Craig Della Valle, MD, a hip and knee surgeon at Midwest Orthopaedics at Rush in Chicago, recently announced the results of a study where he and colleagues from across the country compared complications associated with partial and total knee replacements. The study included 3,000 patients who underwent either PKR or TKR. Dr. Della Valle and his colleagues found:
• Partial knee replacements were associated with a lower risk for post-surgical complications, blood clots and reparations
• Hospital stays were shorter after partial knee replacements
• Patients were more likely to be discharged home after partial knee replacements, while patients were more likely to be discharged to an intensive care unit after total knee replacements
• There were three to four times lower complications with partial knee replacements than total knee replacements
In an additional study, Dr. Della Valle examined patients who underwent partial knee replacements 15 years postoperatively. He found the failure rate of implants was similar for both PKR and TKR, and 90 percent of partial knees done at Midwest Orthopaedics at Rush still intact after 20 years.
Dr. Della Valle discusses these studies and where he sees knee surgery heading in the future.
Question: What was the impetus for comparing partial and total knee replacements?
Dr. Craig Della Valle: I was at a course in Chicago with other physicians and we were in a discussion about knee replacement procedures. We began to talk about who would do a partial or who would do a total and why. We talked about the risks of both procedures and decided we'd rather have partials if it was indicated because the risks were lower, but there isn't much data showing that. So, we decided to look at a consecutive series of totals and partials, adjusting for age, BMI, overall health status and sex. We found the risk for complication was three times lower in partials than in totals.
If you can see the patient is a good candidate for both procedures, I would consider doing the partial knee replacement because of the lower risk for complications. There are a lot of different factors to consider with each patient, but this study shows partial knee replacements are good procedures with less risk of complications that a full knee replacement.
Q: Why are some surgeons reluctant to perform partial knee replacements, even when the patient is a good candidate for the procedure?
CD: There are a couple of reasons why surgeons might choose a total knee replacement over a partial knee replacement. It is a lot more difficult to explain a partial knee replacement than a total knee replacement to patients, which could be one barrier. As physicians, we are all busy and it can be difficult to find a few extra minutes to explain the differences between the two procedures.
It's also a somewhat more difficult surgical technique. If you only do 50 knee replacements per year, the surgeon may not see enough appropriate candidates for partials, to get comfortable and proficient enough with the technique.
Additionally, unfortunately there are a percentage of the patients who still have pain after any type of knee replacement surgery. If a partial knee replacement has been done, the surgeon and patient might both wonder, "Would the patient have no pain if I had done a total knee and replaced the whole joint?" However, if a total knee replacement has been done, and the X-rays look good, we just assume the patient requires more physical therapy or some other form of non-operative treatment. However, when I look at my own practice, there are about the same number of people coming back with pain after partial and total knee replacements, but there's still that anxiety. It's easier to do totals for everyone, but in my practice I think a partial does the same job at a lower risk, so it makes more sense for me to perform them.
Q: Considering your data on the durability of a partial knee replacement, how would you respond to surgeons who describe a partial knee replacement as a "stepping stone" to total knee replacements?
CD: One of the biggest concerns is that partial knee replacements don't last very long, but we found at 20 years the estimated survivorship was just over 90 percent. At our center with our technique, the results seem pretty durable. I would vigorously disagree with it being a step towards total knee replacements. We see partial knee replacements as an alternative to total knee replacements for the appropriately selected patients.
Q: What are the most important factors when identifying patients who are a good candidate for PKR?
CD: There are a couple of things to look for when making an appropriate selection. The patient would have arthritis of just the inside or outside of their knee with a normal knee cap. These patients must have good range of motion and they are usually patients where the ACL is intact.
Q: Do you see partial knee replacements becoming more prominent in the near future?
CD: In orthopedics, things come and go in waves, and sometimes surgeons latch onto the newest fad. However, I think partial knee replacements are becoming more accepted. We see around 5 percent of knee replacements performed as partials right now, and I think it could grow a little bit over time. I don't think it will reach 15 percent, but it could reach 7 to 8 percent.
The trend seems to be more "centralization" of knee replacements with more "high volume surgeons" as patients seek out "knee replacement specialists." Although the trend in the United States right now is that most knee replacements are done by surgeons who do less than 10 knee surgeries per year, I think that is changing. I think we are going to see more surgeons who are doing 500 knee and hip surgeries per year being more comfortable doing partials and hence the number of partial knee replacements being done in the U.S. will grow.
