This week’s Orthopaedic Crossfire® debate was part of the 32nd Annual Current Concepts in Joint Replacement® (CCJR), Winter meeting, which took place in Orlando this past December. This week’s topic is “Patient Specific Instrumentation: Added Cost & Unproven Value.” For the proposition is Denis Nam, M.D., Washington University School of Medicine, St. Louis, Missouri. Opposing is Adolph V. Lombardi, Jr., M.D., Mt. Carmel New Albany Surgical Hospital, New Albany, Ohio. Moderating is Aaron A. Hofmann, M.D., Hofmann Arthritis Institute, Salt Lake City, Utah.
Dr. Nam: I have to say that out of all the Orthopaedic Crossfires® at this meeting, this is the true David versus Goliath debate. I really have no business stepping into the arena arguing against Dr. Lombardi, who hovers towards you from the OR lights. He’s such a huge giant in our field, has had a great impact. But luckily, I have the opportunity to argue against patient-specific instrumentation (PSI) and I think I have a chance at winning this one.
Custom cutting guides have recently been introduced and the proposed benefits are ease of use; decreased OR times and instrument trays; preoperative planning of component position and size; and improved alignment versus standard guides.
But the majority of reports have not confirmed these benefits.
Looking at cost efficiency, a recent study (Watters TS et al., J Surg Orthop Adv. 2011) assessed the fixed and variable costs from 12 consecutive cases performed using PSI versus conventional instrumentation and noted reduced surgical time of approximately 13 minutes with PSI. But the cost of fabrication was approximately $925 per case.
On a per case basis, this is not cost efficient. They did hypothesize that the institution could potentially benefit from OR time savings and decreased turnover times, but I would ask the audience, ‘How many of us really have five primary knee replacements in one OR in one day, that we could capitalize on this marginal benefit?’
A second study (Slover JD et al., J Arthroplasty, 2012) used a Markov decision model and concluded that routine use of PSI for total knee replacement would not be cost effective unless it resulted in a significantly reduced revision rate. I would challenge Dr. Lombardi to demonstrate a decreased revision rate with PSI.
A third study, by Dr. Barrack at our institution, compared an unselected series of 100 PSI and 100 conventional knee replacements. Total cost savings with PSI accounting for 4 fewer instrument trays, processing times and 11 minutes of decreased total operative time was $300 per case. But this was overwhelmed by the $1, 500 additional cost of the MRI and cutting guide.
So maybe cutting guides are better for surgeons. Maybe it will make our lives easier. I think that’s actually not the case. A study out of Utah (Stronach BM et al. Clin Orthop Relat Res, 2013) demonstrated that 161 intraoperative changes were performed in 66 knee replacements when using PSI. The predetermined implant size changed in 77% of femurs and 53% of tibias. The moral of the story is do not go on autopilot when we’re using these devices.
Also, maybe more importantly, the costs are variable, but we know it’s expensive. With bundled payments going into effect across the U.S., how will these additional costs be covered?
So maybe PSI improves accuracy?
Another study (Barrack RL, J Bone Joint Surg Br, 2012) looked at 100 standard and 100 custom knee replacements. There is no difference in the percentage of outliers between the two cohorts. They pulled the relative risks for malalignment. Looking at postoperative films, for mechanical axis malalignment, there was no difference. For tibial component malalignment, they actually found that PSI was worse in coronal and sagittal planes and for femoral component malalignment, they did note that PSI might be superior in the coronal plane, but not the sagittal plane. And for axial alignment there is no difference.
What really matters, I think everybody agrees, is clinical results. In a study, performed at our institution, looking at two-year and three-year follow-up between two cohorts, there were no differences between the two groups for range of motion, UCLA score, SF-12 physical score and Oxford Knee Score.
In the absence of proven improvement and radiographic alignment; clinical outcomes and cost efficiency, I question the continued implementation of this technology.
Dr. Lombardi: Patient-specific instrumentation…I agree with the first that it’s added cost, but what about unproven value?
If you look at the pursuit of perfection, there’s been an evolution of technology with the goal of having better outcomes. I thank Leo Whiteside, sitting in the front row, for coming up with mechanical instruments because when I started total knees, I had a T-bar and I just laid it on the femur; made the cut; laid it on the tibia, marked it, made the cut. That certainly has simplified life, hasn’t it? And there’s been calibrated instruments, small tools, computer navigation, robotics…and now we’re talking about patient-specific guides. All the manufacturers have sort of adopted this technology at different periods of time. Most of them are based on CT or MRI. One marries an MRI or a CT, with a long X-ray.
This trend is expanding. You can use PSI for unicompartmental knee arthroplasty. Zimmer Biomet has two platforms; ConforMIS has a platform. You can use it to position your acetabular components. You can use it to position your shoulder components. You can use it to position your total ankle components. We also know about the deformity correction with these patient-specific guides.
