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Orthopaedics & Traumatology: Surgery & Research 101 (2015) S281–S288

Available online at

ScienceDirectwww.sciencedirect.com

riginal article

usionless surgery in early-onset scoliosis

. Odenta,∗, B. Ilharrebordeb, L. Miladic, N. Khouri c, P. Violasd, J. Ouellete,. Cuninf, J. Kiefferg, K. Kharrath, F. Accadbled i, Scoliosis Study Group

Groupe d’étude de la scoliose)j, the French Society of Pediatric Orthopedics (SOFOP)k,Service de chirurgie orthopédique pédiatrique, CHRU de Tours, université Franc ois-Rabelais de Tours, PRES Centre-Val de Loire université, 49,oulevard Béranger, 37044 Tours, FranceService de chirurgie orthopédique pédiatrique, hôpital universitaire Robert-Debré, université Paris-Diderot, Assistance publique–Hôpitaux de Paris,5019 Paris, FranceService de chirurgie orthopédique pédiatrique, hôpital universitaire Necker-Enfants-Malades, université Paris-Descartes, Sorbonne Paris-Cité,ssistance publique–Hôpitaux de Paris, 149, rue de Sèvres, 75743 Paris cedex 15, FranceService de chirurgie pédiatrique, hôpital Sud, université Rennes 1, boulevard de Bulgarie, 35000 Rennes, FranceShriner’s Hospital, McGill University, Montreal, CanadaService d’orthopédie pédiatrique, hôpital Femme-Mère-Enfant, université Lyon 1, hospices civils de Lyon, 59, boulevard Pinel, 69677 Bron cedex, FrancePediatric clinic, Luxembourg, LuxembourgHôpital hôtel-Dieu, B.P. 166830, Beirut, LebanonService d’orthopédie, hôpital des Enfants, CHU de Toulouse, Toulouse, FranceHôpital Saint-Joseph, rue Raymond-Losserand, Paris, France56, rue Boissonade, 75014 Paris, France

a r t i c l e i n f o

rticle history:eceived 23 March 2015ccepted 17 June 2015

eywords:arly-onset scoliosisusionless spinal surgerypinal growthpinal instrumentation

a b s t r a c t

Background: Surgical treatment of early-onset scoliosis has greatly developed in recent years. Early-onsetscoliosis covers a variety of etiologies (idiopathic, neurologic, dystrophic, malformative, etc.) with onsetbefore the age of 5 years. Progression and severity threaten respiratory development and may result inrespiratory failure in adulthood. Many surgical techniques have been developed in recent years, aimingto protect spinal and thoracic development.Material and methods: Present techniques are based on one of two main principles. The first consists inposterior distraction of the spine in its concavity (single growing rod, or vertical expandable prosthetictitanium rib [VEPTR]), or on either side (dual rod); this requires iterative surgery, for lengthening, unlessmotorized using energy provided by a magnetic system. The second option is to use spinal growth forceto lengthen the assembly; these techniques (Luque Trolley, Shilla), using a sliding assembly, are knownas growth guidance.

Results: These techniques are effective in controlling early scoliotic deformity, and to some extent restorespinal growth. However, they show a high rate of complications: infection, rod breakage, spinal fixationpull out and, above all, progressive spinal stiffness, reducing long-term efficacy. Respiratory gain is harderto assess, as thoracic expansion does not systematically improve respiratory function, particularly dueto impaired compliance of the thoracic cage.

© 2015 Published by Elsevier Masson SAS.

. Introduction

Surgical treatment of early-onset scoliosis has greatly developedn recent years. Early-onset scoliosis covers a variety of etiolo-

ies (idiopathic, neurologic, dystrophic, malformative, etc.) withnset before the age of 5 years. Progression and severity threatenespiratory development and may result in respiratory failure in

∗ Corresponding author. Tel.: +33 0 1 44 49 42 38; fax: +33 0 1 44 38 15 22.E-mail address: t.odent@chu-tours.fr (T. Odent).

http://dx.doi.org/10.1016/j.otsr.2015.07.004877-0568/© 2015 Published by Elsevier Masson SAS.

adulthood. Due to severity of deformity and/or resistance to non-operative management, fusionless surgery may be performed topostpone arthrodesis, which, if performed early, prevents vertebraland thoracic growth. Many such techniques have been developedrecently.

