Stulberg v. Dorr: The Short Stem: Proven Solution for ALL Primary Hips

This week’s Orthopaedic Crossfire® debate was part of the 33rd Annual Current Concepts in Joint Replacement® (CCJR®) – Winter meeting, which took place in Orlando. This week’s topic is “The Short Stem: Proven Solution for ALL Primary Hips.” For is S. David Stulberg, M.D., Northwestern University, Chicago, Illinois. Opposing is Lawrence D. Dorr, M.D., Keck Medical Center of USC, Los Angeles, California. Moderating is Clive P. Duncan, M.D., F.R.C.S.(C), University of British Columbia, Vancouver, British Columbia, Canada.

Dr. Stulberg: Let me start by making sure everybody in the audience knows what kind of a deal Seth dealt me in debating Larry. He’s a very accomplished surgeon. Has published well over several hundred articles. Established the Master Series, which was the first real opportunity to see surgeons doing arthroplasties live. One of the founders of AAHKS, the Knee Society and Operation Walk.

I think the obvious question is “The guy that’s this accomplished, why would he oppose something as obvious as a short stem?”

While it’s true that cementless femoral stems, among a number of designs, inserted by surgeons with a variety of experiences, are working well, there are a number of issues. One is bone remodeling around the proximal femur and bone loss around the proximal femur. Another is mismatch which the short stem made what could have been a difficult situation relatively easy.

But this is the real problem, young patients with Dorr Type A bone, very narrow diaphyses and large metaphyses. Of course, the association of cementless stems with periprosthetic fractures is real.

Then there’s the issue of removing stems, while rare, it can happen because of infection and device failure. And perhaps what’s most relevant to the current climate is the use of stems in the direct anterior approach where stem selection is critical to avoid a problem.

For purposes of this discussion we’re talking about really shortened standard stems, which means that the distal portion of stem is tapered and doesn’t engage the diaphysis. These stems are 120mm in length or less. And they get their fixation primarily in the metaphysis.

In general, if you sort of parse through the current literature, what you find is that these stems seem to work in all age groups. These stems work in active, young patients as well as standard stems. And the outcomes when you look at meta-analyses suggest that fixation is not the issue. If there is an issue, it has to do with correctly inserting these devices and getting the right size.

And there is now data suggesting that bone remodeling is better with these short stems.

What is important to realize is that not all short stems are the same. And that they vary in a variety of ways. For example, the places they contact in the femur. The Trilock is much different as a wedge stem than a circumferentially contacting stem like the ABG-2 or the ARC stem, which is a neck-supported device. This may affect the outcomes.

So, in summary, short stems which engage and fill the proximal metaphysis are reliable and secure well beyond 10 years. What I think we can say, for sure, is these short stems are much easier to remove.

And finally, if you’re doing a direct anterior, it’s a lot easier to use a short stem than it is a standard stem.

Dr. Dorr: So, I guess we ask that question—why should we use it?

So, I designed the first short stem used in the United States. Chit Ranawat and I designed it on a napkin in New Orleans at the Academy in 1981. I put it into four patients and it worked very well for about 18 months.

The failure on these, interestingly enough, was because of the porous coating, which in the early 1980s, was so weak that the implant pulled away from the coating. But the bone did grow in.

A short stem at least proved something.

I still use a current design today, but not in a routine fashion. They’re used most of the time with femurs that are geometrically deformed mostly because of fracture. And I’ve cemented them. And I’ve used them non-cemented. And they all function very well for me. They do function.

I think it’s very clear to understand that these stems function well primarily in type A bone. A recent study out of Korea of 100 patients had 88 that were in type A bone.

The question is “What’s not to like about it?”

There are somethings that are a little bit unique to short stems. You still can get fractures. You can get a calcar fracture if you put it in too big—you can break the medial side off just by the wedge effect. The same wedge effect you get with a blade stem. You can get bone-on-bone impingement. You have to be very, very careful with your biomechanical reconstruction. If you shorten your offset, or you shorten your neck length and you have increased maintenance of the bony neck, you’re going to really increase your risk for bone-on-bone impingement. And you’ll get increased anteversion of the stem.

You have to be careful about how much neck you maintain because you can increase your risk for impingement. For that reason you have to be very compulsive about your biomechanical reconstruction. If you aren’t, then when they go into flexion they’ll get impingement against the anterior ilium and this is particularly a problem if the patient has any sort of stiffness in their spine.

Secondly, the stem will be more anteverted. A good portion of the anteversion that occurs is from the anterior portion of the head. When you take that off, you start reducing your anteversion and the further you cut, the less the anteversion is. If you cut right below the head, you have a very high anteversion of your stem. If you cut just above the lesser trochanter, you’ll have a very low anteversion of your stem. It’s important to remember that as you’re deciding what level you’re going to use for a neck cut.

If you have increased anteversion of your stem, that rotates your greater trochanter posteriorly. And as your greater trochanter rotates more and more posteriorly it shortens the gluteus medius. And as the gluteus medius shortens, your hip gets weaker.

You don’t want to get anteversion that is excessively beyond the normal anteversion of the patient.

If you’re interested in short stems, you have to know what you’re dealing with. You have to know the unique properties of those stems and the unique properties of the operation. You need to be patient. They have proved themselves pretty well in type A bone, but I don’t know if beyond that we have good data.

Moderator Duncan: It seems to me we have more agreement than disagreement.

Dr. Stulberg: If you’re talking about just shortening the stem in a standard stem, then I think the issues of version really are no different than they are for standard stems and they’re important, there’s just no difference.

Moderator Duncan: I tend to agree. Larry, you’ve had a lot of thought about the shape of the femur and so forth, one of the issues that concerns me when I use these shorter stems—and I do—in patients with the very long femur, I’m quite alarmed with the post-op film of this tiny little banana at the very, very upper end. Are we likely to set ourselves up for trouble there by not taking into account a ratio of some sort—stem to femur length ratio—or has it got to do with where the femur becomes very thin at the upper end. Which one of those two is the bigger determinant?

Dr. Dorr: Well, kind of both, but you’re definitely right with the ratio. That short stem I designed in the early ‘80s had three different lengths. If you don’t have that proportionality you lose your area of porous coating for fixation to the patient’s bone. You might not lose stability as long as that tail abuts against the lateral cortex at the level of the lesser trochanter, then you’ve got your antevarus protection of the tilt of the implant. Your level of coating may be significantly changed.

Moderator Duncan: Last question I’m going to pose to you. What are your thoughts on the mantle of cement in cases in which you feel obligated to use a cemented stem?

Dr. Dorr: A cemented short stem?

Moderator Duncan: Cemented short stem.

Dr. Stulberg: Clive, there is data on shortening the Exeter cemented stem and that data is that it’s about the same as a standard length.

Moderator Duncan: Join me in thanking our speakers.

Please visit www.CCJR.com to register for the 2018 CCJR Spring Meeting, – May 20 – 23 in Las Vegas.

Senior Editor: Jay D. Mabrey, M.D., whose 35 year career in orthopedics included residency at Duke University Medical Center, service in the United States Army Medical Corps, Fellowship at the Hospital for Special Surgery and a long, distinguished career at Baylor University Medical Center where, in addition to his overall leadership at that institution, developed the Joint Wellness Program that helped patients get up after surgery more quickly, developed the first virtual reality surgical simulator for knee arthroscopy and chaired the FDA Orthopaedic Device Panel, is Orthopedics This Week’s newest contributing writer and editor.