The pathogenesis of idiopathic scoliosis. Biplanar spinal asymmetry

Abstract

A clinical, cadaveric, biomechanical and radiological investigation of the pathogenesis of idiopathic scoliosis indicates that biplanar asymmetry is the essential lesion. Many normal children have coronal plane asymmetry (an inconsequential lateral curvature of the spine), and certainly all have vertebral body asymmetry in the transverse plane, but when median plane asymmetry (flattening or more usually reversal of the normal thoracic kyphosis at the apex of the scoliosis) is superimposed during growth, a progressive idiopathic scoliosis occurs. Idiopathic kyphoscoliosis cannot and does not exist, from the mildest cases in the community to the most severe cases in pathology museums. Median plane asymmetry is crucial for progression and the lateral profile of the spine must be carefully scrutinised. Increased anterior vertebral height at the apex of the curve with posterior end-plate irregularity characterises the median plane asymmetry and suggests that idiopathic scoliosis is the reverse of Scheuermann's disease.

Biomechanical simulations of the spine deformation process in adolescent idiopathic scoliosis from different pathogenesis hypotheses

“…The initial altered profile used to trigger the deformation process was obtained by imposing on the reference configuration a geometrical eccentricity representing the corresponding initiating hypothesis. The tested eccentricities included 3 mm linear shifts in the frontal (PA) [39] or in the sagittal (Lat) [27] plane (equivalent to a Cobb angle of 2°), 2°rotational shift in the transverse plane (Rot) [6,16,21,24] and combinations Lat-PA and Lat-Rot [12,18]. The initial altered profile was generated only for the first step, by simulating imposed eccentricities in the global axis system at the eighth thoracic vertebra, which was assumed to be the apical vertebra of the (future) scoliotic curve.…”

“…Similarly, Sommerville [27] suggested that the deformity consists of a structural lordosis consequent to a failure of growth of the posterior elements. Other theories state that the deformity results from a reduction of the thoracic kyphosis in a fixed structural lordotic area, which under the influence of transverse or coronal plane asymmetry, rotates to the side and gives rise to a lateral curvature [12,18]. White [39] observed the presence of a slight physiological thoracic curve, thus he associated the prime scoliotic lesion with the precarious coronal balance of the spine and consequent asymmetrical loading of vertebrae, which might rotate into the convexity of the curve.…”

Cervical spine sagittal alignment variations following posterior spinal fusion and instrumentation for adolescent idiopathic scoliosis

“…The sagittal profile often deteriorates when the Harrington technique is used. The consequences include a flat back, an angular increase of lumbar lordosis below the fusion level and low back pain [4][5][6][7][8][9].…”

Efficacy of exercise therapy for the treatment of adolescent idiopathic scoliosis: a review of the literature

“…Patients were allowed to choose between two study groups [1], scientific exercises approach to scoliosis (SEAS) group or [2] usual physiotherapy (PT) group. There were 35 patients in the SEAS group and 39 patients in the PT group all of whom were followed up at 6 and 12 months.…”

“…The exact aetiology of adolescent idiopathic scoliosis (AIS) is unknown [1][2][3] but is deemed to be multi-factorial and includes genetic predisposition, imbalance between anterior and posterior spinal growth, abnormalities in connective tissue, skeletal muscle, muscle contractile mechanisms and neurology. While surgery is a well-recognised treatment of AIS, the role of conservative therapies including exercises, physiotherapy, intensive rehabilitation programmes and bracing has been the source of much debate [4].…”