Current Concepts Review

Acta Orthop. Belg., 2008, 74, 147-160 CURRENT CONCEPTS REVIEW

Congenital scoliosis : Management and future directions

Sameer BATRA, Sashin AHUJA

From Llandough Hospital and University Hospital of Wales, Cardiff, United Kingdom

Congenital scoliosis remains an interesting and chal- abnormality. Scoliosis present at birth that is not lenging diagnostic entity. Vertebral absence, partial associated with an underlying developmental formation or lack of segmentation may cause asym- anomaly is referred to as infantile scoliosis. The metrical growth and resultant deformity. Because of term CS implies that there is always spinal curva- the high frequency of associated anomalies within ture at birth, but only the vertebral malformations and outside the spine, a detailed history and physical examination are mandatory. Maternal, perinatal his- are present at birth in all patients, while the scolio- tory, family history, and developmental milestones sis for some may not develop until later. must be fully explored. An incidence of approximately 0.5 to Plain radiographs remain standard for diagnosis of 1/1,000 births has been observed for CS (37). With congenital anomalies and measuring curve magni- an isolated single vertebral malformation, the tude, progression and perhaps growth potential of chance of a first degree relative having a similar the vertebral anomaly. Preoperative CT scan defines anomaly was estimated to be approximately one the anatomy and avoids any unexpected intraopera- out of a hundred in one study (45), but no pattern of tive posterior element deficiencies. MRI can exclude associated conditions of the spine, cranio-cervical inheritance was found in another report (45). If mul- junction and viscera. The recognition of curves with tiple vertebral anomalies are present, then the risk a bad prognosis at an early stage is pertinent to of similar anomalies in either siblings or children prevent curve progression and possible neurological of the patient is between 10 to 15% (45). complications. Genetic inheritance has been shown responsible The goal of surgery is to achieve a straight spine and for some congenital vertebral anomalies ; however, a physiological sagittal profile while maintaining there is no clear-cut genetic aetiology of CS to flexibility, to arrest progression of the curve with a short fusion segment preserving as much normal spinal growth as possible. Developments in gene research continue to be promising and may potentially lead to early detection of congenital vertebral malformations. ■ Sameer Batra, MRCS, MS (Orth), Spinal Fellow. ■ Sashin Ahuja, FRCS (Orth), Consultant Spinal Surgeon. Keyword : congenital scoliosis. Division of spine surgery, Department of Orthopaedics, Llandough hospital and University hospital of Wales, Cardiff and Vale NHS Trust, Cardiff, United Kingdom. Correspondence : Mr Sameer Batra, Specialist Registrar, BACKGROUND Department of Trauma and Orthopaedics, Royal Gwent hospital, Newport, NP20 2UB, United Kingdom. Congenital scoliosis (CS) is defined as a lateral E-mail : [email protected] curvature of the spine due to a developmental © 2008, Acta Orthopædica Belgica.

No benefits or funds were received in support of this study Acta Orthopædica Belgica, Vol. 74 - 2 - 2008 148 S. BATRA, S. AHUJA

Fig. 1. — Vertebral centrum development from two adjacent segments.

date (15). Basic science research evidence in mice Various theories to explain congenital vertebral suggests that maternal exposure to toxins, such as malformations have included failure of ossification carbon monoxide exposure, may cause congenital as the cause of defects of vertebra formation, scoliosis (16). Associations with maternal diabetes osseous metaplasia of the annulus fibrosus as the and ingestion of antiepileptic drugs during preg- cause of defects of vertebral segmentation, and nancy have also been postulated as possible caus- vertebral development hindered by persistent es (16). notochord (5). The vertebral column develops from pairs of somites, which begin to appear at 3 weeks gesta- CLASSIFICATION tion. The somites are mesenchymal segments, which are on both sides of the neural tube, and the Moe et al (35) classified congenital scoliosis antero-medial wall of the somite is termed a scle- according to morphologic characteristics on plain rotome. Cells from the sclerotomes spread out cen- AP frontal and lateral images as an embryological trally to form an unsegmented, cellular perichordal defect into formation failure, segmentation failure, sheath, which eventually forms the centrum of the and a mixed type. This classification also includes vertebral column. Next a zone of loose cells in the several other factors, such as the level of formation sclerotome forms superiorly where the interseg- failure and the presence or absence of interverte- mental and spinal nerve pass through the plate and bral disc space. Based on this information, the nat- a dense zone forms inferiorly which goes on to ural history of congenital scoliosis and strategic become the posterior neural arch of the vertebra approaches to its treatment have been evaluated and the rib (fig 1). One sclerotome pair forms one and reported (35). level of ribs and posterior elements of the spine. In The failures of formation (fig 2) are charac- the cellular sheath of the notochord, alternating terised by the deficiency of a portion of a vertebral zones of loose and dense zones also appear, but the element, causing 1) hemivertebra (complete) or superior zone of loose cells goes on to form the 2) wedge vertebra (partial). centrum of the vertebra, while the inferior dense Wedge vertebrae present with a height asym- zone goes on to form the intervertebral disk. metry, with one side being hypoplastic, there are

