Kumar A, Ahuja K, Tsirikos AI. Long-term outcomes of adolescent idiopathic scoliosis: Natural history of untreated, braced, surgically treated patients in adult life. World J Clin Cases 2026; 14(15): 118765 [DOI: 10.12998/wjcc.v14.i15.118765]
Corresponding Author of This Article
Athanasios I Tsirikos, MD, PhD, FRCS, Scottish National Spine Deformity Centre, Royal Hospital for Sick Children, Sciennes Road, Edinburgh EH9 1LF, United Kingdom. atsirikos@hotmail.com
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May 26, 2026 (publication date) through May 12, 2026
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Kumar A, Ahuja K, Tsirikos AI. Long-term outcomes of adolescent idiopathic scoliosis: Natural history of untreated, braced, surgically treated patients in adult life. World J Clin Cases 2026; 14(15): 118765 [DOI: 10.12998/wjcc.v14.i15.118765]
Co-corresponding authors: Kaustubh Ahuja and Athanasios I Tsirikos.
Author contributions: Kumar A performed the literature search, data synthesis, and drafted the manuscript; Ahuja K contributed to data interpretation; Ahuja K and Tsirikos AI critically revised the manuscript and they contributed equally to this manuscript as co-corresponding authors; Tsirikos AI conceptualized the study, supervised the work, and approved the final version. All authors have read and approved the final manuscript.
AI contribution statement: Artificial intelligence tools like ChatGPT and Grammarly were used only for language editing and grammar refinement. No AI tool was used to generate scientific content, interpret data, design the study, or draw conclusions. All intellectual content, including literature synthesis, analysis, and interpretation, is the original work of the authors. No images or figures were generated using AI.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Corresponding author: Athanasios I Tsirikos, MD, PhD, FRCS, Scottish National Spine Deformity Centre, Royal Hospital for Sick Children, Sciennes Road, Edinburgh EH9 1LF, United Kingdom. atsirikos@hotmail.com
Received: January 12, 2026 Revised: February 13, 2026 Accepted: March 30, 2026 Published online: May 26, 2026 Processing time: 122 Days and 15.6 Hours
Abstract
To evaluate the long-term clinical, functional, psychosocial, and radiographic outcomes of untreated, braced, and surgically treated adolescent idiopathic scoliosis (AIS) into adulthood. A narrative synthesis of key studies - including prospective cohorts, retrospective analyses, systematic reviews, and patient-reported outcome measure-based investigations - was conducted. Data were organized into three domains: The natural history of untreated AIS, outcomes of bracing, and surgical treatment. Comparative analyses were performed across functional capacity, curve progression, health-related quality of life, patient satisfaction, and complication rates. Untreated AIS with curves < 50° often follows a benign course, with minimal functional limitation, preserved health-related quality of life, and no increase in mortality. However, curves ≥ 50° are associated with progressive deformity, cosmetic dissatisfaction, and potential pulmonary compromise. Bracing is effective in halting progression in skeletally immature patients, particularly when in-brace correction exceeds 50% and daily compliance exceeds 18 hours. Surgically treated patients report the highest long-term satisfaction, particularly in self-image and cosmetic outcomes, though fusion may result in some loss of spinal mobility. Delaying surgery into adulthood increases the risks of operative morbidity, extensive fusion levels, and reoperation. AIS is a heterogeneous condition requiring individualized, evidence-informed care. Observation is appropriate for non-progressive, moderate curves; bracing remains a first-line intervention for growing patients with moderate deformity; and surgery is indicated for progressive or severe curves, with favorable long-term outcomes when timed appropriately. Patient-reported outcomes, psychosocial considerations, and shared decision-making should be integral to treatment planning. Continued prospective research and standardization of bracing and surgical protocols are essential to optimize outcomes across the lifespan.
Core Tip: Adolescent idiopathic scoliosis is a heterogeneous condition with outcomes extending into adult life. This review synthesizes four decades of evidence on untreated, braced, and surgically treated adolescent idiopathic scoliosis. Curves < 50° generally follow a benign adult course, whereas progressive deformity may impair self-image and function. Timely bracing and appropriately indicated surgery provide favorable long-term functional and psychosocial outcomes, highlighting the importance of individualized care and shared decision-making.
