This week’s Orthopaedic Crossfire® debate was part of the 19th Annual Current Concepts in Joint Replacement® (CCJR®), Spring meeting, which took place in Las Vegas. This week’s topic is “The Cementless Knee: The Emergent Game Changer” For is R Kenneth A. Gustke, M.D., Florida Orthopaedic Institute, Tampa, Florida. Opposing is Thomas S. Thornhill, M.D., Harvard Medical School, Boston, Massachusetts. Moderating is Paul F. Lachiewicz, M.D., Duke University Medical Center, Durham, North Carolina.
Dr. Gustke: I’m certainly in favor of cementless total knees under certain circumstances.
The cemented total knee is the gold standard. The literature reports 15-year survivorship, which is excellent. The problem with cement is, however, it is a grout. Not an adhesive. It relies on interdigitation into the bone and the interface is doomed to fail biologically at some point in time.
Post-mortem retrieval studies (Miller et al.; CORR 2014) support this loss of the cement interlock. Trabecular bone initially interlocks. It resorbs, leaving cavities in the cement layer. And you get less bone contact over time.
The problem we have today is that our total knee patients are younger, more active and heavier than in the past (Kurtz et al.; CORR 2009). By 2030 more than half are going to be under the age of 65. We know that the younger the patient is the worse their survivorship (McCalden et al.; JOA 2013).
Obesity is common (Odum et al.; JOA 2013). In 2002 only 6% of total knees had BMIs [body mass index] over 30. In 2009, it was 20%. And most of us estimate in our practices that 40-50% of the patients have BMIs over 30.
A meta-analysis looking at patients with BMIs over 30 showed that there was a 1.23 odds ratio for revision for aseptic loosening (Kerkhoffs et al.; JBJS 2012).
It’s even worse if the BMI is over 40—only 88% 5-year survivorship in one study (McElroy et al.; J Knee Surg 2013).
These young, obese, active patients are going to have increased stress on their prosthesis-cement-bone interface (Odum et al.; JOA 2013).
The theory behind cementless fixation is it’s better able to handle this increasing stress because it’s a biological interface. You have repair potential. The interface actually may strengthen with increasing loading.
A Cochrane Database System Review looking at RSA [roentgen stereophotogrammetric analysis] (Nakama et al.; 2012) to compare cement versus cementless surgeries, showed that the future risk of aseptic loosening was actually 50% less with cementless fixation.
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.