What is a prosthesis?
Each year in France, 250,000 patients are operated for a join replacement of hip, knee, shoulder, elbow or ankle.
These interventions called arthroplasties, although become routine, require however the know-how of a long chain of professionals, of health first, but also of the industrial sector because of a more and more advanced technology of the orthopedic implants.
The medical team chooses to implant a prosthesis most often because of:
- – Joint destruction (osteoarthritis)
- – Deformation
- – Bone destruction (necrosis)
- – Fracture
Sometimes medical treatments (drugs, rehabilitation, or infiltration) are not enough. Then, pain and discomfort constitute the determining elements of the intervention.
A prosthesis aiming to replace the deficient friction surfaces of a joint or to palliate a progressive bone destruction is called joint prosthesis.
It involves two movables elements relative to each other, each extended by one or more other elements for anchoring in the bone.
We name friction torque the combination of the materials of the two parts that restore the contact surface. It varies according to the load transmitted by the joint concerned, the expected longevity of the prosthesis, the level and type of activity of the patient.
When the indication of the prosthesis is a fracture without incipient alteration of the cartilage, only the fractured part is replaces; this is called an intermediate prosthesis. The prosthesis is in direct contact with the remaining cartilage on the healthy part of the joint.
Materials and attachment
The materials constituting the prosthesis are standardized and can be, depending on the type of implants, chromium-cobalt, pure or alloyed titanium, stainless steel or polyethylene.
The prosthesis can be attached to the bone by several means, depending on the bone quality, the loads levels on the joint but also the habits of each surgeon.
There are schematically two implant attachment modes:
- Cemented using a filer polymer between the prosthesis and the bone
- Without cement using a bio conductive coating in the prosthesis to allow the bone to adhere directly
This biological fixation can be supplemented by mechanical attachment means such as screws or pads.
Living with a prosthesis imposes during the first week following the surgery some precautions to avoid possible complications. The consequences of the intervention are usually simple. The activities recovery is done gradually, depending on the joint, muscle and skin scarring.
All precautions are explained and illustrated in this booklet and will be reminded by your physiotherapist who will accompany you throughout your rehabilitation.