Present techniques are based on one of two main principles.The first consists in posterior distraction of the spine in its con-

cavity (single growing rod [1], or vertical expandable prosthetictitanium rib [VEPTR] [2]), or on either side (dual rod) [3]; thisrequires iterative surgery, for lengthening, unless motorized usingenergy provided by a magnetic system. The second option is to use

S282 T. Odent et al. / Orthopaedics & Traumatology: Surgery & Research 101 (2015) S281–S288

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pinal growth force to lengthen the assembly; these techniquesLuque Trolley [4], Shilla [5]), using a sliding assembly, are knowns growth guidance.

Experience with these techniques, combined with fundamen-al research [6–8], has brought progress in the understanding ofpinal and thoracic growth and pulmonary development, leadingo a specific classification of these deformities [9] (Fig. 1).

The topic of the 2014 round-table of the Scoliosis Study GroupGroupe d’étude de la scoliose: GES) in Nice was “Fusionless surgeryn the growing spine”. The present paper groups participants’ variedxperience according to principle and type of instrumentation, with

review of current studies of respiratory function following theseypes of surgery.

. Posterior spinal distraction techniques

These techniques amount to an internal brace accompanyingrunk growth while controlling spinal deformity, without, in prin-iple, performing bone fusion. They are based on the first reportsy Moe and Kharrat, using Harrington’s instrumentation [1].

.1. Dual rod assembly

The principle consists in fitting 4 rods, subcutaneously orntramuscularly, with connectors on each side allowing iterative

Fig. 2. Radiographs of different 2

early-onset scoliosis [9].

distraction at regular predetermined intervals (Fig. 2). The longestexperience is that of the Growing Spine Study Group (GSSG), aninternational group of more than 30 experts, with results from acohort of patients treated by growing rods since 1994. It is note-worthy that, since 2007, the group has ceased using single rods inthe light of the advantages of dual rod assemblies. Current guide-lines reserve this technique to children under 10 years of age, withcurves exceeding 60◦, after the family’s full informed consent toa long treatment program. Given the large number of operationsrequired, non-operative treatment should be used to delay rodfitting for as long as possible, as each year reduces the overall com-plications rate by 13%. To avoid spontaneous fusion in the spine,rods should be positioned intramuscularly, under the superficialfascia, to limit skin impingement. Subperiosteal dissection duringrod fitting should be avoided. Apical fusion, originally performedby some teams, is not recommended, unlike fusion of proximal anddistal anchor points, which should use 4 fixation points on at least2 adjacent vertebrae. Transverse connectors are unnecessary whenfixation is provided by pedicular screws, but are preferable if hooksare used. The primary procedure and subsequent lengthening inter-ventions should be performed under neurophysiological control

and be followed by 6 months’ brace immobilization to achievefusion at the extremities.

Mean intervals between distractions ranged between 10 and 20months until 2003, but the tendency now is to keep them shorter, at

-rod posterior assemblies.

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round 7 months: they should not exceed 6 months if gain in heights to approximate physiological growth (1.2–1.7 cm per year) [2].ongitudinal follow-up of the cohort found a complications rate of5%, with a mean of 2.2 complications per patient [10]. Fifty-eightercent of complications could be resolved during the followingistraction, but unscheduled surgery was still required in 10% ofatients. Dual rods considerably reduced the rate of mechanical

mplant failure, but at the cost of a slightly higher risk of infection11]. Overall, the rate of complications per operation was around8%, and each distraction procedure increased the complicationsisk by 24%. Actuarial survivorship modeling showed that a length-ning program initiated at the age of 6 years requires at least 10engthening interventions up to an age suitable for fusion, with aonsequent complications risk exceeding 65%.

One of the most common complications is material breakage,ith an incidence of 10% for bilateral rods. It usually occurs in the

onvex rod at the thoracolumbar junction, close to the connectors,hich represent an area of increased rigidity [12]. No correlationas found between patient weight or type of implant (screw orook). Thoracic hyperkyphosis, found in 30% of patients, on thether hand, is a major risk factor for mechanical failure, increasingverall complications risk during treatment by a factor of 3 [13].nchor-point failure is relatively rare following primary fusion, but

ncurs a risk of neurologic complications described by Skaggs et al.,specially in case of intra-canal migration of proximal pedicularcrews [14]. It is consequently recommended not to limit proximalxation to a single pedicular screw on either side in long assem-lies, but to add at least one hook or a second screw, to distributenchorage stress.

