Knee Replacement

Knee

Knee replacement is one of the most successful orthopedic surgeries performed today. Most patients experience reduced or eliminated 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 be taken to recovery.

 

What are knee replacement implants made of?

The selection of knee replacement prosthesis design and materials depends on each individual patient. The main implant components are made of metal – usually titanium or chrome-cobalt alloys. The implants are fixated in place either with a cement bonding agent or by osseointegration, in which a porous metal stem extends into the tibia and the patient's natural bone grows into it. A plastic platform or spacer will be inserted between the tibial and femoral implant surfaces. The spacer is made of polyethylene.

Most femoral components are made of metal alloys (cobalt chromium) or metal-ceramic alloys (oxidized zirconium). The patellar component is plastic (polyethylene). The tibial insert component is also plastic (polyethylene). The tibial tray component can be made of the following materials:

• cobalt chromium (metal alloy)
• titanium (metal alloy)
• polyethylene (plastic)
   

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 be tried, including:

• physical therapy
• NSAIDs (nonsteroidal 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:

• pain
• loose implant particles
• knee instability
• infection

When these symptoms arise, orthopedic surgeons recommend having knee revision surgery to replace the original implant. Infection, especially, requires a 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.
 

Can knee replacement be done as an outpatient?

Most patients stay in the hospital one or two nights after surgery. Some patients are able to return home the same day after an outpatient procedure.
 

How long does knee replacement surgery take?

Total knee replacement surgery generally takes about 60 to 90 minutes, but you should expect to be in the operating room for over two hours.
 

How long is it before I can walk after a knee replacement?

Most patients progress to a straight cane, walker or crutches within two or three days after surgery. As the days progress, the distance and frequency of walking will increase.

Patients are usually able to drive a car within three to six weeks after surgery and resume most other normal activities by or before six weeks. Complete recuperation and return to full strength and mobility may take four months or more. However, in many cases, patients are significantly more mobile one month after surgery than they were before they had their knee replacement
 

Knee replacement recovery time and recuperation

Rehabilitation (physical therapy) will begin within 24 hours of surgery. After your surgery, the nursing staff will position you in bed and help you turn until you are able to move on your own. You may have a pillow between your legs if ordered by your surgeon.

Very soon after surgery, a physical therapist will come to your room to teach you appropriate exercises and review your progress. Gentle exercises to improve your range of motion can help prevent circulation problems as well as strengthen your muscles.

Your rehabilitation program will begin as soon as you are medically stable and there are orders from your doctor to begin postoperative mobility. All patients begin rehabilitation within 24 hours of their surgery. Your motivation and participation in your physical therapy program is key to the success of your surgery and recovery. The physical therapist will assist you in the following activities:

• sitting at bedside with your feet on the floor
• transferring in and out of bed safely
• walking with the aid of a device (walker, cane, or crutches)
• climbing stairs with aid of a device
   

Cómo prepararse para el reemplazo de rodilla

There are certain steps that can improve your recovery time and results. It is important to follow your knee replacement surgeon’s instructions both before and after surgery, as well as that of your rehabilitation therapist’s recommendations.