Citation: Kumar A, Ahuja K, Tsirikos AI. Long-term outcomes of adolescent idiopathic scoliosis: Natural history of untreated, braced, surgically treated patients in adult life. World J Clin Cases 2026; 14(15): 118765
Adolescent idiopathic scoliosis (AIS) is a structural, three-dimensional spinal deformity defined by a coronal curvature exceeding 10 degrees with vertebral rotation, and appearing in otherwise healthy children during their growth spurt, typically between the ages of 10 years and 18 years. The term “idiopathic” denotes the absence of any underlying congenital, neuromuscular, or syndromic etiology. AIS is the most common form of scoliosis, representing approximately 80%-90% of all idiopathic scoliosis cases diagnosed in pediatric and adolescent population[1].
The estimated global prevalence of AIS ranges from 0.5% to 5.2%, depending on the population studied and the threshold used for diagnosis[2]. In most cases, the condition is mild and does not require intervention. However, a subset of patients experiences curve progression that may impact function, aesthetics, pulmonary function, or quality of life. The risk of progression is closely linked to growth potential, curve magnitude, and curve pattern[3].
While short-term management strategies such as bracing and surgery have been extensively studied, a critical aspect of AIS care lies in understanding the long-term outcomes of treated and untreated scoliosis. Many patients are diagnosed and treated in adolescence, but the consequences - whether of the curve itself or the interventions - can persist or evolve throughout adulthood. Key domains of interest include pain, disability, spinal mobility, pulmonary function, psychosocial impact, employment capacity, and overall health-related quality of life (HRQoL)[3,4].
Historically, early studies of untreated scoliosis are associated with disability, reduced life expectancy, and cardiopulmonary decline[4]. However, these studies often lacked radiographic confirmation or included patients with non-idiopathic etiologies. More recent long-term investigations, such as those by Weinstein et al[5] and Danielsson et al[6] have demonstrated that many individuals with untreated moderate AIS lead active, productive lives without significant disability. At the same time, modern bracing techniques and surgical advancements have transformed the therapeutic landscape. Bracing, when initiated early and worn consistently, has been shown to prevent curve progression in most patients[7,8]. Surgical correction can offer long-term curve stability and improved self-image but may carry risks of complications, reoperations, and reduced spinal flexibility[9-11]. The balance between these treatment approaches and the natural history of AIS necessitates the understanding of long natural history over the patient’s lifespan.
The primary objective of this review is to synthesize and evaluate the long-term outcomes associated with untreated, braced, and surgically treated AIS. Drawing from a broad array of prospective cohorts, retrospective studies, systematic reviews, and patient-reported outcome analyses, we aim to compare the natural course of untreated AIS against the short- and long-term results of brace treatment and spinal fusion. Particular attention will be paid to curve progression, functional capacity, pain, psychosocial well-being, quality of life, and complications. By integrating data from over four decades of scoliosis research, this review seeks to inform clinicians, patients, and policy-makers of the risks and benefits associated with different treatment strategies. This is particularly relevant for guiding decision-making in moderate curves, where the choice between observation, bracing, or early surgery can have profound implications on long-term outcomes and patient well-being.
This mini-review was conducted as a narrative synthesis of long-term outcomes associated with untreated, braced, and surgically managed AIS. A comprehensive search of PubMed, MEDLINE, Scopus, and Google Scholar was performed for studies published from 1960 to 2025 using the search terms: “adolescent idiopathic scoliosis”, “natural history”, “long-term outcomes”, “bracing”, “spinal fusion”, “patient-reported outcomes”, and “curve progression”. Eligible studies included prospective and retrospective cohorts, systematic reviews, meta-analyses, and randomized controlled trials reporting long-term follow-up in AIS. Studies on non-idiopathic scoliosis and those reporting short-term follow-up were excluded.
Data extraction and synthesis were organized into three domains: (1) Natural history of untreated AIS; (2) Outcomes of bracing; and (3) Outcomes of surgical correction. Heterogeneity in study designs and outcome measures were synthesized narratively, with emphasis on functional capacity, curve progression, patient-reported outcomes, psychosocial effects, and complications.
NATURAL HISTORY OF UNTREATED AIS
Understanding the natural course of untreated AIS is crucial for clinical decision-making, especially when weighing the risks and benefits of conservative vs surgical interventions (Table 1). Historically, AIS was often associated with a poor prognosis; however, contemporary long-term studies have significantly reshaped this perspective. Evidence from long follow-up studies reveals that AIS can exhibit a wide range of outcomes, with many patients experiencing stable or slowly progressive curves, minimal functional limitations, and a quality of life comparable to treated individuals or the general population.
Table 1 Long-term outcomes of untreated adolescent idiopathic scoliosis.