The main problem with conventional growing rods is progres-ive spinal stiffness, with consequently diminishing growth ineight as lengthening proceeds [15], the so-called “law of diminish-

ng returns”: gain in Cobb angle is usually obtained only at the firstrocedure, with the fitting of the first distraction rods; thereafter,1-S1 gain gradually decreases and more or less disappears after 6istractions, or just 3 years of treatment at the optimal rhythm.

Bilateral growing rods are effective in early-onset scoliosis, sta-ilizing spinal deformity while achieving height gain close to thatf physiological growth. Family compliance is essential in respec-ing distraction intervals and due to the high rate of complications.he major problem is progressive stiffening, found on average after

distractions, and partial or complete fusion, found in 80% of cases,ampering definitive fusion. Therefore, it is now recommended toontinue non-operative treatment and delay rod fitting as long asossible.

.2. Single-rod assembly

In France, the first unilateral assemblies were performed in the970s, using a subcutaneous Harrington rod. A brace was system-tically associated. The intrinsic mechanical problems and need forterative retensioning led to multiple proximal and distal fixationseing introduced, with segmental instrumentation, and later to the

ntroduction of a magnetic device (the Phenix rod) to avoid theeed for iterative surgery. This device was abandoned in 2009 asnreliable, bulky and imposing a straight assembly on the spine.t the same time, the proximal and distal fixations were improved,

eading finally to the instrumentation design used today [16,17].The proximal fixation comprises 3 hooks (2 supralaminar

nd 1 pedicular) and distal fixation is provided by 2 pedicularcrews, in what is known as H3S2 assembly [18,19]. The rod, in

oncave or in $ position, is curved according to the target spinalrofile. Frontally, the vertical position increases biomechanicalesistance to breakage. The rod is introduced intramuscularly. Theoft tissue of the intermediate area must be respected to avoid any

urgery & Research 101 (2015) S281–S288 S283

risk of stiffness or auto-fusion. The proximal and distal surgicalapproaches are limited.

Since 2005, 103 H3S2 assemblies have been performed. In somecases, depending on deformity severity, preoperative traction wasused to improve flexibility, and the objective of the primary surgerywas to maintain the resulting gain. Thirty-eight patients had at least2 years’ follow-up. Mean Cobb angle was 65◦ preoperatively, 28◦

postoperatively and 32◦ at last follow-up: i.e., 54% improvement.Most patients showed improved profile. There were 7 proximaljunctural kyphoses. Mean interval between retensioning proce-dures was 10 months. At last follow-up, 6 of the 38 patients (18%)had had at least 1 complication: 1 superficial infection, 2 deep infec-tions that resolved after cleansing and antibiotherapy, and 4 rodbreakages.

2.3. Magnetic growing rods

To avoid the drawback of surgical reintervention to lengthenthe rod and follow physiological growth, rods were developedwhich could be lengthened by magnetic force applied transcu-taneously. The only such system available today is MAGEC®

(Ellipse Technologies, Inc.), comprising 4.5 or 5.5 mm diametertitanium motorized rods with 48 mm distraction reserve (Fig. 3).Contraindications include: age < 2 years, weight < 11 kg, BMI > 25,pacemaker/defibrillator, and MRI required during the rod implan-tation period. Distraction is triggered by a programmable externalmagnet, with a dedicated device to locate the internal magnet.Lengthening is performed in consultation, without the need foranesthesia or analgesia, at a rhythm determined by the surgeon.

Benefit for patient, family and health system comprises [20]:

• fewer complications related to iterative surgery;• less psychological trauma for patient and family;• improved quality of life for child and family, with less time off

school and off work;• high primary outlay which is amortized within 3–4 years by sav-

ings on hospital stay.

The GES 2014 round-table reviewed files for 32 patients treatedin France and Luxembourg using MAGEC® magnetic spinal grow-ing rods for severe progressive scoliosis. The principal objectiveof this short follow-up preliminary study was to assess successfulmagnetic rod lengthening and Cobb angle stabilization. Thirty-twochildren, male and female, aged 5–11 years (mean: 9 years) wereincluded in 6 centers. Forty-two rods were implanted (22 single, 10dual). Mean follow-up was 13 months (range: 4–28 months). Rodlengthening was measured at each session and compared againstthe theoretic lengthening as set on the MAGEC® remote control.

