”It is applied only as a result of calcification of the inner or outer joint surface of the knee. The patient recovers faster than Total knee replacement. The surgical technique is more difficult than the total prosthesis and it is an operation that orthopedic surgeons do not always prefer. Excellent results are obtained with the surgeon's experience and appropriate patient selection."
Orthopedic surgeons at world-renowned HSS perform more hip surgeries and knee replacements—including partial knee replacements—than any other hospital in the nation. As the scientific data demonstrates, patients do best when undergoing surgery at an institution where a high volume of procedures are performed by highly skilled surgeons. Over the course of their lifetimes, approximately one in five Americans will develop knee arthritis. Fortunately, a wide range of nonsurgical and surgical techniques are available to address the discomfort and disability that can accompany this condition. Total knee replacement is the most common surgical procedure for late-stage knee arthritis, but partial knee replacement is a surgical treatment option for patients with unicompartmental arthritis.
Unicompartmental osteoarthritis of the knee is a condition in which degenerative arthritis affects only one part of the knee joint, most often the medial (inner) compartment, while the other compartments remain healthy or not significantly damaged.
Arthritis of the knee may occur in any one of the three compartments that make up the knee joint. The inner or medial compartment of the knee and the outer or lateral compartment of the knee are formed by the articulation (or joining) of the lowest part of the thighbone (femur) and the highest part of the shinbone (the tibia). The third compartment of the knee is formed by the kneecap (patella) and the front part of the femur. This is referred to as the patellofemoral joint.
The medial compartment is the most frequent site of osteoarthritis of the knee, with the disease occurring less frequently in the lateral compartment. (Arthritis that is confined to the patellofemoral compartment of the knee is rare and may require a patelllofemoral joint replacement.)
What is partial knee replacement surgery?
Partial knee replacment is where the bone surfaces of only compartment of the knee joint are removed and replaced with implants or resurfaced, while the bone surfaces of other compartments as well as unaffected cartilage and other soft tissues are preserved.
Who can benefit from partial knee replacement?
Partial knee replacement is appropriate for patients with arthritis that is confined to a single compartment of the knee and is generally restricted to patients who are not morbidly obese. The surgery is not appropriate for patients with marked stiffness in the knee or those with a significant angular deformity. Intact ligaments are generally a requirement for a partial knee replacement. Patients with rheumatoid arthritis are not candidates for partial knee solutions since inflammatory-type arthritis typically involves the entire joint.
Additional considerations are evaluated on a case-by-case basis with the surgeon and patient determining together whether partial knee replacement is the best treatment option. Selecting the right patient is considered one of the most important steps to ensuring a good functional outcome and longevity for a partial knee replacement.
During partial knee replacement, the orthopedic surgeon makes a small incision to gain access to the affected compartment of the knee. He or she gently moves supporting structures of the knee out of the way and removes damaged cartilage and bone tissue from the surfaces of the tibia and the femur in the arthritic area. The surgeon then prepares these surfaces for insertion of the prosthesis components which are specifically sized to the patient’s joint. Cement is used to secure these components. All surrounding structures and tissues are restored to their anatomic position and the incision is closed.
Depending on which compartment is affected and whether the patient’s anterior cruciate ligament (ACL) is intact, the surgeon will use either a unicondylar fixed bearing knee replacement—the most commonly used prosthesis—or a mobile bearing unicondylar knee replacement. These prostheses are made of plastic and metal components.
Following surgery, most patients undergoing partial knee replacement can expect to spend one to two nights in the hospital. At HSS, most patients are able to walk with assistance, or independently, on the same day as their surgery. Typically, the patient is given a cane within a week of surgery to allow for increased independence and begins outpatient rehabilitation. Patients are often finished taking prescription pain medication within four weeks post-surgery.
knee replacement usually involves minimal blood loss and is associated with a low rate of complications; most patients can expect to be back to their daily activities within three to six weeks. Many patients find that after undergoing physical rehabilitation, they are able to return to sports such as golf, within six to ten weeks.
Frequently asked questions
Q: I have been told that I might benefit from partial knee resurfacing. Is this the same thing as partial knee replacement?
A: Yes. Partial knee replacement, partial knee resurfacing surgery, unicompartmental knee replacement, and unicondylar knee replacement all refer to the same procedure.
Q: Are there any age restrictions for partial knee surgery?
A: There are no strict recommendations, but in general, partial knee replacements are appropriate for patients over 40 years old who meet other eligibility criteria.
Q: What is a knee replacement prosthesis made of?
A: Knee prostheses or implants are made of metal and plastic. These surfaces are designed to glide smoothly against one another just as cartilage does in a healthy knee.
Q: Will I be able to resume bicycle riding/tennis/skiing after my partial knee replacement?
A: Although not all patients are able to return to unrestricted sport, many patients are able to resume biking, tennis and skiing.
Q: What kind of complications can occur with partial knee replacement surgery?
A: As with any joint replacement surgery, complications may include instability of the knee, loosening of the implant, infection, nerve injury and deep vein thrombosis. Generally, complications occur less frequently after partial knee replacement than they do following total knee replacement. Be sure to discuss any concerns you have regarding these or other issues with your surgeon.
Q: Is recovery from partial knee replacement painful?
A: All surgeries result in some pain. At HSS, we have robust systems and resources dedicated to address post-operative pain management. While pain varies by patient, typically patients experience less pain and stiffness following partial knee replacement than they do after total knee replacement. After partial knee replacement surgery, most patients receive 7-14 days of prescription pain medication but HSS also offers a limited opioid pathway for patients who do not tolerate opioid medications well. In addition, clinicians and researchers at HSS are currently developing treatment protocols that limit the amount of pain medicine needed after partial knee replacement surgery.
Q: If I decide to have partial knee replacement, does that mean that I will no longer have arthritis of the knee?
A: Partial knee replacement will address the arthritis that is present in the particular compartment of the knee that is affected. However, there is no guarantee that arthritis will not develop elsewhere in the knee. Should this occur, surgical revision to a total knee replacement may be necessary.
Q: How long can I expect my partial knee replacement to last?
A: A well-done partial knee replacement in an appropriately selected patient can have a survival rate that is comparable to that achieved with a total knee replacement in the first decade following surgery. The literature suggests that after the second decade, the revision rate may be somewhat higher for partial knee surgery than for total knee surgery.
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