Author: Lin, Yangmin
Title: Could the effectiveness of orthotic management for patients with adolescent idiopathic scoliosis (AIS) be enhanced via 3D printing technology and pressure-adjustable system?
Advisors: Wong, Man Sang (BME)
Degree: Ph.D.
Year: 2019
Subject: Hong Kong Polytechnic University -- Dissertations
Scoliosis in children
Scoliosis -- Patients -- Rehabilitation
Spine -- Abnormalities
Orthopedic apparatus
Three-dimensional printing
Department: Department of Biomedical Engineering
Pages: xxv, 262 pages : color illustrations
Language: English
Abstract: Adolescent idiopathic scoliosis (AIS) is a three-dimensional (3D) spinal abnormality affecting 1 - 4% of adolescents with unknown causes, defined as the Cobb angle greater than 10°. Orthotic treatment is generally prescribed to manage moderate AIS (Cobb angle 25 - 40°), with which, various factors can influence the effectiveness, such as biomechanical design and patient's compliance. To date, far little attention has been paid to avoid any possible deviations from the original orthosis design custom-made by orthotist during fabrication procedures, as well as to ensure patient's compliance in a scientific way. This study aimed to apply two state-of-the-art technologies in spinal orthotic treatment for patients with AIS in aspects of orthotic design, fabrication, and patients' compliance. With the advancements of 3D printing technology, the accumulated error can be reduced during manual fabrication procedures and facilitate a more versatile design of spinal orthoses such as reduced weight and thickness. These may enhance the patient's compliance and subsequent treatment outcomes. However, the application of 3D printing in spinal orthosis is still at its embryonic stage. There are no rigorous investigations on the feasibility of 3D printing technology in the fabrication of spinal orthoses nor its clinical effectiveness for the management of AIS. Thus, this study conducted a feasibility test to apply 3D printing in spinal orthosis and to provide laboratory evidence. A prospective, randomised controlled trial was then carried to evaluate the treatment effectiveness of 3D-printed orthosis to the conventional one. Cost-effectiveness of using 3D printing to design and fabricate spinal orthosis for AIS was investigated. The findings of technological investigations in the current study suggested that spinal orthoses could be fabricated using fused deposition modelling (FDM) technique and Nylon-12 material. After a mimicked test for 3-year usage, the 3D-printed spinal orthosis was as durable as the conventional polyethene (PE) spinal orthosis. A total 30 females with AIS who met the criteria (age 10-14 years, Cobb angle 20-45°, and Risser sign 0-2) of SRS (Scoliosis Research Society) and SOSORT (Society on Scoliosis Orthopaedic and Rehabilitation Treatment). Patients were randomly allocated into the 3D-printed orthosis (3O, n=15, age 12.4 years, Cobb angle 23.9°) group and the conventional orthosis (CO3, n=15, age 12.5 years, Cobb angle 23.8°) group. The 3O was significantly lighter in weight (p<0.01) by 0.3kg. Comparable immediate in-orthosis correction was observed in the 3O group (12.3°, 37.0%, p<0.001) and the CO3 group (13.2°, 44.7%, p<0.001). There was no significant curvature change between the immediate and 3-month in-orthosis Cobb angle within the 3O group (1.7°, p=1.000) while the CO3 group had a significant increase in Cobb angle (4.8°, p<0.05). However, due to the high cost and long fabrication time, 3D printing technology may not be able to fulfil the clinical demands at the current stage.
Although extensive researches have suggested the importance of patients' compliance, most of the approaches were subjective and difficult to control the real situation, such as oral instruction and reminders. An automated PO (pressure-adjustable orthosis) has been developed aiming to provide a more consistent biomechanical environment for optimisation of treatment effectiveness. Clinical evaluation was proposed to study the effectiveness of this innovative orthosis. This study conducted a prospective bi-centre, randomised controlled trial. Patients with AIS who met the criteria conformed with the criteria (age 10-14 years, Cobb angle 20-40°, and Risser sign 0-2) of SRS and SOSORT were recruited. Compliance sensors were embedded in both groups while the PO was set to adjust the interfacial pressure as prescribed automatically. The clinical evaluation enrolled twenty-four patients and randomly assigned them to the PO (n=11, age 12.4 years, Cobb angle 26.2°) and COP groups, with one drop-out (n=12, age 12.6 years, Cobb angle 27.4°). Both the PO (11.0°, 42.0%, p<0.001) and COP (10.3±5.3°, 37.6%, p<0.001) groups showed significant in-orthosis correction. After a 1-year intervention, no patient with PO progressed while two patients with COP had progression >5° of Cobb angle. The mean daily wearing duration was 1.1 hours longer in the PO group as compared with the COP group (15.4 vs 14.3 hours, p>0.05). Nevertheless, the wearing quality with the targeted pressure was 33.9% higher in the PO group (56.5% vs 23.1%, p<0.001). There was no significant difference in the QoL results between or within the two groups during the study period. This study applied two innovative methods in orthotic management for patients with AIS and suggested that they could provide effective in-orthosis correction. This study is the first attempt to undertake a fundamental study bridging both the technological and clinical aspects of 3D printing technology to the design and fabrication of spinal orthosis for AIS. Besides, it provided new insights in offsetting patient's inappropriate orthosis wearing quality more scientifically and objectively. Nonetheless, it deserves a long-term prospective study until bone maturity with a larger sample size before the relevant treatment outcome with these technologies can be established. Continuous efforts in technology developments are needed to make the 3D printing technology and pressure-adjustable system more user-friendly and practical in orthotic design and fabrication, and management of the patients with AIS.
Rights: All rights reserved
Access: open access

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