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Fig. 2. — Representation of formation failures : (A) wedge vertebra (B) Fully segmented hemivertebra (C) Partially segmented hemivertebra (D) Unsegmented hemivertebra. two pedicles. Next in severity is a hemivertebra, with the absence of one pedicle and a region of the vertebral body. Hemivertebrae may be further Fig. 3. — Representation of segmentation failures : (A) block vertebrae (B) Partially unsegmented bar. (C) combination of classified on the basis of the presence or the hemivertebra and unsegmented bar. absence of fusion to the vertebral bodies above and/or below (29). An unsegmented hemivertebra is fused to the vertebral body above and below ; a partially segmented hemivertebra is fused to the Hemivertebrae usually occur as extra spinal vertebral body either above or below ; and a fully segments and are often accompanied by an extra segmented hemivertebra is separated from the body rib. They may result from an abnormal cleavage of above and below by disk space. Hemivertebrae the primary chondrification center. Wedge vertebrae may occur at ipsilateral adjacent levels of the spine, do not present as extra segments or ribs and thus which produces significantly asymmetrical spine may involve a unilateral failure of development of growth, or one hemivertebra may be counterbal- the chondrification center (31). anced by another hemivertebra on the contralateral Anomalies tend to occur at the apex of a curve. A side of the spine in the same region, separated curve can be upper thoracic (33% of curves), lower by one or several healthy vertebrae (termed as thoracic (31%), thoracolumbar (20%), lumbar hemimetameric shift) (38,41). This anomaly occurs (11%), or lumbosacral (5%) (40). In general, thora- most commonly in the thoracic spine. columbar curves tend to have the worst prognosis The defects of segmentation are characterised by and the greatest progression, followed by lower tho- abnormal bony connections between vertebrae racic curves and then upper thoracic curves. (fig 3). These bony connections may be bilateral The ribs are formed in close association with the and symmetrical, resulting in a block vertebra. vertebrae, and it is, therefore, not surprising to have Segmentation defects caused by unilateral bony a combination of developmental abnormalities fusions are termed bars and may act as a unilateral affecting both the ribs and the vertebrae. An exten- growth tether. Occasionally, a segmentation defect sive thoracic congenital scoliosis due to mixed may span an ipsilateral formation defect, resulting vertebral anomalies associated with fused ribs may in a unilateral bar and a contralateral hemiverte- affect thoracic function and the growth of the lungs bra (24). in young children and lead to a thoracic insuffi- The third category or mixed type comprises the ciency syndrome. An imbalance in the mechanical complex anomalies that include both segmentation thrust of the ribs may also adversely affect spinal and formation errors and at first may be difficult to growth as well as the function of trunk muscles and define, as the spine is only 30% ossified at birth. the pressure within the thorax.

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However, since only the vertebral body and the when asymmetrical or more present on one side of pedicle of the vertebral arch in the malformed ver- the spine than on the other, they have the potential tebrae can be evaluated by this classification, an for asymmetrical growth in that area of the spine. evaluation of the morphology of the posterior com- Thus, fully segmented hemivertebrae with healthy, ponents has not been performed. Furthermore, it is definable disks above and below have much more difficult to evaluate the morphology of vertebral potential to cause a curvature compared with bodies in severe kyphoscoliosis, or in cases of unsegmented hemivertebrae, which are fused to the severe complex malformed vertebrae, using plain vertebrae above and below (33). The presence of AP images alone. either a bar or fused ribs is a good predictor of curve progression. Either can act as a tether, and NATURAL HISTORY the combination tends to produce even more rapid curve progression. Reports in the 1950s by Kuhns and Hormell (12) With recognition of the ‘at-risk’ types of verte- estimated that congenital scoliosis had a generally bral malformations, patients with congenital scol- benign course : only 37% of the children in their iosis can now be classified according to their risk of series had curves greater than 30° at maturity. This curve progression and the frequency of follow-up conclusion was refuted by the independent natural adjusted accordingly. Some deformities, such as a history studies by Winter et al (44) and McMaster unilateral unsegmented bar, were recommended for and Ohtsuka (26) who reviewed a combined total of treatment at time of recognition because of their 485 patients, most until skeletal maturity. They re- invariable tendency for severe progression. The ported that the rate of deterioration and the severity thoracic curves have the poorest prognosis, with of final deformity were predictable according to the the worst anomaly being a unilateral unsegmented type of anomaly and curve location. Upper thoracic bar combined with single or multiple convex curves tend to be less severe than thoracolumbar hemivertebrae, followed by a unilateral unsegment- curves, which tend to be most severe. Curve pro- ed bar, double convex hemivertebrae, and a single gression occurs more rapidly during the first 5 years convex hemivertebra, with a block vertebra having of life and, again, during the adolescent growth the best prognosis (20). period of puberty ; these two periods represent the A unilateral unsegmented bar adjacent to a con- most rapid stages of spine growth (12). tralateral hemivertebra with an average curve pro- These authors found that nearly 75% of patients gression in excess of 10 degrees per year in the tho- studied required treatment, and that 84% of racolumbar region is the most aggressive anomaly. patients who were untreated developed curves It may not be radiographically visible until it ossi- greater than 40° at maturity. For most anomalies, fies when the patient is 3 to 4 years of age. A the deterioration of the curve was steady and unre- hemimetameric shift does not always present with lenting, starting at birth, accelerating during the a balanced spine, and produces occasionally a pro- preadolescent growth spurt, and slowing or stop- gressive deformity especially in thoracolumbar and ping at skeletal maturity. Children with clinical lumbosacral junctions (20). deformities in the first year of life had the worst Block vertebrae are uncommon and tend to be the prognosis and had severe early progression. most benign anomaly producing curves of less than Curve progression is caused by unbalanced 20°. Complex curves consisting of multiple anom- growth of one side of the spine relative to the other. alies occur in 10% of cases (20). Both conditions Spine growth comes from the superior and inferior should be observed until progression is documented. end plates of each vertebral body. Thus by assess- Mixed deformities are unpredictable, and their ing the quality of the disks surrounding the anom- severity depends on the amount of unbalanced alous segment of the spine, growth potential may growth potential. The combination of mixed defor- be inferred. Radiographically definable disks signi- mities and rib anomalies can lead to a global loss of fy the presence of vertebral growth plates and, trunk and thoracic height and width, resulting in

