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Study details current causes of TKA revision, efforts to improve survivorship
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 Richard D. Scott |
Although the reasons for reoperation following total knee arthroplasty have changed in the past 3 decades, today’s revision rates are as low as 1%.
During his presentation, Richard D. Scott, MD, from Harvard Medical School in Boston, said at the Current Concepts in Joint Replacement 2011 Winter Meeting here, that he tells patients their implants are “not like a battery. You are going to have a definite reoperation rate that starts at year 1, and goes [up] at about 0.5% per year for the first 25 years.”
Based on his 27-year study of 4,222 consecutive primary posterior cruciate-retaining total knee arthroplasty (TKA) cases consisting of 3,432 fixed bearing and 790 mobile bearing prostheses, polyethylene wear was the most common reason for reoperation, occurring in 119 cases, Scott said.
Among the fixed bearing TKAs Scott studied, 222 knees needed revising (5.6%) at an average 13 years follow-up, he said. By comparison, there were 11 reoperations among the mobile bearing TKAs.
Discussing implant survivorship, Scott said, “There is a 95% chance you will get 10 years [and] a 90% chance you will get 20 years” of use per implant.
He reported a 20 times higher incidence of reoperation with un-resurfaced patellae than resurfaced knees.
“[Pain] does not occur in the first decade. [Implants] start to hurt 15, 18, 20 years down the line,” Scott said.
Although cemented tibial implants, all-polyethylene patellar implants and both cemented and cementless femoral components have proved lasting, long-term tibial implant survivorship requires further study, according to Scott. Better polyethylene, locking mechanisms and polished chromium cobalt trays currently being developed should help further reduce the revision rate, he added.
Reference:
- Scott RD. Why knees fail in 2011: Patient, surgeon, or device? Paper #105. Presented at the Current Concepts in Joint Replacement 2011 Winter Meeting. Dec. 7-10. Orlando, Fla.
- Disclosure: Scott is a consultant to DePuy and is on the advisory board for ConforMIS.
Polyethylene wear is the leading cause for reoperation in this population with an average of 13 years follow-up. We know from registry studies that infection, instability, pain and aseptic loosening are the most frequent causes for revision in short to intermediate follow-up (Paxton et al, 2011). With a longer follow-up, one would expect a higher rate of revision due to polyethylene wear, as seen in this study. However, the wear rate is probably dependent on the design and manufacturing processes of the polyethylene. Long-term studies like this are important to confirm our assumptions and inspire us to aim for better implants. The average age of arthroplasty patients is decreasing, thus choosing the right implants made of the right material becomes increasingly important.
— Øystein Gothesen, MD
Haugesund Hospital
Bergen, Norway
Disclosure: Gothesen has no relevant financial disclosures.
Reference:
- Paxton EW, Furnes O, Namba RS, et al. Comparison of the Norwegian Knee Arthroplasty Register and a United States arthroplasty registry. J Bone Joint Surg Am. 2011;93(Supplement 3):20-30.