Patient-specific 3D-printed Brace for Adolescent Idiopathic Scoliosis: A Prospective Cohort Study

To evaluate the efficacy and safety of patient-tailored 3D printed brace in the treatment of adolescent idiopathic scoliosis (AIS), and to compare the health-related quality of life (HRQoL) of patients treated with 2 different types of brace.

From September 2017 to August 2020, 103 AIS patients requiring non-operative management were prospectively recruited in this study. All patients were followed up every 6 months, clinical and radiologic examination were assessed at each follow-up time. Full-length anteroposterior radiographs of the spine in the standing position were obtained. At the last follow-up, each patient completed a standardized HRQoL questionnaire. Compliance is defined as that the patient insists on wearing the brace for ≥23 hours every day (full-time wearing) and follow-up every 6 months until bone maturity. The rate of major curve Cobb progression was defined that maximum Cobb angle of major curve greater than 6° compared with that at the initial diagnosis, or aggravated to more than 45° so that orthopedic surgery was recommended during treatment, which was defined as the rate of conversion to surgery. The effects of these 2 types of braces on the rate of major curve Cobb progression and HRQoL were analyzed by independent sample t test and χ² test.

The thickness was 4 mm for thoracolumbosacral orthosis (TLSO) and 3 mm for 3D-printed brace (3DPB). In addition, compared with the material used in TLSO, the weight (600-800 g) of the 3DPB materials with the same area is reduced by about 25% to 30%. In our sample, 55 patients (49.1%) and 48 patients (33.1%) were respectively included in the 3DPB cohort and the TLSO cohort. The maximum Cobb angle of major curve in the 3DPB cohort was significantly lower than those in the TLSO cohort at 6 months, 12 months, and the last follow-up (P < 0.01). The thoracic kyphosis (TK) and lumbar lordosis (LL) of the 2 cohorts at the last follow-up were lower than those before brace treatment, in addition, there was a significant difference in TK (P = 0.001) and LL (P = 0.004) between the 2 cohorts at the follow-up. The scores of physical function, pain, self-image, mental health, and treatment satisfaction in the Chinese version of the 22-item questionnaire of the Scoliosis Research Society in the 3DPB cohort were higher than those in the TLSO cohort (P < 0.01 and P < 0.05, respectively). The scores of the 3DPB cohort were significantly higher than those of the TLSO group in the 4 dimensions (P = 0.008, 0.013, 0.015, and 0.002, respectively) of the EuroQol-5D health description system except for mobility, and the overall health status of EuroQol-5D was higher for the 3DPB cohort (P < 0.001). At the last follow-up, 1 patient in the 3DPB cohort and 10 patients in the TLSO cohort had major curve Cobb progression of greater than 6°, and the rate of major curve Cobb progression in the 3DPB cohort was significantly lower than that in the TLSO cohort (OR 14.2, 95% CI 1.7∼115.8, P < 0.01). One patient in the 3DPB and 7 patients in the TLSO cohorts received subsequent surgery or were recommended for surgery, and the rate of conversion to surgery was significantly lower than in the 3DPB cohort (OR 9.2, 95% CI 1.1∼77.9, P < 0.05).

A patient-tailored 3D-printed brace is lighter, thinner, and more comfortable than conventional braces in the treatment of AIS. It can substantially improve the HRQoL of patients and can significantly reduce the progression of major curve Cobb progression and rate of conversion of surgery.