific

way; for instance, in the case of a lumbar kyphosis

(degenerative or arthrogenic) associated with a thoraco-

lumbar kyphosis, where the thoracolumbar segment will be

included in the construct, it is possible to adopt a strategy

where the thoracolumbar kyphosis can be indirectly cor-

rected by performing a hypercorrection at the lumbar level

(Fig. 1), thus avoiding an additional aggressive procedure

at the thoracolumbar junction. This technique can be most

effectively done in the presence of high low lumbar discs

where high anteriorly placed cages associated with Ponte

osteotomies can improve the lower correction angle to a

hypercorrection. But as previously mentioned, theses

strategies of indirect correction on a site distant from the

deformity should be done in specific cases with special

attention given to the patient with a small pelvic incidence.

Another condition similar to the one previously men-

tioned, but more specific to the elderly population, is when

a postoperative flat back is associated with a thoracolumbar

Eur Spine J

123

kyphosis due to an adjacent syndrome by a compression

fracture; in such cases, performing the PSO at L4 with

correction of the imbalance may indirectly correct the

thoracolumbar kyphosis by opening the fracture site, thus

an additional aggressive procedure is not needed at the

thoracolumbar junction, but anterior complementary

grafting is mandatory in the fracture site (Fig. 2).

Can we accept a residual deformity?

So the best osteotomy area is where the deformity is the

worst, with priority given to the sagittal plane over the

coronal plane; in case of a ‘‘combined imbalance’’, where

the coronal component is less major than the sagittal

component, it could be accepted to perform a single PSO at

Fig. 1 A 64-year-old woman

presenting a severe

thoracolumbar and lumbar

kyphosis. Correction was

achieved by performing an L3

PSO, L4–L5 Ponte osteotomy

with L3–L4 and L4–L5 cages.

Postoperative L1–S1 lordosis

was 67� for a pelvic incidence

of 48�. This lumbar

hypercorrection compensated

thoracolumbar kyphosis and

allowed a good global

alignment

Eur Spine J

123

the apex of the deformity, in order to achieve a good

sagittal balance with a partially or uncorrected coronal

imbalance. This would avoid an additional unnecessary

osteotomy, with its complications, and would in fact be

illogical when we already know from the literature that the

quality of life of spinal deformity patients in the postop-

erative period depends mainly on the quality of their sag-

ittal balance [14]. This is especially applicable at the high

thoracic area, where PSOs are the most risky [15, 16]

(Fig. 3); accepting a residual coronal imbalance to avoid

any further aggressive action should be the rule. These high

thoracic cases are frequently revision cases, their risks

should be decreased by a minutious preoperative planning,

PSO limited to the apex of the deformity, preservation of as

much as possible of the previous construct to avoid

unnecessary instrumentation and blood loss, and the use of

navigation that can be helpful for placement of high tho-

racic screws and to guide the surgeon if the osteotomy is

performed in a bone callus [17].

This rule can also be applied for severe lumbosacral

kyphosis when S1 PSO is indicated. In this situation,

complete correction of the deformity is very hazardous and

partial correction could be accepted in order to decrease

compensatory mechanisms and improve the patient clini-

cally (Fig. 4).

Two PSOs, adjacent or not?

If the major deformity is completely stiff with no mobility

on the dynamic views, and with flat discs, then the only

solution would be to perform two PSOs. When the defor-

mity is thoracic or thoracolumbar, performing two adjacent

PSOs at the apex in a single session is recommended; the

PSO technique should be modified to include the discs

above each osteotomized vertebra. This technique would

enable a bone on bone contact between the two PSO sites

and between the proximal PSO and the level above after

the closure; this significantly decreases the pseudarthrosis

rate and avoids a complementary anterior approach for

grafting. The spinal cord should be widely decompressed

and controlled posteriorly especially at its proximal part to

avoid any kinking effect related to the posterior shortening;

