by Elizabeth Hofheinz, M.P.H., M.Ed., February 20, 2020
The old adage goes something like, “If you want to know the future, look to the past.”
In the case of bilateral total knee
arthroplasty (TKA), that means all eyes on the initial operation. 
Concerned about the 20% of patients who report being dissatisfied after TKA, a team of researchers from the University of California set out to see if complications following an initial TKA increase the risk of the very same issues arising after surgery on the patient’s other knee. Their work, “Staged Bilateral Total Knee Arthroplasty: Increased Risk of Recurring Complications,” appears in the February 19, 2020 edition of The Journal of Bone and Joint Surgery.
Co-author Thomas Vail, the James L. Young Professor and Chair of the Department of Orthopaedic Surgery at the University of California, San Francisco, told OSN, “Dealing with one patient who has two knees needing replacement is an ongoing and vexing issue for surgeons. There is conflicting information on whether to do both at once or one at time, and it is difficult for individual providers and patients to understand the exact risks involved. A pattern emerges when you take into consideration large data sets; we need to pay attention to what it is that may set someone up for problems in that second surgery.”
As for Dr. Vail, he notes that roughly 10% of his operations are bilateral single stage knee surgeries, but a large number of patients come in for a second knee surgery after having one knee done. “As a practice matures people begin coming back for the second operation, so we thought it was important to determine the meaning of someone having an issue after the initial surgery. We need to know how seriously we should take these situations.”
The researchers examined the records of 36,278 patients who underwent bilateral TKAs; data was obtained from the U.S. Hospital Cost and Utilization Project from 2005-2014. “The study revealed that all complications following the initial TKA were associated with both a significantly increased probability of recurrence following the second surgery.”
Dr. Vail: “First of all, it was reassuring to learn that the overall complication rates in these surgeries are very low. However, there was a clear pattern of higher risk in the second operation when a problem arose after the first operation—anything from a myocardial infarction to a GI complication. So this is meaningful information because some of these complications represent modifiable circumstances. For example, take deep vein thrombosis; if someone is on aspirin for the first surgery and still had a blood clot then for the second one, you will ramp up the intervention and give that person a more potent anticoagulant.”
“Or if someone had nausea or another GI issue, you are going take extra care to either medicate them or preemptively address the issue. If there was a cardiac problem related to the initial surgery, then you are going to have the patient thoroughly evaluated by a cardiologist prior to the second surgery—and consider an intervention even if the issue is relatively minor.”
Dr. Vail says that it is important to note that the complications they were able to assess were based on a certain time frame and the level of detail available in the dataset. “We couldn’t study wound complications or infections because those are situations where the available data does not distinguish if the problem occurred after the first or second surgery.”
“There is likely a small group of patients who had the initial operation and were then disqualified for a second due to a serious complication such as a stroke or heart condition, or simply decided to live with the knee pain in the other knee. These folks never return for the second surgery, so we will never know what might have happened.”
Addressing the issue of where surgeons can make the most impact, Dr. Vail says, “We talk about modifiable risk factors and the importance of optimizing patients, but we don’t understand how much risk is mitigated when we do modify certain factors. We need to know, among those modifiable risk factors, what exactly is the important to modify? Let’s say the patient has followed the surgeon’s instructions…how much of a difference does that actually make?”
“If we can more thoroughly understand these adverse events following unilateral TKA, then we can more accurately stratify patients by risk—and counsel them—prior to the surgery on the contralateral knee.”