Background: Adolescent idiopathic scoliosis (AIS) is a three-dimensional distortion of spinal curvature of unknown cause that develops during puberty. If the frontal plane curvature exceeds a Cobb angle of 24°, full-time bracing is recommended to prevent curve progression, negative health consequences or need for surgery. However, many patients decline full-time bracing, and limited evidence exists regarding alternative conservative treatments. Increasing knowledge of risk factors enables better identification of high-risk patients, thereby reducing the risk of over- or undertreatment.  

The overall aim of this thesis was to evaluate evidence of association between scoliosis and postural stability to inform a potential treatment target, to investigate the effectiveness of three alternative conservative treatments for patients who declined full-time bracing, and to develop a prognostic model for future risk of increased curvature in AIS.  

Methods: Data collection is based on one systematic literature review and meta-analysis, and one randomised controlled trial (RCT) for patients with AIS. In Paper I, literature was reviewed, and utilized posturography data to assess static postural stability to identify potential differences between patients with AIS and the control group (CON). In Papers II and III, patients were randomly assigned to either physical activity combined with hypercorrective Boston scoliosis night brace (NB), scoliosis-specific exercises (SSE), or a control group with physical activity alone (PA). Effects on trunk rotation, Cobb angle, self-reported physical activity, spinal appearance, and health-related quality of life were evaluated. Likewise, adherence, capability, and motivation in performing self-managed treatment were assessed. Follow-up was conducted at 6 months intervals until endpoint. The endpoint was defined as non-progression if the curvature increased by 6° or less at skeletal maturity, i.e., less than 1cm of growth over 6 months, or progression if the curvature increased by more than 6° before skeletal maturity. In Paper IV, data from the RCT were used for a longitudinal cohort analysis, developing and validating a prognostic model using Cox Proportional Hazards survival analysis. 

Results: Paper I found reduced postural stability in AIS patients compared to CON with increased sway area, mediolateral and anteroposterior range, and a posterior shift in the sagittal plane. The RCT included 135 individuals, mean age of 12.7 years (SD1.4) and Cobb angle of 31° (SD5.3). At 6 months, patients reported high adherence (72-95%) and motivation (65-92%) to the treatment, particularly in the NB group. Both the SSE and PA groups increased physical activity levels compared to the NB group. At endpoint, adherence remained adequate, but better in the NB and PA groups compared with the SSE group (50-89%). Adherence increased with higher capability and motivation, which explained 53% of the variance in adherence at endpoint. The SSE group had higher proportion of moderate problems in mobility and usual activities than the NB and PA groups, with no other clinically relevant between-group differences. The prognostic model (n=127) for curve progression showed acceptable discriminative ability (0.791), with risk factors including skeletal immaturity, larger major curve, and worsening spinal appearance. The model was adjusted for treatment exposure, as NB reduced the risk of curve progression.  

Conclusions: Patients with AIS have decreased postural stability with a posterior positional shift. Treatment evaluation at endpoint showed few between-group differences. However, the SSE group had higher proportion of moderate problems in mobility and usual activities compared to the other groups. Treatment adherence was adequate, but better in the NB and PA groups. Higher capability and motivation increased long-term adherence to the treatment. The treatment alternatives could be considered as the first option following a clinical decision on treatment. Including self-reported spinal appearance as a risk factor in the prognostic model may be clinically important for predicting which patients are at risk of curve progression. 

Bakgrund: Idiopatisk skolios (AIS) är en tredimensionell ryggradskrökning som uppstår under puberteten utan känd orsak. Om kröken i frontalplanet når en Cobbsvinkel över 24 grader rekommenderas korsettbehandling under större delen av dygnet för att förhindra att kröken blir större och leder till negativa hälsokonsekvenser eller kirurgi. Många har svårt att acceptera dygnskorsett och det saknas kunskap om alternativa icke-kirurgiska behandlingsmetoder. Ökad kunskap om riskfaktorer möjliggör bättre identifiering av högriskpatienter och minskar därmed risken för över- eller underbehandling.  

Övergripande syfte med avhandlingen var att utvärdera evidens om sambandet mellan skolios och postural stabilitet vilket skulle kunna påverka behandlingen, att undersöka effektiviteten avseende tre alternativa icke kirurgiska behandlingar för patienter som avböjt dygnskorsett, samt att utveckla en prognostisk modell för framtida risk av ökad krök vid AIS.  

