Design of a Semi-Robotic Knee Arthroscopy Support System Utilizing a Novel Ball Joint Braking Mechanism

To alleviate the poor ergonomics which surgeons suffer during knee arthroscopy, a semi-robotic device with a novel ball joint braking mechanism was designed for intra-operative assistance. A slit ball joint assembly was developed to transmit the clamping force to the arthroscope inside, and the ball deformation and stress at various angles in relation to the vertical and clamping forces were recorded through finite element analysis (FEA) using Abaqus 2017. The contact forces between the scope and inner surfaces of the ball joint were computed at different clamping forces, and the von Mises stress occurring in the ball joint was found to be under the yield stress limit for polyethylene, with noticeable force preventing the scope from sliding along the ball through-hole under clamping. The ball joint braking mechanism was tested as part of a semi-robotic knee arthroscopy support system, and FEA simulation demonstrated that the maximum von Mises stress and the magnitude of contact forces positively correlated with the clamping force, while the stress incurred remained within the elastic range of the polyethylene prototype.