Prognosis

Sequelae of adolescent idiopathic scoliosis

This varies greatly in adolescent idiopathic scoliosis (AIS) depending on the degree of spinal deformity present and the treatment selected. Most studies on the topic focus on the 4 main sequelae of AIS (curve progression, back pain, cardiopulmonary complications, and psychosocial effects) and their effect on the overall health and functioning of the patient.

Curve progression

  • Curve progression requiring treatment is much more common in female adolescents, with an estimated ratio of 7-8:1.[12] Additionally, the number of affected girls increases exponentially with the magnitude of the curvature.[12]

  • Determination of the risk of further curve progression is the essence of scoliosis treatment.

  • The highest risk is during the rapid period of adolescent growth, although theoretically the risk continues after skeletal maturity. In general, the risk of curve progression depends on the maturity of the patient (determined by estimation of the remaining skeletal growth and pubertal status), the size of the curve, and the position of the curve apex. Curves with a high measured Cobb angle have a high risk of progression with continued growth.[24]

  • Major structural curves with an apex above the level of T12 have a higher likelihood of progression than those with an apex below T12.[25]

  • It has been shown that, if patients reach skeletal maturity without curve progression beyond 30°, quality of life and functionality is similar to those without scoliosis.

  • Based on natural history studies, patients with a scoliotic curvature of >45° and evidence of remaining skeletal growth have a high risk of further curve progression and associated morbidity in adulthood, such as significant back pain, truncal decompensation (severe, clinically apparent deformity in which the trunk is no longer centered over the pelvis, resulting from coronal imbalance in severe curves), and sagittal imbalance.[1][2][12][50][51][52][53][54][55] These patients are therefore treated with surgical spinal arthrodesis.

  • It is estimated that patients with curves of >50° will have continued curve progression of approximately 1° per year after skeletal maturity.[53][54][55]

Back pain

  • There is debate in the literature regarding the prevalence of back pain in patients with scoliosis. Although most experts believe that patients with scoliosis experience back pain with a similar incidence to the general population of age-matched adults, some researchers have shown that patients with scoliosis experience a higher frequency and intensity of back pain.[50][53][55][77][78][79]

  • The majority of patients with scoliosis work and perform daily activities without limitation and do not report significant disability related to back pain compared with their peers.[50][80]

Cardiopulmonary complications

  • Unlike patients with juvenile (or early onset) scoliosis, those with AIS do not generally develop clinically significant cardiopulmonary difficulties that can be linked to the degree of curvature.

  • AIS patients with thoracic curvatures of >50° have been shown to demonstrate abnormalities on pulmonary function testing (PFTs) consistent with a restrictive pattern of lung disease, but these are rarely clinically significant.[55][80][81][82][83][84][85]

Psychosocial effects

  • There is debate in the literature regarding the effect of scoliosis on the overall self-image and perceived health of patients with AIS.

  • Untreated patients with scoliosis who develop a significant deformity do report that they are much less satisfied with their body image and appearance in clothing than age-matched peers.

  • Approximately 30% of untreated patients feel that their curvature and resulting deformity has limited them in some way with respect to self-consciousness and reduced physical ability.[50][77][80]

Surgical complications of AIS are much less common than those experienced with surgical treatment of adults with spinal deformity. The incidence of each complication is variable depending on many patient factors (magnitude and rigidity of the curve, presence of comorbidities), as well as factors associated with the selected surgical technique (anterior approach, posterior approach, combined anterior and posterior approach, type of hardware selected, bone grafting technique). Perhaps the most important measure to consider is whether a particular complication will result in the need for further surgical intervention. This is of utmost importance in the minds of patients and their families. In general, reported reoperation rates in the literature vary from as low as 3% to 4%, to as high as 14%. The most commonly reported reasons for reoperation include request for thoracoplasty (surgical reshaping of the prominent hemithorax for improved cosmetic result), extension of fusion to include cranial or caudal segments (due to the development of symptomatic junctional deformity or coronal/sagittal decompensation), hardware failure (rod breakage), and symptomatic pseudarthrosis. The individual incidence of each complication varies widely throughout the literature.

Risk calculator

A validated prognostic model in untreated AIS has been developed using the skeletal maturity scoring system (SMSS).[86] This model uses measurements from coronal spine views and SMSS from routine hand radiographs to determine the risk of an untreated AIS curve reaching a surgical threshold. It serves as a tool for clinicians and families to use in a shared decision-making process when determining the need for treatment. 

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