Efficacy of Computer-Aided Design and Manufacturing Versus Computer-Aided Design and Finite Element Modeling Technologies in Brace Management of Idiopathic Scoliosis: A Narrative Review

Abstract

The efficiency and design quality of scoliosis braces produced by the conventional casting method depends highly on the orthotist's experience. Recently, advanced engineering techniques have been used with the aim of improving the quality of brace design and associated clinical outcomes. Numerically controlled machine tools have provided enormous opportunities for reducing the manufacturing time and saving material. However, the effectiveness of computer-aided brace manufacturing for scoliosis curve improvement is controversial. This narrative review is aimed at comparing the efficacy of braces made by the conventional method with those made by two computer-aided methods: computer-aided design and manufacturing (CAD-CAM), and computer-aided design and finite element modeling (CAD-FEM). The comparison was performed on scoliosis parameters in coronal, sagittal, and transverse planes. Scientific databases were searched, and 11 studies were selected for this review. Because of the diversity of study designs, it was not possible to decisively conclude which brace-manufacturing method is most effective. Similar effectiveness in curve correction was found in the coronal plane for braces made by using advanced manufacturing and conventional methods. In the sagittal plane, modern braces seem to be more effective than traditional braces, but there is an ongoing debate among clinicians, about which CAD-CAM and CAD-FEM brace provides a better treatment outcome. The relative effectiveness of modern and conventional methods in correcting deformities in the transverse plane is also a controversial subject. Overall, advanced engineering design and production methods can be proposed as time-and cost-efficient approaches for scoliosis management. However, there is insufficient evidence yet to conclude that CAD-CAM, and CAD-FEM methods provide significantly better clinical outcomes than those of conventional methods in the treatment of scoliosis curve. Moreover, for some factors, such as molding and the patient's posture during the data acquisition, in brace curve-correction plan, the orthotist's experience and scoliosis curve flexibility should be explored to confidently compare the outcomes of conventional, CAD-CAM, and CAD-FEM methods.

A Historical Perspective of the Management of Scoliosis

“…The digitizer unit records 3-dimensional data of body shape in digital format, computer software provides the de-sign of the brace in terms of shape, upper and lower borders, pressure areas, expansion chambers etc., and molding according to the patient's body profile. The milling machine is used to create a 3-dimensional model of the trunk (44).…”

Can Computer-Aided Design and Computer-Aided Manufacturing Integrating with/without Biomechanical Simulation Improve the Effectiveness of Spinal Braces on Adolescent Idiopathic Scoliosis?

“…These manually manufactured braces have played an important role in the treatment of scoliosis. However, the manual manufacturing method has the limitation of heavily relying on the clinical experience of the orthotist, prolonged manufacturing time that usually lasted for several days, and difficulty in standardizing the brace design features across different orthotists or patients [ 13 , 15 , 16 , 17 ].…”

“…In order to address the shortcomings of manual manufacturing methods and improve the treatment effect of scoliosis braces, computer-aided design and computer-aided manufacturing (CAD/CAM) technology have been integrated into the traditional manual manufacturing methods. Previous studies have supported that the CAD/CAM technology has the advantages of simpler measurement procedures, less manufacturing time (approximately 1/3 of the time of the manual method [ 18 ]), more comfortable and hygienic experience for patients during the “casting” stage, and more standardized manufacturing processes [ 17 , 18 ]. Due to the strong compatibility of CAD/CAM technology and the improved treatment effect of scoliosis braces, more recently, other advanced technologies that have been integrated with the CAD/CAM technology, such as biomechanical simulation, can help orthotists and physicians to further optimize the brace designing process [ 19 , 20 , 21 , 22 , 23 ].…”

“…However, from the cost-benefit aspect, the CAD/CAM technology with/without more advanced technologies requires the high expenses of purchasing the system and the additional technical training for clinicians [ 17 ], which might be a heavy burden for most hospitals, rehabilitation centers, or clinics. This may also be the main reason restricting the promotion of these new technologies at the moment.…”

Material sensitivity of patient-specific finite element models in the brace treatment of scoliosis

“…If the curve ranges from 20° to 45°, bracing is the only acknowledged non-surgical treatment that decreases the probability and affects the coronal curvature of scoliosis patients ( Karavidas, 2019 ). In addition to the casting method, the development of computer-aided design and manufacturing (CAD-CAM) and CAD and finite element modeling (CAD-FEM) has increased the number of options for brace manufacture ( Bidari et al, 2021 ). According to previous studies, the Cobb angle is better corrected by CAD-FEM and CAD-CAM methods compared with conventional methods ( Weiss and Kleban, 2015 ).…”