A total of 118 lengthening procedures were performed. Meanprogrammed lengthening was 5.85 mm per session, and mean mea-sured lengthening 3 mm. Twenty-one patients had satisfactory reallengthening (> 80% of programmed value) at last follow-up. In 8patients, real lengthening progressively decreased, due to pro-gressive stiffening of scoliosis beyond the mechanical distractioncapability of the rod. Three rods blocked and required replace-ment or abandonment of the technique. Mean Cobb angle was 72◦

preoperatively, 41◦ postoperatively and 45◦ at last follow-up.Complications comprised: 5 proximal anchorage detachments

in 3 patients, 2 rod breakages in 1 patient, 1 open scar exposingmaterial, 1 deep infection requiring material ablation, and 1 super-ficial infection. Complications required 8 revision procedures.

This study confirmed the MAGEC® device’s technical length-

ening capacity, only 7% of rods failing to function. The meanlengthening obtained, however, was almost 50% less than planned.This discrepancy may be explained by loss of force due to malpo-sitioning of the magnetic field, an excessive thickness of soft tissue

S284 T. Odent et al. / Orthopaedics & Traumatology: Surgery & Research 101 (2015) S281–S288

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etween field and rod, and above all insufficient magnetic fieldtrength compared to the inevitable stiffening of the scoliosis overhe period of lengthening, as was clearly found with conventionalrowing rods (so-called “law of diminishing returns”). The presenttudy lacked sufficient follow-up to properly assess this stiffening,hich would seem to be unavoidable.

Cobb angle showed clear improvement with primary surgerynd then stabilized, but did not diminish over successive length-nings. There is a mechanical limit to reduction imposed by therchitectural deformity of the vertebrae and also by the solidity ofnchorage, preventing the assembly progressively adapting to thehanges in shape induced by lengthening.

The complications rate was comparable to that found with non-agnetic growing rods.In conclusion, MAGEC® magnetic growing rods appeared to be

echanically reliable. However, their use associated with the rigidxation currently available fails to prevent progressive spinal stiff-ning. The number of repeat procedures was significantly reduced,ut the complications rate remained high.

.4. VEPTR

VEPTR (Vertical Expandable Prosthetic Titanium Rib) was ini-ially developed for congenital thoracic and spinal deformitiesausing thoracic insufficiency syndrome, defined as the inabilityf the thorax to ensure normal respiration and good pulmonaryevelopment [21]. Such patients usually present “exotic” scoliosis22], a rare, severe and complex subgroup of spinal deformity, oftenssociated with deformed thorax due to the spinal deformity, ver-ebral rotation and dorsal lordosis or kyphosis, inhibiting thoracicnd thus pulmonary growth [2,23]. Thoracic insufficiency may beggravated by associated costal abnormalities, leading to thoracic

age rigidity.

VEPTR is a longitudinal costal expansion implant, compris-ng 1 costo-costal and 1 hybrid component (rib/lumbar hook orib/pelvis). The principle, rather than correcting spinal deformity,

thening system, and radiograph of the magnetic rod in position.

is to enlarge the narrow thorax so as to create an expansion cham-ber allowing the lungs to develop and thereby correct the thoracicinsufficiency syndrome. The main indications are: thoracic defor-mity impairing thoracic function, such as congenital scoliosis withunilateral segmentation disorder and rib fusion (e.g., spondylo-costal dysplasia [24]); unstable thorax due to a missing rib; bilateralrib fusion (e.g., Jarcho-Levin syndrome [25]); short narrow thorax(e.g., Jeune syndrome [26]); or, by extension, severe progressiveinfantile scoliosis. The cost is expensive compared to a classicalassembly using implants derived from the Cotrel-Dubousset instru-mentation.

Like the other fusionless spinal distraction techniques, VEPTRtheoretically requires expansion procedures every 4–6 months toenlarge and increase the height of the hypoplastic thorax, stabi-lize the wall defect and try to progressively improve associatedspinal deformities. Opening thoracotomy may be needed in ribfusion areas or for missing ribs, with resection of pleural fibrosis.Experience shows that costal synostoses recur, requiring iterativecostotomy at each distraction procedure (Fig. 4).

