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Survivorship and Cause-Specific Revision Risk Following Primary Total Knee Arthroplasty Using a Newer Versus Older
Matthew P Kelly1, Heather A Prentice2, Brian H Fasig2
1Department of Orthopaedic Surgery, Southern California Permanente Medical Group, Harbor City, California.
Background:
New implant systems have design modifications seeking to improve total knee arthroplasty (TKA) patient satisfaction and survivorship. We sought to determine whether there was a difference in overall and cause-specific aseptic revision risk between two successive modern TKA designs, both overall and when stratified by constraint type: posterior stabilized, ultracongruent, and cruciate retaining.
Methods:
Adult patients who underwent primary fully cemented TKA for osteoarthritis between 2009 and 2022 were identified using our institutional total joint arthroplasty registry. The study sample was restricted to patients who received either the newer (n = 54,113) or older (n = 39,990) generation implant system from the same manufacturer. Multivariable Cox regressions were used to evaluate risk for aseptic and cause-specific revision.
Results:
The 9-year revision rate for both designs was around 2%. In adjusted analyses, the newer system had a higher aseptic revision risk compared to the older generation (hazard ratio [HR] = 1.22, 95% confidence interval [CI] = 1.09 to 1.37), as well as higher risks for loosening (HR = 1.38, 95% CI = 1.12 to 1.69) and instability (HR = 1.29, 95% CI = 1.06 to 1.58). By constraint, newer generation posterior stabilized bearings had higher risks for aseptic revision (HR = 1.20, 95% CI = 1.06 to 1.37) and loosening (HR = 1.34, 95% CI = 1.07 to 1.68). A higher instability risk (HR = 1.95, 95% CI = 1.12 to 3.37) was observed for newer cruciate retaining, while a higher aseptic revision risk (HR = 1.36, 95% CI = 1.00 to 1.85) was observed for newer ultracongruent.
Conclusions:
Although the overall revision risk was low, we found the newer system did not improve survivorship compared to the preceding system. Surgeons should be aware of these findings when determining polyethylene thickness and level of constraint with the newer system.
Level Of Evidence:
Level III.
