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Prevalence of idiopathic scoliosis in athletes: a systematic review and meta-analysis
  1. Leila Mousavi1,
  2. Foad Seidi1,
  3. Hooman Minoonejad1,
  4. Farshad Nikouei2
  1. 1 Health and Sports Medicine Department, Faculty of Physical Education and Sport Sciences, University of Tehran, Tehran, Iran
  2. 2 Bone and Joint Reconstruction Research Center, Shafa Orthopedic Hospital, Iran University of Medical Sciences, Tehran, Iran
  1. Correspondence to Dr Foad Seidi; foadseidi{at}ut.ac.ir

Abstract

Objective This study aimed to determine the prevalence of idiopathic scoliosis (IS) in child, adolescent and adult athletes of all sports activity levels.

Design Systematic review with meta-analysis.

Data sources Electronic databases (PubMed, Scopus, ProQuest, Sage journals, ScienceDirect, Google Scholar and Springer) were systematically searched up from inception to 28 September 2021.

Eligibility criteria for selecting studies Observational investigations were included to evaluate the prevalence of IS in athletes (engaged in any type of individual and team sports). Congenital scoliosis, neuromuscular scoliosis, Scheuermann’s kyphosis and de novo scoliosis were not included. The risk of bias was assessed using the tool developed by Hoy et al.

Results Twenty-two studies were included (N=57 470, range 15–46544, participants), thirteen studies were of high-quality. The estimated prevalence of IS in athletes was 27% (95% CI 20% to 35%, I2=98%), with a 95% prediction interval (1% to 69%). The prevalence of IS was significantly higher in female athletes (35%, 95% CI 27% to 34%, I2=98%). Ballet dancers showed a high IS prevalence (35%, 95% CI 24% to 47%, I2=98%). Recreational athletes showed a higher IS prevalence (33%, 95% CI 24% to 43%, I2=98%) than at competitive-level athletes (0.05%, 95% CI 0.03% to 0.08%, I2=98%), followed by elite (20%, 95% CI 13% to 27%, I2=98%).

Conclusions The prevalence of IS in athletes was similar or higher to that as seen in other studies of the general population. IS prevalence may have a U-shaped relationship relative to level of competition. Further studies are required to determine which sports have the highest IS prevalence.

  • Sports
  • Spine
  • Meta-analysis
  • Athlete

Data availability statement

Data sharing statement Statistical codes and dataset are available from the corresponding author at foadseidi@ut.ac.ir. Also, these files are available in the online supplemental files 6 (appendix 6) and 7 (data file).

http://creativecommons.org/licenses/by-nc/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

https://doi.org/10.1136/bmjsem-2022-001312

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    WHAT IS ALREADY KNOWN ON THIS TOPIC

    • Although precise idiopathic scoliosis (IS) prediction is impossible, there is a need to prevent the curve progression.

    • The prevalence of IS is higher among females.

    • IS can cause postural changes, standing instability and gait variations, as well as pain, poor quality of life and negative self-image.

    • The prevalence of IS in athletes can be associated with sports injuries.

    WHAT THIS STUDY ADDS

    • The prevalence of IS in athletes was similar or higher to that as seen in other studies of the general population.

    • The prevalence of IS among ballet dancers (0.35) is significantly high.

    • This review showed a U-shaped curve of IS prevalence in athletic sports levels. Recreational and elite athletes exhibited a higher prevalence of IS.

    • Current literature does not provide enough information about all sports to determine which sport causes the highest prevalence of IS.

    • For more strong conclusions, we need high-quality epidemiological studies on male athletes as well as child athletes.

    Introduction

    Idiopathic scoliosis (IS) is a three-dimensional change in the spine.1 The prevalence of SI, which depends on the size of the curve, has been reported to range between 0.47% and 5.2%.2 Spinal health is a common concern in all kinds of sports. Several studies have reported the prevalence of scoliosis among the athletes engaged in ballet and dance,1 3–5 gymnastics,6 volleyball7 and swimming.8 9 The prevalence of IS is higher in women with a curvature equal to or greater than 10°.10

    Because the causes of IS are unknown, it is impossible to definitely prevent this disease. However, there is agreement on the need to prevent the progress of the curve.11 The curve pattern is probably related to increased pain (thoracolumbar curves have the least pain and double curves have the most pain).12 Self-image is frequently affected and diminished.12 IS causes posture changes and standing instability. It is also associated with gait changes in larger curves, which can cause pain and poor quality of life.13 Therapeutic exercises,14 bracing and surgery are all treatment options for this disease.12 Therapeutic exercises, acupuncture, manual therapy alone or in combination with rehabilitation exercises and traction are some of the interventions discussed in the literature for this postural disorder.10 A review of the literature shows that exercise can reduce the Cobb angle and improve the strength, balance and mobility of adolescents with IS.14

    Competitive sports such as javelin throwing, gymnastics and weightlifting impose great pressure on the spine.15 Spinal injuries account for approximately 15% of all sports injuries.16 It is unclear whether the prevalence of IS among athletes from different sports is lower or higher than that of non-athletes.

    Understanding the prevalence of IS in various sports is important for several reasons. Researchers can assess a disease load by knowing the number of people in a population who suffer from a disease or a specific disorder.17 Normal posture may play an important role in sports performance,18 and the loss of normal spinal alignment caused by IS may be related to adjustments in muscular moments that can alter joint alignment.19 As a result, the prevalence of IS in athletes may have an impact on their athletic performance. Since the common prevalence of IS among athletes has been attributed to sports injuries,3 20 21 knowing its exact prevalence in athletes can aid in the use of preventative strategies.

