Dr. Seitz: “I’m going to talk to you about humeral fixation in joint replacement. For intramedullary stem fixation, cement has become the gold standard. The question is, ‘Can a press fit implant stand the test of time?’ For those that have in-growth or on-growth trabecular metal components the question is, ‘Can the tip of the stem get a tight fit?’”
“Cementation is preferable to set the head height appropriately. And a trabecular metal component may help in terms of getting the tuberosity fixation. But still, head height and distal stem fit is the standard for fractures.”
“For elective arthroplasty, humeral stem component fixation is affected by different surfaces. There are in-growth and on-growth surfaces. For the younger person a cup arthroplasty is preferable to a large stem if it’s an elective implant.”
“We’ve learned, after 55 years of follow-up, which press fit implants loosened and which subsided. Then we went to cement. Suddenly we have cement concerns. I think this follows the experience in the hip and knee world where putting these implants in very young patients has happened. My colleague and friend Buzz Burkhead will say that if you don’t cement it the revision is easier, but that’s two operations.”
“Is cementless revision easier? With the new implant designs and techniques for glenoid grafting and impaction, and new techniques for later reconstruction, I think cementless has some good qualities…but the results are still too variable. Besides, if you do have good in-growth and fixation in a cementless prosthesis, a well fixed in-growth stem can be just as difficult to remove as a cemented one.”
“So what does the data show? Harris and Jobe demonstrated that full cementation provided a very tight fixation—better than press fit—in reducing rotational micromotion. Peppers and Jobe demonstrated in other cadaver studies that axial micromotion was present when cementation was not done. Distal canal fill is very important in keeping the stem from rocking and subsiding. The use of a cement restrictor and gentle injection techniques are very effective in preventing this.”
“In one clinical study, Torchia and Coffield showed in 89 patients implant and bone radiolucent lines in 70% of uncemented stems; 40% showed a subsidence and shift in position. In rheumatoid patients it’s even worse. Two studies showed 42% and 27% radiographic loosening while cemented stems showed 0% loosening.”
“Our goal is to have stable humeral fixation. When we do revisions, invariably, if it’s an issue of loosening, it’s not the humeral side…it’s the glenoid side. ”
“Our future directions? Bone in-growth, especially in implants that have trabecular metal, have a real promise in younger patients. If I must do an elective arthroplasty in a younger person I’m going to probably do a minimally invasive resurfacing. If you do have to put a stem in, then you should make sure you have a good tip fill, you have a very tight fit with meticulous canal preparation, but you should still consider that cup arthroplasty.”
“When you need to use a stem, cement with a distal restrictor plug, especially if there’s any questionable bone quality, whenever there is osteoporosis, in rheumatoid arthritic patients, in fractures. This will give you both rotational stability and will avoid axial micromotion.”
Dr. Burkhead: “Seth always picks his favorite guy, like Bill Seitz, and puts me up against him because he knows I’m not that smart. I’m like the Washington Generals up here every year…against the Harlem Globetrotters.”
“Debates are fun at meetings, but in the real world you have to individualize each patient. Sometimes you do need cement, but not all porous coated components and porous coatings are alike. And all the data that Bill showed you is old data using a component that was designed for cement in a cementless fashion. I’ll try to bring you up to date.”
“Charlie Neer’s first implant was a cementless component, and the reason that some of these osteoarthritic patients failed wasn’t because of implant failure…it was because of glenoid wear. In fractures the goal is to create a milieu favorable for tuberosity healing, so using a little cement is probably reasonable. But you want porous coating that will attract in-growth of the tuberosities to the implant as well as promote healing to the shaft. So avoid lots of cement.”
“You also have to look at the design of humeral implants. I’ve always favored a trapezoidal type shape to gain fill in the promixal component. I’m not worried much about distal stem fill.”
“So there is data out there…long term results of uncemented humeral components in shoulder arthroplasty. In 2007 Verborgt showed that these patients did extremely well, and even though radiographically some of them appeared to be at risk at an average of about nine years, none of these patients had been revised.”
“The surface replacements now are all used in a cementless fashion, so you should consider using those in younger patients with osteonecrosis. The fact that cemented components never loosen is a fallacy as well. This data from January 2009 from Mayo Clinic (Cil) involved 38 revision arthroplasties. The humeral components were cemented in 29 of those, with in-growth implants used in nine cases.”
“Rational uses of cementless fixation? Surface replacement or hemiarthroplasty in the young patient; hemiarthroplasty or total shoulder arthroplasty in older individuals. Sometimes the cement can be quite cardiotoxic, so use a small amount in older patients; with a minimal amount of cement in fractures—just enough to get stability; and then obviously the glenosphere in a reverse is cementless currently.”
