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 “Mega Prosthesis for Distal Femoral Peri-Prosthetic Fx’s.” For the proposition is Thorsten Gehrke, M.D., ENDO-Klinik, Hamburg, Germany. Opposing is George J. Haidukewych, M.D., Orlando Health Orthopedic Institute, Orlando, Florida. Moderating is Daniel J. Berry, M.D., Mayo Clinic, Rochester, Minnesota.
Dr. Gehrke: Peri-prosthetic fractures and treatment. Before we talk about treatment, I’d like to introduce you to the Unified Classification System (UCS, Duncan and Haddad, Bone Joint J 2014) with specific interest in Type B, which focuses on bone quality. . Type B1, good bone, no implant loosening. Type B2, good bone with implant loosening. Type B3, poor bone or bone defect with implant loosening. Treatment depends on classification.
Of course, George will tell you about implant systems, probably locking, interlocking screws or retrograde intramedullary nailing. It works, it works if you have good bone stock; if you have good cortical bone; if you have viable bone.
Interestingly there are differences in the outcome of locked plate versus intramedullary nails. One paper (Meneghini, et al, J Arthroplasty 2014) showed that the failure rate of the locked plating was twice that of intramedullary nailing. We know, of course, the usefulness of intramedullary nailing in the case of a peri-prosthesic fracture is quite limited. You need an open box in the femoral component. If you have a closed box, of course, it’s impossible.
Plated ORIF works but the literature tells us that 25% need revisions. Why do they need revisions? Because of two main issues. First of all, if you do not restore the alignment with your plating, it will fail and result mostly in a non-union. This is a problem that’s probably the most difficult step—to restore the alignment of the knee prosthesis with a plate—and sometimes almost impossible. So we prefer, in our hospital, at least if we have a Type B3, a mega prosthesis with distal femur replacement which you can expand to a total femur replacement. In cases with failed osteosynthesis, peri-prosthetic fracture, bad bone quality… we use a distal femur replacement.
Comparing allograft versus revision systems versus distal femur replacement, a recent paper (Saidi, et al., J Arthroplasty 2014) described that operative time and blood loss were found to be significantly less in the revision systems and distal femur replacement compared to the osteosynthesis patients.
Another paper we found compared ORIF versus distal femur arthroplasty (Chen, et al., J Arthroplasty, 2013). They found significantly more surgical procedures for ORIF revision than for distal femur arthroplasty. And they concluded, and this is exactly our opinion, that the distal femur arthroplasty is really indicated in osteopenic patients or patients with bad bone quality or with poor bone stock and I do not think that makes any sense to try to do this with osteosynthesis. If it is needed, you can also choose a big knee prosthesis. It can provide immediate stability and allow early mobilization.
I’d like to conclude that the choice of the procedure depends on, of course, bone quality and the patient’s health conditions. In poor bone quality, distal femur replacement is the safer alternative with less complications despite the fact that there is no metaphyseal support.
Dr. Haidukewych: I will concede to Thorsten that mega prostheses do have a role in the treatment of these fractures, but very, very limited role. In my practice, it’s less than 10%. Perhaps for very distal osteopenic cases where failed internal fixation has occurs. But ORIF remains the gold standard, and I’ll show you why that is.
There are no published prospective randomized studies to compare modern ORIF to mega prostheses to determine what are the outcomes, cost disposition or whether there is any benefit. This is all anecdotal.
Peri-prosthetic fractures are becoming more common. They’re usually low energy. They typically occur in the metaphysis above a well-fixed knee. The knee is almost always functioning well. It’s not loose and there is enough bone for internal fixation. The goals are to maximize distal fixation, get the fracture to heal in the correct alignment, length and rotation, and avoid complications. There are technical challenges to this. Osteopenic bone, very short distal fragments, and obstacles to internal fixation by parts of the femoral component.
There are two general trends in internal fixation for these injuries. Some form of submuscular lock plating, or some form of retrograde nailing with a modern multiplanar angle stable locking screws. Nails are tissue friendly, mechanically sound, but you do need good notch access and it’s hard to avoid malalignment. Here you can see a good case for retrograde nailing—long distal segment, open box, you can get a nail in and good alignment. Most modern total knee arthroplasties do have good notch access for retrograde nailing.
What about plating? Plating is also useful and can allow coronal plane stability, notch access is obviously not required, so they can be used on any arthroplasty. Their obvious advantage is multiple points of fixed-angle fixation compared to the historical devices used to fix these fractures. So the argument about a fracture being too distal to fix—I see that very, very rarely in my practice—you can get almost all the way down on the femoral component and, if you leave the metaphyseal area undisturbed, you can expect good biology and therefore good predictable healing.
We don’t use wires, we don’t use cables, we don’t use dead planks of bone anywhere in the distal metaphysis. Pretty much any manufacturer now has some way to angle and lock a screw and this allows fixation of very distal fractures. With modern implants, you can get extremely distal, and with polyaxiality you can get good fixation areas where you previously could not. You leave it alone. You bridge it. It will heal. The technique is pretty straightforward.