Long-term curve progression after skeletal maturity
Curve progression remains the most predictable feature of untreated AIS. Numerous studies have reported that thoracic curves ≥ 50° at skeletal maturity typically continue to progress into adulthood at an average rate of 0.5° to 1.0° per year, sometimes reaching or exceeding 100° in late life[12-15]. Hassan and Bjerkreim[16] observed that curves between 60°-80° progressed the most rapidly, with an annual increase of 3° in adolescence and 1° after age 20. Conversely, curves < 30° at skeletal maturity were generally stable, while those between 30°-50° showed variable behavior depending on the curve pattern, skeletal maturity, and radiographic indicators such as apical vertebral wedging and coronal imbalance[17,18]. Studies by Luo et al[17] and Ohashi et al[18] further emphasized the role of thoracic location, apical vertebral translation, and curve type in predicting future progression. Farshad et al[19] demonstrated an average curve increase of 20° over 42 years, with no significant difference in outcomes between observed and braced patients[19].
Functional outcomes and disability
Despite radiographic progression, most untreated AIS patients maintain a high level of physical functionality. The Iowa cohort, with over 50 years of follow-up, showed that individuals with significant deformity could lead independent, productive lives, with minimal impact on daily activities[12]. Brandwijk et al[20] reported that although HRQoL scores were reduced compared to the general population, 79% of patients had minimal disability as documented by the Oswestry Disability Index (ODI)[20]. Similarly, Farshad et al[19] and Ascani et al[21] found that even with increased curve magnitudes, physical function remained preserved in most individuals. Gremeaux et al[22] highlighted that although greater spinal curvature was associated with increased body height loss over time, this physical manifestation did not strongly correlate with self-reported disability.
Back pain and quality of life
Chronic back pain is more prevalent among patients with untreated AIS than in the general population; however, it is typically non-disabling. Weinstein[23] noted that 61% of patients reported back pain, yet its severity and duration were similar to age-matched controls. Brandwijk et al[20] and Ohashi et al[18] confirmed that although pain levels were higher in AIS patients, mean visual analogue scale and ODI scores did not suggest clinically significant disability in most cases. Rushton and Grevit[24], in a meta-analysis of 21 cohorts, found that pain and self-image were statistically worse in AIS patients, though clinically significant only in the latter domain. Danielsson[25] also reported no significant long-term differences in HRQoL among untreated, braced, and surgically treated patients.
Pulmonary and cardiopulmonary complications
Pulmonary compromise is rare and typically confined to patients with thoracic curves ≥ 80° to 100°. Weinstein[23] and Pehrsson et al[26] reported decreased pulmonary function in severe thoracic curves, but respiratory failure remained uncommon. Nachemson’s earlier Gothenburg study[27] associated a 2.2-fold increased mortality with severe scoliosis, although this was later attributed to mixed etiologies including congenital and neuromuscular scoliosis. In contrast, recent AIS-specific studies like those by Danielsson and Nachemson[28] and Weiss and Moramarco[29] suggest that idiopathic curves alone rarely result in clinically significant respiratory impairment, reinforcing the importance of excluding early-onset or congenital cases in long-term prognostication.
Psychosocial impact and self-image
While AIS can affect body image especially in patients with visible deformities, long-term studies show that it does not typically impair social function or mental health. Rushton and Grevitt[24] noted that self-image was the most consistently affected domain, while functional and emotional health were not significantly impaired. Brandwijk et al[20] found that scoliosis influenced education and work decisions in some patients, but did not correlate with severe disability. Danielsson and Hallerman[30] observed that braced patients were less satisfied with treatment than surgically treated individuals, although functional outcomes were similar across both groups.
Reproductive health and pregnancy
Evidence from several studies confirms that untreated AIS does not adversely affect fertility, pregnancy outcomes, or delivery mode. Danielsson[25] and Ohashi et al[18] found no increased rates of miscarriage, cesarean delivery, or pregnancy-related curve progression in women with scoliosis. While back pain during pregnancy may occur more frequently, it is also common among the general female population.
Mortality and life expectancy
AIS does not significantly impact overall life expectancy. In the Iowa cohort, long-term survival rates among AIS patients were comparable to those of age- and sex-matched controls[12]. Pehrsson et al[26] observed increased mortality in scoliosis patients, but only among those with non-idiopathic types. No deaths occurred in patients with AIS. Weiss et al[15] and Weiss and Moramarco[29] emphasized that earlier studies showing increased mortality were flawed due to the inclusion of patients with mixed etiologies.
