Disclaimer: This information is an educational resource only and should not be used to make a decision on partial knee replacement or about arthritis management. All decisions about partial knee replacement or about arthritis management must be made in conjunction with your surgeon or a licensed healthcare provider.
Introduction: partial Knee REPLACEMENT
During knee replacement surgery, damaged bone and cartilage is resurfaced with metal and plastic components. With a partial knee replacement only a portion of the knee is resurfaced. This procedure is an alternative to total knee replacement for patients whose disease is limited to just one area of the knee.
Since a partial knee replacement is done through a smaller incision, patients usually spend less time in the hospital and return to normal activities sooner than total knee replacement patients. There are a range of treatments for knee osteoarthritis and Dr Bhimani will discuss with you the options that will best relieve your individual osteoarthritis symptoms.
DESCRIPTION: partial Knee REPLACEMENT
With knee osteoarthritis, the cartilage protecting the bones of the knee slowly wears away. This can occur throughout the knee joint or just in a single area of the knee. Your knee is divided into three major compartments:
Medial compartment (the inside part of the knee)
Lateral compartment (the outside part)
Patellofemoral compartment (the front of the knee between the kneecap and thighbone)
Advanced osteoarthritis that is limited to a single compartment may be treated with a partial knee replacement. During this procedure, the damaged compartment is replaced with metal and plastic. The healthy cartilage and bone, as well as all of the ligaments are preserved.
Multiple studies show that a majority of patients who are appropriate candidates for the procedure have good results with partial knee replacement.
The advantages of partial knee replacement over total knee replacement may include:
Less pain after surgery
Less blood loss
Also, because the bone, cartilage, and ligaments in the healthy parts of the knee are kept, many patients report that a partial knee replacement feels more natural than a total knee replacement. A partial knee may also bend better.
The disadvantages of partial knee replacement compared with total knee replacement include:
Slightly less predictable pain relief
Potential need for more surgery. For example, a total knee replacement may be necessary in the future if arthritis develops in the parts of the knee that have not been replaced.
Candidates for Surgery
If your osteoarthritis has advanced and nonsurgical treatment options are no longer relieving your symptoms, Dr Bhimani may recommend knee replacement surgery.
In order to be a candidate for partial knee replacement, your arthritis must be limited to one compartment of your knee. In addition, if you have any of the following characteristics, you may not be eligible for the procedure:
Significant knee stiffness
With proper patient selection, modern partial knee replacements have demonstrated excellent medium- and long-term results in both younger and older patients.
A thorough evaluation with Dr Bhimani will determine whether you are a good candidate for a partial knee replacement.
Dr Bhimani will ask you several questions about your general health, your knee pain, and your ability to function.
Dr Bhimani will be specifically concerned with the location of your pain. If your pain is located almost entirely on either the inside portion or outside portion of your knee, then you may be a candidate for a partial knee replacement. If you have pain throughout your entire knee or pain in the front of your knee (under your kneecap) you may be better qualified for a total knee replacement.
Dr Bhimani will also test your knee for range of motion and ligament quality. If your knee is too stiff, or if the ligaments in your knee feel weak or torn, then Dr Bhimani will probably not recommend partial knee replacement (although you still may be a great candidate for total knee replacement).
X-rays: These images help to determine the extent of damage and deformity in your knee. Dr Bhimani will order several x-rays of your knee to see the pattern of arthritis.
Magnetic resonance imaging (MRI) scans: Dr Bhimani may also order an MRI scan to better evaluate the cartilage.
A partial knee replacement operation typically lasts between 1 and 2 hours.
Inspection of the joint: Dr Bhimani will make an incision at the front of your knee. He or she will then explore the three compartments of your knee to verify that the cartilage damage is, in fact, limited to one compartment and that your ligaments are intact.
If Dr Bhimani feels that your knee is unsuitable for a partial knee replacement, he or she may instead perform a total knee replacement. This contingency plan will have been discussed with you before your operation to make sure that you agree with this strategy.
There are three basic steps in the partial knee replacement procedure:
Prepare the bone: Dr Bhimani will use special saws to remove the cartilage from the damaged compartment of your knee.
Position the metal implants: The removed cartilage and bone is replaced with metal coverings that recreate the surface of the joint. These metal parts are typically held to the bone with cement.
Insert a spacer: A plastic insert is placed between the two metal components to create a smooth gliding surface.
As with any surgical procedure, there are risks involved with partial knee replacement. Dr Bhimani will discuss each of the risks with you and will take specific measures to help avoid potential complications.
Although rare, the most common risks include:
Blood clots: Blood clots in the leg veins are a common complication of knee replacement surgery. Blood clots can form in the deep veins of the legs or pelvis after surgery. Blood thinners prescribed by Dr Bhimani can help prevent this problem.
Infection: After surgery an infection may occur in the skin over the wound or deep in the wound. An infection may happen while you are in the hospital or after you go home. You will be given antibiotics before the start of your surgery and these will be continued for about 24 hours afterward to prevent infection.
Injury to nerves or vessels: Although it rarely happens, nerves or blood vessels may be injured or stretched during the procedure.
Risks of anesthesia
Need for additional surgery
Partial knee replacement patients usually experience less postoperative pain, less swelling, and have easier rehabilitation than patients undergoing total knee replacement. In most cases, patients go home 1 to 3 days after the operation. Some patients go home the day of the surgery.
After surgery, you will feel some pain, but Dr Bhimani and nurses will make every effort to help you feel as comfortable as possible. Treating pain with medication can help you feel more comfortable, which will help your body heal and recover from surgery faster.
You will begin putting weight on your knee immediately after surgery. You may need a walker, cane, or crutches for the first several days or weeks until you become comfortable enough to walk without assistance.
A physical therapist will give you exercises to help maintain your range of motion and restore your strength.
You will continue to see Dr Bhimani for follow-up visits at regular intervals.
You will most likely resume all of your regular activities of daily living by 6 weeks after surgery.
The vast majority of Dr Bhimani’s patients who undergo a partial knee replacement surgery experience favourable long-term outcomes including relief from pain and increased stability and function.
Complete pain relief and restoration of function is not always achievable, however, and some patients may still experience pain or knee stiffness following revision surgery. Surgery is not a pleasant prospect for anyone, but for some people with arthritis, it could mean the difference between leading a happier normal life or putting up with a debilitating pain and immobility.
Dr Bhimani believes that surgery should only be considered once non-operative treatment has failed, and that the decision to have surgery should be a considered one.
Although most people are extremely happy with their new knee, complications can occur. It is important you understand these potential complications and if you have any questions to speak with Dr Bhimani.
Partial knee replacement
In a partial knee replacement, only one area of the knee is resurfaced.
(Left) Osteoarthritis that is limited to the medial compartment. (Right) This x-ray shows severe osteoarthritis with "bone-on-bone" degeneration in the medial compartment (arrow).
Normal knee joint
(Left) A normal knee joint: The medial, lateral, and patellofemoral compartments are shown with red arrows. (Right) An x-ray of a normal knee joint showing healthy space between the bones.
An advantage of partial knee replacement over total knee replacement is that healthy parts of the knee are preserved, which helps to maintain more "natural" function of the knee.
PRE and Post
X-rays of a good candidate for partial knee replacement. (Left) Severe osteoarthritis limited to the medial compartment. (Right) The same knee after partial knee replacement.