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- Dufvenberg, Marlene, 1961-
(author)
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Adolescent Idiopathic Scoliosis : Postural Stability, Prognostic factors and Impact of Conservative Treatments on Radiologic, Clinical and Self-Reported Outcomes
- 2024
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Doctoral thesis (other academic/artistic)abstract
- 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.
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