Acta Orthopædica Belgica, Vol. 74 - 2 - 2008 CONGENITAL SCOLIOSIS 151 severe volume and motion restriction leading to include dermoid cysts, epidermoid cysts, ter- respiratory failure. atomas, and lipomas as well as tethered spinal cord and they may all need treatment prior to spinal ASSOCIATED SURFACE DEFORMITY surgery to minimise risk of subsequent neural injury. With such a high incidence of associated A cosmetic deformity occurs with most curves. intraspinal anomalies, routine MRI screening of In upper thoracic curves, elevation of the shoulder patients with congenital scoliosis has been suggest- on the convexity of the curve, with tilting of the ed (4). The specific indications for MR imaging for head into the concavity, may be seen. Structural possible intraspinal anomalies in congenital scolio- congenital curves tend to have only a mild rota- sis include : the presence of neurological defects tional component ; thus, they produce only a mild such as weakness, sensory loss, bowel or bladder rib hump. Unbalanced curves in the lower thoracic dysfunction ; an associated skin abnormality over region and the lumbar region produce a pelvic the spine such as a dimple, hairy patches, or nevi ; obliquity with apparent shortening of the leg on the complaints of back or leg pain ; patients with lum- concave side of the curve. The trunk tends to list brosacral kyphosis ; radiographic evidence of inter- away from the apex of the curve, and this can cause pedicular widening, diastematomyelia or presence difficulty in ambulation and balance. of a unilateral congenital bar with a contralateral hemivertebra ; and any patient who is to undergo ASSOCIATED ANOMALIES spinal stabilisation surgery (4). Another important aspect of congenital scoliosis Unrecognised abnormalities of the renal system is the recognition of the presence of concurrent may be present in 25 to 33% of patients and include abnormalities of the spinal cord, the kidneys, and unilateral horseshoe kidney, renal agenesis, the heart, which may be present in 61% of patients duplicated kidney/ureters and hypospadias (13). All and in an even higher percentage in patients with patients with congenital scoliosis warrant a renal mixed defects (2). There is some evidence in the lit- evaluation by either intravenous pyelogram or renal erature to support the development of organ mal- ultrasound/MRI. formations at the body segment at which vertebral Congenital heart disease is present in 10% of malformations occur. The developmental field con- patients, ranging from atrial and ventricular septal cept described by Opitz (32) is useful in providing a defects, which are the most common abnormalities, framework for understanding multisystem involve- to complex congenital heart defects, such as ment and a defect in one system should prompt tetralogy of Fallot and transposition of the great evaluation of others. vessels. A screening echocardiogram and cardio- Neural axis abnormalities are present in up to logic evaluation is needed for patients under- 35% of patients, as detected with MRI, patients going surgical correction for a congenital spine with mixed or segmentation defects being at high- deformity. est risk (5). These abnormalities include (but are not The development of restricted pulmonary func- limited to) diastematomyelia (split cord), cord teth- tion is a concern. Recent studies imply that curve ering, Chiari malformations, and intradural lipo- magnitude directly affects pulmonary function, but mas. The absence of cutaneous signs of dysraphism the development of restrictive lung function occurs and the absence of neurological deficit do not rule only as the curve approaches 90° (30). Severe out an intraspinal dysraphism. Diastematomyelia curves in young children tend to produce the most is found in up to 20% of patients with congenital severe pulmonary compromise. This restriction scoliosis and should be treated by resection before may be due more to hypoplastic lung development proceeding with corrective surgery of the spine than to a physical constriction from the curve ; because of the risk of stretching the spinal cord alveolae continue to develop in the growing child tethered at the site of the anomaly (46). Other up to 8 years of age. Vital capacity screening is rec- lesions of the cord seen in congenital scoliosis ommended for patients with severe curves.

