Idiopathic Scoliosis Workup

Updated: Nov 21, 2018
  • Author: Charles T Mehlman, DO, MPH; Chief Editor: Jeffrey A Goldstein, MD  more...
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Workup

Laboratory Studies

Laboratory workup for patients with scoliosis consists primarily of preoperative testing. Most, if not all, patients undergo preoperative assessment of hemoglobin and hematocrit levels. Autologous blood predonation is also a common practice.

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Imaging Studies

Radiography

Multiple authors have cited the value of bending radiographs, including those over a fulcrum. [63] Klepps and Lenke et al found that thoracic fulcrum bending radiographs worked best for them when dealing with isolated main thoracic curves. [64]

After the publication of the King classification in the early 1980s, the thoracic curve patterns found in adolescent idiopathic scoliosis (see the images below) were commonly classified according to this system. [65] Subsequently, significant questions were raised regarding its reliability and reproducibility. [66, 67] In addition, it was noted that the King classification alone (in its original form) does not allow comprehensive curve classification (eg, lumbar and thoracolumbar curve patterns). [68]  Many now regard the King classification as primarily of historical interest. The Lenke classification has become more commonly used for adolescent idiopathic scoliosis. [95]

Mild juvenile scoliosis. Mild juvenile scoliosis.
Anteroposterior (AP) radiograph shows mild adolesc Anteroposterior (AP) radiograph shows mild adolescent scoliosis.
Lateral view of mild adolescent scoliosis. Lateral view of mild adolescent scoliosis.
Moderate scoliosis. Moderate scoliosis.

Multiple authors have analyzed the ability of orthopedic surgeons to reliably measure scoliosis radiographs. Morrissy et al used 50 radiographs and four examiners (two experienced orthopedic surgeons, one fellow, one senior resident) to study their ability to make Cobb angle measurements. With the examiners choosing end vertebrae and measuring scoliotic curves accordingly, intraobserver variability was 4.9°. [69]

Carman et al used eight scoliosis radiographs measured by five examiners (four orthopedic surgeons, one physical therapist) to evaluate interobserver and intraobserver variation. They found that a 10° measurement difference is necessary before there is a 95% confidence level that one Cobb angle measurement is truly different from another. [70]

Magnetic resonance imaging

Magnetic resonance imaging (MRI) has been suggested to be primarily indicated in patients with idiopathic scoliosis with unusual complaints such as severe unexplained headaches and when clinical findings such as ataxia or cavus feet are present. [71] Routine MRI evaluation of all patients with adolescent idiopathic scoliosis is not recommended. [72]

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Other Tests

Pulmonary function studies have been used extensively in the evaluation of patients with idiopathic scoliosis. [7, 73, 74, 75] In general, patients whose scoliosis surgery does not involve disruption of their chest wall can be expected to experience improved postoperative pulmonary function. [76, 58] Other authors have suggested that an impairment in respiratory mechanics may persist after successful scoliosis surgery. [77] Preoperative pulmonary function testing is of questionable value in patients with moderate deformity (average Cobb angle 48°), as most of these patients can be expected to have normal or only mildly abnormal results. [78]

Efforts at screening for scoliosis (most often in school populations) have met with mixed success. A 2-year evaluation of more than 80,000 Greek 9- to 14-year-old students screened by their schools with the Adams forward-bending test was conducted by Soucacos et al. Overall, they found school screening to be simple and effective. These authors found that they identified 181 new children with scoliosis requiring treatment (11 surgically, 170 with bracing). [79]

Peak height velocity has been studied extensively as a predictor of curve progression. [80]

A small study found that computerized photogrammetry, a novel method for nonradiographic evaluation, exhibited equivalent scoliosis angle measurements in 16 patients compared with the traditional Cobb radiographic method. Although more studies are needed to assess this new tool, it may be a potential new method as a coadjuvant tool in serial monitoring of scoliosis treatment. [81]

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Histologic Findings

Scoliosis is clearly a disease that is strongly influenced by, if not completely rooted in, spinal growth. It has even been referred to by some as "an unsynchronized growth." [82]

Hsu et al from Vanderbilt studied muscle biopsies from 27 patients with idiopathic scoliosis who were undergoing posterior spinal fusion. Specimens were obtained from the paraspinal musculature of both the convex and concave side in all patients. All patients had thoracic curves in the range of 37-81°. [83]

In this study, 68% of the patients demonstrated abnormalities in muscle fiber distribution. The abnormalities were similar on the convex and concave sides, the most notable being a reversal of the normal type 2 fiber ratio, so that type 2A fibers predominated over type 2B fibers in the study subjects. These changes are similar to those seen in endurance training and might be due to the extra work of trying to maintain posture in the setting of scoliosis. [83]

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