How effective is a full-time brace when lying supine, compared to a dedicated night- time brace?

Adolescent Idiopathic scoliosis (AIS) is a three dimensional (3D) spinal
deviation from normal growth of the spine and trunk, with a prevalence of 2-4%
in the general population that may interfere with normal cardio-pulmonary
development. Its management depends on the magnitude of the spinal curvature,
as expressed by the Cobb angle, and by maturation status mainly assessed by the
Risser method, which uses the iliac crest maturation. Observation is indicated
for mild curves and brace treatment is normally recommended for curves between
20° and 40° of Cobb angle, while bigger curves often require surgery. Although
the effectivity of brace treatment has long been debated, there is now Level-1
evidence that braces can modify the natural history of AIS in a positive way.
There are many braces on the market and all of them apply different degrees of
external corrective forces to the trunk to correct the complex spinal
deformity. Most braces are designed to be worn at least 18-20 hours per day,
but evidence is increasing that dedicated night-time braces work very
effectively. A possible explanation for the similar effectiveness of full time
versus night-time braces could be that full time braces, that are measured,
applied and checked with the patient upright, provide (much) less correction
than expected when the patient lies down. This would mean that the spine is not
well corrected during the many hours that the child is in bed. There is
therefore a need to elucidate the correction of the full-time brace provides
when laying down.

Understanding the effectiveness of full-time braces in both upright and supine
positions is therefore crucial. While correction in the upright position is
widely studied for full-time braces, the impact of laying down on these braces'
corrective mechanism remains unknown while it has been demonstrated that spinal
morphology changes in the supine position compared to upright. This study aims
to address this knowledge gap. Although full-time braces like the Cheneau brace
are prescribed for 18-21 hour wear, data on their efficacy in the supine
position is lacking. We hypothesize that, due to the altered spine shape in the
supine position, the additional correction provided by this type of brace may
be limited. This could explain why dedicated night-time braces, which are also
much better accepted by the adolescent patient, have shown comparable results
to full-time braces.

With help of an innovative MRI technique, so called BoneMRI (BoneMRI,
MRIGuidance, Utrecht, the Netherlands), it is now possible to capture both,
bony structures and soft tissues, in detail within one imaging modality. Both
structures are involved in the onset and development of this common deformity.
This new MRI technique is built by an algorithm based on a Convolutional Neural
Network (CNN) which permits to develop a high quality synthetic CT (sCT),
providing great bony detail as well as the well-known quality of soft tissue
imaging, without harmful radiation.

To quantify how much a full-time brace corrects the spine in 3D in AIS patients
when supine, compared to a dedicated night-time brace.

prospective multicentre observational cohort study

These patients will undergo brace treatment and follow-ups according to
standard clinical care. The inclusion criteria are generally accepted criteria
for AIS brace treatment. Standard care includes a full-spine radiograph before
brace treatment, after the patients gets used to wearing the brace (to check
for in-brace correction) and at 6-monthly follow-ups. In between brace
measurement and delivery of the brace to the patient, it normally takes 3-4
weeks.
This study can only be done within these subject groups, because
scoliosis-braces are only used in this population. These scans are important to
understand how the brace treatment corrects the 3D shape of the spine in its
bony structures as well as the intervertebral disc (IVD). Obviously, ionizing
radiation should be avoided thus the choice for MRI. The duration of the MR
imaging in this study is minimized (shortened from 45 to 20 minutes) contrast
or sedation are not needed. According to the *Toetsing van onderzoek met
minderjarige proefpersonen* of the CCMO, MRI (without sedation and contrast)
are research procedures with minimal risk and burden.