    If the prevalence of IS varies from sport to sport, this information can lead to earlier diagnosis of IS in those sports. This can help to lower the risk of progression and the need for surgical intervention and also improve the health status and performance of athletes. This study aims to determine the prevalence of IS among athletes of different sports.

    Methods

    Protocol and registration

    This systematic review was conducted according to the recommendations in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 statement.22 The study protocol was registered in the PROSPERO database with this ID: CRD42021270390.

    Study eligibility criteria

    This study reviewed observational investigations (cross-sectional, case–control and cohort) along with those on the following diagnostic methods for IS: surface topography imaging and spinal deformity assessment, radiography-based imaging and evaluation of IS, MRI-based evaluation of IS, CT, Adam’s forward bend test, scoliometer measurements, individual Moiré topography,23 the Watson-MacDonncha Posture Analysis (WMPA) and spinal mouse. The studies that investigated the prevalence of IS in child, adolescent and adult athletes (any type of sports; individual and team sports) were also reviewed.

    Participants were selected from among the athletes aged 8–60 years. Sports activity was classified into three levels: a recreational athlete is someone who engages in a sports team for fun and does not train or compete on a national or international level,24 a competitive athlete is someone who plays in a competitive sports team, trains and/or competes in local competition, and an elite athlete is someone who plays on a competitive sports team and competes on a national or international level.24 25 The case studies and case series with a sample size of less than 6, letters and opinion pieces and studies on congenital scoliosis, neuromuscular scoliosis, Scheuermann’s kyphosis and de novo scoliosis were excluded from this review. Unpublished studies were not sought. It is noteworthy that papers in all languages were included in this review.

    Sources and study selection

    Electronic databases (PubMed, Scopus, ProQuest, Sage journals, ScienceDirect, Google Scholar and Springer) were searched for eligible studies from inception to 28 September 2021. Reference lists of included studies were searched to identify further appropriate studies. keywords were searched for subject headings (MeSH headings). The complete search strategy is presented in online supplemental appendix 1. To identify relevant outcome, we included the term: ‘Scoliosis’. To identify relevant sports, we included the terms: ‘Sports’ or ‘Sport’ or ‘Athletics’ or ‘Athletic’ or ‘Athletic performance’ or ‘Physical fitness’ or ‘Youth Sports’ or ‘ Racquet Sports’ or ‘Water sports’ or ‘ Team sports’. To identify relevant populations, we included the terms: ‘Athlete’ or ‘Athletes’ or ‘Professional athlete’ or ‘Professional athletes’ or ‘Elite athletes’ or ‘Elite athlete’ or ‘College athletes’ or ‘College athlete’. Also, to identify relevant populations, we included the terms: ‘Physical Activities’ or ‘Physical Activity’ or ‘Physical Exercise’ or ‘Physical Exercises’.

    Supplemental material

    No language or time limitations were applied. These search filters were used to extract related studies on ProQuest; audio and video content, magazines, trade journals, reports, newspapers and other sources were excluded.

    The results were screened by title, abstract and full text to identify relevant studies. If abstracts or articles needed to be translated into another language, a translator was asked to do so. (MO) screened the literature for inclusion and (MI) double-checked the decision. Disagreements were settled through discussion. If the disagreement had persisted, the third reviewer’s (SE) decision would have been final.

    Data extraction and management

    For each study, the following information was extracted: first author, year of publication, country, language, sports fields, levels of sports activity, sample size, gender and age of participants, number of athletes, number of controls, diagnosis method, Cobb angle limit considered as scoliosis, IS prevalence in athletes and IS prevalence in the control group. The data were extracted collaboratively by two reviewers (LM and FS). Discussion was used to settle disagreements. Reviewers communicated for unreported data or extra details in the case of missing data. There was no blinding of study authors, institutions or journals during data extraction. Data were recorded in a data extraction form.

    Assessment of methodological quality

    Two authors (LM and FS) independently assessed the quality of studies using the JBI critical appraisal tool, which was developed by Munn et al.26 Intraclass correlation coefficient (ICC) was calculated to ensure inter-rater reliability (ICC=0.85, 95% CI=0.55 to 0.95). This tool included 10 criteria for evaluating the methodological quality of studies reporting prevalence data. Answers to the questions can be yes, no, unclear or not applicable. Because the appraisal tool does not provide a specific definition of acceptable quality, the acceptable quality scores were defined to be five or higher. Disagreements were settled through consensus discussions. The same authors (LM and FS) independently assessed the risk of bias in prevalence studies using the tool developed by Hoy et al.27 The tool consists of 10 items that evaluate both internal and external validity. To ensure inter-rater reliability, the ICC was calculated (ICC=0.87, 95% CI=0.65 to 0.95). Disagreements were settled through consensus discussion.

    Data synthesis

    Under a random-effects model, the weighted summary proportion was estimated using the arcsine transformation and the inverse variance approach. Due to significant heterogeneity, the random-effects model was used. Publication bias was assessed graphically using funnel plots, and Peters’ test was used to assess publication bias and the small study effect statistically. The inverse SE was used in the y-axis of the funnel plots because conventional funnel plots are not recommended for meta-analyses of proportion studies.28

    Heterogeneity was assessed using I2 statistics, which shows the percentage of the total variation in all studies resulting from heterogeneity between studies.29 Subgroup analysis was performed in the subsequent classes: gender, age, sports fields and levels of sports activity. The leave-one-out meta-analysis was used for sensitivity analysis. To quantify the range of existing heterogeneity, we calculated predictive intervals. The CI measures the precision of an estimated effect, whereas the prediction interval accounts for the true effect of a future study.30 A p≤0.05 was considered statistically significant for all statistical tests. The meta-analysis was carried out using the package ‘meta’ in R V.4.0.5.

