A Canine internal stifle stabilizing (CISS) system is provided as a three part modular, stifle stabilizing device that can be permanently or temporarily surgically implanted and attached onto the medial side of the distal femur and proximal tibia of quadrupeds. The stabilizing device is centered over the medial aspect of the quadruped stifle joint. The device includes three parts: a femoral component, a tibial component and an articular sliding insert component. The tibial and femoral components are fastened to the medial aspect of the femur and tibia by a varying number of fasteners. The distal end of the femoral component contains a ball and stem. The ball and stem is attached to the femoral component. The proximal tibial component has a rectangular space that accepts and holds the articular sliding insert component, such as by a pressure fit into the rectangular space provided on the proximal tibial component. The articular sliding insert component includes a groove that accepts and holds the ball that is attached to the femoral component. This locks the femoral and tibial components together. Also on the underside of the articular sliding insert component is a flange. In operation, the flange is located between the femoral and tibial components and has a bevelled edge (for example a ten (10) degree bevelled edge) on either side. This bevelled edge allows for a maximum internal and external rotation of the stabilized stifle joint. This device permits normal stifle joint movement in all planes, while continually providing support.