VEPTR is used in a wide variety of etiologies apart from its pri-mary indication for thoracic insufficiency, making it difficult toassess the published results and the impact on respiratory function.

As with fusionless distraction techniques using single or dualrods, initial angular gain subsequently stagnates or diminishes [27].Moreover, the complications inherent to fusionless spinal distrac-tion surgery are frequent. A recently published review of the FrenchVEPTR series reported a high complications rate, comparable toother series [28], although, with experience, recommendations canbe made to limit the incidence.

Thus, more precise assessment of this technique would haveto be based on the indications for which it was initially designed:thoracic insufficiency syndrome and malformative scoliosis with

associated costal abnormality. Assessment, if it is to determineefficacy, should include not only vertebral and costal deformity atfollow-up but also respiratory function, which is difficult to explorein small children. Even so, VEPTR is a means of optimizing the

T. Odent et al. / Orthopaedics & Traumatology: Surgery & Research 101 (2015) S281–S288 S285

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anagement of patients with major trunk deformity, sometimest the limit of therapeutic possibility.

. Growth guidance

Two growth guidance techniques are currently most widelysed: the Shilla technique [5] and Modern Luque Trolley rods [4].

.1. Shilla

The principle of the Shilla instrumentation, described bycCarthy in 2008, is to control the scoliosis by guiding growth with

single posterior procedure, without iterative surgery or brace [5].he assembly uses 2 rods fixed to 3 or 4 pedicular screws inserted inhe apical vertebrae, with fusion of the summit of the curve; pedicu-ar screws are inserted extra-periosteally in the proximal and distalxtremities of the rods, enabling the rods to slide, guiding spinal

rowth (Fig. 5).

For this round-table, 11 prepubertal children aged 4 years 6onths to 11 years 6 months were reviewed at a mean 3 years’

ollow-up (range: 2–4.5 years). Six had undergone definitive fusion

–C. Baseline radiograph and CT scan. D, E. Postoperative radiograph. F, G. Radiologic

by end of follow-up. The number of instrumented vertebrae rangedfrom 11 to 14. Mean initial Cobb angle was 57◦. Five had 1 and 6had 2 unscheduled procedures. Four curves showed good control(57◦ Cobb angle corrected to 42◦) and 7 failed to maintain correc-tion (57◦ angle unchanged). In the 4 children free of complications,seated height increased from 67 cm to 72.5 cm; in McCarthy’sseries, it increased by a mean of 12%. Global angle was less wellcontrolled than in McCarthy’s series (70◦ corrected to 34◦). Sevenof the 11 children had unexpected complications, compared to 50in McCarthy’s series. The high rate of material disassembly wasdue to poor screw fixation in small pedicles, with excessive stress;this explains the metallosis found on revision surgery. A crankshaftphenomenon was found in 7 children, both at the curves and at thefused summit; these problems occurred in children with a meanage of 10 years 9 months: i.e., at pubertal growth, which over-powered the instrumentation, despite fusion of the summit. The4 children with well-controlled scoliosis had a mean age of 7 years

8 months, before the dangerous pubertal growth peak; many chil-dren in McCarthy’s series were still far from this age. Surgery wasaggressive, due to the size of the approach, the length of surgerytime (4 h 54 min) and quantity of blood loss (425 cc for McCarthy).

S286 T. Odent et al. / Orthopaedics & Traumatology: S

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evision surgery was always heavy, due to the degree of fibrosis.cCarthy’s main argument is that his technique avoids too great a

umber of reoperations [5]: a mean of 2.7 per patient, compared to.9 with other techniques, avoiding 49 scheduled distractions. That

s the obvious advantage of the Shilla technique, but it is much moreggressive than the classic growing rod methods.

.2. Luque trolley

In 2011, the Modern Luque Trolley technique, updating the tech-ique devised by Eduardo Luque 40 years previously, was described4]. It comprises fixed distal anchorages with vertebral fusion asso-iated to a system of rods that slide at the apex of the deformity.he technique uses modern anchors (pedicular screws) and a sur-ical approach sparing soft tissue. The sliding anchors are insertedransmuscularly, to limit the risk of spontaneous fusion.

