Long-term results in 109 of 138 patients with AIS who were treated with Boston brace at Sophies Minde Orthopaedic Hospital (Orthopaedic Department, Oslo University Hospital, Rikshospitalet) in Oslo, Norway from 1976-88 and who had their last earlier follow-up no longer than 2 years after brace weaning, have been published previously . These patients were not included in the present study.
We carefully evaluated the medical journals of the remaining 480 patients who had been braced for scoliosis and prospectively followed during the same period, and identified 369 patients with idiopathic scoliosis. These patients were invited for long-term follow-up. We included both patients with late-onset juvenile and AIS. Late-onset juvenile idiopathic scoliosis is discovered at 7 to 10 years, while AIS is discovered at 10 years of age or older .
In general we followed the SRS committee criteria, which recommend bracing for curves that measure between 25° and 40° and surgery for curves that are greater than 45° during the growth phase and that the brace should be prescribed until growth of the spine has stopped http://www.srs.org/professionals/conditions_and_treatment/adolsescent_idiopathic_scoliosis/treatment.htm. Accordingly, the indication for bracing was a major scoliotic curve ≥ 20° with an observed progression > 5° after 4 months and Risser sign < 4. Prior to bracing standing radiographs were taken in the front and lateral projections. Patients had follow-up with clinical and radiological examination at 4 months intervals throughout the brace treatment period. Wearing of the brace was assessed by one orthopaedic surgeon (JEL) and reported as used as prescribed, irregular, or aborted. Patients were recommended to use the brace for 23 hours daily. Wearing of the brace < 20 hours daily was described as irregular.
Physiotherapy was not prescribed in addition to bracing, but in general patients were recommended to participate in physical activity at school and leisure time. They were advised not to carry heavy loads, and in case they had a long walk to school they were given two sets of schoolbooks.
Brace weaning was carried out either 2 years after menarche or at Risser sign 5, in some patients at Risser sign 4. After weaning all patients had follow-up examination at 6, 12, and 24 months.
A standardised form was used to obtain clinical and radiological data. Radiological measurements were performed by an orthopaedic surgeon (JEL) and controlled by an experienced radiologist (RG). Both used the Cobb method, digital measurements were used at long-term follow-up. The intra-observer error for the Cobb angle was about 3° in a recent study using manual and digital measurements, and < 5° in a previous study [12, 13]. In the present study the measurement error was within these limits as evaluated by the reproducibility of radiographic readings of repeated measurements of all radiographs from 10 patients at regular intervals. In patients with double thoraco-lumbar curves the largest curve prior to bracing was defined as the major curve.
At long-term follow-up, all patients first filled in a standardised questionnaire and thereafter they had clinical and radiological examination. The questionnaire comprised validated measures of pain, disability, quality of life and work, and questions about demographics.
Evaluation of work status included questions about paid work (full-time, part-time, not working) and status if not working (on sick leave, vocational or medical rehabilitation, disability pension, unemployed, homemaker, or student) . Norway has a National Social Security System that covers all inhabitants. Patients on sickness certification receive 100% benefit up to one year. Thereafter, they receive medical or vocational rehabilitation in order to reduce disability. If the patients are not able to work after rehabilitation they receive a disability pension with a lower benefit.
The General Function Score (GFS) was used to measure back-related disability in activities of daily living . Patients answered nine questions wherein 100% represents maximum disability.
The Norwegian version of the original Oswestry Disability Index (ODI) (version 1.0) was used to evaluate back-specific disability [14, 16]. This score has 10 questions about pain and pain-related disability in activities of daily living and social participation wherein 100% represents the worst imaginable pain and disability.
Patients rated their overall function by the Global Back Disability Question . This is a single question designed to measure the patients' overall rating of their back disability today. There were five response alternatives ranging from "excellent, none or unimportant complaints," to "miserable, worse, not self-reliant in activities of daily living".
EuroQol is a generic (non-disease specific) instrument for measurement of quality of life [17–19]. The questionnaire includes five items regarding quality of daily life, covering the domains of mobility, self-care, usual activities, pain and discomfort, and anxiety and depression (EQ-5D), and a visual analogue score for assessment of overall current health (EQ-VAS). The index score (EQ-5D) range from -0.59 for the worst possible health state to +1.00 for the best possible health state. Patients rate their overall current health (EQ-VAS) from 0 (worst imaginable) to 100 (best imaginable).
The Scoliosis Research Society 22 questionnaire (SRS-22) is validated and widely used for evaluation of health-related quality of life in AIS [20, 21]. A recently translated and validated Norwegian version was used in the present study . The SRS-22 covers five domains (function/activity, pain, self-perceived image, mental health, and satisfaction with treatment). Each item has 5 verbal response alternatives ranging from 1 (worst) to 5 (best). Results are expressed as the mean for each domain ranging from 1 (worst) to 5 (best).
The committee for medical research ethics in the health Region South-East in Norway and the institutional review board (hospital's patient ombudsman) approved the study (REK 2010-3677).
All patients with available data were included. Statistical analyses were performed with SPSS software, version 18.0 (SPSS Inc., Chicago) and Statistical Analysis System (SAS version 9.2; Cary, NC). Results are presented as means (standard deviation, range) or percentages. The normal distribution of baseline, follow-up data, and differences were checked by histograms. The success rate at maturity was calculated according to Nachemson and Peterson . They defined success of treatment as an increase in the primary curve of less than 6° from the start of bracing. Surgical patients were classified as non-success. In addition we calculated the percentage of patients who had a decrease ≥ 6°. Baseline characteristics in those who did not attend and those who attended long-term follow-up and in patients with adolescent and late-onset juvenile idiopathic scoliosis, respectively, were compared with independent t-tests. A General Linear Model One-way analysis of variance was used to test differences in continuous variables at baseline, weaning, and long-term between the 3 subgroups: 1) brace treated patients with final major curve < 45°, 2) brace and surgery, and 3) brace and final major curve ≥ 45°, and between patients with different curve types. With the assumption of unequal variances in unequally sized groups, Dunnett's T3 was used for post hoc multiple comparisons. Chi-square analyses were applied for testing of categorical variables. Spearman-R test was used to evaluate the correlation between pre-brace curve size and follow-up curve size and HRQL.