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• Hospital stays were shorter after partial knee replacements
• Patients were more likely to be discharged home after partial knee replacements, while patients were more likely to be discharged to an intensive care unit after total knee replacements
• There were three to four times lower complications with partial knee replacements than total knee replacements
In an additional study, Dr. Della Valle examined patients who underwent partial knee replacements 15 years postoperatively. He found the failure rate of implants was similar for both PKR and TKR, and 90 percent of partial knees done at Midwest Orthopaedics at Rush still intact after 20 years.
Dr. Della Valle discusses these studies and where he sees knee surgery heading in the future.
Question: What was the impetus for comparing partial and total knee replacements?
Dr. Craig Della Valle: I was at a course in Chicago with other physicians and we were in a discussion about knee replacement procedures. We began to talk about who would do a partial or who would do a total and why. We talked about the risks of both procedures and decided we'd rather have partials if it was indicated because the risks were lower, but there isn't much data showing that. So, we decided to look at a consecutive series of totals and partials, adjusting for age, BMI, overall health status and sex. We found the risk for complication was three times lower in partials than in totals.
If you can see the patient is a good candidate for both procedures, I would consider doing the partial knee replacement because of the lower risk for complications. There are a lot of different factors to consider with each patient, but this study shows partial knee replacements are good procedures with less risk of complications that a full knee replacement.
Q: Why are some surgeons reluctant to perform partial knee replacements, even when the patient is a good candidate for the procedure?
CD: There are a couple of reasons why surgeons might choose a total knee replacement over a partial knee replacement. It is a lot more difficult to explain a partial knee replacement than a total knee replacement to patients, which could be one barrier. As physicians, we are all busy and it can be difficult to find a few extra minutes to explain the differences between the two procedures.
It's also a somewhat more difficult surgical technique. If you only do 50 knee replacements per year, the surgeon may not see enough appropriate candidates for partials, to get comfortable and proficient enough with the technique.
Additionally, unfortunately there are a percentage of the patients who still have pain after any type of knee replacement surgery. If a partial knee replacement has been done, the surgeon and patient might both wonder, "Would the patient have no pain if I had done a total knee and replaced the whole joint?" However, if a total knee replacement has been done, and the X-rays look good, we just assume the patient requires more physical therapy or some other form of non-operative treatment. However, when I look at my own practice, there are about the same number of people coming back with pain after partial and total knee replacements, but there's still that anxiety. It's easier to do totals for everyone, but in my practice I think a partial does the same job at a lower risk, so it makes more sense for me to perform them.
Q: Considering your data on the durability of a partial knee replacement, how would you respond to surgeons who describe a partial knee replacement as a "stepping stone" to total knee replacements?
CD: One of the biggest concerns is that partial knee replacements don't last very long, but we found at 20 years the estimated survivorship was just over 90 percent. At our center with our technique, the results seem pretty durable. I would vigorously disagree with it being a step towards total knee replacements. We see partial knee replacements as an alternative to total knee replacements for the appropriately selected patients.
Q: What are the most important factors when identifying patients who are a good candidate for PKR?
CD: There are a couple of things to look for when making an appropriate selection. The patient would have arthritis of just the inside or outside of their knee with a normal knee cap. These patients must have good range of motion and they are usually patients where the ACL is intact.
Q: Do you see partial knee replacements becoming more prominent in the near future?
CD: In orthopedics, things come and go in waves, and sometimes surgeons latch onto the newest fad. However, I think partial knee replacements are becoming more accepted. We see around 5 percent of knee replacements performed as partials right now, and I think it could grow a little bit over time. I don't think it will reach 15 percent, but it could reach 7 to 8 percent.
The trend seems to be more "centralization" of knee replacements with more "high volume surgeons" as patients seek out "knee replacement specialists." Although the trend in the United States right now is that most knee replacements are done by surgeons who do less than 10 knee surgeries per year, I think that is changing. I think we are going to see more surgeons who are doing 500 knee and hip surgeries per year being more comfortable doing partials and hence the number of partial knee replacements being done in the U.S. will grow.
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