Bilateral simultaneous total knee arthroplasty (TKA) may be more cost effective for the hospital, and it’s within the standard of care, but it’s riskier, asserts Leo Whiteside. But this is a good operation in the fit, bilaterally affected patient, counters Tom Sculco.
This week’s Orthopaedic Crossfire® debate is “Sequential Bilateral TKA: Double Trouble.” For the proposition was Leo A. Whiteside, M.D. from the Missouri Bone & Joint Center. Against the proposition was Thomas P. Sculco of Hospital for Special Surgery; moderating was William J. Maloney III, M.D. from Stanford Hospital and Clinics.
Dr. Whiteside: “I’m going to talk a lot about risk to benefit ratios. One of the major things we deal with in total knee replacement (TKA) is fat embolism. Fat embolism in bilateral total knee replacement was first identified by Larry Dorr as a significant issue. He found that in 12% of patients he had to see clinically he discovered fat embolization. In another study he had to cancel 5 out of 79 and found that clinical signs were unreliable and had to monitor bilateral knee replacements with a Swann-Ganz Catheter. It’s more than double the risk when you double the operation.”
“Part of the problem is the tourniquet; it releases all the emboli that occur at one time. Another issue is the intermedullary rod; it can be put in wrong, pressurizing the medullary canal and leading to embolization. Cement is a significant issue in putting implants in. As the implant is pressed in, cement can come to the surface; as it’s driven in further, fat comes further to the surface, runs out, and you know where that fat is going. Berman pointed this out in relation to cement and most total TKA are done with cement. When the tourniquet is released the heart rate increases…you don’t really know what is going on unless you consider what is going through the heart at this time.”
“There is also selection bias here. A blinded, randomized controlled study is not possible because it’s tougher on a patient to have bilateral TKA, and you select a healthier group. It should have a lower complication rate. The selection bias favors the stronger, healthier group. There are several studies showing that the results are about equal for staged bilateral versus simultaneous bilateral, but they are generally smaller studies and they don’t include a large enough group to point out the differences. In Ritter’s study, one of the best and biggest studies looking at Medicare data, he found that there was a three time greater death rate when you compared staged bilateral to simultaneous bilateral…and two times the number of ICU days. So it’s not just twice as bad it’s more than twice as bad.”
“Another study which looked at the Swedish literature found that the 30 day mortality rate was 1.94 times higher when two knees were done simultaneously as opposed to staged out for about three months. In a large meta-analysis Restrepo found that the chances of pulmonary embolism, cardiac complications and mortality were way higher when you did two together versus two separated by three months or more. How much less safe than unilateral total knee? Luscombe found wound complications: 6% versus 0.7%; deep infections: 3.5% versus 0.7%; cardiac complications: 3.5% versus 0.7%. Lane’s study showed much higher complication rate than unilateral total knee and not just by a factor of two, but a factor of 17 in some cases.”
“Thirty day mortality in a large Mayo Clinic study was related to cement fixation and to bilateral simultaneous total knee replacement. The results of treatment of infection in both knees after bilateral TKA (Wolf) significantly relates to the way the patient does postoperatively. I suggest that you minimize your risks. A low pressure, flat reamer decreases the pressure in the medullary canal and aspirates the medullary canal before you put in the medullary rod. Use intermedullary alignment, but do it carefully and discretely so that you don’t embolize the patient as you go.”
“Cementless tibial and femoral components embolize the patient much less. Bilateral simultaneous TKA may be more cost effective for the hospital, and it’s within the standard of care, but it’s riskier. You should share those numbers with the patient, let them know it’s riskier, and do everything you can to minimize the risk—consider a Swann-Ganz Catheter and careful monitoring.”
Dr. Sculco: “I recommend bilateral simultaneous TKA in selected patients; I do 40-50 a year. I do this operation because overwhelmingly patients prefer to have both knees done in one setting. There is less overall recovery time, it’s one operative procedure, so the risk may be a little higher in terms of that procedure, but that patient is coming back for a second procedure and the risks are attendant to that second operation when they return. It’s symmetrical recovery and it’s less costly overall.”
“Ideal patient: one who has significant bilateral flexion deformities because if you correct just one, inevitably the one you’ve done will return to the flex posture until you’ve corrected the second side. Cost savings have been demonstrated to be less overall—as high as 36% with one stage bilateral procedures.”
“Leo has pointed out the disadvantages. However, in a paper we published looking at 501 consecutive simultaneous TKA at our hospital we had no deaths, strokes, or myocardial infarctions—mostly because of patient selection. These patients were monitored very carefully postoperatively and were kept in the ICU overnight; some spend more than one night there. We looked at complications: major complications, we found cardiac was 5.6%, 2.1% pulmonary (2.7% but none went on to mortality).”
