Knee replacement is one of the most successful orthopaedic surgeries performed today. Most patients experience reduced or eliminated the knee pain, increased ability to move and an overall improvement in quality of life.
What is knee replacement surgery?
Knee replacement is where portions of the bones that form the knee joint are removed and replaced with artificial implants. It is performed primarily to relieve knee pain and stiffness caused by osteoarthritis.
Most people who get this surgery have advanced knee arthritis, in which the knee cartilage is worn away and the surface of the knee becomes pitted, eroded, and uneven. This causes pain, stiffness, instability and a change in body alignment. Knee replacement surgery can also help some people who have a weakened knee joint caused by an injury or other condition.
What are the different types of knee replacement surgery?
There are two main types:
- Total knee replacement, where the entire joint is replaced with artificial surfaces
- Partial knee replacement, where only one damaged compartment of the knee is replaced
Total knee replacement is the more common of these two procedures.
How is a total knee replacement performed?
First, the orthopedic surgeon makes an incision (cut) in the knee and moves the patella (kneecap) to the side. If are any bone spurs (small bony growths) are present, as sometimes occurs in osteoarthritis, they will be removed.
Next, the two menisci between the femur and tibia are removed, as are the anterior cruciate ligament (ACL) and, in some cases, the posterior cruciate ligament (PCL). In some types of knee replacement, the PCL is retained.
During the main phase of the operation, the surgeon cuts and remove cartilage and some bone from the upper part of the tibia and lower sections of the femur. The femoral sections removed are two knobby protuberances called the femoral condyles. The tibia and femur are then be capped with metal implants to create new surfaces for the joint. The surface of the femoral component mimics the shape of the original femoral condyles. If the kneecap has also degraded, the surface on its underside may also be cut away and replaced with a polyethylene implant.
Finally, the various layers of tissue are repaired with dissolvable sutures and the skin incision is closed with sutures or surgical staples. A bandage will be wrapped around the knee and the patient is being taken to recovery.
Fixed-bearing knee implant with a polyethylene articulating surface (plastic tray) sandwiched between the metal tibial implant and metal femoral implant.
Can I avoid or postpone a knee replacement?
The choice on whether to have surgery to address arthritis of the knee joint depends on multiple factors, including:
- the condition of the knee joint
- the patient’s age and activity level
In cases where the damage from arthritis is minimal, and/or if the patient does not have a very active lifestyle, nonsurgical treatments by being tried, including:
- physical therapy
- NSAIDs (non-steroidal anti-inflammatory drugs), such as ibuprofen
- weight loss to reduce pressure on the knee
How do I know if I need knee replacement surgery?
You may need surgery if:
- Your knees are stiff and swollen.
- There is pain throughout the day, even at rest.
- Walking, getting up or climbing stairs is difficult and painful.
- Medication and therapy do not offer enough relief.
- Knee cartilage is so damaged and worn away that you are walking “bone on bone,” in which the bones of the joint are scraping together.
How long does a knee replacement last?
Knee replacement implants are expected to function for at least 15 to 20 years in 85% to 90% of patients. However, the implants do not last forever.
After a period of 15 to 20 years, general wear and tear may loosen the implant. Depending on the patient, this may cause no symptoms, or it may cause any of the following:
- Loose Implant Particles
- Knee Instability
When these symptoms arise, it is recommended to have knee revision surgery to replace the original implant. Infection, especially, requires prompt revision surgery. Infection after knee replacement surgery is rare, but a knee replacement implant cannot defend itself from infection if bacteria are introduced to the body.