Partial or Total Knee Arthroplasty
Reducing pain and restoring function
Knee arthroplasty
There are many options for knee replacement replacement that some surgeons do not do! The classic total knee arthroplasty (TKA) is a common procedure that orthopaedic surgeons perform. Partial or unicompartmental knee arthroplasty (UKA) is one some orthopaedic surgeons perform, and patellofemoral arthroplasty (PFA) is one few perform. I will do my best to explain who I think are the ideal candidates for each of them.
Do I need a knee replacement?
This is the #1 question patients with knee pain ask. To answer concisely, to qualify for a knee replacement, patients must fulfill 2 criteria. First, they must have radiographic evidence of “bone-on-bone” arthritis. Second, they must have failed conservative treatment and the pain is having a severe impact on their activities of daily living.
Often, I receive second or third opinions on patients who have continued pain or dissatisfaction after their knee replacement. Sometimes it is a detectable reason such as malpositioning, instability, infection or loosening. Other times, it may be for poor indications such as minimal arthritis on the preoperative radiograph, or poor preoperative consultation discussing expectations for knee replacement surgery.
It is important for patients to understand that if they are reasonable functional even with some pain, as long as it is not debilitating, there is no rush for a knee replacement. The problem is instrumentation for knee replacement surgery has become so easy, especially with robotics, that patients may be getting unnecessary surgery. One component that may explain that 20% of patients are dissatisfied after knee replacement.
What are the different types of knee replacement?
Patients are often surprised to learn that there are different types of knee replacements. We can categorize knee replacements into 3 types. Before we describe them, we must understand that the knee joint is comprised of 3 articulating compartments: the medial (inner), the lateral (outer) and the patellofemoral (kneecap) compartment.
The first type of knee replacement is unicompartmental (UKA) or partial knee arthroplasty. This can replace the medial or lateral joint only. Not many orthopaedic surgeons perform this operation for many reasons. The risks and benefits of the partial replacement is that it has a better pain and function outcome compared to total knee replacement, but at risk of lower survivorship. The rate of revision is higher for partial knee replacement, but with a high chance of undergoing conversion to total knee replacement (TKR). TKR revisions will result in more bone loss after each surgery, hence I try to perform the least invasive surgery. I also know that my UKA patients do 10% better outcome-wise than my TKAs.
The second type of knee replacement is the patellofemoral arthroplasty (PFA). This replaces the kneecap and the trochlea, which is the articulation of the kneecap on the femur. This is a rare procedure, usually done in younger females. I did the most at our institution for a number of years, as I believed in performing the most bone conservating surgery for the right indications. I know that my patellofemoral patients have done similar to my total knee patients.
The third type of knee replacement is the traditional total knee arthroplasty (TKA). This surgery replaces all 3 compartments of the knee, as well as removes the anterior cruciate ligament (ACL). Most patients are both in the good and excellent category and are satisfied with the procedure, and it is a reproducible operation for reducing pain and improving function. Survivorship of TKA can easily last into the second decade or longer. My average Oxford Knee Score is 40/48 if you calculate all my patients, no exclusions, complications included. My average Oxford Knee Score for my partial knees is 43.5/48.
Who should perform my knee replacement?
Patients want to know who to select as a surgeon! When they meet the patient, they are trying to vet out the orthopaedic surgeon, to see if they are good, if they have done many, if they understand the patient’s concerns and show care and empathy towards their situation. I think these are all very valid concerns. I would say the #1 important quality for the surgeon is that they have done many of these procedures. Complication rates for TKA vary, depending what is defined as a major (deep infection, reoperation, dislocation, DVT) or minor complication (superficial infection treated with oral antibiotics, stitch abscess, UTI, post-operative ileus). A knee replacement surgeon who does more than 200 per year, or over 1000 total will be better than someone who does less. They will have seen and managed complications, and understand how to best avoid complications or best manage them. No one has 0 complications unless they have done the procedure 0 times. I would also recommend someone who is fellowship trained in that field, as they are even more specialized. Whoever the patient chooses, I would ensure they feel confident and comfortable with that surgeon and their team.