“You also see fat emboli in unilateral knees. In a study of transcranial Doppler monitoring where 60% of patients with unilateral TKA you could detect fat emboli during the initial procedure; it wasn’t really any different in the bilateral group. Other major complications were gastrointestinal, confusion, and wound infection, none of which led to mortality or significant disability. As patients got older, probably because there was more comorbidity we saw a higher incidence of major complications. ”
“Additionally, and this goes along with age for the most part, as the ASA Classification for those patients went up prior to surgery, we saw an increased risk of complications. Patient selection is key. This is not an operation for patients with significant comorbidity. The problem with most of the studies in the literature is that they are low volume. So we looked at a large database of over four million total knee replacements over 14 years. About 4% of those underwent bilateral TKA; we looked at complications after those series and found that comorbidities are less than the unilateral group or a revision group. When we looked at complications we saw that mortality was greater in the bilateral one stage group, as was pulmonary embolism.”
“Also, inpatient mortality was somewhat higher in the bilateral group. But this dropped down. If you looked at every five year intervals you see that the complications were reduced from 1990 to 2004 due to better anesthetic management and better patient selection. Overall, you can reduce complications in this operation…I think it’s a good operation in the fit, bilaterally affected patient. We have better intraoperative and postoperative monitoring, and you’ve got to do this surgery quickly.”
Dr. Whiteside: “Tom is right. Selection is the key, as is being careful. You must think about fat embolization, tissue trauma, and be ready to abort the procedure if you see any changes. Tom, do you do a Swann-Ganz Catheter to monitor those patients? Do you ever do true bilateral simultaneous with one team on each side of the table working together?”
Dr. Sculco: “We used to use Swann-Ganz Catheters almost routinely in these patients, but we didn’t find it that helpful…and there’s some morbidity to putting a Swann-Ganz in. So we do it very infrequently now. Most patients are pretty fit, so the feeling of the anesthesiologist is that they don’t need it to manage the patient. In terms of doing it simultaneously, I think that’s not a good idea…not a good idea to have two tourniquets up at the same time. When you release the tourniquets they get a huge bolus of fat from both knees at the same time. So we stage them in the operating room.”
Moderator Maloney: “Leo, is there any patient that you will do a bilateral TKA in?”
Dr. Whiteside: “Those who have a strong desire for bilateral TKA and who I think are healthy enough and they’ve been presented all of the risks…that’s about one a year.”
Moderator Maloney: “What about the patient with the bad deformity that Tom mentioned? Let’s say a bilateral 30-40 degree flexion contracture with a 30 degree varus deformity. When would you do the second one?”
Dr. Whiteside: “Three months later. I especially don’t like to do two very complex knee replacements at the same time.”
Moderator Maloney: “How do you prevent the flexion deformity from reoccurring?”
Dr. Whiteside: “I haven’t seen that to be a significant issue. They use a walker. If they can fully extend the knee they do, and they walk on the tip toes of the other side.”
Moderator Maloney: “Tom?”
Dr. Sculco: “I’ve seen the opposite…on occasion where the patients are very sick and you’ve had to stage them, and I find that the first side that I’ve corrected tends to go into the flex posture because it’s almost impossible to walk with one flex knee and one straight knee. So they end up flexing the operative leg and you lose extension when you do the second side.”
Moderator Maloney: “Patient indication: what are the red flags for not wanting to do a bilateral total knee replacement?”
Dr. Sculco: At our hospital we just had a conference between our anesthesiologists, internists, and knee surgeons. We’re trying to develop some guidelines and benchmarks for who is the patient we should NOT do it on. Patients with significant cardiac risk, patients who have had CABG’s (Cardiac Bypass Grafts), severe Type 1 diabetes, those over the age of 80, patients with severe pulmonary disease.”
Moderator Maloney: “COPD tends to be a real risk factor for complication, as does congestive heart failure and bad valvular heart disease. What about the morbidly obese patient who is malnourished?”
Dr. Sculco: “We felt that a BMI of greater than 40 was a contraindication for doing both at the same time.”
Moderator Maloney: “So that’s the patient who’s not maybe at risk for a general medical complication, but wound healing. So there’s some consensus that there’s a role for this operation in carefully selected patients.”
Dr. Sculco: “We’re looking at ways to modulate the pulmonary hit that the patient gets, and we’re looking at enzymatic reactions. The lung produces desmosin and it seems that if you treat patients preoperatively with a low dose of cortisone you may be able to lessen that lung injury hit.”
Moderator Maloney: “Every knee replacement has some embolization. You agree, Leo?”
Dr. Whiteside: “Yes.”
Moderator Maloney: “Tom, comments on what Leo said about cementless fixation?”
Dr. Sculco: “We documented in the hip that the non-cemented are protected more from fat emboli, but also stem length is important. We use a prosthesis with a central peg but it’s not very long. With all due respect, yours is longer and that would push more fat into the system, so it’s somewhat of a tradeoff.”
Moderator Maloney: “Thank you, gentlemen.”
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