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 hospi- tal, 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 Acta Orthopædica Belgica, Vol. 74 - 2 - 2008 CONGENITAL SCOLIOSIS 149 Fig. 2. — Representation of formation failures : (A) wedge vertebra (B) Fully segmented hemivertebra (C) Partially seg- mented 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. Acta Orthopædica Belgica, Vol. 74 - 2 - 2008 150 S. BATRA, S. AHUJA 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