What about obese patients? We’ve previously shown that there is a two-fold increased risk and failure in this cohort of patients (Abdel, et al., J Arthroplasty 2015). We also report that aseptic tibial loosening increases in obese patients with a BMI of 35 or greater …all with cemented fixation.
Is cementless fixation reliable in obese patients? I’ll draw your attention a publication by Bagsby and Malkani (J Arthroplasty 2016) which looked at 292 total knee arthroplasties in morbidly obese patients. All with a BMI greater than 40. Equally divided between cemented and cementless fixation. Impressive data. Revision was 13% for cemented but less than 1% in the cementless group. Revision for loosening, 6% in the cemented group, but 0% in cementless group.
Finally, we have improved protheses (biomaterials, manufacturing and design) that allow us to more reliably and reproducibly provide cementless fixation to our patients. There are multiple materials now available on the market that help with the process and multiple improvements in the design, particularly on the tibial side with keel and peg designs allowing for rigid initial fixation and biologic ingrowth.
Finally, what about the 3D printing? 3D printing is here, it’s available and allows us to do this in a rapid fashion. Denis Nam, et al. (J Arthroplasty 2017), looked at 3D printed cemented knees (n=62), cementless knees (n=66). No revision at 2 years.
In summary, I would argue that there is excellent historical long-term data and contemporary literature for cementless fixation.
Dr. Schmalzried: He’s really good. I almost believed that myself. That was incredible.
This is a timeless debate. There are many causes of TKA revision and, no question, younger people are at greater risk.
Now, you can improve fixation…better cementless, for example. And, there’s this tendency where something doesn’t work for you, you blame the technology. I’m going to suggest that we look at ourselves. Can we do better surgery? And can we do better cementing? Are we going to go for new improved or new and unproven?
In this debate the burden of proof remains on the cementless side. We all cherry pick registry data and I’m going to cherry pick. There are more revisions of cementless knees in the Australian Joint Registry—when it’s risk-adjusted for age and gender. The lower revision rate is in the cemented knees.
What’s the difference? The difference is that alignment matters.
We’ve got to look at ourselves. When you get the alignment right, especially when the patient is obese, you can get good survivorship. But, if you’re going to operate on obese people and you don’t get your alignment right, don’t be surprised if you get loosening, especially with a varus deformity.
I am a patient of Dr. Schmaltzreid, who performed a double total knee replacement surgery on me nearly 20 years ago. For the past 20 years I have not experienced even the slightest discomfort, pain nor movement impediment. I am absolutely amazed by the astounding success and best possible results that he was able to achieve!! I am absolutely convinced that the artificial knees that he installed, but most importantly his thorough knowledge, incredible skills and understanding not to mention his vast experience in performing this type of surgery were the determining factors responsible for the amazingly successful results that he was able to achieve on my total knee replacement surgery. I am immensely grateful to Dr. Schmaltzreid for having given me 20 years and counting of pain-free and worry-free life! He is definitively the greatest hero of my life!