“So if you don’t believe me, Bill, and you don’t believe Rick Matsen or Bob Coffield, maybe one of my patients can convince you [showing video]. I was telling him that JP Warner at Harvard couldn’t get a good result with this operation. Patient: ‘I had my right shoulder done in November ’94, so that would be 14 years this November. It’s been fantastic…pain free. The left shoulder was done six months ago and it too is totally pain free. Now I don’t know what’s wrong with those *&^%$ up at Harvard, but you got to work at it to get it better baby.’”
Patient drops and does pushups…says, “Don’t mess with Texas.”
Moderator Thornhill: “Buzz, you obviously didn’t look on the schedule to see where the moderator was from.”
Dr. Burkhead: “Oh, I absolutely knew where he was from. He’s talking about your patients, not the faculty at Harvard.”
Dr. Seitz: “That was an impressive video. The only thing is that I didn’t see any scars on his shoulder. You’re a really fine surgeon.”
Dr. Burkhead: “Well he does and I am. Thank you.”
Moderator Thornhill: “Bill, many years ago we looked at our rheumatoid patients and found that uncemented humeral components worked well. These were plasma spray, no in-growth; a little bit of subsidence…not much loosening…this was on the humeral side. In hips we started with all cemented implants, then hybrids. Most hips of type A and type B bone are uncemented…so you’re telling me now that I should start cementing my total shoulders on the humerus?”
Dr. Seitz: “If you look at the rheumatoid patients that you looked at 23 years ago they’re very different than the surgical rheumatoid patients today. Those patients tended to be very low demand, very sedentary. Today’s rheumatoid patients have a lot of disease modifying drugs…by the time they get their shoulder they still have a fair amount of activity and they frequently have better soft tissues. They should be cemented. I don’t think that you should cement everybody. Obviously, Seth gives us a charge to take a passionate stand, but I think that in anybody where there is a question of bone stock, then I would cement them. And a hip is very different than a shoulder in terms of the forces on it.”
Moderator Thornhill: “But our rheumatoids also have better bone quality, with their DMARDs [Disease-Modifying Anti-Rheumatic Drugs] so it may go both ways. Buzz, you said that doing an uncemented will prevent cardiotoxicity of the cement. Do you really believe that?”
Dr. Burkhead: “In an older patient with a four part fracture—when I used to do hip surgery, I had two intraoperative cardiovascular events using cement, so yes I absolutely believe it.”
Moderator Thornhill: “Because it turns out that the monomer itself probably doesn’t give it enough quantity to do it. It may be just the embolization of marrow elements and fat that is the cardiotoxicity.”
Dr. Burkhead: “But the monomer has been shown to be cardiotoxic, hasn’t it?”
Moderator Thornhill: “In massive doses injected on its own. Um, Bill, cement restrictors…Alan Boyd looked up a group of our periprosthetic fractures and they frequently occurred at the junction right between the bone and the end of the cement restrictor. One of the suggestions from that was that maybe it would be better not to have it because they didn’t loosen and you didn’t want to have that sharp demarcation. Is that a bunch of baloney?”
Dr. Seitz: “The technique of cement injection in a humerus is different than that in a hip. In general we don’t use as much pressurization in a humerus…there’s a transition point. The issue is that you don’t want the cement which is injected to dribble down the intramedullary canal. So I use a cement restrictor, but I can think of two patients of my own who have had periprosthetic fractures…in both of them it was well below that…they were in the supracondylar area.”
Moderator Thornhill: “When you have to remove cement that is well fixed in the humerus, what is your preferred technique?”
Dr. Seitz: “My preferred technique is to get the implant out first. If it’s really good, hard bone then I will try to fragment it and remove it with ribbon osteotomes and power. I don’t use ultrasound. If I have to slot the bone I will, especially if it’s weaker bone.”
Dr. Burkhead: “I usually use an episiotomy—single split—and then advancing sized drills into the deeper part of the cement mantle after you get past the implant. I want to make one point on the fractures: these two events that I had were hips that were fractured, but people that come in with fractured shoulders also can be hypovolemic. If they have a big metaphyseal split they can also put a lot of blood into their arm, just like somebody can put into their thigh. And that was really the point…that if you have somebody that’s in extremis it’s a good idea to skip the cement and go to an uncemented component.”
Moderator Thornhill: “Thanks to both speakers.”
Please visit www.CCJR.com to register for the upcoming 2012 CCJR Spring Meeting, May 20-23 in Las Vegas, Nevada.