The data is pretty clear from all over the world. Nails and plates, fixation success rate 88% to 100%. Twelve different studies, the fracture’s going to heal over 90% of the time if you do a decent job fixing it, whether you use a nail or a plate. So why would you throw away that distal fragment to perform an expensive distal femoral replacement if you can get union most of the time?
So why not perform a mega-prosthesis? Obviously, Thorsten has told you the advantages—full weight bearing, there’s no fracture to heal, you can start early range of motion. But they are very expensive and the complications are not minor. They do require expertise in arthroplasty and if you’ve ever done any of these you see extension mechanism problems relatively frequently. If ORIF fails, I can still do a mega-prosthesis. What do I do if a mega-prosthesis fails, just keep going up to a total femur? Something about that just doesn’t make sense to me.
What Thorsten is not showing you is the complications of distal femoral replacements. They are not insignificant. Infection rates are double digits in many of these series. I don’t like dealing with infected mega-prostheses. It does not make my day fun. So when do I do a mega-prosthesis? I’ll concede this to Thorsten—last resort. Distal, severe osteolysis. Internal fixation is very, very likely to fail. We’ll replace the distal femur. Multiply-operated cases, such as he showed. Excellent indication.
So in conclusion, mega-prostheses do have a limited role in treating peri-prosthetic fractures above a well-fixed total knee. Why? In my opinion, the complication rates are significant. These are very, very expensive implants and they require expertise in arthroplasty. ORIF remains, clearly, the gold standard for this fracture because it works.
Moderator Berry: Just to start with, George, I think I heard you concede that there is a role for mega-prostheses in at least a few patients, right off the bat. Is that right?
Dr. Haidukewych: That is correct.
Moderator Berry: Thorsten, would you also concede there’s a role for internal fixation in some patient’s right off the bat?
Dr. Gehrke: Of course.
Moderator Berry: So you both agree that there’s a role for what the other person’s espoused. I’m just going to ask you about a couple of things that are probably frequently discussion points for the surgeon in his own brain when he’s trying to figure out what to recommend. First of all—patient comorbidities—does a sicker patient make you more likely to do a mega-prosthesis? Or more likely to want to do a ORIF? I think you could argue it both ways, but I want to hear what you say. George, let’s start with you.
Dr. Haidukewych: I think the comorbidities have less of an impact on what I choose to do because internal fixation works in the vast majority of cases. I think renal failure, other situations where a patient has a higher incidence of a fracture non-union. You can make an argument to just replace it. But, again, you can argue that a big distal femoral cemented arthroplasty is a big hit physiologically, that’s not necessarily a safer thing. We don’t have data to prove any of this.
Moderator Berry: That’s why I asked you the question. If you shove a big implant up with cement up the femoral canal, that does put a bit of a hit on the cardiovascular system, right?
Dr. Haidukewych: I agree and usually cementing the tibia and the femur, that’s not a rapid operation. I make the decision mostly on the fracture characteristics rather than comorbidity.
Moderator Berry: More so than medical comorbidity. Thorsten, how do you feel about this? Maybe you feel differently.
Dr. Gehrke: I think they are quite high…comorbidities have quite a high impact because if you have a really sick patient who you’d like to bring out of the bed, the distal femur replacement allows a patient to get up out of the bed on the second day and get some full weight bearing on this leg. This is not allowed normally if you are doing internal fixation.
Moderator Berry: That’s a great point. George, one benefit of the mega-prosthesis is immediate, early weight bearing and with ORIF maybe not always. How do you view that in terms of balancing the pros and cons of these two attempts?
Dr. Haidukewych: I’m comfortable letting people weight-bear on that nail construct. Not so much on a plate. And it also depends on the fracture characteristics. If I get good bony compression, simple oblique fracture, I’ll let you weight-bear on a plate partial. On a nail I’ll typically let you full weight-bear. We’ve been very comfortable with that and not seen a high rate of failures.
Moderator Berry: So if you have a patient that’s quite weak and you feel that they’re not going to be protectively weight bear, will that push you towards a mega-prosthesis at all, George, or you still go just based on the fracture?
Dr. Haidukewych: I still go on the fracture and if we need to do bed-to-chair—many of these patients that are so frail that they can’t even protect their weight bearing—they can tolerate that for a short period of time. We’ll see some healing at six weeks, and let them progress to weight bearing.
Moderator Berry: So you think that’s enough to get them up to a chair and they’ll get through the operation even if you do that?
Dr. Haidukewych: Yes, sir.
Moderator Berry: George, it does seem as though this is an area where the tools and techniques have gotten a lot more sophisticated and having many of these cases go to somebody who is really good at using these trauma tools is important if you want to get the kind of results you talked about. Is that fair to say?
Dr. Haidukewych: I think that’s right. Both operations are highly technically demanding. To get alignment right with internal fixation you have to really pay attention and do it often. Same with arthroplasty. Distal femoral replacement to avoid extensor mechanism problems, get the rotation right at the femur, that’s not a ridiculously simple operation—you’ve got to pay attention.
Moderator Berry: Thank you both very much.
Please visit www.CCJR.com to register for the 2016 CCJR Winter Meeting, – December 14 – 17 in Orlando.
