Robert Barrack: “It’s rare for us to see a revision knee from the community that failed in 12-15 months, but it’s the norm for MIS knees.” Adolph Lombardi: “But Robert, if your community has a number of surgeons who are attempting MIS, you’re going to see more failures.”
This week’s Orthopaedic Crossfire® debate is “MIS: A Risk Factor for Early TKA Failure.” For the proposition was Robert L. Barrack, M.D. from Washington University Medical School in St. Louis. Against the proposition was Adolph V. Lombardi, Jr., M.D. of the Mt. Carmel New Albany Surgical Hospital in Ohio; moderating was Steven J. MacDonald, M.D., F.R.C.S.(C) of the University of Western Ontario.
Dr. Barrack: “There is some support in the literature for short term benefit to an MIS TKA [minimally invasive surgery total knee arthroplasty]. The data is pretty soft and is for 6-12 weeks. There are a lot of problems with these studies, however. These are all done by designers and proponents of the system utilized; they’re prone to selection and observer bias. These are very experienced, high volume surgeons, and may not be representative of the results that most surgeons with less experience and lower volume can expect. There is little or no literature on MIS total knees performed by community surgeons.”
“We did a study looking at all revision total knees at three referral centers that do revisions from community surgeons. These are first time revisions—not infections or re-revisions. In an MIS knee…it looks cosmetically excellent. The incision is only about 10cm; the definition in the literature is generally <14cm…ours were between 10 and 12cm. And the proximal extent of the incision was within 1cm of the proximal portion of the patella. We had 236 first time revisions; about 80% had been done through a standard approach. In this time period we had done 44 revisions of MIS knees. So we compared the MIS revisions to those done through a standard approach…by gender, diagnosis, time to revision, and reason for revision.”
“We found: MIS patients were younger, there were more females and large females…and the time to revision was shocking. Less than 15 months to revision for the average MIS knee compared to about seven years to revision of a component placed through a standard incision. MIS failures were much more likely to occur in the first year; more than 80% occurred within two years. They were much more likely to fail through malrotation or instability. Yet, they were much less likely to have lysis or wear as a cause of failure.”
“Examples: One knee surgery was done by a surgeon who took three hours, so he bailed out to a standard incision in the other knee and did it in half the time. The right knee was painful, with tibia loosening at a year. In another case of patellar instability, the femur and tibia were malrotated…requiring revision at eight months.”
“These are the ‘catastrophic’ failures that were revised within 1-2 years. What are the mid- and long-term results of those that do stay in place? MIS procedures magnify the common errors of total knee replacement. In one case, a varus knee in a large female with limited motion, the patient had a standard knee on the opposite side and had more motion and better clinical results. Her postoperative course was somewhat better in the standard knee side than the MIS side.”
“The downside of the MIS knees: higher complication rate, more outliers (even among the experts). There has been a published result of a prospective, randomized study of MIS versus standard among proponents of MIS knees and at 12 weeks they found no difference, although the MIS knees did have a significant number of delayed wound healing. Their conclusion was that there was no improvement over a standard approach.”
“The title of this debate is NOT: ‘the complication rate of MIS is invariably higher’ or ‘MIS is a bad, bad thing.’ The question is, ‘Is MIS a risk factor for early failure of TKA?’ I would say, based on the high number of early revisions that we’re seeing and our published results, the answer is ‘yes.’”
Dr. Lombardi: “MIS: it’s not a risk factor for early failure. A patient came to see me last week, and was obviously not an MIS patient…only eight months postop. There was radiolucency on the medial tibial plateau; a range of flexion of about 60 degrees. Another patient with a long incision…and again, a painful, malaligned knee. Technique trumps incision length.”
“My data: From 1994-96 with a standard medial parapatellar approach in 1, 291 knees. We’ll compare that to a limited incision done by two of us—Keith Berend and myself—and 3, 631 knees. The male/female distribution was quite similar. We did more CRs [cruciate retaining] in the MIS group than in the standard group, but less patients required manipulation in the limited incision group…and there were less reoperations in the limited incision group.”
“MIS is also ‘Multidisciplinary Interactive System.’ It’s the 10 steps you need to pull the whole operation together. Do a good orthopedic assessment, a good history and physical, align patient expectations with your expectations, and motivate your patient. Also, have a good preoperative clearance, so when the patient hits the OR they’re going to be a candidate for surgery that day. And we know that preoperative rehabilitation can decrease length of stay and anxiety. If we educate our patients better they will come through surgery quicker with less pain, less anxiety, decreased length of stay, and increased satisfaction.”
