Endoprosthetics

Endoprosthetics is a surgical operation that involves the complete or partial removal of a damaged joint and its replacement with an artificial implant – endoprosthesis. This operation is an effective and fast way to treat severe diseases of the hip joint. Recently, it has become the main method for restoring movement in the joint and supporting the leg, as well as returning a difficult patient to an active lifestyle.

Currently, there are three methods of arthroplasty, differing in the method of fixing parts of the endoprostheses: cement, cementless and hybrid. Cement method of endoprosthetics involves the use of polymer cement that fills the space between the stem of the endoprosthesis and the bone, forming a stem bed. With cementless endoprosthetics (Fig. 1) the cup and stem of the endoprosthesis have a porous surface that allows bone tissue to grow into the implant and provide a strong attachment. The hybrid method of arthroplastycombines both methods of fixation: some of the components are fixed in a cementless type, and some in a cement one. Cementless arthroplasty has a number of advantages over other methods – in particular, this method provides better secondary stability of the implant and a lower risk of complications.

Fig. 1 Cementless endoprosthesis with indication of its components

 

The long-term stability of a cementless endoprosthesis is largely facilitated by the possibility of ingrowth of biological tissues of the body (especially bone) into the surface of the endoprosthesis. To ensure this, the company’s employees are developing a new hydroxyapatite-polymer coating of metal parts of the endoprosthesis, formed from a dispersion of a mineral component in a polymer solution or a mixture of polymers in a biologically compatible solvent (Fig. 2). Due to the content of a biodegradable polymer and a mineral component similar in nature to bone tissue, such a coating should ensure good survival of the endoprosthesis. The components of the initial dispersion were determined and their optimal composition was determined for obtaining a uniform coating (Fig. 2), the sedimentation stability of polymer-mineral dispersions was investigated, and the optimal conditions for the formation of coatings were proposed.

Fig. 2. Polymer-mineral dispersion for forming coatings