Contemporary literature strongly suggests that untreated AIS, while associated with curve progression, often follows a benign clinical course - particularly for curves under 50°. Functional independence, psychosocial integration, and normal life expectancy are frequently preserved. While chronic back pain and body image concerns are more common than in the general population, they are rarely disabling[31-36]. These findings stress the importance of individualized risk assessment and suggest that conservative management, including observation, may be appropriate for many patients, particularly those with moderate, balanced curves.
Bracing in AIS; long term outcome
Bracing remains the most widely accepted non-operative intervention for managing progressive curves in AIS. It aims to halt curve deterioration during growth, reduce the need for surgery, and preserve spinal function into adulthood (Table 2). The effectiveness of bracing depends on appropriate patient selection, brace quality, compliance, and early intervention. Recent high-quality studies, including the pivotal Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST), have provided level I evidence for its utility when applied judiciously and monitored closely[37]. Garg et al[38] narrative review emphasizes about efficacy of orthotic management in AIS is optimized through early initiation during peak growth, precise brace customization and structured multidisciplinary protocol ensuring radiographic in-brace correction and adherence monitoring, which can mitigate the risk of curve progression. In a longitudinal cohort study analysing the effect of Boston brace, 54% of idiopathic scoliosis patients and 64% of AIS subgroup patients avoided progression to surgical thresholds, with thoracolumbar/lumbar curves demonstrating significantly greater mean correction than thoracic curves. Even in treatment failures, bracing delayed definitive surgery by approximately 3 years without compromising long-term patient-reported outcomes. Brace success was primarily determined by scoliosis etiology, skeletal maturity, and initial curve magnitude. Idiopathic scoliosis, AIS subtype, smaller Cobb angles, closed triradiate cartilage, higher Risser grade, and post-menarchal status predicted favorable outcomes, whereas juvenile onset, open growth plates, and non-idiopathic scoliosis were associated with higher failure rates. These findings highlight the importance of early detection and appropriate patient selection for optimal bracing outcomes[39].
Table 2 Long-term outcomes of bracing in adolescent idiopathic scoliosis.
Indications and criteria for bracing: According to the Scoliosis Research Society (SRS) and endorsed by International Scientific Society on Scoliosis Orthopaedic and Rehabilitation Treatment, bracing is indicated in skeletally immature patients (Risser 0-2 or Sander’s stage ≤ 4) with a Cobb angle between 25° and 40° and documented progression or high risk of progression. In patients nearing 45°, bracing may still be offered when surgery is declined or delayed. The goal is to prevent progression to or beyond 50°, a threshold commonly associated with adult progression and surgical consideration[7,40,41].
Long-term curve control and progression: Long-term follow-up studies by Weinstein et al[7] and Simony et al[42] have consistently demonstrated that bracing, when properly indicated and followed, can halt or reduce curve progression in the majority of AIS patients. In the BrAIST trial, 72% of brace-treated patients avoided curve progression to surgical levels, compared with 48% in the observation-only group. This success of bracing was confirmed in a subsequent longitudinal study in a national spinal center where 73.2% of patients with AIS of 20°-40° treated in a Boston brace did not require scoliosis correction at the end of brace treatment. Follow-up into adulthood shows that most braced patients maintain curve stability, with minimal deterioration if compliance was adequate during adolescence.
Impact on HRQoL and psychological outcomes
Bracing, particularly when initiated during early adolescence, may raise concerns about body image. However effective bracing can preserve or even improve long-term HRQoL. Patients who successfully avoid surgery through bracing tend to report similar or better SRS-22, Short-Form 36 (SF-36), and Brace Questionnaire scores than those who undergo surgery, particularly in physical function and pain domains. Psychological effects such as anxiety or depressive symptoms are more closely linked to poor brace compliance or ineffective treatment rather than the brace itself[6,41-43].
Physical development and adult function: Contrary to early fears, bracing does not impair spinal mobility, physical growth, or adult function. Long-term studies by Simony et al[42] and Danielsson et al[43] found that braced individuals reach normal adult height and demonstrate comparable muscle strength and endurance to unbraced peers. Participation in sports and physical activities is largely unaffected, especially in compliant and early-treated patients.
FACTORS AFFECTING LONG-TERM BRACING OUTCOMES
Predictors of brace success
Cobb angle: Initial curve magnitude is a strong predictor of bracing outcomes. Curves < 35° respond best to treatment, while those between 35°-45° may still stabilize if brace wear is optimal. In larger curves approaching 50°, success becomes more dependent on other modifiable factors, especially compliance[44,45].