“We’ve also understood from the MIS movement how to handle pain better…and we need to treat it on a multifactorial basis…epidurals/spinals/regional blocks/local anesthetic; we need to use anti-inflammatories preop and perioperatively, and get them started on a long-acting Oxycontin or another medication.”
“You need a very responsive anesthesia team to get a good spinal if that’s what you prefer—or a femoral nerve block. We don’t like a femoral nerve block, however, because that means we can’t get the patient up without a knee immobilizer. We have a multimodal prophylactic antimetics system consisting of Decadron, Zofran, and a Scopolamine patch.”
“The operative intervention is critical. If you’re going to approach this patient with a small incision, proceed with caution in these patients: muscular male, those with increased BMI [body mass index], osteopenia, patella baja, decreased ROM [range of motion], a significant flexion contracture or deformity, severe bone loss, thin skin (patient with RA [rheumatoid arthritis] or diabetes), and those patients who had an open reduction or an osteotomy of some type.”
“Use an incision that you are familiar with. If you’ve been doing a midvastus, make it smaller. If you’ve been doing a medial parapatellar, maybe shrink that one down. We know there’s literature to confirm that indeed these patients do better early on, probably because we don’t violate as much of the suprapatellar pouch.”
“And we’re making sure we protect the key ligamentous structure during the whole operation. We’re identifying the landmarks that we need to get good rotational control, and I think this has been helped by instrumentation that has been streamlined by all the manufacturers to help us make smaller incisions and get the products in correctly. Also, you can combine this with navigation.”
“Or you can use an MRI-generated total knee where we make an actual mold of the patient’s anatomy to give you a jig to put on the patient. You can do this through a smaller incision and appropriately align the parts.”
“We are aggressive with pain management…and patients are out of bed within hours of the operation—full weight bearing. Our average length of stay in 1997…3.9 days for traditional; as we incorporated rapid recovery it went down to 2.8 days in 2003. As we progressed with a standard incision and the rapid recovery, it was 2.7 days; as we added smaller incisions we got down to 2.2 days.”
“The reality of MIS is that it’s multifactorial. My take home message is: MIS is here to stay.”
Moderator MacDonald: “Robert, what would it take in terms of a prospective, randomized clinical trial to sway you…or do you think it’s more complicated than that?”
Dr. Barrack: “It’s not that MIS is bad—I do MIS on most of my knees. It’s rare for us to see a revision knee from the community that failed in 12-15 months, but it’s the norm for the MIS knees. The question for the audience is, ‘What applies to their practice?’”
Dr. Lombardi: “But Robert, if your community has a number of surgeons who are attempting MIS, you’re going to see more failures. In our community we still have a large number of surgeons doing longer incisions. Hence, my patients who come in have long incisions and have the same types of problems you’re talking about with MIS.”
Dr. Barrack: “Are you seeing failures in 12-15 months?”
Dr. Lombardi: “Both of those patients were 8 to 9 months postop.”
Dr. Barrack: “We looked at all of our revisions over several years and it’s relatively rare to see a revision in a year or two. And I don’t think MIS is being done on that large a scale—and this was an experience at three centers, so I’m concerned that there is a high risk. You’re not going to get as good fixation, exposure, and ligament balance early on without more work, so you have to be more selective.”
Moderator MacDonald: “Adolph, the ideal indication in your practice would be the thin, non-osteopenic woman—just kidding.”
Dr. Lombardi: “That is where you should start…thin female, maybe with a valgus knee, where the patella subluxes very easily. Once you accomplish that you move on into more difficult cases.”
Moderator MacDonald: “Robert, what do you tell a patient who is pushing MIS?”
Dr. Barrack: “Three-fourths of the time I do it, but if I have a 300lb patient or someone with too much deformity I tell them that it may not be the best thing for them.”
Dr. Lombardi: “I encounter that all the time.”
Dr. Barrack: “I take a pen and put a dot at the top of their kneecap and below the joint line and say, ‘that’s the minimum.’ A lot of patients are shocked and think we’re doing an arthroscopic procedure.”
Moderator MacDonald: “Adolph, how much benefit have you seen from the multimodal approach versus from a smaller incision?”
Dr. Lombardi: “We’re getting patients out faster with a shorter incision; and you can’t determine the psychological perspective of the patient. When they see a small incision, closed, subcuticular with wound glue, they’re excited. So perhaps this has much to do with organizing a good team around you and doing the right thing with respect to managing pain.”
Dr. Barrack: “We’ve seen equal, surprisingly good results through standard incisions if you use all those modalities. If you shrink your incision a little you’ll probably get similar results.”
Moderator MacDonald: “Thank you.”
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