Dr. Thornhill: Let me just remind you that this debate is called “The Cementless Knee: The Emergent Game Changer.” What is the game changer in total knee replacement?
Right now, 15-20% of patients with total knees are not fully satisfied. Will cementless total knee designs change this? I think not. Now that I’ve won this debate, I’d like to thank you.
But I have a little more time.
There are some advantages to cementless total knees.
First, it’s a shorter operative time. You don’t have to use a tourniquet. I use a tourniquet when I cement.
It’s probably better for MIS [minimally invasive surgery], but that to me is like having a two-handed strangle hold on a loser.
Now the concerns of cementless knees are captured in the history of it, which Ken so nicely covered to support my point. In our first 10-year PFC study cementless femurs did uniformly well—in fact the bone looked better than the cemented ones (Schai, JBJS-Br 1998).
I think the fact is, as Ken pointed out, that the data is old, but if you look at 10-year survivorship, 92% for cemented; 61% for cementless (Rand et al.; JBJS-Am 2003).
Some of the problems were screw fixation, component breakage. The Gordian Knot of this argument is the patella.
Variable substrate. The fact is that in the tibia you have to worry about different kinds of substrates because you can have sclerotic bone on one side and osteoporotic bone on the other. In that case, cement creates a uniform proximal tibial mantle to support tibial fixation.
Surgical cut precision. You have to be more precise in the cementless design. Matter of fact, the old expression is “A little putty, and a little paint makes a carpenter what he ain’t.”
Cost is an important issue here. And you can work those data any way you want in terms of the cost of the cementing, the cost of the operative time, versus the increased implant cost. And as you all know, different institutions pay different prices for the same implants.
The new material technology. I think there are three companies—at least three companies—that have material available with improved coefficient of friction, surface roughness, the ability to cut it, porosity, and ultrastructure.
The tipping point will be the new material technology, solving the patella issue and cost effectiveness.
As a physical therapist specializing in the rehab of patients who undergo total joint replacement, that was a great debate to read. I’m curious if we should or need to change our approach to rehab in terms of loading fully, gradually, or more delayed spending upon the use of cement or in the cementless cases. Now I’ll be able to ask my question intelligently when I see the surgeons up on the floors after their cases. Thanks for publishing.