Conventional wheelchairs, the well-known technology transfer devices, always have certain limitations in providing proper therapeutic exercises to the upper and lower limbs of the human body. Therefore, in this work, the concept of a modular wheelchair is proposed to allow shoulder, elbow, and knee joint movements in addition to the wheeler mobility requirements. The proposed device is designed in FUSION 360 software for three therapy modules: shoulder abduction/adduction, elbow flexion/extension, and knee flexion/extension. The former two modules are designed with spring-based passive actuation methods, while the latter one is provisioned with linear actuators. The leg rest is designed with a telescopic arrangement to make the device eligible for people of different leg widths. Taking the critical design parts, the loading conditions are computed and specified with boundary constraints. Thereafter, dynamic modeling of the rear-arm rest, forearm rest, and leg rest is formulated mathematically using Newtonian approach. Finally, finite element analyses (FEAs) for the critical components are carried out based on the loading and boundary conditions. Moreover, the dynamic modeling results are plotted with different design parameters, demonstrating the motion behavior of different therapy modules. Such modular wheelchair devices could be a potential solution to reduce the burden of physiotherapists by automatically performing the tiresome and repetitive rehabilitation process.