A retrospective review was performed of 13 patients undergo-ng surgical correction between 2003 and 2011, using either the

odern Luque Trolley assembly or modified VEPTR. Mean age was 6ears. At a mean of 4 years’ follow-up (range 2–8 years), the primaryurvature was initially corrected from 73◦ to 27◦ and maintained at5◦. Intra-operatively, a 1.9 cm gain was observed between instru-ented levels; total length gain between T1 and S1 was 3.8 cm. Aean of 10 vertebrae were spanned, enabling vertebral segmentsithin the curve to grow by 2.0 cm in 4 years: i.e., by 50% of the

xpected growth, while allowing a mean 3.5 cm growth in T1-S1.ight unscheduled procedures were performed over the period: 4or growth beyond the initial assembly, requiring a new rod; 2 forupplementary spinal anchorages to enhance control of scoliosis;

for rod breakage; and 1 for crossover to classic dual growing rod.here was no junctional kyphosis. T5-T12 kyphosis decreased by

mean of 24◦ and L1-S1 lordosis increased by a mean of 7◦ overre-surgical values by end of follow-up.

In conclusion, self-sliding assemblies provide adequate main-enance of curve correction in most cases. Although only 51%f expected spinal growth and 50% of growth between instru-ented segments were obtained, sagittal balance was maintained

nd no junctional kyphosis was induced. At least 83 proceduresere avoided (7 per patient), if results are compared to thoseith standard techniques using rods requiring lengthening every 6onths.

urgery & Research 101 (2015) S281–S288

4. Growing rods in neuromuscular pathology

Fusionless instrumentation in neuromuscular scoliosis concernspatients who are often malnourished, with poor quality bone andexposure to frequent complications such as implant detachmentor protrusion. Preoperative nutritional, respiratory or orthopedicpreparation (by progressive traction via a cranial halo) facilitatessurgery and limits risk.

To reduce the rate of complications, and of mechanical com-plications in particular, a certain number of guidelines are to berespected. Spinal fixation should use multiple solid anchors. Fix-ation should not be onto the ribs, which are fragile, but ratheronto the vertebrae, with supra- or sub-laminar hooks, which resistdetachment better than screws. Proximal anchorage should extendup to the first thoracic or even last cervical vertebrae, to avoid therisk of proximal junctional kyphosis. In non-walking patients, dis-tal fixation should be supported by the pelvis, with solid, stable,small anchorage. Pelvic fixation by iliosacral screws meets theserequirements [29,30]. Spinal assembly should be fairly symmet-rical, to neutralize balance disorder in the trunk and pelvis anddistribute stress. This means it must be bilateral, supported by thepelvis (Fig. 6). To reduce operative risk in fusion, surgery should beas non-invasive as possible, restricting the approach to two shortincisions over the anchor points.

Fusionless instrumentation is indicated in neuromuscular sco-liosis in case of failure, impossibility or difficulty of non-operativetreatment or of contraindications to fusion due to fragile diathe-sis. The indication should be early, before onset of puberty, whilethe spinal deformity is still supple and reducible. The benefits offusionless instrumentation in neuromuscular scoliosis are, in ourexperience, multiple: improved health and functional status andimproved quality of life for both patient and family.

5. Definitive fusion surgery

A key point in treatment is the transition from distractions todefinitive fusion. Until recently, the literature was sparse, but Flynnet al. reported a series of 99 patients, aged 11–13 years, undergoinglengthening over a mean of 5 years [31].

Definitive fusion was indicated either because the patient hadreached maturity, or because spinal stiffening was so severe thatdistraction no longer provided benefit, or again because of mechan-ical or infectious complications. The fusion levels were the same asfor lengthening rods in 55% of cases, but extension to a further 1 or2 levels, usually distally, was required in respectively 15% and 9%of cases. Proximal extension was usually due to mechanical failureor proximal junctional kyphosis, while distal extension was moreoften to improve frontal balance. Intra-operative findings includeddifficulty of exposure, a mean 3-fold more bleeding than in clas-sical fusion, and spontaneous fusion in 62% of cases. The fusedanchorages were generally reused, changing implants. The rate ofneurologic complications was 3%, with favorable evolution in allcases. Due to stiffening or complete fusion, the number of implantswas usually small, and frontal correction was limited: < 50% inalmost 75% of cases, despite frequent (24%) use of osteotomy. Theauthors also highlighted the difficulty of sagittal correction in thesespines with little mobility.

