Author: Tam, Eunice Wai-si
Title: Development of functional splint for De Quervain’s disease treatment
Advisors: Yip, Joanne (SFT)
Yick, Kit-lun (SFT)
Ng, Sun-pui Zerance (SPEED)
Degree: Ph.D.
Year: 2022
Subject: Splints ,Surgery)
Hand -- Wounds and injuries
Arm -- Wounds and injuries
Hong Kong Polytechnic University -- Dissertations
Department: School of Fashion and Textiles
Pages: xxxvii, 334 pages : color illustrations
Language: English
Abstract: De Quervain's tenosynovitis (DQV) is the inflammation of the synovial sheaths of the abductor pollicis longus and extensor pollicis brevis tendons in the first dorsal compartment of the hand. This hand condition is more prevalent in women in their forties to sixties. Patients with DQV may feel pain, soreness and tenderness at the radial side of their wrist, which can cause inconvenience and difficulties in their daily life activities. To treat patients with DQV, splinting is a safe, universal and non-invasive form of therapy, especially for those with minimal symptoms. Long splints which are composed of rigid thermoplastic materials and short splints which are fabricated of soft materials, are prescribed to patients according to their severity. Problems of existing splints, such as causing feelings of excessive warmth, discomfort due to a poor fit, and bulkiness, have been shared by wearers, and these problems may lead to a reduction of wear compliance. To solve the problems, studies have proposed new splint designs. However, the efficacy of the proposed splints in the literature remains ambiguous due to the lack of wear trials. Therefore, the aim of this study is to develop a splint that can effectively treat DQV with a good fit and wear comfort. A wear trial is conducted to evaluate the performance of the proposed splint.
This study consists of five parts, including: (a) a review on the fabrication processes of clinical splints and the problems of existing splints, (b) an investigation on the ergonomic shape of the hands of healthy and DQV patient groups, (c) the design and development of a functional splint with a good fit and wear comfort to treat DQV, (d) a clinical study of the proposed functional splint for evaluation purposes, and (e) the development of a finite element model to investigate the pressure distribution on the wearer's hand from the splint.
A review of ten splinting products from the online market is conducted which shows that most of the splints are embedded with stays to support the thumb and the wrist. Two market products are purchased to undergo a range of motion (ROM) test, in order to investigate the effectiveness of the splints in controlling hand movements. The result shows that the ability of the two splints to limit wrist deviations and stabilise thumb joints is inadequate. A clinical visit is then conducted to understand more about the fabrication processes of clinical splints. Problems with the clinical splints, such as low air permeability and bulkiness, are observed. Therefore, developing a functional splint with a good fit and wear comfort is necessary.
To develop a functional splint with a good fit, it is important to understand the shapes of the hand. Three groups of subjects: healthy young subjects, healthy mature subjects, and subjects with DQV are recruited for 3D scanning of their hands. The angles of the wrist and thumb such as the degree of wrist extension, angle between the extension of the ulna and carpals, and flexion angle of the MCP joint, have been measured. Comparisons between the measured angles of different groups and correlation testing between the angles of the patient groups have also been carried out. The measurements of the patient group is subsequently used as reference for developing the proposed splint.
To address the restrictiveness of the thermoplastic splint, the proposed splint is composed of both rigid and soft components. The thumb and ulna supporters are rigid and designed based on the measured angles in this study, so that they accommodate the shape of the hand. The supporters can stabilise and support the injured wrist. For the soft materials, spacer, powernet and satinette fabric samples have been subjected to testing to determine the most suitable fabrics for the body of the splint, and address the problems of excess warmth and bulkiness.
The performance of the proposed splint is evaluated by conducting a clinical study. Thirteen (13) female subjects with DQV are recruited to participate in a 3-month wear trial. Of the 13, 12 of the subjects underwent the entire treatment, while 1 subject terminated treatment early after the second month as her DQV is successfully treated. The study results show that the level of pain with two hand movements: thumb and finger extension and hand opposition, is significantly reduced after the intervention. The majority of the subjects indicate a reduced pain score during the extension of the thumb and fingers, while a large percentage of the subjects feel less pain during opposition of the hand. The pain scores for implementing different daily activities are also reduced. Both grip and pinch strengths are increased after the treatment. The ROM test of various splints indicates that the proposed splint can prevent the wearer's hand from excessive extension and deviation with adequate control. The splint related questionnaires that were completed by the subjects show that they are satisfied with the properties of the proposed splint, for instance, the appearance, wear comfort and durability. The results of the QuickDASH questionnaire show that the QuickDASH Disability/Symptom scores of the subjects are significantly reduced after the splinting treatment. Furthermore, the results of the SF-12 v2 questionnaire indicate that the quality of life of the subjects is enhanced over the last session of intervention.
The design of the proposed splint aims to accommodate the hand of the patient and stabilise the affected hand effectively with wear comfort. Excessive pressure exerted onto particular areas of the hand can be detrimental. In this study, a finite element model is developed to simulate the wear process of the proposed splint. The model facilitates the simulation of splint wear numerous time instead of the tedious and time-consuming task of recruiting and conducting experiments with real subjects. The model predicted results show the pressure distribution on the hand from the splint. The results are validated by comparisons with the actual pressure measurements of the subject. Since only small steps can be successfully analysed with the developed model, the predicted stress results are much lower than the actual measurements. However, the predicted results can still act as a reference. The results show that relatively higher stress is found around the wrist area, which may be due to the location of the holding straps of the supporters. Higher stress also appears on the surface area of the splint underneath the supporters. It is interesting to find higher stress between the two types of materials in the palm region, which indicates that the seam in that area can withstand higher forces during the wear process. As for the pressure exerted onto the hand of the patient, the predicted results demonstrate an evenly distributed low level of pressure over the skin of the hand. Thus, it is believed that patients can wear the proposed splint with wear comfort and well distributed pressure.
The research results provide useful information on investigating the ergonomic shape of the human hands, utilising 3D printing technology to develop splint supporters, and designing a functional splint for treating DQV. The study results show that the proposed splint is effective enough to stabilise the affected hand of patients and reduce the level of pain caused by DQV. Furthermore, the study patients are satisfied with the proposed splint in terms of its functionality, aesthetics and wear comfort. Therefore, the proposed splint can be an alternative option for patients with DQV who are required to undergo splinting treatment. The finite element model can be used to predict the pressure distribution on the hand of the wearer from using the splint, and optimise the design of the splint with modifications to the data. The findings of this study can also be extended to the development of other splints and orthoses, which can provide wear comfort and high effectiveness to treat DQV or other hand disorders.
Rights: All rights reserved
Access: open access

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