Finite Element Analysis of an Under-Actuated Robotic Device for Knee Loading Applications

Knee loading is one form of joint loading modalities, which potentially provides a therapeutic regimen to stimulate bone formation and prevent degradation of joint tissues [1]. Healing of knee injuries is sensitive to many environmental stimuli. Since mechanical stimuli are crucial for the growth, development, and maintenance of articular cartilage and bone, we have developed an innovative robotic knee loading device to achieve this goal [2]. This device induces mechanical loading to stimulate articular cartilage and bone, and it potentially reduces the healing time of injuries such as bone fractures. The robotic device, described in this study, is an improved version over previous joint loading devices [1], in which loads are applied at specific points with non-uniform loading around the knee joint. In this paper, finite element analysis (FEA) of this robotic device has been presented that includes static structural analysis and modal frequencies of the device for two different material configurations used in the design. The study shows that the design with ABS plastic material offers the desired margin of safety while reducing the weight and cost.