    Results

    The preliminary search identified 90 670 records for further investigation (duplicates were manually deleted during the initial search and were not recorded). Figure 1 shows a flow diagram for study selection as well as details for excluding studies. The full texts of 64 articles were evaluated for eligibility; 42 were excluded (online supplemental appendix 2) and data from 22 studies were extracted.

    Supplemental material

    Figure 1
    Figure 1

    Flow diagram for study selection process.

    Study characteristics

    This analysis included 22 studies with a total sample size of 59 161 (the total number of athletes was equal to 7453). Seven studies were conducted in Asia, eight in Europe, four in North America and three in Australia.

    X-ray was the most commonly used data collection tool. Only three of the eight studies that used Adam’s test used a scoliometer to evaluate trunk rotation. Thirty different sports were studied. On the risk of bias scoring criteria,27 16 studies received 0–3 points (low risk), 6 received 4–6 points (moderate risk) and no study received 7–9 points (high risk). The characteristics of the studies that were included are presented in online supplemental appendix 3, table 1–3.

    Supplemental material

    Methodological assessment

    The quality assessment score of the 22 studies is shown in online supplemental appendix 3, table 1 and 2. The mean quality score of the reviews was 6.9±0.2; 95% CI 6.3 to 7.5 (maximum possible quality score was 10). Studies frequently failed to meet the criteria for being recruited in an appropriate manner (88.8%), have an adequate sample size (77.7%), report on appropriate statistical analysis (88.8%), identify and account for confounding factors (88.8%), or use objective criteria for identifying subpopulations (66.6%). In 15 studies, a score equal to or greater than 6 was obtained. Two studies met the criteria but were excluded from the data pooling; one reported the presence of lower limb dissymmetry in athletes (5 mm or more),31 and the other did not report the number and prevalence of scoliosis in athletes.32 As a result, 13 studies were included in the data pooling, with a total sample size of 57 470 (range 15–46544) and 5979 athletes (range 15–1288) (online supplemental appendix 3, table 2).

    Ballet dance, classical ballet, dance, modern dance and jazz were all classified under ballet dance and also gymnastics, rhythmic gymnastics and artistic gymnastics under gymnastics during data analysis. Del Castillo Campos et al 33 reported two types of IS prevalence, one for basketball and one for other sports. As a result, we analysed them in the following manner: campos 1: various sports; campos 2: basketball. Watanabe et al 34 reported nine distinct prevalence rates for various sports. We analysed them in the following manner: (1) swimming, (2) rhythmic gymnastics, (3) classical ballet, (4) dancing, (5) artistic gymnastics, (6) tennis, (7) basketball, (8) badminton and (9) volleyball.

    Definition of IS

    For identifying IS in athletes, the majority of studies used radiography and Cobb limits of 10°. In one study, Cobb limits of 15° for IS were considered.34 In seven studies, Cobb limits for IS were considered 10°6–8 31 35–37 ; in two studies, Cobb limits for IS were considered 5°33 38 and in one study, the Cobb limit was not reported.5 Adam’s test was used without a scoliometer in five studies1 4 18 39 40; one study used Adam’s test with a scoliometer and a 5° limit of trunk rotation21 and two studies used Adam’s test with a scoliometer and a 7° limit of trunk rotation.32 41 WMPA was used in one study,42 and Spinal Mouse was used in another.43 Photography was used in one study.44

    Prevalence of IS in athletes

    The IS prevalence data in various sports are available in online supplemental appendix 3, table 3. The pooled prevalence of IS in athletes (13 studies, see figure 2) was 27% (95% CI 20% to 35%, I2=98%).1 5–8 21 33–37 39 41 In this review, the predictive interval ranged from 0.01% to 0.69%, and it is appropriate for a future study based on previous knowledge.

    Figure 2
    Figure 2

    Forest plot of IS prevalence in athletes.

    Publication bias and sensitivity analyses

    The funnel plot revealed asymmetry, indicating possible publication bias and high heterogeneity (figure 3). Peters’ test revealed no evidence of small study bias (Peters’ test, p=0.65). Sensitivity analyses were performed in all meta-analyses by sequentially removing studies. The overall effect sizes (ESs) from the leave-one-out meta-analysis were all close to the overall ES, and the sensitivity analysis did not affect the significance or direction of the ESs, with point estimates ranging from 0.26 to 0.29. This means that there are no studies that have a significant impact on the results of our meta-analysis (online supplemental appendix 4).

    Supplemental material

    Figure 3
    Figure 3

    Funnel plot and Peters’ test result.

    Subgroup analysis

    We were able to estimate the ES for each subgroup using subgroup analysis (table 1). Online supplemental appendix 5 contains the forest plots for all subgroup analyses.

    Supplemental material

    View this table:
    Table 1

    Subgroup analysis of gender, age, sports fields, levels of sports activity

    Subgroup analysis for the prevalence of IS in athletes and gender

    We discovered that female athletes had a significantly larger ES when we compared prevalence rates across subgroups (table 1 and online supplemental appendix 5). We compared female-only studies to studies that included both male and female subjects. We were unable to locate a high-quality article in which the subject was solely male.

    Subgroup analysis for the prevalence of IS in athletes and age

    Although adolescent athletes have a prevalence rate of 0.30 (table 1), there was no significant difference in IS prevalence when we compared athletes of different ages.

    Subgroup analysis for the prevalence of IS in athletes and sports fields

    The prevalence of IS was highest in ballet dance, according to pooled results (0.35). When different sports were evaluated together, the prevalence of IS was lower than in other sports fields (0.16). Figure 4 shows the forest plot of subgroup analysis for sports fields.

