| Author: | Kwan, Mei Ying |
| Title: | Ergonomic design of textile orthoses for patients with hallux valgus |
| Advisors: | Yick, Kit-lun (SFT) Yip, Joanne (SFT) |
| Degree: | Ph.D. |
| Year: | 2024 |
| Subject: | Hallux valgus -- Treatment Orthopedic apparatus Hong Kong Polytechnic University -- Dissertations |
| Department: | School of Fashion and Textiles |
| Pages: | xxi, 213 pages : color illustrations |
| Language: | English |
| Abstract: | Hallux valgus, a common foot deformity affecting around 23% of adults, is characterized by the deviation of the first metatarsal ray, leading to subluxation and pain in the first metatarsophalangeal joint. Hallux valgus can cause a range of problems such as foot pain, swelling, blisters, decreased mobility, poor balance, and even walking disability. Hallux valgus can have a significant impact on the quality of life and self-esteem of patients. Severe cases sometimes require surgical intervention. In the United States, more than 200,000 people undergo hallux valgus surgery each year, but the recurrence rate after surgery is relatively high at around 16%. A non-surgical approach to alleviating symptoms is the use of hallux valgus orthoses. However, current orthotic designs made of rigid, semi-rigid, or neoprene foam materials have several issues related to comfort, fit, and functionality. Their bulky and rigid design makes them difficult and uncomfortable to wear with shoes, leading to poor compliance and reduced treatment efficacy. Given the increasing prevalence of hallux valgus and its associated complications, there is an urgent need for improved orthotic design. A systematic review and meta-analysis were conducted to evaluate the effectiveness of orthoses in treating hallux valgus. The study focused on interventional research that examined the design of hallux valgus orthoses and their outcomes. The results indicated that orthoses with toe separators were the most effective in reducing the hallux valgus angle (SMD: 0.50, 95% CI: 0.189 to 0.803) and relieving foot pain (SMD: 1.13, 95% CI: 0.319 to 1.887). They allow the foot to form the correct anatomical alignment. Whereas pooled estimates of dynamic orthoses showed a small effect on hallux valgus angle reduction (SMD: 0.27, 95% CI: -0.211 to 0.751). Additionally, prefabricated full-length orthoses with arch support could significantly reduce plantar pressure by 16.8 kPa (SMD: 0.65, 95% CI: -0.090 to 1.354). Adequate arch support plays a role in restoring the proper alignment of the foot. An experimental study was also conducted to investigate the direct effects of soft and semi-rigid hallux valgus orthoses on balance, plantar pressure, hallux valgus angle, and subjective sensation. The study involved ten female subjects with healthy feet and six with hallux valgus. The results demonstrated that wearing orthotics can reduce the hallux valgus angle in patients (semi-rigid orthosis: 2.5°, soft orthosis: 2.6°). However, the angle reduction with a semi-rigid orthosis is negatively correlated with pressure reduction of the forefoot during walking (r = -0.889, p = 0.018). The comparison between the two types of orthoses revealed that the orthosis made of soft and thin material was more effective in reducing the angle, providing greater comfort, and reducing plantar pressure on the hallux. These findings offer insights into the design of hallux valgus orthoses and provide practical guidance for selecting orthoses that balance performance and comfort. The longitudinal arch of the foot is an intrinsic factor associated with the lateral deviation of the hallux. This study quantitatively examined the improvement of the first metatarsal and arch conditions through arch support. The study measured the footprints of seventy-six female subjects to investigate the effect of arch support on arch elevation and correction of hallux valgus pathology. The results showed that arch support significantly improved the curvature of the foot arch. Subjects with both hallux valgus and flatfoot had a 0.063 reduction in foot type index (p = 0.013). Whereas a slight hallux angle reduction could be found (1.536°, p = 0.086). Among the arch parameters, arch breadth and foot type index (r = 0.960, p < 0.001) were identified as key indicators for characterizing foot shape and arch condition. The developed numerical model further shows that the use of arch support can effectively redistribute pressure and load from the forefoot to the midfoot region. Soft materials are found to be more effective at achieving optimal plantar pressure distribution, while hard materials are more effective at providing arch lift while standing. Wear trial results obtained from twenty-two female subjects showed that the soft silicone arch support provided better balance and significantly reduced plantar pressure in the forefoot (p = 0.049). Given the paucity of studies on the design of hallux valgus orthoses, this study employed a scientific approach based on foot anthropometry and biomechanics. It utilized suitable textile materials, three-dimensional scanning and printing technologies to produce an in-shoe hallux valgus orthosis with the appropriate amount of corrective force, and improved fit and comfort. To optimize the design, a biomechanical model was created to simulate the effect on the mechanical properties of corrective bands made with materials of different hardness and structures. The results showed that more than 6 Newtons of force were required to reduce the hallux valgus angle from mild to normal. The results suggested the use of Shore A 30 silicone band with an auxetic structure. A total of twenty-two females with mild to moderate hallux valgus and shoe sizes EU 37 to EU 39 were recruited to evaluate the immediate and short-term effects of the proposed orthosis on angle reduction, plantar pressure, balance, and subjective perception through wear trials. In a one-hour wear trial, the new orthotic design significantly corrected the hallux valgus angle (3.5°, p < 0.001), reduced plantar pressure in the lateral toe region (p = 0.026), and had a positive effect on comfort. After fourteen days of wear, the hallux valgus angle was reduced to 5.47° (p < 0.001), which was greater than the reduction observed in the one-hour trial. This suggests that the duration of orthosis wear may influence the effect of hallux valgus angle reduction. These results provide valuable information for designing ergonomic hallux valgus orthoses. |
| Rights: | All rights reserved |
| Access: | open access |
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