nevertheless, this kinking risk is less important compared

to the lumbar level, as the aim of the surgery is to create a

flat or slightly kyphotic segment and not lordotic with the

risk of an acute sharp angulation (Fig. 5). When the

deformity is lumbar, it is advised to perform two non-

adjacent PSOs either in one or in two separate sessions, for

several reasons: given the size of the vertebras, the cor-

rection amount is usually important which may lead, in the

case of two adjacent PSOs, to an acute lordotization on a

short segment, which is not physiological, may result in a

potential anterior vascular injury [18], and biomechanically

could create shearing forces; a second reason related to the

size of the vertebras is the creation of an important pos-

terior shortening that could be harmful to the roots and the

cord (kinking effect), mainly at the high lumbar level. In

case of remaining discs that even are flat, the persistent

micromotion within three discs surrounding the two PSOs

may lead to pseudarthrosis, especially if part of the cor-

rection is done unintentionally in a disc making it open

anteriorly; the bleeding rate of two adjacent PSOs is major

Fig. 2 A 78-year-old patient presenting an L1 fracture above an L2–

L5 iatrogenic flat back inducing a severe kyphosis. Correction was

achieved with an L4 PSO and posterior release at L1. An L1

reconstruction was then performed to fill the gap at the fracture site

Eur Spine J

123

and the proximity of the two sites makes it difficult to have

a good field visibility; the bleeding risk is the main reason

that would make the surgeon think about performing two

lumbar PSOs in a single stage [19] or in two separate stages

[20]. In summary, it is advised to leave one or two levels

between the two PSOs as this will spread the correction

angle and the cord shortening minimizing any potential

neurovascular injury. In addition there would be a more

stable bone-implant construct; separating the two PSOs in

two sessions significantly decreases the bleeding rate, and

the risk for the patient. It also enables anterior grafting of

the discs by posteriorly placed transforaminal lumbar

interbody fusion (TLIF) cages if needed, avoiding the

anterior complementary approach; this would be impossi-

ble in case of two lumbar PSOs performed in a single

session, as the bleeding would increase significantly.

Multifocal deformity with fixed scoliosis

With coronal malalignment

The association of a sagittal and coronal imbalance, in

what is called a ‘‘combined imbalance’’, is frequent; per-

forming a PSO in such a case should obey to specific rules

and techniques to avoid any aggravation of the deformity

especially in the coronal plane. Two categories of com-

bined imbalance should be differentiated depending on the

coronal aspect of the deformity, the concave imbalance,

and the convex imbalance. In the case of a concave

imbalance, the subject is tilted toward the concavity of the

main curve. In the case of a convex imbalance, there is an

oblique takeoff at the lumbosacral junction and the subject

is tilted toward the convexity of the main curve. The sur-

gical strategy for a PSO in case of a rigid combined

imbalance will closely depend on the type of imbalance.

For a concave imbalance, the osteotomy should be realized

at the apex of the main curve. For a convex imbalance, the

osteotomy should be done at the lumbosacral junction, to

correct the oblique takeoff; otherwise if it is done at the

apex of the main curve, it will aggravate the coronal

imbalance creating an iatrogenic coronal imbalance (the

proximal part of the body is shifted into the wrong direc-

tion far away from the center of the sacrum). The osteot-

omy that is done in these cases is usually an asymmetric

PSO. In a concave imbalance, the amount of bone resected

at the level of the convex pedicle of the apex vertebra is

more important than the concave pedicle, closure of the

osteotomy is always done on the opposite side of the

imbalance, i.e., the convex side, two rods (one proximal

and one distal to the osteotomy site) connected by a

domino are put in place, and progressive compression on

the domino is done, and the two rods are gradually and

gently brought toward one another which closes the oste-

otomy site. In a convex imbalance, the osteotomy is done at

the lumbosacral junction with more bone resected at the

convexity of the fractional curve, the principle of reduction

and closure is similar to the concave imbalance case, and is

performed at the side opposite to the imbalance, i.e., the

Fig. 3 A 58-year-old man with a complex posttraumatic deformity of the upper thoracic spine and lower cervical segment. An asymmetric T5

