The Etiology of Total Knee Arthroplasty Failure Influences on Improvement in Knee Function: A Follow-Up Study

Background: Outcomes following total knee arthroplasty (TKA) revisions are variable, and it is hypothesized that the underlying cause of primary TKA failure impacts postoperative outcomes. This study analyzes the results of TKA revisions seven years after surgery, in relation to the etiology of primary failure and other influencing factors. A previous study conducted in 2013 examined the same cohort of patients three months after revision surgery. Methods: From the original study, 97 patients were followed up, and 49 patients were eligible for inclusion. Patients were classified into four groups: "periprosthetic infection" (PPI), "aseptic loosening," "instability," and "arthrofibrosis." Outcomes were analyzed using established scores (the Knee Society Score (KSS), New Knee Society Score (nKSS), and the Western Ontario and McMaster Universities (WOMAC) index) and considering factors such as age, gender, BMI, and ASA classification. The outcomes were analyzed using three time intervals: "Outcome Short" (preoperative to 3 months postoperative); "Outcome Long" (preoperative to 7 years postoperative); and "Delta PostOP" (3 months postoperative to 7 years postoperative). Results: Significant improvements were observed in all time intervals, especially in the "Outcome Short" (p < 0.001) and "Delta PostOP" (p < 0.001) periods. The "instability" and "aseptic loosening" groups showed better outcomes in terms of range of motion and knee scores than the "arthrofibrosis" and "infection" groups (p < 0.05). A lower BMI and an ASA status of II were associated with better outcomes (p < 0.05). Women also showed superior results in the nKSS (p < 0.05). Discussion: Patients with "aseptic loosening" and "instability" had the best long-term outcomes. Lower BMI and better ASA status also correlated with improved results. These findings can inform patients of the potential outcomes of revision surgery, thereby facilitating informed decision-making.