This week’s Orthopaedic Crossfire® debate was part of the 35th Annual Current Concepts in Joint Replacement® (CCJR®), Winter meeting, which took place in Orlando. This week’s topic is “The Primary Modular Tibia: Regardless of Age & BMI.” For is Aaron A. Hofmann, M.D., Hofmann Arthritis Institute, Salt Lake City, Utah. Opposing is Michael E. Berend, M.D., Midwest Center for Joint Replacement, Indianapolis, Indiana. Moderating is Paul F. Lachiewicz, M.D., Duke University Medical Center, Durham, North Carolina.
Dr. Hofmann: I do have a major conflict of interest: I use some all-poly tibias. That’s a confession of sins to start with.
As I’ve gotten older, I’ve learned to never say “never’” or “always” in orthopedics. There is a place for everything, but I primarily use modular tibias. Interesting that we refer back to Dr. Ranawat so often. He taught us so much and he proposed that we use the all-poly tibia in elderly patients weighing 180 pounds or less. I looked at my schedule—I couldn’t find any of those. There’s a place for all-poly tibias, but not very often.
Here’s the basic problem with all-poly tibias, load transfer to the tibia and the bending loads that affect the fixation or the bone underneath (Reilly, 1982).
Certainly not having modularity has some problems. In a case, a patient fell off the toilet and ruptured the medial collateral ligament. I couldn’t just pop in a more constrained all-poly insert. So, this patient went back for a repair and actually turned out well. You really tie your hands…at least one hand…behind your back if you’re using all-poly tibias all the time.
They certainly can take out more bone. Sometimes that’s a good thing. In an infected case, that was a great place for an all-poly tibia, but not in our standard patients. One patient that I’ve been watching for the last couple of years who refuses to have a revision. He’s worn out the poly on his monoblock tibia. I don’t really know what to do with this patient. It would have been so simple if he had a modular tibia to revise.