PSO was performed with a good correction of the sagittal plane and an acceptable malalignment in the coronal plane

Eur Spine J

123

convexity of the lumbosacral junction (which is the side of

the concavity of the main curve). Careful attention should

be paid during the execution of an asymmetrical PSO when

removing the bone at the concavity of the main curve,

because, given the rotation of the vertebras, the identifi-

cation of the lateral wall is not as clear as the contralateral

side, with a deeper field, which puts the segmental vessels

at higher risk of being injured (Figs. 6, 7).

Without coronal malalignment

In some cases of fixed kyphoscoliotic deformities, the

global malalignment is only in the sagittal plane. In such

cases, the surgical target should be the correction of the

sagittal plane without worsening of the coronal alignment.

The osteotomy should be done at the level of the apical

vertebra considering the sagittal plane and careful attention

must be paid to avoid overcorrection on the convex side,

which is very frequent and can lead to secondary coronal

malalignment (Fig. 8).

Non-adjacent deformities

When there are two deformities in two separated sites, far

from each other, it is logical to perform two PSOs in two

separate sessions. This is typically the case in an anky-

losing spondylitis patient with an important loss of lumbar

Fig. 4 A 56-year-old woman with an L5 spondyloptosis operated on

30 years ago with L2S1 in situ fusion. She presented a severe sagittal

malalignment. An S1 PSO was performed. Lumbosacral kyphosis was

partially corrected; it allowed a better but not perfect global alignment

PT decrease from 46� to 30�, SVA from 150 to 30 mm. CT scan

shows fusion at osteotomy site

Eur Spine J

123

lordosis (Fig. 9) associated with a limitation of the forward

gaze in relation to a fixed flexion deformity of the cervical

spine [21]. It is recommended to perform the first PSO at

the lumbar level, as this could significantly improve the

global balance of the patient including the gaze; therefore

the second PSO, usually done at the cervicothoracic area

(C7), will be done later on when the horizontal gaze of the

patient becomes impaired. The only exception to this rule

is when the deformity is extremely severe as in a ‘‘chin-on-

pubis’’ deformity [22] making it impossible to put the

patient prone on the table; in that case, the cervical spine is

done first, in a sitting position, and the other osteotomies

are done in a second stage, in a prone position. If the two

PSOs are to be done in the lumbar and thoracic area, the

lumbar osteotomy would be done first, followed by the

thoracic in a separate session.

Summary of techniques and indications in multifocal

deformities

In summary, the surgical management of multifocal spinal

deformities is done through a thorough preoperative plan-

ning where spinal and pelvic parameters are accurately

Fig. 5 Case of a global congenital hyperkyphosis at the thoracic

spine and thoracolumbar junction. Adjacent two-level PSOs were

performed to correct 60� of kyphosis. The disc above the

osteotomized vertebra was removed to obtain a bone-on-bone contact.

Operative view showed the osteotomy site and the remaining T11

vertebra between the two PSOs

Eur Spine J

123

determined. The calculation of lumbopelvic indexes can

also help in the decision-making and defining the best

strategy [23, 24]. It is advised to perform the PSO at the

apical vertebra, as it is located most superficially and is

easiest to osteotomize; a more physiological contour can

also be achieved by directly attacking the angular pathol-

ogy. Thus, we recommend the following:

– ‘‘Asymmetrical’’ PSO is recommended in the case of a

combined imbalance, or a rare pure coronal imbalance.

– The ideal indication for two adjacent PSOs would be a

long rigid thoracic or thoracolumbar kyphosis, iatro-

genic or congenital. The two non-adjacent PSOs at the

lumbar area would be done in an ankylosing spondylitis

patient with major lumbar kyphosis.