Metod: Datainsamlingen baserades på en systematisk litteraturöversikt med metaanalys och en randomiserad kontrollerad studie (RCT) för patienter med AIS. Delarbete I granskade litteratur och sammanvägde data från posturografi där postural stabilitet undersöktes för att kunna diagnostisera möjliga skillnader mellan patienter med AIS jämfört med kontrollgrupp (CON). I delarbete II och III lottades patienterna till endera fysisk aktivitet i kombination med nattkorsett (NB), eller skolios-specifik träning (SSE), eller kontrollgrupp med enbart fysisk aktivitet (PA). Effekter på bålrotation, Cobbsvinkel, samt självrapporterad fysisk aktivitet, ryggens utseende och hälso-relaterad livskvalité utvärderades. Likaså följsamhet, motivation och egenförmåga att genomföra behandlingen. Uppföljning utfördes var sjätte månad fram till studiens slut. Slutpunkten definierades som ej progress om kröken ökade med 6° eller mindre vid skelettmognad (mindre än 1 cm längdtillväxt under 6 månader) eller progress om kröken ökade mer än 6° före skelettmognad. I delarbete IV användes data från RCT-studien till en longitudinell kohortanalys för att utveckla och validera en prognostisk modell med Cox Proportional Hazards överlevnadsanalys.  

Resultat: Delstudie I visade nedsatt postural stabilitet hos patienter med AIS jämfört med CON genom ökat postural svaj, även framåt-bakåt samt i sidled med tyngdpunkten förskjuten mot hälarna. I RCT-studien deltog 135 individer med en medelålder på 12,7 år (SD1.4) och en Cobb vinkel på 31° (SD5.3). Vid 6 månader fanns hög följsamhet (72-95%) och motivation (65-92%) till behandlingen, med den högsta andelen i NB-gruppen. Både SSE- och PA-grupperna ökade sin totala nivå av fysisk aktivitet per vecka jämfört med NB-gruppen. Vid studiens slut hade SSE-gruppen en högre andel av måttliga problem när det gällde att kunna röra sig och utföra vanliga aktiviteter jämfört med NB- och PA-grupperna, utan andra mellangruppsskillnader. Adekvat följsamhet till behandlingen kvarstod men var bättre i NB- och PA-grupperna jämfört med SSE-gruppen (50-89%). Följsamheten ökade med högre grad av egenförmåga och motivation vilket var tydligare vid studiens slut jämfört med vid 6 månader. Den prognostiska modellen (n=127) för kurvprogess visade acceptabel diskrimineringsförmåga (0.791) där riskfaktorer var skelettomognad, större ryggradskrökning samt försämrad uppfattning om ryggens utseende. Modellen justerades för behandling då nattkorsett minskade risken för ökad ryggradskrökning.  

Konklusion: Patienter med AIS hade nedsatt postural stabilitet med en tyngdpunktsförskjutning mot hälarna. Utvärderingen av behandlingen visade få skillnader mellan grupperna vid studiens slut. SSE-gruppen hade fler med måttliga problem att röra sig och utföra aktiviteter jämfört med övriga grupper. Följsamheten till behandlingen var adekvat vid slutpunkten men var bättre i NB- och PA-grupperna. Högre motivation och egenförmåga ökade långsiktigt följsamheten till behandlingen. Behandlingsalternativen skulle kunna ses som första alternativ efter kliniskt beslut om behandling. Att inkludera självrapport om ryggens utseende som riskfaktor i den prognostiska modellen kan vara kliniskt viktigt för att förutsäga vilka patienter som riskerar progress av kröken.   

Background and purpose: The study’s purpose was to develop and internally validate a prognostic survival model exploring baseline variables for adolescent idiopathic scoliosis curve progression.

Methods: A longitudinal prognostic cohort analysis was performed on trial data (n = 135) including girls and boys, Cobb angle 25–40°, aged 9–17 years, remaining growth > 1 year, and previously untreated. Prognostic outcome was defined as curve progression of Cobb angle of > 6° prior to skeletal maturity. 34 candidate prognostic variables were tested. Time-to-event was measured with 6-month intervals. Cox proportional hazards regression survival model (CoxPH) was used for model development and validation in comparison with machine learning models (66.6/33.3 train/test data set). The models were adjusted for treatment exposure.

Results: The final primary prognostic model included 127 patients, predicting progress with acceptable discriminative ability (concordance = 0.79, 95% confidence interval [CI] 0.72–0.86). Significant prognostic risk factors were Risser stage of 0 (HR 4.6, CI 2.1–10.1, P < 0.001), larger major curve Cobb angle (HRstandardized 1.5, CI 1.1–2.0, P = 0.005), and higher score on patient-reported pictorial Spinal Appearance Questionnaire (pSAQ) (HRstandardized 1.4, CI 1.0–1.9, P = 0.04). Treatment exposure, entered as a covariate adjustment, contributed significantly to the final model (HR 3.1, CI 1.5–6.0, P = 0.001). Sensitivity analysis displayed that CoxPH maintained acceptable discriminative ability (AUC 0.79, CI 0.65–0.93) in comparison with machine learning algorithms.

