Rheumatoid arthritis (RA) is an inflammatory disease, which can cause pain, stiffness, and
swelling in the joints of hands and feet. The foot is a major site for RA involvement and a
major source of disability resulting from this disease. This paper introduces research which
aims to create a mass customisation process for customised orthoses for patients with RA.
3D laser scanning, and gait analysis will be used to generate the orthosis geometry and
rapid manufacturing, namely the selective laser sintering (SLS) process, will be used to
produce the orthoses. The SLS process enables the incorporation of compositional
functional elements, such as locally adjusted stiffness or flexibility, into the orthosis
design.
The process involved two central elements. The first was a literature survey to identify
orthotic design rules for foot impairments in RA. This survey will form a platform for the
design rule development and will be complemented by data obtained from two patient
trials. The second is a virtual three-segment foot model, created in Anybody dynamics
modelling software which can be motivated by data measured from patients using 3D
motion capture and force plate systems. Once the measured data has been applied to the
model, a virtual insole can be used to simulate the effects of various features in the
orthosis.
Considerable variation was noted in the literature for types of material, design and
methods of orthotic construction. Pressure redistribution using cushioning materials was
consistently mapped to painful deformed joints. Orthoses with contoured surfaces, either
custom- or mass produced in thermoplastic materials of varying stiffness and density were
mapped to joint motion control and deformity prevention. The paper will also describe
applying patient gait data to the Anybody model, and then altering the gait pattern by
applying the insole model. Future work will also be discussed.Mechanical Engineerin