Octogenarians Face Higher 90-day Medical Risk but Lower 1-year Revision Rates After Primary Total Knee Arthroplasty.

BACKGROUND

Prior studies evaluating age-related outcomes after total knee arthroplasty (TKA) have examined medical complications and revision risk separately. We asked whether octogenarians have higher rates of 90-day medical complications, 30- and 90-day readmissions, and all-cause and etiology-specific revision after primary TKA.

MATERIALS AND

METHODS

PearlDiver all-payer claims (2010 to 2022) identified isolated, first-instance unilateral primary TKA, excluding index revision, fracture/malignancy, concomitant other-joint arthroplasty, staged/simultaneous bilateral TKA within 30 days, and prior arthroplasty within 1 year. Patients were stratified by age (<65, 65 to 79, 80 to 89 years). Outcomes included 90-day medical complications, 30- and 90-day readmissions, and 1-year all-cause and etiology-specific revision (ie, prosthetic joint infection, mechanical loosening, instability/dislocation, periprosthetic fracture). Multivariable logistic and Cox regression adjusted for sex, Elixhauser Comorbidity Index, and body mass index.

RESULTS

Among 376,914 TKAs with complete covariate data, octogenarians had higher adjusted odds of 90-day medical complications and 30- and 90-day readmissions (P < .0001). Patients <65 years had the highest 1-year all-cause revision and higher adjusted odds of all-cause revision, prosthetic joint infection, and mechanical loosening or instability/dislocation revision, whereas octogenarians had a higher hazard of revision for periprosthetic fracture (P < .05).

CONCLUSION

Octogenarians experienced greater early medical morbidity but lower observed 1-year revision hazards than did younger patients. These findings support age-calibrated counseling emphasizing perioperative optimization in older patients while informing younger patients of their greater early revision risk. Because mortality was unavailable as a competing event, lower revision hazards in octogenarians should be interpreted cautiously and not assumed to reflect superior implant durability. Future studies incorporating competing-risk methodology, frailty measures, and patient-reported outcomes are needed.