Conclusion: The prognostic model (Risser stage, Cobb angle, pSAQ, and menarche) predicted curve progression of > 6° Cobb angle with acceptable discriminative ability. Adding patient report of the pSAQ may be of clinical importance for the prognosis of curve progression.

Adolescents with idiopathic scoliosis (AIS) often receive conservative treatments aiming to prevent progression of the spinal deformity during puberty. This study aimed to explore patient adherence and secondary outcomes during the first 6 months in an ongoing randomised controlled trial of three treatment interventions. Interventions consisted of physical activity combined with either hypercorrective Boston scoliosis night brace (NB), scoliosis-specific exercise (SSE), or physical activity alone (PA). Measures at baseline and 6 months included angle of trunk rotation (ATR), Cobb angle, International Physical Activity Questionnaire short form (IPAQ-SF), pictorial Spinal Appearance Questionnaire (pSAQ), Scoliosis Research Society (SRS-22r), EuroQol 5-Dimensions Youth (EQ-5D-Y) and Visual Analogue Scale (EQ-VAS). Patient adherence, motivation, and capability in performing the intervention were reported at 6 months. The study included 135 patients (111 females) with AIS and >1-year estimated remaining growth, mean age 12.7 (1.4) years, and mean Cobb angle 31 (±5.3). At 6 months, the proportion of patients in the groups reporting high to very high adherence ranged between 72 and 95%, while motivation ranged between 65 and 92%, with the highest proportion seen in the NB group (p = 0.014, p= 0.002). IPAQ-SF displayed significant between group main effects regarding moderate activity (F = 5.7; p = 0.004; η_p² = 0.10), with a medium-sized increase favouring the SSE group compared to NB. Walking showed significant between group main effects, as did metabolic equivalent (MET-min/week), with medium (F = 6.8, p = 0.002; η_p² = 0.11, and large (F = 8.3, p = < 0.001, η_p² = 0.14) increases, respectively, for the SSE and PA groups compared to NB. From baseline to 6 months, ATR showed significant between group medium-sized main effects (F = 1.2, p = 0.019, η_p² = 0.007) favouring the NB group compared to PA, but not reaching a clinically relevant level. In conclusion, patients reported high adherence and motivation to treatment, especially in the NB group. Patients in the SSE and PA groups increased their physical activity levels without other clinically relevant differences between groups in other clinical measures or patient-reported outcomes. The results suggest that the prescribed treatments are viable first-step options during the first 6 months.

Background

Postural stability deficits have been proposed to influence the onset and progression of adolescent idiopathic scoliosis (AIS). This study aimed to systematically identify, critically evaluate and meta-analyse studies assessing postural stability during unperturbed stance with posturography in AIS compared to typically developed adolescents.

Methods

Studies from four electronic databases (PubMed, Scopus, CINAHL, PEDro) were searched and case-control methodological quality assessed using a risk-of-bias assessment tool and a posturography methodological quality checklist. Pooled data regarding centre of pressure (COP) parameters such as sway area, Mediolateral (ML) and Anteroposterior (AP) position and range were compared for AIS and typically developed adolescents using Cohen’s d effect size (ES) and homogeneity estimates.

Results

Eighteen studies for quality analysis and 9 of these for meta-analysis were identified from 971 records. Risk-of-bias assessment identified 6 high, 10 moderate and 2 low risk-of-bias studies. The posturography methodological quality checklist identified 4 low, 7 moderate and 7 high-quality studies. Meta-analysis was performed for sway area whereas ML and AP are presented in three different meta-analyses due to divergent measurement units used in the studies: ML position 1 (MLP1), ML position 2 (MLP2) and ML range (MLR); AP position 1 (APP1), AP position 2 (APP2) and AP range (APR). Cohen’s d showed a medium ES difference in sway area 0.65, 95% CI (0.49–0.63), whereas ML showed no (MLP1, MLP2) and large (MLR) ES differences; MLP1 0.15, 95% CI (0.08–0.22); MLP2 0.14, 95% CI (0.08–0.19); and MLR 0.94, 95% CI (0.83–1.04). Cohen’s d for AP showed small ES (APP1) and large ES difference (APP2 and APR); APP1 0.43, 95% CI (0.31–0.54); APP2 0.85, 95% CI (0.72–0.97); and APR 0.98, 95% CI (0.87–1.09). Cochran’s Q and Higgins I² showed homogeneity between studies.

Conclusions

There is moderate quality evidence for decreased postural stability in AIS measured as COP parameters sway area, ML and AP range with a positional shift posteriorly in the sagittal plane. The findings support studying postural stability in early stage AIS and also prospectively identify cause and effect of the curvature as well as effectiveness of postural control interventions in the prevention of scoliosis progression.

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