A total prosthesis is an artificial implant that is used to replace the joint surfaces of the knee when they have suffered a deterioration that causes pain and limitation of mobility that can not be resolved by medical treatment.
It is usually caused by a degenerative process related to age, although it can also be due to trauma, rheumatic processes and certain diseases (vascular necrosis).. They are composed of metal components for the joint surfaces of the femur and tibia and plastic components (polyethylene) for the kneecap and to promote movement between the femur and the tibia. There are different types of prosthesis: cemented or not, with preservation of the posterior cruciate ligament, constricted, etc.
Treatment by surgery
The surgical intervention aims to improve pain and limitation of mobility and thereby increase the quality of life of the affected person. The surgery is usually done with spinal anesthesia. In the first 24 hours passive movements are initiated and assisted walking begins again when the patient's general conditions allow it, between 48 and 72 hours. Hospital admission usually lasts 3 to 5 days.
The main complications of surgery in total knee prosthesis; independently of those of any surgical intervention; they are the joint infection, the instability and the aseptic loosening.
Success and control
Total knee prosthesis achieves more than 90% success. Most patients do not have pain or have any discomfort related to changes in temperature or pressure. The remaining 10% continues with pain or presents new discomforts such as stiffness or inflammation.
The main causes of revision before 2 years from the implantation of the prosthesis, are the infection, the instability and the bad position of the components. The main causes of late revision, after 2 years, are polyethylene wear, loosening and instability. The correct identification of the factors that can lead to the failure of the prosthesis and that require the replacement of the same are essential for the success of the same. For this we have the anamnesis, a good physical examination and complementary tests , both image and laboratory.
In most cases, it is possible to identify the problem that causes pain and malfunction of the prosthesis. When this is not possible, a meticulous discussion with the patient is essential to assess the risk / benefit of the surgery.