    Figure 4
    Figure 4

    Forest plot of subgroup analysis for sports fields.

    Subgroup analysis for the prevalence of IS in athletes and levels of sports activity

    Our findings revealed a significant difference between athletes of various levels. The highest and the lowest prevalence of IS was observed at the recreational level (0.33) and the competitive level (0.05), respectively.

    Sensitivity and subgroup analyses

    We used sensitivity and subgroup analysis based on gender, age, sports fields and levels of sports activity to explore potential sources of heterogeneity but heterogeneity remained high.

    Discussion

    This study aimed to investigate the prevalence of IS in athletes of different sports using a meta-analysis study. The overall ES of IS in athletes was 27%, based on data pooling from 13 high-quality studies in this review. The predictive interval in this study ranged from 1% to 69% and includes the possibility that new research would detect an IS prevalence in this range.

    The study findings showed that the prevalence of IS was significantly higher in female athletes. We were unable to identify a high-quality article in which the subject was solely male. As a result, this estimate should be interpreted cautiously. The female to male ratio ranges from 1.5:1 to 3:1 and can reach 7.2:1 in 40° curves.2 The high prevalence of adolescent IS has been reported among female adolescents.2 Swimming, according to Zaina et al,32 has a different effect on the spine depending on the gender of the swimmers. Swimming has a greater effect on the spine of female adolescents (OR=2.50) than male adolescents (OR=1.21). Their findings could explain the high prevalence of IS in females. Adolescent athletes have received the most attention from researchers. There was no special high-quality study for children, and only a few studies included adult athletes. It has been reported that there is a link between age and the prevalence of IS.45 The prevalence of IS is higher in patients over the age of 15 (after puberty).2 The study findings indicated that the prevalence of IS was higher in adolescents than in other age groups. McMaster et al 46 investigated the relationship between age and the prevalence of adolescent IS in swimmers and discovered that scoliosis is more common in those who begin swimming lessons as children.

    Scoliosis develops due to a variety of causes, but once the scoliotic curve appears, it progresses according to its internal laws and ‘scoliosis emancipates from its aetiology’.6 The study findings showed that the highest prevalence of IS was observed among ballet dancers (0.35). Some authors suggested that the high prevalence of IS in ballet dance is due to body type selection by trainers and dancers themselves.1 21 However, some studies have shown that vigorously mobilising sports can hasten the progression of scoliosis.6 It has been suggested that ballet dancers may be predisposed to scoliosis due to their longer growth period. Ballet dancers who restrict their weight and exercise excessively are thought to be predisposed to bone development delays and abnormal pubertal growth associated with late menarche and secondary amenorrhoea.5 21 Generalised joint hypermobility (GJH) is very common in ballet dancers1 21 and has been implicated in scoliosis. It has been reported that collagen structure changes in GJH dancers may affect spinal stability and the development of scoliosis.47 The majority of young dancers with scoliosis and GJH experience delayed puberty.1 21 As a result, all repetitive and high-intensity activities may have an impact on the bone growth plates and contribute to the progression of IS.1

    The prevalence of IS in athletic sports levels was found to be U-shaped in this review. Proprioceptive deficits were reported in AIS patients in a recent review and meta-analysis article by Lau et al.48 A relationship between vestibular system abnormalities and IS has also been reported.49 These data suggest that patients with IS experience changes in system complexity.

    Complexity is defined as the number of system components and their interactions.50

    Low levels of complexity are associated with poor performance and unhealthy systems.51 In elite athletes, low complexity combined with intense training load and years of training may contribute to the high prevalence of IS. According to the literature, long-term exercise can gradually lead to specific postural adaptations in athletes, and these postural adaptations are related to the specific movements and postures of the sports.52 53

    Athletes need movement variability to effectively adapt to changes in sports activities. If the same movements are performed repeatedly, the same tissues are more likely to be severely overloaded. Movement variability may adjust loads from repetition to repetition, reduce injury risk and allow for variations in coordination patterns.54 Variability has a chaotic structure that is essential for functional movement and health. Perversion from a chaotic structure in biological systems can result in either too robotic and rigid or unstable and noisy systems. These states are less tolerant of perturbations and are associated with pathological conditions or a lack of skill.55 Injuries could result from either decreased or increased variability.56–59

    It can be hypothesised that recreational and elite athletes who have lost chaotic structures of movement variability of their spines are more vulnerable to deviation from the normal alignment of the spine or make progress in their abnormal alignment of the spine because elite athletes have more hours of training and recreational athletes are in primary phases of learning to discover possible solutions for a specific task. It can be hence suggested that an athlete who has lost chaotic structure of movement variability (for any reason) is less likely to develop scoliosis if he or she exercises at the competitive level, and thus, the prevalence of scoliosis is lower at this level.

    Clinical implications

    It is possible that using a preventive strategy in athletes can help reduce the prevalence of IS. These data can be used by researchers, coaches and physiotherapists to develop prevention strategies for high-prevalence IS. To reduce the prevalence of IS among these athletes, it is critical to develop specific exercises to meet their spinal needs. Coaches and physicians should collaborate to create screening programmes that will effectively identify athletes with scoliosis.

    Future research

    The paucity of high-quality epidemiological studies on male athletes and child athletes indicates that more research is needed before strong conclusions can be drawn. We gathered data from seven different sports, so researchers should look into other sports fields. Prospective studies in all sports should be used to determine the prevalence of IS in athletes, while longitudinal studies will reveal long-term results.

