There are four basic steps to a knee replacement procedure.
Prepare the Bone: The damaged cartilage surfaces at the ends of the femur and tibia are removed along with a small amount of underlying bone.
Position the Metal Implants: The removed cartilage and bone is replaced with metal components that recreate the surface of the joint. These metal parts may be cemented or "press-fit" into the bone.
Resurface the Patella: The under-surface of the patella (kneecap) is cut and resurfaced with a plastic button. Some surgeons do not resurface the patella, depending upon the case.
Insert a spacer: A medical-grade plastic spacer is inserted between the metal components to create a smooth gliding surface.
The decision to have total knee replacement surgery should be a cooperative one between you, your family, your family physician, and your orthopedic surgeon.
WHEN SURGERY IS RECOMMENDED
The decision to have total knee replacement surgery should be a cooperative one between you, your family, your family doctor, and your orthopaedic surgeon. Reasons to consider a total knee replacement include:
Severe knee pain or stiffness that limits your everyday activities, including walking, climbing stairs, and getting in and out of chairs. You may find it hard to walk more than a few blocks without significant pain and you may need to use a cane or walker
Moderate or severe knee pain while resting, either day or night
Chronic knee inflammation and swelling that does not improve with rest or medications
Knee deformity — a bowing in or out of your knee
Failure to substantially improve with other treatments such as anti-inflammatory medications, cortisone injections, lubricating injections, physical therapy, or other surgeries
CANDIDATES FOR SURGERY
There are no absolute age or weight restrictions for total knee replacement surgery. Typically patients are between 50-80 years old. Your body weight may have an effect of the difficulty of your rehabilitation and your long term results following surgery.
More than 90% of people who have total knee replacement surgery experience a dramatic reduction of knee pain and a significant improvement in the ability to perform common activities of daily living. But total knee replacement will not allow you to do more than you could before you developed arthritis.
With normal use and activity, every knee replacement implant begins to wear in its plastic spacer. Excessive activity or weight may speed up this normal wear and may cause the knee replacement to loosen and become painful.
Realistic activities following total knee replacement include unlimited walking, swimming, golf, driving, light hiking, biking, ballroom dancing, and other low-impact sports. However, there are no strict limitations placed on you after surgery and many patients have gone back to more strenuous activities.
UNI-COMPARTMENTAL (PARTIAL) KNEE REPLACEMENT
Patients with osteoarthritis that is limited to just one part of the knee may be candidates for uni-compartmental knee replacement (also called a"partial" knee replacement). This procedure has been performed in patients of all ages but is more commonly done in patients less than 60 or older than 75.
Your knee is divided into three major compartments: The medial compartment (the inside part of the knee), the lateral compartment (the outside part), and the patellofemoral compartment (the front of the knee between the kneecap and thighbone). In a uni-compartmental knee replacement, only the damaged compartment is replaced with metal and plastic The healthy cartilage and bone in the rest of the knee is left alone.
Advantages of Partial Knee Replacement
Uni-compartmental knees have been shown in multiple studies to perform excellent in the right patient. In the right patient this option may provide a more “natural” feeling knee by sparing the majority of your native knee. The advantages of partial knee replacement over total knee replacement include:
Less pain after surgery
Less blood loss
Uni-compartmental knee may also bend better and provide better function
Disadvantages of Partial Knee Replacement
The disadvantages include a possible decreased life span of the knee. There may also be progression of the arthritis to other parts of the knee causing pain.