Partial Knee Replacement
Arthritis caused by wear and tear is the most common form of the disease. The cartilage that protects and cushions the bones of the knee joint starts to wear away. In advanced cases, the bones start rubbing together and the pain gets worse as time goes on. Knee replacement surgery entails resurfacing the damaged bone and cartilage with metal and plastic components.
Patients considering total knee replacement surgery to relieve arthritis pain may be candidates for a less invasive alternative known as a unicompartmental knee replacement. "This is actually a partial knee replacement, and it generally leads to a faster recovery, shorter hospital stay and less pain after surgery," says Dr. Geoffrey Westrich, Director of Research Emeritus in the Adult Reconstruction and Joint Replacement Service at Hospital for Special Surgery. "Instead of replacing the total joint, we replace only the arthritic area of the knee to relieve pain and help patients return to activities they have been forced to give up."
Patients whose arthritis is confined to just one area of the knee joint may qualify for the less invasive surgery, also referred to as a "uni."
Candidates for a Partial Knee Replacement
Arthritis can occur throughout the entire knee joint or in a specific area. The knee has three main compartments ‐ medial (the inside part of the knee), lateral (the outside of the knee), and patellofemoral (the kneecap region). Arthritis can involve one, two or all three of these areas. One would be a candidate for a partial joint replacement if only one section of the knee is damaged and the other compartments are intact. Patients who have arthritis in more than one of the compartments would need a total knee replacement.
Over the past few years, Dr. Westrich has been seeing more candidates for the less invasive procedure. They are generally younger patients eager to return to an active lifestyle or a sport.
"Patients who qualify for a partial knee replacement generally have a quicker recovery and rehabilitation," Dr. Westrich explains. "Yet the procedure completely relieves arthritis pain and allows them to return to activities they were forced to give up. Another advantage is that it preserves the normal bone, cartilage, and cruciate ligaments in the rest of the knee that would typically be replaced in a total joint procedure. Also, patients with partial knee replacements often comment that their knee feels almost normal."
Patellofemoral Knee Replacement
Patients whose arthritis is limited to the area under their kneecap and experience pain in the front of their knee may be candidates for another less invasive option called a patellofemoral knee replacement. For these individuals, the orthopedic surgeon sometimes orders a custom-made implant based on the patient’s anatomy.
Compared to a total knee replacement, patellofemoral knee replacement surgery is an easier alternative for patients whose arthritis is caused by worn cartilage under the kneecap. Those who qualify are generally in their 40s or 50s.
The Right Diagnosis is Important
If a doctor recommends a total knee replacement, Dr. Westrich says patients may want to inquire if they might be a candidate for a partial knee replacement. They should also ask if it’s a procedure that their orthopedic surgeon commonly performs. "From a technical perspective, partial knee replacements are best performed with a Mako robotic-assisted technique that more accurately places the implant, ensures proper ligament balancing, and recreates almost perfect implant tracking," he adds.
On the flip side, Dr. Westrich has seen patients who’ve had a partial knee replacement when their arthritis was more widespread. He emphasizes that the right diagnosis is critical. "Unfortunately, some surgeons push the limit on partial knee replacement surgery. It’s important for a patient to be a good candidate. Done inappropriately, an individual will continue to have pain and will need the partial procedure converted to a total knee replacement."
Choosing an orthopedic surgeon whose practice is dedicated to joint replacement helps ensure the correct diagnosis, proper treatment and best surgical outcome. Having the surgery at a hospital that performs a high volume of joint replacements and where Mako robotic technology is used frequently, such as Hospital for Special Surgery, also provides the best chance for a good result.