    Limitations of this review

    The grey literature was not included in this review study. At no point were reviewers blind to the authors’ identities. As previously stated, Cobb limits for included studies varied, and one study36 assessed only the lower half of the thoracic and lumbar spines and half of the sacrum with radiography. These factors could have influenced the outcome. We did not receive all of the authors’ requested information. Some studies’ missing results may result in a reduction in statistical power. Unfortunately, the prevalence of scoliosis in all sports has not been studied. As a result, current evidence is insufficient to determine which sports have the highest prevalence.

    Conclusion

    It should be cautiously concluded that there is a cause-and-effect relationship between the prevalence of IS and sports activity, and more studies are needed to explain these findings. Researchers have been attempting for years to identify the sports that cause the highest prevalence of IS. The review’s findings and research synthesis can help patients and parents make informed decisions about which sports to participate in, as well as professionals who work with athletes to conduct prevention and treatment programmes. Although IS has been commonly reported among athletes, not all sports have been studied in this regard. Therefore, more studies are needed to fill this research gap.

    Supplemental material

    Supplemental material

    Data availability statement

    Data sharing statement Statistical codes and dataset are available from the corresponding author at foadseidi@ut.ac.ir. Also, these files are available in the online supplemental files 6 (appendix 6) and 7 (data file).

    Ethics statements

    Patient consent for publication

    Ethics approval

    Not applicable.

