Joint prostheses are mechanical medical devices conceived for total or partial replacement of an articulating joint afflicted with highly invalidating degenerative diseases such as arthritis.  They are designed to restore normal joint functionality.

There are prostheses available for all skeletal joints; those most commonly necessitating surgery are the hip and the knee joints. Less often used are those regarding the shoulder, ankle, elbow, wristle and the small joints in the hand.

The materials used to manufacture these prosthetic components (biomaterials) are medical grade metal alloys such as Titanium, Cobalt Chrome, Stainless steel, bioceramic materials and ultra high molecular weight polyethylene, which have been used for clinical purposes for more than 50 years and have demonstrated high biocompatibility and reliability.

Prosthetic components can be fixed directly to the bone (cementless biological fixation) or by using special acrylic bone cements (cemented fixation) interposed between the bone and the prosthesis. The choice between these options is made by the orthopaedic surgeon after evaluation of different parameters such as biological age of the patient, his level of activity and the quality of the bony tissue.

In cementless hip replacements, fixation is guaranteed by interlocking of the components directly to the receiving bone (press-fit insertion). This technique requires maximum care and precision in preparing the bony site to ensure optimal primary stability to the implant, basic condition to achieve it's osteointegration, which is given by formation of new bone all around and directly onto the porous surface of the component. This option is generally used for relatively young patients with biologically active bone structure suitable to guarantee optimal integration of the implant.

In cemented hip replacements, fixation is achieved by the interpositioning of a filling interface (acrylic bone cement) between the prosthesis and the bone. This technique guarantees immediate stability of the implanted components and their perfect fitting to the bony site, even with low quality bone tissue (osteoporosis). Use of cemented fixation is generally preferred for elder patients, or whenever the bone structure would not be of suitable quality to ensure fixation of a biological cementless device.