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Musculoskeletal anomalies occur frequently in thoracic insufficiency syndrome (10). In young chil- association with congenital spine anomalies. dren, the Adams forward bending test (looking for Disorders, such as clubfeet, Sprengel deformity, prominence of the ribs in the thoracic spine or Klippel-Feil deformity, developmental dysplasia transverse processes in the lumbar spine) is not of the hip, and upper and lower limb deformities possible, but the test can be simulated by laying the warrant a detailed evaluation and management child in a prone position over the knee of the exam- prior to spinal surgery. iner. Curve flexibility can be assessed by placing Vertebral malformations have been shown to be the child in a lateral position over the knee of the associated with hemifacial microsomia, Alagille, examiner or by suspending the infant over the arm Jarcho-Levin, Klippel-Feil, Goldenhar, Joubert, of the examiner. and VACTERL syndromes as well as basal cell Spinal balance in both the coronal and the sagit- naevus, trisomy 18, and diabetic embryopathy (3). tal planes must be evaluated. Truncal imbalance, head tilt, shoulder inequality, and pelvic balance CLINICAL AND RADIOGRAPHIC should be addressed. Photographs serve as an ASSESSMENT important aid in sequential evaluation of progress. Given the association of neural axis abnormalities Clinical Evaluation and the possibility of neurological compromise in congenital spine deformities, a detailed motor, sen- Clinical evaluation begins with a comprehensive sory and reflex examination, (including abdominal history and physical examination. A prenatal histo- reflexes) is mandatory. Muhonen et al (29) ry of the mother, including all health problems, pre- described the absence of an abdominal reflex as the vious pregnancies, and medications, is recorded. only objective finding seen in some patients with a Birth history of the child should include details Chiari malformation. When the results of reflex such as length of gestation, type of delivery (vagi- testing are abnormal, the reflex is usually absent on nal or caesarean), birth weight, and complications. the convex side of the curve. Given that the presence of cognitive delay has been The vital capacity of patients with congenital shown to correlate with curve progression in some scoliosis has been compared with those with idio- patients, particular attention should be paid to pathic scoliosis. For any given Cobb angle the loss whether the child has appropriately reached devel- in vital capacity was approximately 15% greater in opmental milestones (10). congenital compared with idiopathic scoliosis. This The physical examination should start with the greater impairment in lung function in congenital height and the weight of the patient, given that scoliosis has been proposed to be due to the associ- growth plays a significant role in curve progres- ated rib deformity or to an underlying lung anom- sion. The skin must be examined for abnormalities aly (30). Vital capacity screening has been recom- such as “café au lait” spots or axillary freckles as mended for patients with severe curves. A full seen in neurofibromatosis and midline patches of spirometry work-up is recommended if surgery is hair for any evidence of spinal dysraphism. Spinal planned for those with a vital capacity < 60% of dysraphism may also manifest itself in the lower normal (30). extremities, and signs would include asymmetrical calves, cavus feet, clubfeet, vertical tali, and abnor- RADIOGRAPHIC ASSESSMENT mal neurological findings. The spinal examination itself focuses on any evidence of truncal or pelvic Plain radiographs remain standard for diagnosis imbalance. Rib cage deformities, chest or flank of congenital anomalies and measuring curve mag- asymmetry, chest excursion and anomalies need to nitude, progression and perhaps growth potential of be evaluated, as does the inspiratory and expiratory the vertebral anomaly. Conventional radiography capacity of the chest wall. Limitation in chest often is difficult to interpret because of the patient’s excursion may indicate a syndromic scoliosis and small size, the complex nature of the deformity,

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Magnetic resonance imaging (MRI) has had a revolutionary impact on imaging the neural axis and its role has been widely studied and documented in patients with congenital scoliosis and spinal dysraphism (4). The prevalence rate of spinal dysraphism detected using MRI approaches 30% in patients with congenital spine deformities. Imaging of the brainstem to the bottom of the sacrum is required to exclude associated conditions of the spine, the cranio-cervical junction and the viscera. In our institution, we perform coronal T1, sagittal T1 and T2 weighted scans through the whole spine with axial gradient echo images through the cervical spine and T2 weighted images through the apex of the curve and through the lumbar spine. The coronal T1 weighted images are useful for demon- Fig. 4. — Preoperative three-dimensional reconstructed com- strating if the cord is single and for assessing the puted tomography scan defines the anatomy of the curve and shape of the scoliosis. may aid in the positioning of the implants. MANAGEMENT superimposed structures obscuring visualisation of The skill in managing a patient with a congeni- the anomaly, and spine deformity in a plane other tal spine deformity lies not only in the ability to than that of the radiograph. perform major complex salvage surgery in patients Preoperative CT scan helps define the anatomy presenting at a late stage with a severe rigid defor- and avoid any unexpected intraoperative posterior mity, but in recognising those curves with a bad element deficiencies (fig 4). The combination of 3- prognosis at an early stage to prevent curve pro- D images and 2-D coronal and sagittal multiplanar gression and possible neurological complications. reformatted CT images curved to match the con- Meticulous management planning requires an tour of the spine can be extremely beneficial in the astute knowledge of the natural history of all types assessment of hemivertebrae for which it is diffi- of congenital spine deformity and the methods of cult to determine the degree of segmentation or the treatment that are available. Once high-risk anom- presence of a contralateral unsegmented bar by alies such as unilateral unsegmented bars with con- plain radiography or 2-D CT imaging. We obtain tralateral hemivertebrae are recognised, treatment CT with 3-dimensional reconstructions for preop- is initiated regardless of age to prevent deformity. erative assessment and evaluation of complex deformities, but not for routine observation or seri- NON-SURGICAL TREATMENT al documentation. Computed tomography scan helps in evaluation Congenital vertebral anomalies can be recog- of chest wall deformity and lung volume in con- nised fortuitously on radiographs of infants before genital deformities with chest wall anomalies, clinical deformity develops. Both these and chest deformity, or thoracic insufficiency. The use patients diagnosed later in life should be followed of 3-D CT data to define lung volumes in patients carefully at 4 to 6 month intervals until the end of who were too young for pulmonary function tests growth. The goals of observation are to recognise has been described and subsequently used to mea- the presence of vertebral anomalies, which require sure improvement in lung function following immediate treatment, and to detect the progression expansion thoracoplasty (18). of curves.

