Table of contents
- What causes the need for a knee replacement?
- What are the types of knee replacement implants?
- What are the risks of knee replacement surgery?
- How long does a knee implant last?
Knee replacement surgery is a treatment for pain and knee disability. Knee replacement surgery aims to replace the parts of the knee that have been damaged by disease and relieve pain that other treatments cannot handle. The knee is replaced by implants which can be characterized by the nature of the materials that rub against each other when the knee is flexed. This procedure is also called arthroplasty, and it is a very safe and effective procedure that improves mobility and reduces or eliminates pain.
What causes the need for a knee replacement?
The most common condition which causes the need for knee replacement surgery is osteoarthritis. The breakdown of the knee joint cartilage characterizes this disease. Individuals with severe degenerative joint disease are usually unable to carry out normal activities which require knee involvement, like walking, running, climbing stairs, or even bending the knee. The joint is unstable, and this may lead to it giving way. Other conditions which may lead to an individual requiring a knee replacement include:
- Swelling and inflammation
- Pain and stiffness
- Knee injuries and trauma
What are the types of knee replacement implants?
There are four main types of knee replacement implants which are mainly characterized by the type of materials that rub together when the knee is bent. These include:
Metal on plastic
This is the most common type of implant that is used in knee replacement surgeries. It has a metal femoral part that glides on a polyethylene plastic spacer attached to a tibial component. Some of the metals which can be used are cobalt, chromium, titanium, nickel, and zirconium. This type of implant is the cheapest and is recorded to be very safe with a very long span. An issue with this type of implant is that it can trigger an immune reaction due to the tiny particles that can come from the wear of the polyethylene spacer. This can also cause the breakdown of the bone and the loosening and eventual failure of the implant. However, advancements in manufacturing and production have greatly reduced the wear of the spacer part of the implant.
Ceramic on plastic
This type of implant replaces the metal femoral part with ceramic. It can also use a metal component with ceramic coating. It also rides on a polyethylene plastic spacer. This type of implant is usually suggested to individuals with sensitivity to the nickel that is used in metal implants. However, the plastic particles from the wear can also lead to an immune reaction.
Ceramic on ceramic
The femoral and the tibial components are both made of ceramic. The ceramic is the least likely component to react in an individual. The main disadvantage of ceramic implants is their tendency to shatter into pieces on heavy impact or pressure and must be removed by surgery. This, however, only occurs on rare occasions. Another issue with it is that it can make squeaking noises when walking.
Metal on metal
The femoral and the tibial components of the implants are made of metal. This particular type of implant has become less desirable due to the concern of traces of metal leaking into the blood. The metal traces are usually from the breakdown of the implant hardware. These metal traces can cause inflammation, organ damage, and pain. The metal on metal implants can be considered only for young and active men because they have the ability to last longer than any other material. Women of childbearing age should not receive a metal-on-metal implant because the impact of the metal traces in the bloodstream on a fetus remains unknown.
What are the risks of knee replacement surgery?
Complications can occur in knee replacement surgery. Some of the complications may include the following:
- Blood clots
- Continued pain
- Wearing of the implants
- Loosening or dislodging of the implants
- Numbing of the surgical area
Other complications may also arise depending on the particular medical condition the individual is suffering.
What happens before the surgical procedure?
The individual consults with the doctor, who explains the procedure properly and answers any questions that the person may have. The doctor will get a complete medical history of the patient, and a physical examination will also be done. This is done to ensure that the individual is healthy and fit enough to undergo surgery and recover properly. A blood test and other diagnostic tests are also done for the individual. The individual is asked to fast for at least 8 hours before the procedure, and the doctor may also ask for other specific preparations depending on the medical state of the individual. The individual may also meet with a physical therapist to consult on the rehabilitation process before getting the surgery.
During the procedure
This surgery is a procedure that requires hospitalization, the level of which is dependent on the patient’s health and the type of procedure. The procedure also requires general anesthesia. First, the surgical area is cleansed, and an incision is made. Then, the damaged surfaces of the knee joint are removed, and the area is resurfaced by the prosthesis. The prostheses are usually cemented; uncemented prostheses are not so common anymore. The prosthesis usually comprises three components which are: the tibial component, the femoral component, and the patellar component. After the replacement, the incision is then closed with stitches or staples. A drainage tube may be placed in the site in order to remove the fluid. A sterile dressing or bandage can be applied over the site of the injury.
After the procedure
The patient is then taken to the recovery room for observation. Once the blood pressure, pulse and breathing are stable, and the patient is then taken to the hospital room. Knee replacement surgery usually requires hospital admission for several days. It is also important to begin the movement of the new joint after the surgery. The pre-planned therapist will meet with the patient to plan the exercise program.
A continuous passive motion machine may be used to begin physical therapy. The pain is controlled with medication, so the patient can participate in the exercise. The patient is discharged either to their home or a rehabilitation center. In either case, the doctor will instruct the continuation of physical therapy until a good range of motion and muscle strength are regained. The patient is also given specific instructions on the care of the surgical site. The stitches are usually removed during a follow-up visit to the hospital. The doctor also instructs the patient to notify them in case they notice the following signs:
- Redness or swelling in the surgical site
- Excessive bleeding or another drainage from the surgical site
- Increased or persistent pain around the surgical site
The patient should also avoid strenuous activities, lifting heavy weights or falling for some time after the surgery or some months after the surgery.
How long does a knee implant last?
Most modern implants last for at least 15 years or longer after the surgery. They wear down or loosen eventually following normal activity. Usually, because of this wear, younger people will sometimes need a second knee replacement later in life.