Idiopathic Scoliosis

Overview

Idiopathic scoliosis is the most common type of scoliosis. The child is otherwise healthy. The curve develops during growth.

Classifications

• Early onset Scoliosis: Less than 10 years can be sub classified into Infantile (0-4years) and Juvenile (4-9years).
• Adolescent: (2^nd growth spurt)

Prevalence: 2% of growing children have curve greater than 10°, 0.3% will have curves greater than 20°, and 0.2% will have curves greater 30°. More than 80% of cases are the adolescent type.

Etiology: unknown, multi-factorial; hereditary factors and tends to run in families with females more affected than males

Presentation: Idiopathic scoliosis is painless condition. Rule out any possible causes for scoliosis, neurofibromatosis, Marfan, neuro-muscular conditions, congenital, before reaching the diagnosis of idiopathic scoliosis. A complete neurological examination -asymmetrical abdominal reflex will indicate a possible intra-spinal lesion. Observe curve pattern, flexibility, rotation, and trunk decompensation

Imaging Studies:

• Radiographs: AP (front to back) & Lateral (Side to side). Standing on 3 feet long film (side bending views are indicated to prepare for surgery to check the flexibility of the curve. They are done in a forced supine position)
• MRI is obtained to rule out brain or spinal canal abnormality (tethered cord, syringomyelia, diastomatomyelia, tumors). Therefore, it is indicated in cases with unusual curves (left thoracic curve), and in cases with abnormal neurological exam. Routine MRI for Idiopathic scoliosis is unnecessary and costly.
• Pulmonary function tests: obtained before surgery for the patients, who have pulmonary symptoms, and in curves higher than 90°. Reduction of vital capacity to 60% of normal is considered significant, which might increase the risks of surgery. With good hospital support team, surgery can be done for vital capacity as low as 30% of normal.

EARLY ONSET IDIOPATHIC SCOLIOSIS

Infantile Scoliosis

More than 80% will resolve spontaneously (Etiology: Positional). Boys>girls and most curves are left thoracic and thoracolumbar. Pulmonary compromise occurs in progressive thoracic curves

Management:

• Curve progression: Serial casting has been shown to arrest progression if applied early and can be followed by bracing.
• Surgery: Insertion of growing rods with extension procedure every 6 to 8 months. (The final fusion is done as near maturity as possible.
• MAGEC Rods are implantable spinal rods with magnetic device that can communicate with external remote controller for non-invasive adjustment performed as an outpatient procedure every 3 to 4 months.

Juvenile Scoliosis:

• 70% will progress (long interval to maturity)
• MRI, for very young patient and for fast progressing curve (R/O intra-spinal cause)

Management:

• Bracing: this is for curves greater than 25° (wear schedule depends on curve behavior)
• Surgery: this is for curves greater than 25°
• Curves greater than 40°: for the very young, growing rods are advised. For the older child, anterior and posterior fusion to prevent crankshaft deformity

Summary: Early onset Idiopathic Scoliosis

Growing rod technique: A limited fusion with long instrumentation as indicated for infantile and Juvenile curves apply here

• Most of the correction obtained at initial procedure
• Repeat lengthening every 6 months to prevent stiffening
• Average growth approximates 1cm per year during program
• High rate of implant related complications
• Kyphosis a common occurrence at the proximal junctional level
• Final fusion at pre puberty or early adolescence
• Posterior fusion for mild residual curves

Consider anterior posterior for large residual curves with severe rotational deformity to prevent continued growth and crankshaft

ADOLESCENT IDIOPATHIC SCOLIOSIS

Progression depends on: Curve magnitude and stage of maturity

• Natural history of curve progression:

Risk of progression (Bunnell 1986) in an immature patient, a 20° is 20%, 30° is 60%, 50°is 90%

• Risk of progression in relation to Risser sign (Lonstein 1984)

• Definition of maturity is by the:
  • Risser sign: R1 is around the time of menarche (menstruation). The peak of growth spurt occurs before R1. R2-4 is slow period of growth (slow progression)
  • Tanner classification: five stages (0-5) of growth and maturity to describe the onset and progression of pubertal changes in boys and girls. A peak in growth spurt is in stage 2 whilst menarche (menstruation) is in stage 3.
  • Peak of growth velocity: at the peak of the growth spurt, the increase in height is approx. 8-10cm in one year (so if a child did not increase in height of 8-10cm during any given year then he or she did not go through the peak of the spurt, thus he or she is in high risk of scoliosis progression)

MANAGEMENT OF AIS

Treatment Guidelines

Curves less than 25° at pre-menarche if progressive should be braced

Curves at 30° -40° pre menarche at first review should be braced.

Curves less than 40° at post menarche if progressive should have surgery

Curves greater than 45° pre menarche (Surgery) should have surgery

Curves greater than 50° of a should have surgery

*Exercises, manipulation, electric stimulation including lack of documented scientific proof would change the natural history.

Bracing: Recent multicenter studies in the United State has shown effective brace treatment for those who wore braces for more than 13hrs /day to have close to 90% success rate of stopping curve progression and of avoiding surgery

Surgical Treatment of adolescent Idiopathic Scoliosis

Goals for Treatment

• Correction of coronal (Frontal), sagittal (Side) and rotational (Cross-section and Rib Hump)
• Achieve an arthrodesis (Spine Fusion)
• Maximum motion segment preservation for growth and function

Surgical Considerations

Posterior fusion and instrument 

• Most common procedure for majority of single thoracic, thoracolumbar/lumbar and

double major curves

• Facet fusion with local bone with or without Iliac crest bone graft has been shown to

have a high rate of fusion.

• For patients with significant rib hump deformity a thoracoplasty procedure will

provide excellent cosmetic outcome.

• External immobilization is not generally needed post operatively with current

segmental fixation systems that combine the use of hooks, screws, wires, and rods.

Anterior Spine fusion

Limited indication for single thoracic and Thoracolumbar and Lumbar fusion

Combined procedures

• Anterior and posterior spine fusion with posterior instrumentation
• Indicated for very young patients at risk for crankshaft
• Severe and rigid deformities
• Increased morbidity from the thoracotomy approach
• Affects pulmonary function (15% reduction)

Consider adjunctive treatment for Severe deformities

• Halo Gravity Traction
• Posterior Column Osteotomies (Cutting through bone to achieve curve flexibility

Spinal Cord monitoring is a useful adjunct for Complex Deformity correction.

Author

Prof. Oheneba Boachie-Adjei

CEO, FOCOS Orthopedic Hospital

Orthopedic Surgeon, FOCOS Orthopedic Hospital