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Bracing (4) Carefully monitored use of controlled hypoten- sion to minimise blood loss to prevent the Bracing plays a very limited role in the manage- occurrence of cord ischaemia, especially dur- ment of congenital scoliosis, especially as a prima- ing any corrective manoeuvres. ry form of treatment because these curves are typi- (5) Motor- and sensory-evoked potential monitor- cally inflexible.Less than 10% of congenital curves ing, supplemented by a wake-up test in cases can be treated by bracing. Bracing is sometimes with intraoperative changes in neurological used to prevent progression of secondary curves monitoring that do not return to baseline. that develop above or below the congenital curve (6) The postoperative monitoring of a patient’s and are causing balance problems. The Milwaukee neurological status, given that paraplegia after brace is the brace of choice for upper curves. deformity surgery may present in a delayed A TLSO (thoracic/lumbar/sacral orthosis) brace is fashion, especially in the first 72 hours (28). adequate for lumbar curves. The optimum duration (7) Early and aggressive treatment of deformities of daily brace wear is still under investigation. before they become severe. As long as the curve remains controlled, treatment The procedures are broadly divided into (a) should continue until skeletal maturity. The those preventing further deformity and (b) those brace may not arrest or correct development of the that correct the present deformity ; with the latter curve, but it may slow progression and maintain type further subdivided into techniques that correct flexibility, allowing surgery at a later age. Bracing the curve gradually and those that correct the curve serves no function in short, sharp, rigid curves. acutely.

Prevention of Future Deformity SURGICAL TREATMENT In Situ Fusion Principles of surgery In situ fusion is a safe technique and a good choice for many progressive curves with minimal As a guiding principle, it has been widely recog- deformity involving a relatively short section of the nised in studies that it is easier to prevent a defor- spine. mity than allow it to progress and attempt correc- It is ideally done in patients with unilateral tion at a later stage (17). The goal of surgery is to failure of segmentation such as a unilateral achieve a straight spine, a physiological sagittal unsegmented bar and should be accomplished very profile while maintaining flexibility, to arrest pro- early, before a significant curve develops, which gression of the curve and as short a fusion segment would then make a more extensive correction nec- as possible, preserving as much normal spinal essary. growth as possible. The risk of neurological injury A patient with no trunk imbalance with a curve with surgical treatment of patients with congenital less than 40 degrees not requiring substantial cor- spinal deformities is greater than in patients with rection is best fused in situ without instrumentation idiopathic spinal deformity (34). The occurrence of with some modest correction by postoperative cast- a perioperative neurological deficit may be min- ing (17). One of the major controversies surround- imised in multiple ways by : ing in situ fusion is whether a combined anterior (1) A routine use of MRI evaluation of the spinal and posterior fusion is required (24). There is less cord. potential for anterior growth in a spine with con- (2) Earlier treatment of a spinal cord anomaly. genital scoliosis because the growth plates may not (3) Preventing lengthening the spinal cord intraop- be properly formed. In an in situ fusion for con- eratively by avoiding distraction and using genital scoliosis, a shorter segment is fused and shortening procedures. there is less rotation in the segment, which makes a

Acta Orthopædica Belgica, Vol. 74 - 2 - 2008 CONGENITAL SCOLIOSIS 155 true crankshaft phenomenon (continued anterior cation was curve progression in one patient. More growth in presence of posterior fusion) unlikely. predictable alternatives to convex hemiepiphysio- McMaster (25) and Winter and Moe (43) recom- desis for a short segment deformity include mended an early prophylactic in situ fusion to pre- hemivertebra excision or wedge resection, and vent the unbalanced growth of the spine in a unilat- growth-oriented procedures, such as VEPTR eral unsegmented bar, with or without contralateral (Vertical expandable prosthetic titanium rib) or hemivertebrae with best results reported before the growing rods, when a longer segment of spine is age of two years. A convex growth arrest procedure involved. or simply dividing the unsegmented bar will not Hemivertebra excision correct this type of deformity because there is no growth potential in the unsegmented bar on the A hemivertebra causing marked truncal imbal- concavity of the curve. This usually necessitates a ance and progression of the curve can be managed combined anterior and posterior fusion to control with wedge resection in patients whom an isolated the severe spinal growth imbalance in these in situ fusion or convex epiphysiodesis would not patients. The argument that an early spine fusion result in a balanced spine. It is best performed at will stunt the growth of the spine in these young approximately 2 years of age when the child can patients is of no relevance because the unsegment- still tolerate a cast and fusion is more likely. It ed bar is not contributing to vertical height and only offers nearly complete correction over a short making the spine more crooked. fusion segment and may be performed via anterior- The decision regarding which curves may be posterior surgery or posterior-only surgery (19).To fused in situ can be complex. The location of the close the gap after resection of the hemivertebra, curve and likelihood of progression and the impact compression instrumentation is necessary and of the curve on the balance and cosmetic appear- allows for strong fixation into adjacent vertebrae. ance of the child must be taken into account. Ruf and Harms (35) previously argued that hemiver- Deformities at the lumbosacral and cervicothoracic tebra resection via a posterior-only approach with junction are more likely to lead to cosmetically dis- transpedicular instrumentation was the ideal proce- figuring deformities and therefore should be fused dure for correction in young children. They opined in situ very early or alternate treatments considered. that this methodology was not only less invasive but also prevented the development of secondary Convex hemiepiphysiodesis curves and severe local deformities. It is indicated for a unilateral formation failure Suk et al (39) also support the use of a posterior- i.e. hemivertebra. Because there must be adequate only approach, arguing that the combined approach growth potential on the concave side, this proce- requires prolonged operative time, and that when dure is contraindicated in segmentation defects, used in the treatment of lumbosacral deformity, it such as bars that have no potential for concave poses a risk to the anterior vascular and visceral growth. The epiphysiodesis is done by removing structures. Consequently, based on their retrospec- the convex lateral half of disks adjacent to the tive review of treatment of fixed lumbosacral defor- hemivertebra, with no exposure of the spine on the mity with posterior vertebral-column resection, concave side. Winter et al (42) suggest that this pro- they maintained that this technique offers the cedure should be reserved for patients younger than advantages of single-stage surgery, the ability to 5 years of age, with a progressive curve of address the deformity at the apex, and of controlled < 70 degrees involving 5 segments or less, and pre- shortening across the resection gap. senting with a pure scoliosis not involving the cer- Bollini et al (5) on the other hand advocate a vical spine with no major kyphosis or lordosis. In combined anterior and posterior fusion because of their series, 38% of patients had an average correc- greater correction capabilities, including correction tion of 10 degrees, 54% had a stabilisation effect in the sagittal plane secondary to disc excision. without significant correction, and the only compli- This approach gives better visualisation of the

