Author: Hassan Beygi, Babak
Title: Design and evaluation of orthotic treatment for patients with adolescent idiopathic scoliosis using a purpose-design assessment frame and 3-dimensional clinical ultrasound analysis
Advisors: Wong, Man Sang (BME)
Degree: Ph.D.
Year: 2020
Subject: Three-dimensional imaging in medicine
Scoliosis in children
Scoliosis -- Patients -- Treatment
Orthopedic apparatus
Orthopedic braces
Hong Kong Polytechnic University -- Dissertations
Department: Department of Biomedical Engineering
Pages: xix, 140 pages : color illustrations
Language: English
Abstract: Adolescent idiopathic scoliosis (AIS) is considered as a three-dimensional structural spinal deformity characterized by abnormal lateral curvature over 10° with concomitant axial rotation of the spine and no known reason. The incidence rate of scoliosis has been reported to affect between 1 to 3% of the population. Spinal orthotic treatment is commonly prescribed to the patients with moderate AIS and its effectiveness has been accepted by recent studies. According to the literature and clinical judgment, various factors contribute to the orthotic treatment outcome, and initial in-orthosis correction is a crucial parameter to evaluate the long-term treatment effectiveness of spinal orthoses. To obtain the most effective treatment, orthotists need to design the orthosis that comprises the optimum in-orthosis correction with regard to the level of subject's accepted tolerance. To achieve this, the pressure pads should be applied at proper level, location, magnitude and orientation. Nevertheless, in current clinical practice, the arrangement of the pads is chosen empirically according to the experience of orthotist as well as general guidelines on different orthosis designs. The immediate in-orthosis correction (or the correction rate of the curvature) cannot be checked immediately during the process of measurement and fitting of the spinal orthosis. Conventionally, after the fitting of orthoses, the patients are referred to take radiographs to check the effectiveness of orthoses. The current practice is to request the patients to wait for the appointment of taking X-ray, and within this period the clinical effectiveness of the orthosis cannot be monitored. Furthermore, taking the frequent X-ray will increase the dosage of radiation to the adolescents as well as intensify the risk of breast cancer. In addition, the suboptimal pad placement and pressure will affect the level of initial in-orthosis correction which can only be determined after a few weeks of adaptation to the orthosis and obtaining the X-ray; the long-waiting results of in-orthosis radiograph may even necessitate further modification of the pad placement without real-time feedback to the orthotist. 3-D clinical ultrasound (CUS) technique can be counted as a low-cost alternative to the X-ray since it is considered as a radiation-free approach and an immediate assessment method to be implemented in an approximately real-time assessment of scoliosis. Therefore, this study aimed to develop a purpose-design assessment frame for determination of biomechanical parameters of the pad pressure in spinal orthosis in the process of orthosis measurement and fitting under the guidance of the 3-D CUS system and to evaluate the feasibility of this treatment method on a cohort of patients with AIS.
After development of the assessment frame and checking the feasibility of the system, 39 consecutive subjects with AIS who were prescribed with the spinal orthosis served as the control group and were compared with the test group. Twenty-four subjects with AIS were prospectively recruited and assigned into the test group in this non-randomized clinical controlled trial. There was no significant difference in respect to the Cobb angle and corresponding radiographic and demographic data between the two groups at the baseline of this study. Ethical approval was obtained, and subjects and their guardians/parents agreed to participate in the study by signing the consent form. The subjects in the test group were requested to sit inside the assessment frame while the strategic pads applied the corrective forces and the level of correction was monitored by the CUS system to meet at least 30% correction of the curvature. Once achieved, the trunk shape of the subjects was captured using the CAD/CAM scanner and proper orthoses were designed for the subjects in this group under the integrated system of assessment frame, CUS and CAD/CAM. Subjects in the control group received the orthoses as scanned and fabricated in routine clinical practice of the hospital (under the same group of orthotists). The pre-orthosis and initial in-orthosis X-ray of the subjects in both groups served as a reference for the comparison while the follow-up X-ray comparison was administrated for the subjects reached to that specific time point of study completion. The assessment of in­orthosis X-ray showed that the mean Cobb angle of the major curves in the test group (n=24) decreased from 28.3°±5.2° (pre-orthosis) to 17.2°±8.1° (in-orthosis) while the mean Cobb angle of the major curves in the control group (n=39) showed a decline from 28.9°±6.9° to 22.8°±8.2°. The correction rate in the test group (40.2%) was significantly (p <0.05) higher than that of the control group (22.6%). In terms of apical vertebral rotation (AVR), the magnitude of rotation reduction in the major curves of both groups was statistically significant, despite the fact that there was no significant difference between two groups. In the sagittal plane, although the application of the orthosis in both groups caused a significant reduction in the lumbar lordosis, no significant difference was observed in comparison of two groups. While the thoracic kyphosis significantly declined in the control group, the decrease of kyphosis was not significant in the test group. By combining the curves altogether in the test group, the values of the Cobb angle in pre-orthosis standing X-ray and CUS demonstrated a good and significant correlation (r =0.81) at the 0.05 level. Likewise, in-orthosis X-ray and "simulated" in-orthosis US showed a good and significant correlation in terms of Cobb angle and AVR as the Pearson correlation coefficient was found 0.78, and 0.83, respectively. The between-group comparison of X-ray parameters in 10 subjects in each group and in three time points of pre-orthosis X-ray, in-orthosis X-ray and the follow-up out of orthosis radiograph did not reveal any significant difference across all parameters of Cobb angle, AVR, kyphosis, and lordosis. The results of this study suggested that the development of this combined design method might have the potential to assess the scoliosis, improve the orthotic treatment outcome in more documented method being implemented into the current practice and decrease the risk of surgical intervention occurrence in patients with AIS. Furthermore, the force application to the patient's trunk in the assessment frame may be considered as guidance for fitting of the patient similar to what he or she may experience later in the orthosis, so his or her feedback, comfort and level of acceptance to the pressure could be helpful and be evaluated in the process of decision making on adjustment of force magnitude before the real orthosis being made and fitted. This study may impact on control of the deformity, treatment effectiveness and probably improvement of the efficacy of orthotist's clinical judgment, objectively. In the future, the design of assessment frame can be further improved to target a variety of curves in different levels especially high thoracic curves; finally, further development of CUS system and consideration of the PMC concept may facilitate a real-time fast 3-D reconstruction of the spine in the plane with maximum deformity, and at the same time, the importance of establishment of handheld portable CUS units in the process of assessment of spinal deformities should not be neglected.
Rights: All rights reserved
Access: open access

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