Fig. 6 A 48-year-old woman with concave coronal and sagittal malalignment; asymmetric PSO was performed at the apical vertebra. It allowed

correction in both planes

Fig. 7 A 68-year-old woman with convex coronal and sagittal

malalignment; asymmetric PSO was performed at the lombosacral

curve to restore the oblique takeoff at the lumbosacral junction. It

allowed correction in both planes. The red arrows show what the

result would be if PSO were performed at the apical vertebra with

worsening of the coronal malalignment

Eur Spine J

123

– VCR is performed in the case of a severe scoliosis

above 120� or a severe kyphoscoliosis to correct both

planes simultaneously, or in the case of a sharp

angulated sagittal deformity.

– The navigation is very helpful in the management of

complex cases, especially in revision cases, in high

thoracic osteotomy for a secondary posttraumatic

kyphosis or iatrogenic kyphosis; also in a rare PSO

Fig. 8 A 58-year-old woman with multiple surgery for a kyphosco-

liosis present severe sagittal malalignment with acceptable coronal

alignment. A PSO was performed at the apex of the sagittal

deformity. Special attention must be paid to avoid postoperative

coronal malalignment during correction maneuvers. Operative view

showing fusion mass and pure sagittal correction at the apex of the

deformity, navigation was used for implants insertion and to control

bone resection during the osteotomy

Eur Spine J

123

case such as PSO in S1 for severe dysplastic

spondylolisthesis.

Conflict of interest None.

References

1. Obeid I, Hauger O, Aunoble S, Bourghli A, Pellet N, Vital JM

(2011) Global analysis of sagittal spinal alignment in major

deformities: correlation between lack of lumbar lordosis and

flexion of the knee. Eur Spine J 20(Suppl 5):681–685

2. Bridwell KH, Lewis SJ, Lenke LG, Baldus C, Blanke K (2003)

Pedicle subtraction osteotomy for the treatment of fixed sagittal

imbalance. J Bone Joint Surg Am 85:454–463

3. Bridwell KH, Lewis SJ, Rinella A, Lenke LG, Baldus C, Blanke

K (2004) Pedicle subtraction osteotomy for the treatment of fixed

sagittal imbalance. Surgical technique. J Bone Joint Surg Am

86(Suppl 1):44–50

4. Obeid I, Bourghli A, Boissiere L, Vital JM, Barrey C (2014)

Complex osteotomies vertebral column resection and decancel-

lation. Eur J Orthop Surg Traumatol 24(Suppl 1):S49–S57

5. Wang Y, Lenke LG (2011) Vertebral column decancellation for

the management of sharp angular spinal deformity. Eur Spine J

20:1703–1710

6. Auerbach JD, Lenke LG, Bridwell KH, Sehn JK, Milby AH,

Bumpass D et al (2012) Major complications and comparison

between 3-column osteotomy techniques in 105 consecutive spinal

deformity procedures. Spine (Phila Pa 1976) 37:1198–1210

7. Bianco K, Norton R, Schwab F, Smith JS, Klineberg E, Obeid I

et al (2014) Complications and intercenter variability of three-

column osteotomies for spinal deformity surgery: a retrospective

review of 423 patients. Neurosurg Focus 36:E18

8. Barrey C, Perrin G, Michel F, Vital JM, Obeid I (2014) Pedicle

subtraction osteotomy in the lumbar spine: indications, technical

aspects, results and complications. Eur J Orthop Surg Traumatol

24(Suppl 1):S21–S30

9. Elgafy H, Bransford RJ, McGuire RA, Dettori JR, Fischer D

(2010) Blood loss in major spine surgery: are there effective

measures to decrease massive hemorrhage in major spine fusion

surgery? Spine (Phila Pa 1976) 35:S47–S56

10. Buchowski JM, Bridwell KH, Lenke LG, Kuhns CA, Lehman RA

Jr, Kim YJ et al (2007) Neurologic complications of lumbar

pedicle subtraction osteotomy: a 10-year assessment. Spine (Phila

Pa 1976) 32:2245–2252

11. Lafage V, Schwab F, Vira S, Hart R, Burton D, Smith JS et al

(2011) Does vertebral level of pedicle subtraction osteotomy

correlate with degree of spinopelvic parameter correction?

