ackground: Prior studies on conversion total knee arthroplasty (cTKA) have reported increased technical challenges and risk of complications compared with primary knee arthroplasty. The purpose of this study was to compare two-year postoperative complication/revision rates between patients undergoing cTKA after prior periarticular open reduction and internal fixation (ORIF) and those undergoing primary TKA.
Methods: Patients who underwent cTKA after prior periarticular ORIF of the ipsilateral knee were identified in a national all-payer claims database from 2010 to 2018. This ORIF-cTKA cohort was propensity matched to participants undergoing primary TKA based on age, gender, Charlson comorbidity index, and obesity status. Univariate analysis was performed to analyze differences in two-year complication and revision rates.
Results: After propensity matching, 823 patients were included in the ORIF-cTKA cohort and 1640 patients in the primary TKA cohort. No differences in demographics or comorbidities existed between cohorts. Relative to the primary TKA cohort, the ORIF-cTKA cohort had significantly higher incidences of all-cause revision (5.47% vs 2.47%, P = .001), periprosthetic joint infection (PJI; 4.74% vs 1.34%, P < .001), and intraoperative or postoperative periprosthetic fracture (1.58% vs 0.55%, P = .01) at two years postoperatively. There was also a nonsignificant trend toward increased rates of aseptic loosening (1.82% vs 0.91%, P = .052) in the ORIF-cTKA.
Conclusion: Relative to primary TKA, cTKA after periarticular ORIF is associated with significantly increased rates of all-cause revision, PJI, and periprosthetic fracture at two years postoperatively. Surgeons should counsel these patients about the increased risks of these postoperative complications and consider treating them as high risk for PJI in the perioperative period.
Keywords: ORIF; conversion TKA; fracture; postoperative complications; revision rate.