In-brace correction: The percentage of curve correction observed while the brace is worn (in-brace X-ray) is a key predictor. Several studies report that achieving at least 50% in-brace correction is associated with significantly better outcomes. Donzelli et al[44] found that less than 20% correction typically predicts brace failure, while greater correction correlates with curve stabilization or improvement.
Compliance and wear-time: Compliance remains the single most important modifiable factor in brace success. Weinstein et al[7] demonstrated in the BrAIST study a clear dose-response relationship: Patients wearing the brace more than 13-18 hours/day had significantly higher rates of treatment success, defined as avoidance of progression to ≥ 50°. Electronic compliance monitors have confirmed the strong correlation between wear-time and reduced need for surgery[37].
Comparative outcomes: Full-time vs part-time bracing
While some part-time and night-time braces (e.g., Providence or Charleston braces) show favorable short-term outcomes, full-time bracing (18-23 hours/day) with rigid thoracolumbosacral orthoses remains the gold standard for moderate curves. Comparative studies by Capek et al[46] and Swaby et al[47] demonstrate higher success rates and lower progression risk in full-time bracing cohorts, particularly in curves exceeding 30°. Night-only bracing may be reserved for select patients with lower-risk curves and excellent compliance potential. The Bracing Adolescent Idiopathic Scoliosis United Kingdom National randomized controlled study is currently in progress and this is comparing the effectiveness of full-time vs night-time bracing in patients with AIS. The results of this trial will provide unequivocal information on the efficacy of these two bracing protocols that can guide brace care in patients with AIS[47].
Bracing in juvenile vs adolescent scoliosis
Bracing in juvenile idiopathic scoliosis presents unique challenges due to earlier curve onset and prolonged period of accelerated spinal growth. While bracing can be effective, the risk of failure is higher compared to adolescent-onset AIS[39]. The need for longer treatment duration, evolving curve patterns, and compliance difficulties make surgical conversion more likely. However, Aulisa et al[48] reported successful long-term stabilization is still possible in motivated, compliant patients, especially with modern bracing protocols[49,50].
Surgical management of AIS; long term outcome
Surgical treatment remains the definitive management for patients with AIS whose spinal curves exceed the threshold for progression risk or cause functional, cosmetic, or psychosocial impairments. With advancements in instrumentation, surgical techniques now offer high correction rates, improved safety, and long-term satisfaction. This section explores the indications, outcomes, and considerations related to spinal fusion surgery in AIS (Table 3).
Table 3 Long-term outcomes of surgical treatment in adolescent idiopathic scoliosis.
265 patients; mean follow-up 10-25 years (≥ 10 years)
Mixed pediatric deformities including AIS
HRQoL (SRS-22, Short-Form 36), pain, general health
Sustained improvements in HRQoL and pain comparable to general population. Postoperative scores were similar to those of age-matched controls, including the AIS subgroup
Indications for surgery: Surgery is typically indicated when the Cobb angle exceeds 45-50° in skeletally immature patients, due to the high likelihood of continued progression after growth cessation[7]. Other indications for surgical intervention include documented curve progression despite adequate bracing, severe trunk deformity or imbalance that significantly impacts posture or body image and persistent back pain. Additionally, thoracic curves exceeding 80° may compromise pulmonary function and patient preference driven by psychological or social concerns necessitate surgical correction. While a threshold of 50° is widely accepted, curves above 40° in skeletally immature patients showing rapid progression may also justify operative intervention[6,43,51].
Outcomes in self-image, function and pain: Surgical correction of AIS leads to marked improvements in body image and self-esteem, often exceeding gains seen with bracing[52-55]. Multiple long-term studies such as Danielsson et al[43]; Larson et al[55] using the SRS-22 questionnaire confirm that the self-image and satisfaction domains improve significantly postoperatively, with scores approaching or exceeding those of healthy controls. Danielsson et al[52] and Herdea et al[53] reported functional outcomes including participation in physical activities and daily living tasks are typically preserved. Although spinal mobility is partially reduced due to fusion, most patients report minimal disability and pain, especially when fusion levels are minimized and spinal balance is maintained.