J Neurosurg Spine 14:184–191

12. Roussouly P, Gollogly S, Berthonnaud E, Dimnet J (2005)

Classification of the normal variation in the sagittal alignment of

the human lumbar spine and pelvis in the standing position. Spine

(Phila Pa 1976) 30:346–353

13. Hovorka I, Rousseau P, Bronsard N, Chalali M, Julia M, Carles

M et al (2008) Extension reserve of the hip in relation to the

spine: comparative study of two radiographic methods. Rev Chir

Orthop Reparatrice Appar Mot 94:771–776

14. Chang KW, Leng X, Zhao W, Ching-Wei C, Chen TC, Chang KI

et al (2011) Quality control of reconstructed sagittal balance for

sagittal imbalance. Spine (Phila Pa 1976) 36:E186–E197

15. O’Shaughnessy BA, Kuklo TR, Hsieh PC, Yang BP, Koski TR,

Ondra SL (2009) Thoracic pedicle subtraction osteotomy for

fixed sagittal spinal deformity. Spine (Phila Pa 1976) 34:2893–

2899

16. Pellise F, Vila-Casademunt A, European Spine Study G (2014)

Posterior thoracic osteotomies. Eur J Orthop Surg Traumatol

24(1):S39–S48

17. Cui G, Wang Y, Kao TH, Zhang Y, Liu Z, Liu B et al (2012)

Application of intraoperative computed tomography with or

without navigation system in surgical correction of spinal

deformity: a preliminary result of 59 consecutive human cases.

Spine (Phila Pa 1976) 37:891–900

18. Ji ML, Qian BP, Qiu Y, Wang B, Zhu ZZ, Yu Y et al (2013)

Change of aortic length after closing-opening wedge osteotomy

for patients with ankylosing spondylitis with thoracolumbar ky-

phosis: a computed tomographic study. Spine (Phila Pa 1976)

38:E1361–E1367

19. Zheng GQ, Song K, Zhang YG, Wang Y, Huang P, Zhang XS

et al (2014) Two-level spinal osteotomy for severe thoracolumbar

kyphosis in ankylosing spondylitis. Experience with 48 patients.

Spine (Phila Pa 1976) 39:1055–1058

20. Chen IH, Chien JT, Yu TC (2001) Transpedicular wedge oste-

otomy for correction of thoracolumbar kyphosis in ankylosing

spondylitis: experience with 78 patients. Spine (Phila Pa 1976)

26:E354–E360

21. Van Royen BJ, De Gast A, Smit TH (2000) Deformity planning

for sagittal plane corrective osteotomies of the spine in anky-

losing spondylitis. Eur Spine J 9:492–498

22. Kim KT, Lee SH, Son ES, Kwack YH, Chun YS, Lee JH (2012)

Surgical treatment of ‘‘chin-on-pubis’’ deformity in a patient with

ankylosing spondylitis: a case report of consecutive cervical,

thoracic, and lumbar corrective osteotomies. Spine (Phila Pa

1976) 37:E1017–E1021

23. Boissiere L, Bourghli A, Vital JM, Gille O, Obeid I (2013) The

lumbar lordosis index: a new ratio to detect spinal malalignment

with a therapeutic impact for sagittal balance correction decisions

in adult scoliosis surgery. Eur Spine J 22:1339–1345

24. Boissiere L, Vital JM, Aunoble S, Fabre T, Gille O, Obeid I

(2014) Lumbo-pelvic related indexes: impact on adult spinal

deformity surgery. Eur Spine J. doi:10.1007/s00586-014-3402-z

Fig. 9 A 52-year-old man with severe global kyphosis secondary to

ankylosing spondylitis. Staged two-site PSOs were performed on L4

and C7

Eur Spine J

123