Adolescent Idiopathic Scoliosis Study, Skeletal Maturity and Surgical Considerations

Meeting highlight from the American Association of Orthopaedic Surgeons 2017 Annual Meeting

In his presentation at the American Association of Orthopaedic Surgeons 2017 Annual Meeting, Baron S. Lonner, MD, described an evaluation of differences in operative data and outcomes between patients with adolescent idiopathic scoliosis vs those with adult idiopathic scoliosis. Dr. Lonner is Professor of Orthopaedic Surgery at Mount Sinai Medical Center, New York.

In a matched case-control, retrospective study, Dr. Lonner and colleagues tested the hypothesis that patients with adult idiopathic scoliosis who have undergone a natural history of curve progression will experience greater operative morbidity and be at higher risk of complications than matched patients with adolescent idiopathic scoliosis.

They found that treatment of the patient with adult idiopathic scoliosis who has undergone an estimated natural history of progression is characterized by greater levels fused and operative time, as well as higher complication rates than counterparts with adolescent idiopathic scoliosis. Longer-term follow-up of adolescent idiopathic scoliosis is needed to define the benefits of early intervention of relatively asymptomatic adolescent patients vs late treatment of symptomatic disease in the adult.
Husband and wife with two small children picturedSurgical and other treatment recommendations for adolescent Idiopathic scoliosis in the past half century have largely been guided by radiographic parameters with relatively little attention given to patient and family priorities and values. IIntroduction
Surgeons treating adolescent patients with idiopathic scoliosis commonly find themselves in the consultation room with patient and family facing the decision as to whether or not to proceed with surgical correction. This is particularly true for the patient who has reached skeletal maturity in whom curve progression in the near future is unlikely and in whom body image, pain, and impact on activities are not a major concern.

Surgical and other treatment recommendations for adolescent idiopathic scoliosis in the past half century have largely been guided by radiographic parameters with relatively little attention given to patient and family priorities and values. In the current era, patient choice and alternative treatment options, quality and safety are at the forefront of care decisions. Decisions should be informed by optimal data on the nature of those choices.

The decision by the family to proceed with surgery for the skeletally mature adolescent is impacted by the natural history of untreated disease—that is, curve progression, pain, and disability—and pulmonary dysfunction in the adult. Additionally, the nature of the surgical intervention in the adolescent in terms of surgical morbidity—levels fused, impact on function, and complication rates—as opposed to waiting to undergo an operative intervention when the patient potentially becomes symptomatic as an adult are important considerations for the family to take into account.

This last consideration was the basis for Dr. Lonner’s study. The team investigated the extent of fusion, peri- and postoperative morbidity, and 2-year quality of life outcome differences between surgical intervention for the skeletally mature adolescent and the adult patient who was diagnosed with adolescent idiopathic scoliosis and underwent the natural history associated with aging.

Methods
In this retrospective study, consecutive patients were selected from two prospectively collected registries. One is a pediatric adolescent idiopathic scoliosis registry. The other is an adult spinal deformity operative registry.

The pediatric adolescent idiopathic scoliosis registry was established in 1995 and is the largest prospective adolescent idiopathic scoliosis patient database in existence. Fourteen sites participate (12 in the US and two in Canada) and over 4000 operative patients are enrolled.

The adult spinal deformity operative registry consists of 11 sites and 15 physicians across the US. Consecutive series of 737 patients with adult spinal deformity have been enrolled since 2008 in this multicenter prospective database registry.

Six hundred and sixty-one skeletally mature (Risser 4/5) surgical patients with adolescent idiopathic scoliosis with preoperative major curve ranging from 40-degrees to 70-degrees from the adolescent idiopathic scoliosis registry and 55 adult patients with previously untreated adolescent idiopathic scoliosis (adult idiopathic scoliosis) from the adult registry were reviewed.

Minimum 2-year follow-up and complete radiographic, surgical, and quality of life data in the form of the Scoliosis Research Society 22 (SRS-22r) questionnaire were included in the matching process.

The matching process took into account the curve type and magnitude and the estimated natural history of progression in a skeletally mature patient with adolescent idiopathic scoliosis with similar curve type. This process consisted in taking an adult patient’s record and back calculating to its skeletally matured adolescent counterpart in the adolescent idiopathic scoliosis registry since many more patients were included in the adolescent idiopathic scoliosis registry to choose from, given its homogenous nature and longer time in existence.

Based on natural history data by Weinstein et al, a curve progression of 0.3-degrees per year for the first 10 years after skeletal maturity, and 0.5-degree curve progression per year after the first 10 years was assumed for purposes of estimating the curve magnitude in the untreated adult idiopathic scoliosis counterpart.

An example was developed of the natural history of progression over 50 years for adolescent idiopathic scoliosis with 40-degree curvature at skeletal maturity. Idiopathic etiology in the adult idiopathic scoliosis cohort was determined in which adult cases were reviewed for radiographic parameters thought to be consistent with idiopathic scoliosis. These included:

  • Significant apical rotation
  • Typical curve patterns
  • Apex location

Adult idiopathic scoliosis with any sagittal plane deformities was excluded; however, an increase of kyphosis over time was taken into consideration in the natural history assessment. Matching was performed in a 1:2 weighting of adult: adolescent due to the larger number of accessible adolescent idiopathic scoliosis cases.

Clinical and radiographic data collected included age at surgery, gender, height, weight, levels instrumented, anchor type, level of upper and lower instrumented vertebra, inclusion of the sacrum/pelvis, major Cobb angle, T5 - T12 kyphosis, and lumbar lordosis.

Operative parameters were total operative times, estimated blood loss, percent of estimated blood loss, number of levels fused, length of stay, major complications, as well as SRS-22r quality of life outcome measures. A major complication (or serious adverse event) is formally defined as any untoward medical occurrence that:

  • Results in death
  • Is life-threatening
  • Requires inpatient hospitalization or prolongation of existing hospitalization
  • Results in persistent or significant disability/incapacity
  • Is a congenital anomaly/birth defect

Adult and pediatric minimal clinically important difference in SRS-22r subdomains were based on reported values by Crawford et al and Carreon et al. Quality of life outcome measures were further normalized by dividing the observed data with age-gender normative data in healthy adult or gender normative data in healthy adolescents described by Baldus et al and Daubs et al, respectively.

Operative data was further stratified and analyzed by Lenke curve types, Lenke 1 and 2 (primary thoracic curves); Lenke 3, 4, and 6 (double or triple major curves). Lenke 5 (single curves) types were grouped based on nature of the curvature to increase sample size for statistical purposes.

Updated on: 02/08/18
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Adolescent Idiopathic Scoliosis, Skeletal Maturity, Surgery—Study Statistical Analysis
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