Complication rates and reoperations: Reames et al[51] in a large multicenter review reported overall complication rates ranging from 5% to 10%, with serious adverse events being uncommon, particularly in experienced centers. Roberts and Tsirikos[56] highlighted that the most frequent issues include surgical site infections (1%-3%), neurological injury occurring in less than 1% of cases, implant failure or loosening and pulmonary complications - especially in patients with large thoracic curves. Long-term follow-up studies such as those by Larson et al[55] have shown that reoperation rates over 10 years to 20 years range between 10% and 15% most often due to late infection, pseudarthrosis, proximal junctional kyphosis, or the need to extend the fusion for distal curve progression[56-59].
Long-term satisfaction and spinal mobility: Long-term studies by Danielsson et al[52] and Larson et al[55] have shown high patient satisfaction with over 85% of patients stating they would undergo the surgery again under similar circumstances. While spinal mobility is reduced due to fusion particularly in long constructs, most patients retain sufficient flexibility for daily and recreational activities. Tsirikos and García-Martínez[60] demonstrated that spinal deformity surgery during childhood or adolescence leads to improvements in HRQoL and pain scores, with outcomes in congenital scoliosis and Scheuermann kyphosis approaching those of age-matched general population controls even in the long-term.
Obstetric outcomes post-fusion: Danielsson and Nachemson[28] showed that women with AIS who undergo spinal fusion generally experience normal pregnancy and delivery outcomes. Several studies have shown that fertility is unaffected and the majority of women are able to carry pregnancies to term without complications related to the fusion. However, Herdea et al[53] noted that patients fused to the lower lumbar spine may have slightly higher cesarean section rates and more back pain during pregnancy while Weinstein et al[7] emphasized that epidural anesthesia may be more challenging, especially if fusion extends into the lumbar region, but remains feasible with modern imaging guidance.
Factors affecting long term outcomes
Impact of timing (adolescent vs adult surgery): Weinstein et al[7] have demonstrated that surgery performed during adolescence typically results in better correction, shorter fusion levels and lower complication rates than adult surgery for untreated scoliosis. In contrast, Zhu et al[9] reported that adult scoliosis surgery often requires more extensive procedures such as osteotomies or anterior column support, with higher rates of blood loss, implant failure, and postoperative pain. Early surgical intervention, before curves exceed 70°-80°, is associated with better outcomes in both function and alignment and avoids the complexities of adult deformity correction.
Comparison of early-onset vs adolescent surgery
Gillingham et al[36] have reported that patients with early-onset scoliosis including juvenile idiopathic scoliosis, often require surgical strategies such as growing rods, vertical expandable prosthetic titanium rib, or multiple staged procedures due to ongoing spinal and thoracic growth. Pishnamaz et al[33] found that outcomes in early-onset scoliosis are generally less favorable than in AIS, with higher complication and revision rates, more frequent pulmonary compromise, and limited spinal mobility due to longer fusion segments. In contrast, surgery in AIS allows for more predictable correction, better preservation of lung function, and lower long-term morbidity, provided it is timed appropriately[58].
Comparative outcomes: Untreated vs braced vs surgical
Understanding the comparative outcomes of untreated, braced, and surgically managed AIS is essential for guiding clinical decisions and aligning treatment with patient values (Table 4). Though AIS is often asymptomatic in adolescence, the long-term consequences-especially curve progression-can significantly influence function, self-perception, HRQoL, and occupational capacity. This section synthesizes the functional, psychosocial, and radiographic outcomes across the three primary treatment modalities.
Table 4 Comparative long-term outcomes of adolescent idiopathic scoliosis.
Outcome
Untreated AIS
Braced AIS
Surgically treated AIS
Level of evidence
Functional outcomes
Good for curves < 50°; ≥ 50° may develop stiffness and mild limitations
Similar or slightly better than untreated if curve stabilized
Excellent when fusion levels are limited and sagittal balance preserved
II-III
Health-related quality of life
Lower self-image and pain scores in large progressive curves
Comparable to controls when brace successful; prevents decline
High satisfaction; best self-image and satisfaction scores
II
Radiological progression
Curves ≥ 40°-50° progress (0.5°-1°/year)
Bracing halts or slows progression in most moderate curves
Fusion halts curve progression
I (BrAIST) for bracing; II for surgery
Self-image/patient perception
Lower, especially in curves > 60° and with visible deformity
Can be negatively affected during bracing but improves long-term if progression is controlled
Greatest improvement due to correction and cosmetic results
II-III
Pain/back pain
Chronic pain more frequent but usually mild/non-disabling
Similar or slightly less than untreated when bracing is successful
Generally improved pain after correction
II-III
Physical capacity and occupational impact
Most remain active; severe curves (> 60°) may affect physical work
Near-normal function; good occupational outcomes if stabilized
Good occupational outcomes; slight restrictions if fusion extends to lower lumbar
II-III
Surgical avoidance/risks of delayed surgery
High risk of requiring surgery if progression occurs
72% avoid surgery if brace compliance adequate (BrAIST)
Delayed surgery after severe progression linked to higher complications and longer fusions
Functional outcomes: Long-term studies indicate that untreated AIS patients with moderate curves (< 50°) generally maintain good function into adulthood. However, curves ≥ 50° are associated with greater risk of back pain, spinal stiffness, and functional limitation over time. Braced patients, particularly those who achieved stabilization, demonstrate similar or slightly better function than untreated peers, while surgically treated patients typically maintain excellent function when fusion levels are limited and sagittal balance is preserved[6,43,58,59].