    References

    1. ↵
      2. Steinberg N ,
      3. Tenenbaum S ,
      4. Zeev A , et al
      . Generalized joint hypermobility, scoliosis, patellofemoral pain, and physical abilities in young dancers. BMC Musculoskelet Disord 2021;22:1–11.doi:10.1186/s12891-021-04023-z
      OpenUrl
    2. ↵
      2. Konieczny MR ,
      3. Senyurt H ,
      4. Krauspe R
      . Epidemiology of adolescent idiopathic scoliosis. J Child Orthop 2013;7:3–9.doi:10.1007/s11832-012-0457-4 pmid:http://www.ncbi.nlm.nih.gov/pubmed/24432052
      OpenUrlCrossRefPubMed
    3. ↵
      2. Wong AYL ,
      3. Chan C ,
      4. Hiller C , et al
      . Is scoliosis associated with dance injury in young recreational dancers? A large-scale cross-sectional epidemiological study. J Dance Med Sci 2022;26:41.doi:10.12678/1089-313X.031522f pmid:http://www.ncbi.nlm.nih.gov/pubmed/34865681
      OpenUrlPubMed
    4. ↵
      2. Hamilton WG ,
      3. Hamilton LH ,
      4. Marshall P , et al
      . A profile of the musculoskeletal characteristics of elite professional ballet dancers. Am J Sports Med 1992;20:267–73.doi:10.1177/036354659202000306 pmid:http://www.ncbi.nlm.nih.gov/pubmed/1636856
      OpenUrlCrossRefPubMedWeb of Science
    5. ↵
      2. Warren MP ,
      3. Gunn JB ,
      4. Hamilton LH , et al
      . Scoliosis and fractures in young ballet dancers. N Engl J Med Overseas Ed 1986;314:1348–53.doi:10.1056/NEJM198605223142104
      OpenUrl
    6. ↵
      2. Tanchev PI ,
      3. Dzherov AD ,
      4. Parushev AD , et al
      . Scoliosis in rhythmic gymnasts. Spine 2000;25:1367–72.doi:10.1097/00007632-200006010-00008 pmid:http://www.ncbi.nlm.nih.gov/pubmed/10828918
      OpenUrlCrossRefPubMedWeb of Science
    7. ↵
      2. Modi H ,
      3. Srinivasalu S ,
      4. Smehta S , et al
      . Muscle imbalance in volleyball players initiates scoliosis in immature spines: a screening analysis. Asian Spine J 2008;2:38.doi:10.4184/asj.2008.2.1.38 pmid:http://www.ncbi.nlm.nih.gov/pubmed/20411141
      OpenUrlPubMed
    8. ↵
      2. Aydın CG ,
      3. Öner A ,
      4. Hekim HH
      . The prevalence of scoliosis in adolescent swimmers and the effect of swimming on adolescent idiopathic scoliosis. Spor Hekimliği Dergisi 2020;55:200–6.doi:10.5152/tjsm.2020.176
      OpenUrl
    9. ↵
      2. Meliscki GA ,
      3. Monterio LZ ,
      4. Maman D , et al
      . Postural assessment and joint instability in athletes of federated brazilian swimmers. Br J Sports Med 2010;44:i4–5.doi:10.1136/bjsm.2010.078972.13
      OpenUrlAbstract
    10. ↵
      2. Green BN ,
      3. Johnson C ,
      4. Moreau W
      . Is physical activity contraindicated for individuals with scoliosis? a systematic literature review. J Chiropr Med 2009;8:25–37.doi:10.1016/j.jcm.2008.11.001 pmid:http://www.ncbi.nlm.nih.gov/pubmed/19646383
      OpenUrlPubMed
    11. ↵
      2. Rigo MD ,
      3. Grivas TB
      . "Rehabilitation schools for scoliosis" thematic series: describing the methods and results. Scoliosis 2010;5:1.doi:10.1186/1748-7161-5-27 pmid:http://www.ncbi.nlm.nih.gov/pubmed/21184672
      OpenUrlCrossRefPubMed
    12. ↵
      2. Asher MA ,
      3. Burton DC
      . Adolescent idiopathic scoliosis: natural history and long term treatment effects. Scoliosis 2006;1:1–10.doi:10.1186/1748-7161-1-2
      OpenUrlPubMed
    13. ↵
      2. Daryabor A ,
      3. Arazpour M ,
      4. Sharifi G , et al
      . Gait and energy consumption in adolescent idiopathic scoliosis: a literature review. Ann Phys Rehabil Med 2017;60:107–16.doi:10.1016/j.rehab.2016.10.008 pmid:http://www.ncbi.nlm.nih.gov/pubmed/27986427
      OpenUrlPubMed
    14. ↵
      2. Fusco C ,
      3. Zaina F ,
      4. Atanasio S , et al
      . Physical exercises in the treatment of adolescent idiopathic scoliosis: an updated systematic review. Physiother Theory Pract 2011;27:80–114.doi:10.3109/09593985.2010.533342 pmid:http://www.ncbi.nlm.nih.gov/pubmed/21198407
      OpenUrlCrossRefPubMed
    15. ↵
      2. Cotta H ,
      3. Steinbrück K
      . Langenbecks Archiv für Chirurgie. In: 82. Wirbelsäulenschäden beim Leistungssportler. 349, 1979: 385–8.doi:10.1007/BF01729540
    16. ↵
      2. Williams JG
      . Biomechanical factors in spinal injuries. Br J Sports Med 1980;14:14:.doi:10.1136/bjsm.14.1.14 pmid:http://www.ncbi.nlm.nih.gov/pubmed/7378663
      OpenUrlFREE Full Text
    17. ↵
      2. Migliavaca CB ,
      3. Stein C ,
      4. Colpani V
      . How are systematic reviews of prevalence conducted? a methodological study. BMC Med Res Methodol 2020;20:1–9.doi:10.1016/j.jclinepi.2020.06.039
      OpenUrlCrossRefPubMed
    18. ↵
      2. Vařeková R ,
      3. Vařeka I ,
      4. Janura M , et al
      . Evaluation of postural asymmetry and gross joint mobility in elite female volleyball athletes. J Hum Kinet 2011;29:5.doi:10.2478/v10078-011-0034-9 pmid:http://www.ncbi.nlm.nih.gov/pubmed/23486553
      OpenUrlPubMed
    19. ↵
      2. Fortin C ,
      3. Feldman DE ,
      4. Tanaka C , et al
      . Inter-rater reliability of the evaluation of muscular chains associated with posture alterations in scoliosis. BMC Musculoskelet Disord 2012;13:1–9.doi:10.1186/1471-2474-13-80
      OpenUrlCrossRefPubMed
    20. ↵
      2. Supartono B ,
      3. Gamma R ,
      4. Wiyono S
      . P-3 the influence of scoliosis towards secondary osteoarthritis of the knee joint in athletes. BMJ Open Sport Exerc Med 2016.doi:10.1136/bjsports-2016-097120.56
    21. ↵
      2. Longworth B ,
      3. Fary R ,
      4. Hopper D
      . Prevalence and predictors of adolescent idiopathic scoliosis in adolescent ballet dancers. Arch Phys Med Rehabil 2014;95:1725–30.doi:10.1016/j.apmr.2014.02.027 pmid:http://www.ncbi.nlm.nih.gov/pubmed/24662812
