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Five-year conventional vs highly crosslinked TKA polyethylene results were no different
Longer-term follow-up needed to identify differences in wear rates between groups.
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Results of a prospective randomized study of polyethylene used in total knee arthroplasty prostheses revealed no differences in survivorship at 5-year follow-up based on the type of polyethylene used. However, investigators recommended patients with total knee arthroplasties with either highly crosslinked or conventional polyethylene continue to have routine follow-up as the investigators would not expect to see differences in wear rates, osteolysis or aseptic loosening until 10 years or 15 years postoperatively.
“There was also no significant difference in clinical outcomes and, importantly, no significant difference in complications with the highly crosslinked polyethylene,” Matthew P. Abdel, MD, associate professor of orthopedic surgery and consultant at the Mayo Clinic in Rochester, Minn., said when he presented the level 1 study at the American Academy of Orthopaedic Surgeons Annual Meeting.
No significant differences
Abdel and his colleagues studied 515 patients undergoing total knee arthroplasty (TKA) with the all-cemented, posterior-stabilized, fixed-bearing Stryker Triathlon Total Knee System with patellar resurfacing. Overall, 259 patients received X3 Polyethylene (Stryker) — which is highly crosslinked — and 256 patients received conventional N2vac Polyethylene (Stryker).
The 5-year survivorship analysis showed no differences between the groups in terms of being free of a revision or reoperation, Abdel said.
There were also essentially no significant differences between the two groups at middle-term follow-up regarding clinical outcomes based on the Knee Society scores and the SF-12 physical and mental component scores.
“With regard to complications, you can see there is a similar rate between the X3 and N2vac group,” Abdel said. “Of important note in this mid-term follow-up study, there were no early failures due to X3 highly crosslinked polyethylene fractures, particularly at the tibial post or the patellar pegs,” he said.
Source: Matthew P. Abdel, MD
More data needed
In an interview with Orthopedics Today, Abdel said that although the study was well-designed, the study timeframe was its biggest limitation.
“It is still only 5 years and when we are looking at wear rates between highly crosslinked polyethylene and conventional polyethylene, it is the 10-[year] and 15-year data that will provide us with that information,” he said in the interview.
The researchers anticipate there will be lower wear rates among the highly crosslinked polyethylene group at the 10-year follow-up. In addition, a 15-year radiographic, clinical and complication investigation should be completed to identify failures among the two groups, according to Abdel.
“The next step would be to do the 5-year radiographic, clinical and complications investigation to make sure that none of the polyethylenes have failed and to look at the radiographs and revision rates to see if the revision [rate] for wear and loosening did indeed decrease at 10 years,” Abdel said. – by Susan M. Rapp and Casey Tingle
- Reference:
- Abdel MP, et al. Paper #169. Presented at: American Academy of Orthopaedic Surgeons Annual Meeting; March 14-18, 2017; San Diego.
- For more information:
- Matthew P. Abdel, MD, can be reached at Mayo Clinic, 200 1st St. SW, Rochester, MN 55905; email: abdel.matthew@mayo.edu.
Disclosure: Abdel reports he is a paid consultant for Stryker, which manufactures the products studied and funded the study.