Mechanical loading of the knee is an innovative modality developed for rehabilitation of the knee joint as well as the femur and tibia that are subjected to bone fractures, osteoarthritis and osteoporosis. Loading essentially applies a lateral and periodic force to the knee joint [1]. In this paper, we propose the design of an electro-mechanical device that is capable of applying such dynamic loads. The key variable attributes of this device are the magnitude of the loading force, together with displacement and frequency. A DC motor with a controller actuates the device to produce the necessary force. The loading force is applied to the knee by a set of pads in a restricted linear motion. The operation of the device is approximated using the software package, SimMechanics of MATLAB. The simulations show that the device is capable of producing a suitable loading force with desired frequency. This simulation helps in constructing the device and performing experiments with appropriate frequencies. The device is expected to stimulate the fluids in porous skeletal matrix, resulting in strengthening the knee and bones. It can be employed for clinical trials for necessary evaluations and improvements.

This paper presents the design of an innovative device that applies dynamic mechanical load to human knee joints. Dynamic loading is employed by applying cyclic and periodic force on a target area. The repeated force loading was considered to be an effective modality for repair and rehabilitation of long bones that are subject to ailments like fractures, osteoporosis, osteoarthritis, etc. The proposed device design builds on the knowledge gained in previous animal and mechanical studies. It employs a modified slider-crank linkage mechanism actuated by a brushless Direct Current (DC) motor and provides uniform and cyclic force. The functionality of the device was simulated in a software environment and the structural integrity was analyzed using a finite element method for the prototype construction. The device is controlled by a microcontroller that is programmed to provide the desired loading force at a predetermined frequency and for a specific duration. The device was successfully tested in various experiments for its usability and full functionality. The results reveal that the device works according to the requirements of force magnitude and operational frequency. This device is considered ready to be used for a clinical study to examine whether controlled knee-loading could be an effective regimen for treating the stated bone-related ailments.

The mechanical loading of knee is an effective regimen for treatment of bone related ailments like fractures, osteoarthritis, and osteoporosis [1–2]. Efficacy of knee loading is evident from the previous studies done on rodents and other small animals [3]. In order to test this loading concept on human subjects, a prototype of a portable and compact device was designed previously. In this study, the prototype device was re-designed with a modified slider crank mechanism. Since this device has multiple moving parts, durability of the parts under stress is a key factor for its success. Thus, this paper focuses on its mechanical characteristics using finite element analysis (FEA). In particular, structural deformities and modal frequency characteristics are analyzed. The FEA analysis is performed on a CAD model of the device. The static structural and modal analyses are performed on two different configurations, in which different materials were used for selected components. Individual parts were meshed and solved extensively to obtain useful results under maximum loading conditions, such as total deformation, Von Mises stress, and modal frequencies. The analysis results show that ABS plastic based design provides an optimal solution in terms weight, cost, and usability.