Acta Orthopædica Belgica, Vol. 74 - 2 - 2008 156 S. BATRA, S. AHUJA anatomy including the spinal column and nerve achieved acutely at the time of the initial proce- roots, as well as affording the surgeon the opportu- dure, thus postoperatively,a corrective cast is used nity to apply a corrective force to the spine from an to encourage fusion of the spine in a somewhat cor- anterior position while simultaneously applying rected position, which will therefore improve the compressive instrumentation. It also decreases the starting point and permit the ultimate correction to likelihood of pseudoarthrosis and prevents the rely less on the growth of the spine The total cor- development of crankshaft phenomenon by the rection obtained by performing a convex hemiepi- removal of the growth plates (6). The procedure is physiodesis varies because the younger the child at best performed in the thoracolumbar junction or the time of the operation, the more potential that lower because the spinal cord in the thoracic spine exists for correction over time. is not as amenable to manipulation, but this view Growing Rods has been recently refuted (11). Single and Dual Growing Rods Correction of the present deformity The growth of the spine is greatest during the Gradual correction is obtained through the use first 5 years of life as sitting height reaches two of a hemiepiphysiodesis and/or hemiarthrodesis of thirds of the adult level by age 5, while thoracic the spine. Immediate or acute correction may be volume reaches 30% of the adult size by five years accomplished through several different techniques : of age. Congenital scoliosis is associated with short excision or decancellisation of the hemivertebra stature and diminished trunk height. Long fusions and definitive or staged instrumentation using a performed on younger children may have a further growing rod. For patients with thoracic insufficien- deleterious effect on trunk height and thoracic vol- cy syndrome, expansion thoracoplasty and stabili- ume, leading to thoracic insufficiency. In the sation via the VEPTR addresses this issue by rib absence of congenital rib fusions, early progressive distraction on the concave side of the curve. For deformities may best be managed using a growing fixed deformities, it may be necessary to perform rod technique, pioneered by Paul Harrington (43) in an osteotomy to balance the spine and correct the the 1960’s. If the child is still very young, the pri- cosmetic deformity. mary congenital curve can be treated with fusion in Gradual correction situ, hemiepiphysiodesis and/or hemiarthrodesis, excision, or osteotomy, and the corrected curve can Hemiepiphysiodesis and Hemiarthrodesis then be treated with a growing rod until the child is These techniques are used for failure of forma- older. This avoids fusing the entire curve, which tion, relying on the future growth of the spine on will lead to growth retardation and potentially the concave side. In segmentation failure, there is harmful pulmonary effects. no potential for growth to occur. The procedure is The goals of treatment have been to achieve cor- unlikely to correct curves with low concave growth rection of the spinal deformity without extensive potential such as those due to a convex hemiverte- fusion, maintain correction during the subsequent bra opposed by a concave unsegmented bar (41). growth period, allow spinal growth and lung devel- Dubousset (14) has contributed much to growth opment, and avoid or eliminate the need for defini- arrest procedures of the spine by pointing out the tive fusion of the spine at an early age. relationship between sagittal and coronal growth Akbarnia and McCarthy (1) reported their series disturbance of the spine with congenital deformity of a dual growing rod construct due to problems and how mechanical instability must be considered associated with a single-rod implant, including in the treatment. The goal is to arrest the growth on hook dislodgement and rod breakage. This is per- the convex side of the curve ; the concave side of formed by subperiosteal dissection of the anchor the spine is not exposed surgically, as doing so sites proximally and distally and by placement of could lead to spontaneous fusion. Much of the cor- claw constructs. Rods are then placed subcuta- rection associated with hemiepiphysidesis is neously on each side and joined with tandem con-