6. Respiratory function results

6.1. Reminders

During postnatal lung growth, alveolae multiply from 20–50million in neonates to 300 million by the age of 2 years. Their sizethen increases, doubling between 2 years of age and adolescence

T. Odent et al. / Orthopaedics & Traumatology: Surgery & Research 101 (2015) S281–S288 S287

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32]. Thoracic volume increases, reaching 30% of adult volume by years and 50% by 10 years of age [33]. Compliance is high in the

nfant thorax, and decreases by 30% between the ages of 5 and 16ears.

Respiratory function study requires cooperation, and is noteasible until 5 or 6 years of age. Assessment criteria essen-ially comprise forced vital capacity (FVC) and maximal expiratoryolume per second (MEVS). Thoracic insufficiency syndrome, a con-ept introduced by Campbell, is defined as the inability of the thoraxo ensure normal respiratory function and pulmonary growth [34].t may be of thoracic or spinal origin. It is not determined by anybjective quantitative value.

.2. Influence of scoliosis

Depending on severity, scoliosis may induce respiratory restric-ion syndrome. For Cobb angles exceeding 100◦, FVC is reduced by0%; above 120◦, there is a risk of respiratory failure and chroniculmonary heart disease. Scoliosis induces a specific respiratoryrofile, with reduced current volume and superficial polypnea,

ncreased respiratory work and a 3-to-5-fold increase in the energyost of tissue oxygenation. In neuromuscular scoliosis, there is poororrelation between Cobb angle and the severity of the restrictionyndrome, due to multiple associated factors.

.3. Effect of distraction

Olson et al. studied the effect of costal distraction in an exper-mental animal model of costal synostosis in rabbit [6]. Synostosis

as induced at 5 weeks of life, followed in one group by resectionnd implantation of a thoracic distractor at 10 weeks; healthynimals constituted the third (control) group. Pathologic exami-ation of the pulmonary parenchyma at 24 weeks of life found, inhe synostosis-only group, larger alveolar volume, emphysema and

educed vessel size; in the synostosis + distraction group, vascula-ization was considerably better, suggesting a positive remodelingffect. Motoyama et al. studied the effects of VEPTR distraction at 3ears’ follow-up in 24 children with congenital scoliosis, aged 2–11

sacral screws. The lengthening system comprises 2-bore connectors, allowing rod

years [7]. FVC increased by a mean of 11% per year, particularly inthe younger patients (< 6 years). On the other hand, there was a 44%decrease in thoracic compliance, due to parietal stiffening. Mayeret al., in a multicenter prospective study of 53 patients aged 4–15years treated by VEPTR for thoracic insufficiency syndrome, foundreduced FVC and MEVS despite significant improvement in Cobbangle (from 95◦ to 61◦) by 8 months’ follow-up. The same teammore recently showed an absence of correlation between Cobbangle and FVC in 10 children with infantile or congenital scoliosisunder 3 years of age [8]. Moreover, in 15 patients aged 2–10 yearsmanaged by VEPTR, they found no correlation between improve-ment in Cobb angle and evolution of FVC at 13 months’ follow-up.Yoon et al., in 6 children with neuromuscular scoliosis aged 5–10years, reported the effect of spinal distraction by MAGEC® mag-netic rods on respiratory function [35]; at 2 years’ follow-up, Cobbangle showed 34◦ improvement, FVC 14% and MEVS 17% over ini-tial values. These results may have been due to early surgery anditerative non-invasive lengthening, limiting fibrous parietal retrac-tion. However, the series was small and the study involved severalbiases; the results need confirming.

The increase in thoracic volume following costal distraction isnot accompanied by improved respiratory function. Relations arecomplex and associated factors numerous. Motorized vertebral andcostal distraction reduces fibrosis and thus thoracic stiffness, andmay in future offer a solution.

7. Conclusion

Surgical techniques that conserve spinal growth are effectivein controlling early scoliosis and to some extent restoring spinalgrowth, but show a high rate of complications. They require multi-disciplinary teams with specific experience, given all the associatedabnormalities such as respiratory disorder and denutrition. Gain in

respiratory function is harder to assess: increased thoracic volumeallowing pulmonary development does not systematically lead toimproved respiratory function, particularly due to decreased tho-racic compliance. For all these reasons, these techniques should

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isclosure of interest

The authors declare that they have no conflicts of interest con-erning this article.

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