This paper presents an orthopedic stabiliser to be used for the treatment of periarticular fractures of the knee joint. The design of the device is documented by experimental research of the knee joint kinematics. Experimental and simulation research suggest the use of a four-bar linkage mechanism. This research has also made it possible to define the range of adjustment to adapt the stabiliser kinematics to the individual properties of the patients. A sensitivity analysis points to the fact that the stabiliser must be positioned very precisely during installation. The stage of prototype construction was preceded by the design of a virtual model in CAD system. The stabiliser makes it possible to move the lower leg relative to the thigh throughout the treatment. Stabiliser tests that have been made on artificial models of knee joint have proved correctness of its working. This paper also presents results of first clinical stabiliser trials.