HRQoL across treatment groups: Bracing and surgery both improve HRQoL when progression is prevented or deformity is corrected. In contrast, untreated patients with progressive deformities often report lower self-image and pain scores, especially in curves exceeding 60°[43]. Braced patients report comparable HRQoL to controls when compliance is high and curve control is successful. Surgical patients particularly those fused in adolescence, consistently report high satisfaction and improved self-image, even when some loss of spinal mobility occurs[48,59]. The SRS-22 questionnaire - a validated tool - has been widely used to assess these outcomes. Surgical patients often score highest in self-image and satisfaction domains, while braced patients fare well across function and pain dimensions. Untreated patients score lowest in self-perception and satisfaction, particularly when curves are large or visibly deforming[25].
Patient satisfaction and self-perception: Bracing can negatively impact body image during treatment due to visibility and physical restriction, though long-term perception tends to improve if the brace is effective. Surgical patients show the greatest improvement in self-perception due to immediate cosmetic results and spinal realignment. Untreated individuals with major deformities often express long-term dissatisfaction with appearance, particularly women[52-54,61].
Physical capacity and occupational impact: Most patients in all treatment groups are able to lead normal lives, including careers, sports, and pregnancy. However, untreated curves > 60° may limit physical capacity in adulthood and increase the risk of work-related back pain or disability. Braced individuals retain near-normal function when successful, while surgical patients may experience some limitations in range of motion, especially with longer fusions[48,52,60]. Studies show that the majority of surgically treated AIS patients are employed full time, participate in physical activities, and report no limitations in occupational engagement - particularly when fusion does not extend to the lower lumbar spine[57,58].
Surgical avoidance and delayed intervention risks: Avoiding surgery is often a key goal for patients and parents, especially due to concerns about complications and loss of mobility. Bracing offers a non-invasive path to surgical avoidance, with the BrAIST trial showing that 72% of braced patients avoided progression beyond 50°, compared to 48% in observation alone[7]. Delayed surgical intervention, especially beyond 70°-80°, is associated with increased complication rates, reduced correction, and more extensive fusion levels. Early surgical correction - when clearly indicated - leads to better long-term outcomes and fewer reoperations[3,62].
Radiological progression vs long-term clinical outcome: Untreated AIS curves generally progress beyond skeletal maturity, particularly when ≥ 40°-50° at the end of growth. Weinstein et al[7] documented a mean progression of 0.5°-1° per year, leading to clinically significant deformities decades later. Radiological progression alone however does not always equate to clinical disability or pain, which complicates treatment decisions in moderate curves. Bracing effectively halts or slows progression in most moderate curves, and surgical fusion corrects the curve but introduces potential stiffness. The balance lies in understanding whether curve magnitude correlates with functional impact - a difference requiring individualized patient-centered care[7,12].
Patient-reported outcomes and shared decision-making in AIS
The role of patient-reported outcome measures in AIS management: The management of AIS extends beyond radiographic correction to encompass patient-centered goals such as physical functioning, self-image, pain, and satisfaction. As the field shifts toward value-based care patient-reported outcome measures (PROMs) have become essential in evaluating these domains and are increasingly incorporated into both clinical decision-making and research. The most widely used PROMs in scoliosis care include.
SRS-22: This disease-specific tool evaluates domains of function, pain, self-image, mental health, and satisfaction. It is widely used in both surgical and non-surgical AIS populations.
SF-36: A generic quality-of-life measure used to compare scoliosis patients with the general population. It assesses physical and mental health, though less sensitive to spinal deformity-specific concerns.