So it is an advancing technology.
We have published a number of articles on this and our conclusion is that it facilitates preoperative alignment, eliminates the IM canal penetration and improves alignment. It improves our OR efficiency and there’s potential for decreased contamination via the decreased inventory of instruments that you need for the procedure.
Now, there have been a large number of cohort studies and a large number of review articles that have been published on this topic.
Let’s take a look at the randomized, controlled trial (RCT) studies that have been published. And if you look at those, the RCTs with coronal and sagittal alignment with PSI were equal in the vast majority; they were improved in a smaller number. There were two articles that said that the alignment was worse with PSI.
If you look at RCTs with findings of femoral rotational alignment, that was examined in five studies. It was equal in one study; improved in four studies. If you look at RCTs with findings talking about OR time, trays utilized and blood loss with PSI, they were improved in a large number. OR time decreased in three studies. OR time/blood loss was equal in one.
There were some studies that aborted the technology, 16% to 32%. And then there were several studies that looked at functional outcomes; most of them saying that they were similar, some of them suggesting that they may have been a little better in the PSI group.
I think it definitely offers an advantage to lower volume surgeons.
It’s also extremely useful in the patient who has retained hardware or extra-articular deformity.
PSI is also in a state of constant evolution. One big criticism right now is the need for a preoperative CT or MRI. Guess what? That’s not going to be the case in the future.
You have to always think about what’s going to happen in the future. What’s happening right now, here and now, is that we are acquiring standard X-rays with markers, creating a 3D model from that, and creating the jigs. So X-ray acquisition is an AP of hip; an AP lateral of the knee; and AP of the ankle with a special marker. We use a 3D bone models generated from a 10-year analysis by Dr. Mahfouz. The model is then fed into the current pipeline of steps that we use, create the jigs, and we’re starting an IDE [investigational device exemption] study to see that because I do believe that’s the future of this technology.
Because the delivery of implants to us is going to change.
We know from the study by Michael Mont, that single use instruments can really help us in the OR; eliminate almost all of the trays, and really improve efficiency in the operating room. It already exists. The iTotal is delivered in a package with all the jigs you need. It’s a reality outside the United States…Medacta has a whole pack with the patient-specific guides, with all the instruments, and then the implants come delivered to you. And the Visionaire FastPack, very, very similar.
So this is the future delivery of the implants. What I think is going to happen is that patient-specific guides are going to be married with these single-use instruments, which will decrease our OR set up time; OR turnover time. It will be delivered by that drone right to your OR, you’ll see ‘em next week. And this will definitely increase your efficiency.
Actually, if you think about it, you might chuckle about it, but this is really what’s going to drive the increased number of total joints are being done in outpatient facilities because now you’re not going to have to sterilize all these instruments.
Now, remember as my protégé Vince Lombardi said, “Gentlemen, we are going to relentlessly chase perfection, knowing full well we will not catch it, because nothing is perfect. But we are going to relentlessly chase it, because in the process we will catch excellence. I am not remotely interested in just being good.”
And I agree 100%. At the end of the day, our report cards are created by our patients, so look at every piece of technology; look what it does for you and how it makes you a better surgeon, to deliver the best operation for your patient. Because that’s what’s important at the end of the day.
What about value? Well, I don’t know about you, but if you can save a half hour to an hour of your time, what’s the value of your time? I know what the value of mine is.
Moderator Hofmann: First of all, let me ask Denis. Nobody is usually, “I never did this.” Or “I always do that.” Are there cases where you’ll use a patient-specific system? You’ve obviously had a lot of experience with it.
Dr. Nam: I agree with Dr. Lombardi in stating there are cases where there’s extra-articular hardware… I actually use computer navigation for those cases rather than patient-specific instrumentation, so I don’t have an indication for using it currently.
Moderator Hofmann: I think this technology tends to gravitate and find its home. Just like computer navigation. We don’t hear much about that any more, but I was navigating all my cases for ten solid years. Now it’s been back to the patient that has deformity, hardware, and so there’s always a place for this technology. And as Dr. Lombardi pointed out, nothing stays stationary. Everything continues to evolve.
Let me ask, have you ever had an insurance company deny paying for a CT scan or MRI because you’re doing it for a jig system and not for a pathology that they’re going to be treating directly?
Dr. Lombardi: When we initially started doing this, we did, but we had to explain to the companies what we were doing and it has not been an issue of late.
Moderator Hofmann: Thank you, gentlemen, for an excellent debate and discussion.
Please visit www.CCJR.com to register for the 2016 CCJR Winter Meeting, – December 14 – 17 in Orlando.
