Comments on: ‘Night time bracing with the Providence thoracolumbosacral orthosis for treatment of adolescent idiopathic scoliosis: A retrospective consecutive clinical series’ by Davis et al. (2019)

We would like to thank the authors for introducing this very interesting topic. This paper is a retrospective analysis of patients with adolescent idiopathic scoliosis (AIS) who were followed and treated with the ‘Providence night-time brace’ (Davis et al 2019). Patients met the Scoliosis Research Societyinclusion criteria for studies on bracing which makes the results comparable to other studies on bracing. A 57.1% success rate is reported. As the authors discussed, there is a high variability in outcomes after Providence brace treatment. When compared to the results of Boston brace treatment (70%–78%), the Providence results seem poor. In the Bracing in Adolescent Idiopathic Scoliosis Trial (BRAIST) trial, ¹ the overall rate of treatment success was 72% in the bracing group and 48% in the observation group. The rate of treatment success was 75% among patients randomly assigned to bracing, as compared with 42% among those randomly assigned to observation.

In this study, the authors cited the BRAIST study and possibly by mistake reported an incorrect rate of treatment success – 93% in the bracing group, a significant statistical error.

When searching the results of high-correction asymmetric braces, there are reports of success rates above 80%, most of them with success rates of 90% and above.^2,3 In the light of these results, there seems no indication for part-time bracing in the normal range of curvatures (25°–40°). Indeed, there is a meta-analysis by Rowe et al. (1997) clearly showing that part-time bracing is inferior to full-time bracing. Studies using night-time brace prescription seem inadequate when compared with such significantly more improvements in Cobb angle are observed in a more full-time capacity.

In the light of other studies with better outcomes, and the error noted, there seems no indication for part-time bracing in the normal range of curvatures (25°–40°). Considering the growth dynamics of the patients at risk, no time or patient growth should be wasted with low impact treatments when there are interventions available with much less risk of failure.^3,4 With modern asymmetric brace design the aim is not limited to preventing curve progression, when considering there is evidence that when worn full time, improvements of Cobb angle, as well as improvements of trunk asymmetry can be achieved in a high percentage of the cases.^2,3 Cosmetic improvements seem to be the most relevant considering that AIS does not lead to severe health problems in later adulthood.

In this study, patients have been included with an age range of 10–18 years and Risser 0–2. The age range and the correlating Risser signs as presented seem to be not appropriate; usually in a mixed-sex population, the age range is 10–15 years and it seems unlikely that even a 18-year-old male would present with a maturity of Risser 2 only. ¹

Most of the patients had minor curvatures (with a correlating better prognosis even without treatment) and the best results have been achieved in more mature patients with Risser 1 or 2. In contrast, the results in high-correction asymmetric full-time bracing are usually the opposite, the more immature patients have the best results.^2,3

The authors of this study provided no clarity as to whether the in-brace or out-of-brace X-rays have been taken in a standing or in supine position. The standard is to take all X-rays in a standing upright position, ² while usually in-brace X-rays for night-time braces are made in supine position. In the latter case, the in-brace corrections as achieved with the Providence brace are not comparable to the in-brace corrections of the full-time braces.

And our final comment, we would like to suggest that studies about bracing should be accompanied by illustrations showing examples of patients wearing the brace, especially when considering braces for the treatment of scoliosis. This is to provide visual clarity and demonstration of how the brace is designed for different types of curves or patterns of curvature, so that readers can understand the brace design and a transparency of how the brace addresses the scoliosis.