Study design:

Single-center prospective randomized controlled trial.

Objective:

To assess the computer-aided design/manufacturing (CAD/CAM) brace design approach, with and without added finite element modeling (FEM) simulations, after two years in terms of clinical outcomes, 3D correction, compliance and quality of life (QoL).

Summary of background data:

Previous studies demonstrated that braces designed using a combination of CAD/CAM and FEM induced promising in-brace corrections, were lighter, thinner and covered less trunk surface. Yet, their long-term impact on treatment quality has not been evaluated.

Methods:

One-hundred-twenty AIS patients were recruited following SRS standardized criteria for brace treatment; 61 patients in the first subgroup (CAD) were given braces designed using CAD/CAM; 59 in the second subgroup (CAD-FEM) received braces additionally simulated and refined using a patient-specific FEM built from 3D reconstructions of the spine, rib cage and pelvis. Main thoracic (MT) and thoraco-lumbar/lumbar (TL/L) Cobb angles, sagittal curves, and apical rotations were compared at the initial visit and after two years. Patient compliance and QoL were tracked respectively by using embedded temperature sensors and SRS-22r questionnaires.

Results:

Forty-four patients with CAD-FEM braces and 50 with CAD braces completed the study. Average in-brace correction was 9° MT (8° CAD-FEM, 10° CAD, p = 0.054) and 12° TL/L (same for both subgroups, p = 0.91). Out-of-brace 2-year progression from initial deformity was < 4° for all 3D measurements. Sixty-six percent of all cases (30 CAD-FEM, 35 CAD) met the ≤5° curve progression criterion, 83% (38 CAD-FEM, 43 CAD) stayed below 45° and 6% (5 CAD-FEM, 1 CAD) underwent fusion surgery. 3D correction, compliance and QoL were not significantly different between both subgroups (p > 0.05).

Conclusions:

After two years, patients with braces designed using CAD/CAM with/without FEM had satisfying clinical outcomes (compared to the BrAIST study), 3D corrections, compliance and QoL. A more comprehensive optimization of brace treatment remains to be accomplished.

Level of evidence:

2.