      OpenUrlPubMed
    22. ↵
      2. Page MJ ,
      3. McKenzie JE ,
      4. Bossuyt PM , et al
      . The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. Syst Rev 2021;10:1–11.doi:10.1186/s13643-021-01626-4
      OpenUrlCrossRef
    23. ↵
      2. Karpiel I ,
      3. Ziębiński A ,
      4. Kluszczyński M , et al
      . A survey of methods and technologies used for diagnosis of scoliosis. Sensors 2021;21:8410.doi:10.3390/s21248410 pmid:http://www.ncbi.nlm.nih.gov/pubmed/34960509
      OpenUrlPubMed
    24. ↵
      2. Stirling AE ,
      3. Kerr GA
      . Perfectionism and mood states among recreational and elite athletes. Athl Insight J 2006;8:13–27.
      OpenUrl
    25. ↵
      2. Cobley S ,
      3. Baker J ,
      4. Wattie N , et al
      . Annual age-grouping and athlete development. Sports Medicine 2009;39:235–56.doi:10.2165/00007256-200939030-00005
      OpenUrlCrossRefPubMedWeb of Science
    26. ↵
      2. Munn Z ,
      3. Moola S ,
      4. Riitano D , et al
      . The development of a critical appraisal tool for use in systematic reviews addressing questions of prevalence. Int J Health Policy Manag 2014;3:123.doi:10.15171/ijhpm.2014.71 pmid:http://www.ncbi.nlm.nih.gov/pubmed/25197676
      OpenUrlPubMed
    27. ↵
      2. Hoy D ,
      3. Brooks P ,
      4. Woolf A , et al
      . Assessing risk of bias in prevalence studies: modification of an existing tool and evidence of interrater agreement. J Clin Epidemiol 2012;65:934–9.doi:10.1016/j.jclinepi.2011.11.014 pmid:http://www.ncbi.nlm.nih.gov/pubmed/22742910
      OpenUrlCrossRefPubMed
    28. ↵
      2. Hunter JP ,
      3. Saratzis A ,
      4. Sutton AJ , et al
      . In meta-analyses of proportion studies, funnel plots were found to be an inaccurate method of assessing publication bias. J Clin Epidemiol 2014;67:897–903.doi:10.1016/j.jclinepi.2014.03.003 pmid:http://www.ncbi.nlm.nih.gov/pubmed/24794697
      OpenUrlCrossRefPubMed
    29. ↵
      2. Higgins JPT ,
      3. Thompson SG
      . Quantifying heterogeneity in a meta-analysis. Stat Med 2002;21:1539–58.doi:10.1002/sim.1186 pmid:http://www.ncbi.nlm.nih.gov/pubmed/12111919
      OpenUrlCrossRefPubMedWeb of Science
    30. ↵
      2. Higgins JPT ,
      3. Thompson SG ,
      4. Spiegelhalter DJ
      . A re-evaluation of random-effects meta-analysis. J R Stat Soc Ser A Stat Soc 2009;172:137–59.doi:10.1111/j.1467-985X.2008.00552.x pmid:http://www.ncbi.nlm.nih.gov/pubmed/19381330
      OpenUrlCrossRefPubMed
    31. ↵
      2. Ramos-Álvarez JJ ,
      3. Del Castillo-Campos MJ ,
      4. Polo-Portés CE
      . Comparative study between symmetrical and asymmetrical sports by static structural analysis in adolescent athletes. Arch Med Deporte 2016;33:98–102.
      OpenUrl
    32. ↵
      2. Zaina F ,
      3. Donzelli S ,
      4. Lusini M , et al
      . Swimming and spinal deformities: a cross-sectional study. J Pediatr 2015;166:163–7.doi:10.1016/j.jpeds.2014.09.024 pmid:http://www.ncbi.nlm.nih.gov/pubmed/25444007
      OpenUrlPubMed
    33. ↵
      2. Del Castillo Campos MJ ,
      3. Ramos Alvarez JJ ,
      4. Antelo Suarez O
      . Prevalence of scoliosis in young elite athletes of madrid. Arch Med Deporte 1997;14:119–25.
      OpenUrl
    34. ↵
      2. Watanabe K ,
      3. Michikawa T ,
      4. Yonezawa I , et al
      . Physical activities and lifestyle factors related to adolescent idiopathic scoliosis. J Bone Joint Surg Am 2017;99:284–94.doi:10.2106/JBJS.16.00459 pmid:http://www.ncbi.nlm.nih.gov/pubmed/28196030
      OpenUrlAbstract/FREE Full Text
    35. ↵
      2. Heitkamp HC ,
      3. Horstmann T
      . Complaints and injuries of the spine and medical examinations in female gymnasts. Sportverletz Sportschaden 2005;19:77–81.doi:10.1055/s-2005-858206
      OpenUrlCrossRefPubMedWeb of Science
    36. ↵
      2. Hellström M ,
      3. Jacobsson B ,
      4. Swärd L , et al
      . Radiologic abnormalities of the thoraco-lumbar spine in athletes. Acta Radiol 1990;31:127–32.pmid:http://www.ncbi.nlm.nih.gov/pubmed/2372454
      OpenUrlCrossRefPubMed
    37. ↵
      2. Trexler ET ,
      3. Smith-Ryan AE ,
      4. Roelofs EJ , et al
      . Body composition, muscle quality and scoliosis in female collegiate gymnasts: a pilot study. Int J Sports Med 2015;36:1087–92.doi:10.1055/s-0035-1555781 pmid:http://www.ncbi.nlm.nih.gov/pubmed/26332905
      OpenUrlPubMed
    38. ↵
      2. Ogon M ,
      3. Riedl-Huter C ,
      4. Sterzinger W , et al
      . Radiologic abnormalities and low back pain in elite skiers. Clin Orthop Relat Res 2001;390:151–62.doi:10.1097/00003086-200109000-00018 pmid:http://www.ncbi.nlm.nih.gov/pubmed/11550861
      OpenUrlCrossRefPubMed
    39. ↵
      2. Steinberg N ,
      3. Hershkovitz I ,
      4. Peleg S , et al
      . Morphological characteristics of the young scoliotic dancer. Phys Ther Sport 2013;14:213–20.doi:10.1016/j.ptsp.2012.07.003 pmid:http://www.ncbi.nlm.nih.gov/pubmed/23146194
      OpenUrlCrossRefPubMed
    40. ↵
      2. Becker TJ
      . Scoliosis in swimmers. Clin Sports Med 1986;5:149–58.pmid:http://www.ncbi.nlm.nih.gov/pubmed/3512101
      OpenUrlPubMed
    41. ↵
      2. Zaina F ,
      3. Donzelli S ,
      4. Lusini M , et al
      . Tennis is not dangerous for the spine during growth: results of a cross-sectional study. Eur Spine J 2016;25:2938-44.doi:10.1007/s00586-016-4452-1 pmid:http://www.ncbi.nlm.nih.gov/pubmed/26920135
      OpenUrlPubMed
    42. ↵
      2. Langdon E ,
      3. Snodgrass SJ ,
      4. Young JL , et al