ODI: Although used for adult back pain, ODI may provide insights into functional limitations in adult patients with a history of AIS, especially untreated or post-fusion. Studies have demonstrated that surgical patients report higher SRS-22 scores in the self-image and satisfaction domains, while braced patients maintain scores similar to healthy controls in function and pain when treatment is successful[7,59]. Untreated patients may show good function but lower self-perception, especially when curves exceed 60°[12].
Shared decision-making and ethical considerations
Treatment decisions in AIS have long-term implications. Shared decision-making is increasingly regarded as the ethical standard, integrating clinical expertise with the patient’s values and preferences. This involves treatment options - observation, bracing, and surgery - with risks and benefits, while considering emotional factors, family dynamics, and the patient’s maturity. Ensuring patients and parents understand the limitations and outcomes of each intervention. The BrAIST trial highlighted ethical dilemmas in bracing compliance and randomization, emphasizing the need for autonomy and assent in pediatric care[7,37]. Similarly, delaying surgery in borderline cases for cosmetic or psychological reasons must be weighed against increasing surgical complexity or long-term progression.
Current challenges and research gaps in AIS management
Despite decades of clinical practice and research in AIS, numerous challenges persist in understanding the long-term outcomes and optimizing treatment protocols. The complexity of AIS lies in its multifactorial nature - ranging from biomechanical to psychosocial components. As a result, evidence-based clarity is still evolving, especially regarding the comparative long-term impact of untreated, braced, and surgically treated scoliosis.
Need for prospective long-term studies: The limitations in AIS literature is the paucity of high-quality prospective long-term studies that follow patients into adulthood and beyond. Most available studies are retrospective or observational, often lacking control groups or sufficient follow-up to have outcomes such as spinal degeneration, quality of life, and occupational impact. The landmark BrAIST trial provided robust prospective data on bracing efficacy, but similar rigorously designed trials comparing all three modalities - observation, bracing, and surgery - over decades are scarce[7]. Additionally, many long-term studies are limited by attrition bias, loss to follow-up, or evolving surgical techniques that complicate generalization.
Lack of high-quality data on untreated patients: The natural history of untreated AIS remains partially understood due to ethical limitations in withholding treatment for high-risk curves. While classical studies by Weinstein et al[7] and colleagues offer valuable insights into curve progression, pain, and function in untreated individuals, such cohorts are now difficult to ethically replicate due to the availability of effective bracing and surgical options[12].
Underreporting of psychosocial and functional outcomes: While radiographic parameters such as Cobb angle remain central to scoliosis evaluation, psychosocial, emotional, and functional outcomes are underrepresented in both clinical practice and research. For instance, self-image and body dissatisfaction - major motivators for AIS treatment - are often assessed using non-standardized or inconsistent methods. Studies using validated PROMs, such as the SRS-22 or SF-36, are increasing but still insufficiently implemented in long-term follow-up[6,7,43,59].
Variability in bracing protocols and surgical thresholds: Another critical challenge lies in the heterogeneity of bracing practices. Although the SRS and International Scientific Society on Scoliosis Orthopaedic and Rehabilitation Treatment have proposed standardized criteria for brace prescription and outcome assessment, real-world adherence to these guidelines is inconsistent[48,49]. Differences in brace type (e.g., Boston, Chêneau, night-time), daily wear-time, weaning protocols, and monitoring strategies contribute to variability in reported effectiveness. Similarly, indications for surgery vary widely, with some surgeons recommending fusion at 40° for younger patients, while others wait until 50° or even 60° depending on the curve type and patient preference. Standardized surgical thresholds based on evidence and patient-reported metrics are still lacking. Addressing these challenges requires a coordinated, multidisciplinary approach that incorporates long-term, prospective data collection, robust PROM integration, and standardization of treatment protocols.
CONCLUSION
AIS remains a complex condition that demands evidence-based and patient-centered care. While the majority of individuals with AIS live healthy, functional lives, the trajectory of the condition - particularly in untreated or inadequately managed cases - can lead to spinal deformity, compromised quality of life and increased psychosocial burden in adulthood. This review has compared the natural history of untreated AIS with outcomes from bracing and surgical treatment, providing insights into each pathway’s benefits and limitations.
Future guidelines should emphasize holistic, multidisciplinary care involving spine surgeons, physiatrists, psychologists, physical therapists, and patient advocates. A paradigm shift from “curve-centric” to “patient-centric” care is essential to improve long-term satisfaction and function.
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