Acta Orthopædica Belgica, Vol. 74 - 2 - 2008 CONGENITAL SCOLIOSIS 157 nectors placed at the thoracolumbar junction, intraspinal abnormalities must be dealt with prior where the lengthening may occur. An apical fusion to the instrumentation procedure. Computed involving the congenital anomaly may be needed ; tomography with three-dimensional reconstruction this will obtain control of the apex of the curve and, is very helpful for the assessment of local anatomy if a hemiepiphysiodesis and/or hemiarthrodesis has and as an aid in pre-operative planning. been performed, will possibly permit improvement The safe use of traction in congenital spine of the apical curvature with growth. deformities, particularly in cases involving However, apical fusion is a must if the apical preexisting neurological deficits, was questioned in curvature is due to failure of segmentation. Their past reports by MacEwen et al (22) due to the risk patients showed an average Cobb angle improve- of traction-induced paraplegia in congenital defor- ment from 82 to 38 degrees at follow-up and an mities. Recently, the use of traction has been popu- average growth of the T1-S1 segment of 1.2 cm per larised for severe deformities, including congenital year. deformities (34).Rinella et al (34) reported the use of Halo gravity traction which can be applied in bed Acute Correction Techniques or while in a wheelchair or walker device allowing Correction and Fusion with Instrumentation for gradual curve correction before or following an The partial or complete correction of a deformity associated anterior release. depends on the congenital anomaly itself and the Hemivertebra excision degree of deformity. The choice of fusion levels is difficult when there are multiple noncontiguous Hemivertebra excision may be an ideal proce- anomalies but the aim should be to achieve a bal- dure for long standing curves with significant anced spine with the safest possible correction. The deformity or truncal imbalance. The ideal indica- whole curve needs to be fused, but there may be tion is a hemivertebra at the lumbosacral junction, abnormal segments cephalad or caudad to the curve as this particular deformity often leads to major that will not be included or two curves may need to imbalance or very serious compensatory curves. be included in the instrumentation. High thoracic It is possible to combine this procedure with a and cervical curves need special precaution as convex hemiepiphysiodesis and/or hemiarthrode- overcorrection of a lower thoracic or thoracolum- sis, with use of a nonfusion rod or a definitive bar curve may lead to shoulder imbalance or neck instrumentation of a longer curve. The excision of obliquity. Congenital anomalies associated with a hemivertebra may be performed by using com- relatively normal segmentation, flexibility (as bined anterior and posterior procedures. Posterior- revealed by radiographs), and less severe truncal only hemivertebra excision in growing children has deformity may be managed by means of a standard recently been reported with successful results. Ruf posterior arthrodesis and instrumentation. Those and Harms (35) reported their results on hemiverte- cases with well-defined disk spaces seen on imag- bra excision using a posterior-only approach and ing imply significant remaining growth ; these segmental transpedicular instrumentation. They patients may be at risk of a crankshaft phenomenon reported excellent results in patients younger than and should have in addition anterior surgery in the 6 years, with an average Cobb measurement of form of either an open or a thoracoscopic anterior 45 degrees. At 3.5 years follow-up, the Cobb mea- release and fusion. The amount of correction surement had been maintained at 14 degrees, with obtained by instrumentation in congenital scoliosis no patient having a neurological complication. is usually much less than that obtained in idiopath- Reconstructive osteotomy ic scoliosis and one should not attempt to gain dra- matic correction of large, stiff congenital curves. Pelvic obliquity, severe truncal decompensation, Complications of treatment have declined as expe- progressive deformity, and developing neurological rience has increased with the most common prob- deficit are indications for reconstructive osteo- lem being progression of the curve. Occasionally, tomies. They are considered for fixed curves with

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poor thoracic and lung parenchymal development with inability to support normal lung function and growth. The tethering effect of congenital rib fusions add to the scoliotic effect of the spine to produce a concave, constricted hemithorax, which is diminished in height and function. The growth of the lung, the respiratory tree, and the alveoli cell multiplication are greatest in the first 8 years of life. Fifty percent of the thoracic volume is attained at 10 years of age ; thus, early fusions may have an even more profound effect on thoracic development than on spine height. Having borderline pulmonary capacity at the end of growth can be a serious risk factor for developing respiratory insufficiency in late adulthood because approximately 400 cc’s of vital capacity is lost in the normal aging process and even further losses may occur from obstructive respiratory disease or infection. The possible effect of early spinal fusion on thoracic development may compound the preexisting thoracic insufficiency associated with congenital scoliosis and fused ribs (8). In children with congenital scoliosis and severe curve progression early surgical curve stabilisation Fig. 5. — Postoperative radiograph of a four-year-old boy with was based on the belief that ‘a short straight spine a volume-depletion deformity resulting from fused ribs and is always preferable to a long crooked one’ (21). congenital scoliosis. The VEPTR stabilisation expansion Therefore, early posterior or combined anterior and thoracoplasty lengthened and widened the constricted posterior spinal fusion, convex anterior epiphy- hemithorax, corrected the scoliosis indirectly without growth inhibition, restored truncal balance, and corrected pelvic seodesis or arthrodesis has been performed in the obliquity. past (23). The total growth inhibition effect on the thoracic spine due to these procedures was thought to be negligible because of the assumption of unacceptable cosmesis and cannot be successfully diminished growth potential of the concave managed with procedures described so far. An side (21). A recent study (7) challenged this assump- osteotomy may be part of a combined approach tion by showing an increase in length of the unilat- that involves resection of the hemivertebra and eral unsegmented bars and equal increases in instrumentation and fusion of a more extended length of the concave and convex sides of the tho- curve. A cosmetically displeasing but well bal- racic spine in children with congenital scoliosis, anced curve is probably best treated with stabilisa- unilateral fused ribs and unsegmented bars treated tion alone. by VEPTR. The surgical concept of the expansion thoracoplasty and stabilisation with the VEPTR EXPANSION THORACOPLASTY implant is based on the expansion of the thorax by AND VEPTR rib distraction on the concave side of the curve achieving indirect correction of the curve (fig 5). Congenital spine deformities with rib fusions Spinal fusion may be necessary once skeletal matu- may be associated with thoracic insufficiency, a rity is reached and thoracic spinal growth is no term coined by Robert Campbell et al (8) to explain longer an issue.

