Optimization of Location and Size of Metatarsal Pad for Patients with Metatarsalgia

• Main Authors: Jiun-Ling Chang, 張君翎
• Other Authors: 鄧復旦
• Format: Others
• Online Access: http://ndltd.ncl.edu.tw/handle/r4s44t

碩士 === 國立臺北科技大學 === 機電整合研究所 === 105 === Metatarsalgia is a common foot disorder caused by high repetitive pressure on the soft tissues under metatarsal heads for a long period of time. Metatarsal pad was often used to treat the symptom of metatarsalgia in clinical practice. Previous studies have investigated the effects of different metatarsal pad locations on the plantar soft tissue pressure distributions under the metatarsal bones either by experiment or finite element analysis. However, no optimal position and design of metatarsal pad have been proposed. The aim of this study was to investigate the effects of different locations, heights and sizes of metatarsal pad on the plantar pressure and to propose suggestions on the optimal location and design of the metatarsal pad. Three-dimensional finite element models of foot-shoe complex, including soft tissue, bone, articular cartilage, metatarsal pad, insole, outsole, plantar fascia and plantar ligaments were created. The kinematic parameters obtained from gait data of a subject wearing footwear without metatarsal pad were used as boundary condition for a dynamic finite element analysis. A healthy, male subject who provided foot geometry for the generation of the finite element foot model was recruited for gait analyses and plantar pressure measurements when wearing custom-made footwear with metatarsal pads. The custom-made footwear was designed and fabricated using computer-aided design and manufacture software. The ground reaction forces and plantar pressures under the second metatarsal head (MTH2) were obtained from both experiment and dynamic finite element analysis for different metatarsal pad conditions with five locations (5mm distal to MTH2, 0mm, 5mm, 10mm and 15mm proximal to the MTH2), three heights (5mm, 10mm and 15mm) and three sizes (original size, decreasing and increasing size of 10%, respectively). From the results of experiment and finite element analysis, when compared to the no pad control condition, the best metatarsal pad location for largest peak pressure reduction was 10 mm proximal to MTH2. When metatarsal pad was placed at this location, while increasing the metatarsal pad height to 15 mm could provide more metatarsal bone support and to enhance further pressure reduction. When decreasing 10% of the metatarsal pad size, it may decrease the contact area and the squeezing effect in between the soft tissue under the MTH2 and the metatarsal pad and thus reduce the pressure. In addition, the current finite element analysis was verified with the results from experiment. These findings showed that finite element analysis can be a useful method for investigating the biomechanical interactions between foot and metatarsal pad, and can provide suggestions for clinicians when prescribing metatarsal pads for patients with metatarsalgia.