When should a prosthesis be implanted?
Implanting a prosthesis is necessary when the patient’s joint loses or alters its function. This alteration occurs when the articular surfaces are altered by post-traumatic, degenerative and/or inflammatory causes; which results in the alteration of the articular function causing: cancellation or limitation of mobility, pain and lameness. The end result is a loss of quality of life mainly due to pain, which is the cause of the patient’s limited mobility.
The main objective of joint replacement with a prosthesis is to improve the quality of life. In this sense, the patient is the best qualified to decide the moment to carry out the replacement, once the indication has been established by the specialist in Traumatology and Orthopedic Surgery.
What types of prostheses exist?
Joint degeneration is closely related to mechanical stress, in addition to its primary causes. This is maximal in load-bearing joints. The lower extremities, the hip and the knee are the joints in which osteoarthritis, the most common cause for the indication of a prosthesis, appears most frequently. The frequency of its occurrence in recent years is very slightly higher in the knee (gonarthrosis).
A joint replacement prosthesis consists of components made of different materials with specific characteristics, which are studied, planned and designed to improve their biocompatibility, fixation to the bone, their durability and to facilitate their sliding (friction). As they are mechanical elements, they are subject to wear and loosening of their attachment to the bone. This is proportional to the work they will have to perform due to the mechanical stress to which they will be subjected. Therefore, the prognosis of duration is better in those patients older than 70 years and, consequently, prostheses reduce their duration in young, very active and demanding patients.
When is a prosthesis replacement performed?
It is up to the patient himself to decide the moment of implantation of the “primary” prosthesis because he experiences the existing limitations in his relationship life. In prosthesis replacements, however, this is not the case. Once the prosthesis is implanted, it suffers a wear that causes:
- Degradation of the implant.
- Wear of the polyethylene.
- Alterations of the sliding surfaces.
- Failure of its union to the bone.
- Migration of prosthetic components.
All this can be included in what is known as silent disease of the prosthesis. When prosthesis degradation appears, this is progressively evidenced in the established annual controls. When the specialist diagnoses this prosthesis wear, he must anticipate the events in order to avoid serious bone loss and destruction of the implants, which would make their reconstruction more complex and difficult. In many cases, although not in all, the degradation occurs asymptomatically for the patient, so the professional should perceive and convince the patient of the need for implant revision.