      . Posture of rugby league players and its relationship to non-contact lower limb injury: a prospective cohort study. Phys Ther Sport 2019;40:27–32.doi:10.1016/j.ptsp.2019.08.006 pmid:http://www.ncbi.nlm.nih.gov/pubmed/31465936
      OpenUrlPubMed
    43. ↵
      2. Lotfian S ,
      3. Moghadam N ,
      4. Hassnamirzaie B , et al
      . Are lower extremity injuries related to spinal form abnormalities in professional football players? a prospective cohort study. Asian J Sports Med 2017;8.doi:10.5812/asjsm.55543
    44. ↵
      2. Snodgrass SJ ,
      3. Ryan KE ,
      4. Miller A , et al
      . Relationship between posture and non-contact lower limb injury in young male amateur football players: a prospective cohort study. Int J Environ Res Public Health 2021;18:6424.doi:10.3390/ijerph18126424 pmid:http://www.ncbi.nlm.nih.gov/pubmed/34198516
      OpenUrlPubMed
    45. ↵
      2. Kebaish KM ,
      3. Neubauer PR ,
      4. Voros GD , et al
      . Scoliosis in adults aged forty years and older: prevalence and relationship to age, race, and gender. Spine 2011;36:731–6.doi:10.1097/BRS.0b013e3181e9f120 pmid:http://www.ncbi.nlm.nih.gov/pubmed/20881515
      OpenUrlCrossRefPubMed
    46. ↵
      2. McMaster ME ,
      3. Lee AJ ,
      4. Burwell RG
      . Physical activities of patients with adolescent idiopathic scoliosis (AIS): preliminary longitudinal case–control study historical evaluation of possible risk factors. Scoliosis 2015;10:1–10.doi:10.1186/s13013-015-0029-8
      OpenUrl
    47. ↵
      2. Binns M
      . Joint laxity in idiopathic adolescent scoliosis. J Bone Joint Surg Br 1988;70:420–2.doi:10.1302/0301-620X.70B3.3372564 pmid:http://www.ncbi.nlm.nih.gov/pubmed/3372564
      OpenUrlPubMed
    48. ↵
      2. Lau KKL ,
      3. Law KKP ,
      4. Kwan KYH , et al
      . Timely revisit of proprioceptive deficits in adolescent idiopathic scoliosis: a systematic review and meta-analysis. Global Spine J 2021;0:1–10.doi:10.1177/21925682211066824 pmid:http://www.ncbi.nlm.nih.gov/pubmed/34911378
    49. ↵
      2. Scheyerer MJ ,
      3. Rohde A ,
      4. Stuermer KJ , et al
      . Impact of the vestibular system on the formation and progression to idiopathic scoliosis: a review of literature. Asian Spine J 2021;15:701.doi:10.31616/asj.2020.0308 pmid:http://www.ncbi.nlm.nih.gov/pubmed/33189104
      OpenUrlPubMed
    50. ↵
      2. Vaillancourt DE ,
      3. Newell KM
      . Changing complexity in human behavior and physiology through aging and disease. Neurobiol Aging 2002;23:1–11.doi:10.1016/s0197-4580(01)00247-0 pmid:http://www.ncbi.nlm.nih.gov/pubmed/11755010
      OpenUrlCrossRefPubMedWeb of Science
    51. ↵
      2. Muelas Pérez R ,
      3. Sabido Solana R ,
      4. Barbado Murillo D ,
      5. Pérez RM ,
      6. Solana RS ,
      7. Murillo DB , et al
      . Visual availability, balance performance and movement complexity in dancers. Gait Posture 2014;40:556–60.doi:10.1016/j.gaitpost.2014.06.021 pmid:http://www.ncbi.nlm.nih.gov/pubmed/25086798
      OpenUrlPubMed
    52. ↵
      2. Hashem Boroojerdi M ,
      3. Rahimi A ,
      4. Roostayi MM , et al
      . Thoracic and lumbar sagittal spinal curvature adaptations between elite Iranian road and speed cyclists. J Biomed Phys Eng 2021;11:297.doi:10.31661/jbpe.v0i0.2001-1058 pmid:http://www.ncbi.nlm.nih.gov/pubmed/34189118
      OpenUrlPubMed
    53. ↵
      2. Antequera-Vique JA ,
      3. Oliva-Lozano JM ,
      4. Muyor JM
      . Effects of cycling on the morphology and spinal posture in professional and recreational cyclists: a systematic review. Sports Biomech 2022:1–30.doi:10.1080/14763141.2022.2058990 pmid:http://www.ncbi.nlm.nih.gov/pubmed/35440291
    54. ↵
      2. Bartlett R ,
      3. Wheat J ,
      4. Robins M
      . Is movement variability important for sports biomechanists? Sports Biomech 2007;6:224–43.doi:10.1080/14763140701322994 pmid:http://www.ncbi.nlm.nih.gov/pubmed/17892098
      OpenUrlCrossRefPubMed
    55. ↵
      2. Stergiou N ,
      3. Decker LM
      . Human movement variability, nonlinear dynamics, and pathology: is there a connection? Hum Mov Sci 2011;30:869–88.doi:10.1016/j.humov.2011.06.002 pmid:http://www.ncbi.nlm.nih.gov/pubmed/21802756
      OpenUrlCrossRefPubMed
    56. ↵
      2. Hamill J ,
      3. van Emmerik RE ,
      4. Heiderscheit BC , et al
      . A dynamical systems approach to lower extremity running injuries. Clin Biomech 1999;14:297–308.doi:10.1016/s0268-0033(98)90092-4 pmid:http://www.ncbi.nlm.nih.gov/pubmed/10521606
      OpenUrlPubMed
    57. ↵
      2. Heiderscheit BC ,
      3. Hamill J ,
      4. van Emmerik REA
      . Variability of stride characteristics and joint coordination among individuals with unilateral patellofemoral pain. J Appl Biomech 2002;18:110–21.doi:10.1123/jab.18.2.110
      OpenUrlCrossRef
    58. ↵
      2. James CR ,
      3. Dufek JS ,
      4. Bates BT
      . Effects of injury proneness and task difficulty on joint kinetic variability. Med Sci Sports Exerc 2000;32:1833–44.doi:10.1097/00005768-200011000-00004 pmid:http://www.ncbi.nlm.nih.gov/pubmed/11079511
      OpenUrlCrossRefPubMed
    59. ↵
      2. Hamill J ,
      3. Palmer C ,
      4. Van Emmerik REA
      . Coordinative variability and overuse injury. BMC Sports Sci Med Rehabil 2012;4:1–9.doi:10.1186/1758-2555-4-45
      OpenUrl

    Supplementary materials

    Footnotes

    • Contributors LM conceived the presented idea. LM and FS developed this theory. Search process, quality assessment and bias assessment were performed by LM, FS and HM. Analytical calculations performed by LM. All authors discussed the results and contributed to the final manuscript.

    • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.