The specification and evaluation of personalised footwear for additive manufacturing

The personalisation of footwear offers advantages not only for runners, but to anyone who wishes to become more active. Additive manufacturing (AM) technology has the potential for making footwear personalisation economically feasible by allowing direct manufacture from CAD models and its tool-less capability. This thesis aims to develop and explore the process of footwear personalisation using AM and evaluates such footwear in terms of discomfort and biomechanics. To start to explore this process a repeated measures pilot study was conducted. Six recreational runners had anthropometric measurements of the foot taken and the plantar surface of both feet scanned. From the scans and measurements, personalised glove fit insoles were designed and manufactured using AM. Participants were then fitted with footwear under two experimental conditions (control and personalised), which were compared in terms of discomfort, performance and biomechanics. The findings of this pilot confirmed the feasibility of the personalisation process. A longitudinal study was then conducted to evaluate the short and medium term use of personalised footwear in terms of discomfort and biomechanics. A matched pairs study design was utilised and 38 recreational runners (19 pairs) were recruited. Control (generic shape) and personalised geometry insoles were designed and manufactured using AM. The participants wore the footwear each time they went running for a 3-month period. They also completed an Activity Diary after each training session and attended 4 laboratory sessions during this period. The results showed significantly lower discomfort ratings in the heel area and for overall fit with the personalised insoles. However, discomfort was reported under the arch region for both conditions (supported by the Activity Diary), indicating that the foot scanning position and material may need modifying. With regard to the biomechanics, the personalised insoles also led to significantly lower maximum ankle eversion and lower peak mean pressure under the heel, which are potentially positive effects in terms of reducing injury risk. A case study is then reported which explored foot capture using a dynamic scanner for the design and manufacture of insoles using AM. Through the development of four insoles, it was found that the selection and manipulation of the scan data from the series of frames generated during ground contact were the most demanding elements of the process. Finally, recommendations and guidance are given for the footwear personalisation process (foot scan position, anthropometry, insole design and AM), together with its potential benefits and limitations.