Patient-reported outcomes are increasingly used as complementary measures to clinical outcomes in total knee arthroplasty (TKA). However, their prognostic importance has yet to be established. We aimed to determine whether the long-term revision risk in TKA relates to pain and Knee Society Score (KSS) measures at baseline, 1, and 2 years.
This was a registry-based study of primary TKA procedures at a large tertiary care institution between 1995 and 2010. Patients completed pain and KSS questionnaires both preoperatively and at 1 and 2 years of follow-up. Clinical information including revision outcomes and mortality was collected and recorded by trained registry personnel. Age and gender-adjusted Cox regression models were used to assess the association between pain and KSS measures and revisions and mortality as outcomes.
Both the 1-year and 2-year pain and KSSs were significantly associated with the risk for revisions (P < .0001 for trend). The risk for revision was 50%-100% higher among individuals reporting poor or fair KSS at 1 year. Similarly, ≥10 points worsening on the KSS was associated with about 2-fold higher risk for revision (hazard ratio, 2.50; 95% confidence interval, 1.25-5.47). The predictive power of the 1- and 2-year KSS diminished but persisted for revisions that occurred furthest from the reporting time points. The results with pain scores were similar but stronger than the KSS.
Patient-reported outcomes in TKA have long-term prognostic importance and should be taken into account when planning frequency of aftercare of TKA patients.