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DIRECTIONS FOR FUTURE WORK 4. Belmont PJ Jr, Kuklo TR, Taylor KF et al. Intraspinal anomalies associated with isolated congenital hemiverte- Congenital scoliosis remains an interesting and bra : the role of routine magnetic resonance imaging. J Bone Joint Surg 2004 ; 86-A : 1704-1710. challenging diagnostic entity. Developments in 5. Blake NS, Lynch A, Dowling F. Spinal cord abnormalities gene research continue to be promising and may in congenital scoliosis. Ann Radiolol 1986 ; 29 : 237- potentially lead to early detection of congenital 241. vertebral malformations. It is likely that different 6. Bollini G, Docquier P, Viehewger E et al. Lumbosacral approaches will enable an elucidation of the genet- hemivertebrae resection by combined approach. Spine 2006 ; 31 : 1232-1239. ic and environmental basis of CS. Since CS is due 7. Campbell RM, Hell-Vocke AK. Growth of the thoracic to localised alterations in vertebral body develop- spine in congenital scoliosis after expansion thoracoplasty. ment as opposed to a more widespread distribution J Bone Joint Surg 2003 ; 85-A : 409-420. of vertebral malformations, a model needs to be 8. Campbell RM Jr, Smith MD, Mayes TC et al. The char- developed that incorporates position identity and acteristics of thoracic insufficiency syndrome associated failure of segmentation. The association of renal, with fused ribs and congenital scoliosis. J Bone Joint Surg 2003 ; 85-A : 399-408. cardiac, skeletal and spinal cord malformations 9. Cobb JR. Scoliosis – quo vadis ? J Bone Joint Surg 1958 ; with CS may reflect the involvement of different 40-A : 507-510. genes that are associated with developmental path- 10. Conner AN. Developmental anomalies and prognosis in ways in several organs. Epidemiologic studies can infantile idiopathic scoliosis. J Bone Joint Surg 1969 ; provide assistance in determining whether various 51-B : 711-713. 11. Deviren V, Berven S, Smith JA et al. Excision of environmental factors contribute to CS. hemivertebrae in the management of congenital scoliosis John Cobb (9) wrote in 1958 that “In the future involving the thoracic and thoracolumbar spine. J Bone study of scoliosis it will be necessary to keep our Joint Surg 2001 ; 83-B : 496-500. eye on the patient and not on the curve.” Important 12. Dimeglio A. Growth in pediatric orthopaedics. J Pediatr issues to be addressed in the future about thoracic Orthop 2001 ; 21 : 549-555. 13. Drvaric DM, Ruderman R, Coonrad R et al. Congenital insufficiency syndrome and VEPTR include char- scoliosis and urinary tract abnormalities. J Pediatr Orthop acterisation of the natural history of the thoracic 1987 ; 7 : 441-443. insufficiency syndrome by anatomic classification, 14. Dubousset J. The Pediatric Spine : Principles and correlating progressive three-dimensional thoracic Practice, Raven press, Ltd, New York, 1994 ; pp 245-257. deformity with the onset of respiratory insufficien- 15. Erol B, Tracy MR, Dormans JP et al. Congenital scoliosis and vertebral malformations : characterization cy and whether the procedure can halt or reverse of segmental defects for genetic analysis. J Pediatr Orthop progressive three-dimensional thoracic deformity 2004 ; 24 : 674-682. after the onset of respiratory insufficiency. 16. Farley FA, Hall J, Goldstein SA. Characteristics of Furthermore, continued advances in surgical tech- congenital scoliosis in a mouse model. J Pediatr Orthop nique and instrumentation will provide surgeons 2006 ; 26 : 341-346. with an array of safe and efficacious modalities for 17. Hall JE, Herndon WA, Levine CR. Surgical treatment of congenital scoliosis with or without Harrington instrumen- these patients with complex conditions. tation. J Bone Joint Surg 1981 ; 63-A : 608-619. 18. Hedequist D, Emans J. Congenital scoliosis. J Am Acad REFERENCES Orthop Surg 2004 ; 12 : 266-275. 19. Hedequist DJ, Hall JE, Emans JB. Hemivertebra exci- 1. Akbarnia B, Marks DS, Boachie-Adjei O et al. Dual sion in children via simultaneous anterior and posterior growing rod technique for the treatment of progressive exposures. J Pediatr Orthop 2005 ; 25 : 60-63. early-onset scoliosis : a multicenter study. Spine 2005 ; 20. Kuhns JG, Hormell RS. Management of congenital scol- 30 : S46-S57. iosis. Review of one hundred seventy cases. Arch Surg 2. Basu PS, Elsebaie H, Noordeen MH. Congenital spinal 1952 ; 65 : 250-263. deformity : a comprehensive assessment at presentation. 21. Letts R, Bobechko W. Fusion of the scoliotic spine in Spine 2002 ; 27 : 2255-2259. young children. Effect on prognosis and growth. Clin 3. Beals R, Rolfe B. Current concepts review VATER associ- Orthop 1974 ; 101 : 136-145. ation : a unifying concept of multiple anomalies. J Bone 22. MacEwen GD, Bunnell WP, Sriram K. Acute neurolog- Joint Surg 1989 ; 71-A : 948-950. ical complications in the treatment of scoliosis. A report of

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