Preoperative anxiety and tourniquet use are associated with early postoperative pain trajectories after total knee arthroplasty: a retrospective cohort study

<title>Abstract</title> <p>Background Early pain after total knee arthroplasty (TKA) often shapes the first week of mobilization and rehabilitation. Preoperative anxiety and tourniquet exposure are both clinically plausible contributors, but their associations with repeated early pain measurements have not been well described. Methods We studied 236 patients who underwent primary unilateral TKA for knee osteoarthritis in a retrospective cohort. Preoperative anxiety was measured with the anxiety subscale of the Amsterdam Preoperative Anxiety and Information Scale (APAIS; range, 4–20). The primary outcome was overall visual analogue scale (VAS) pain on postoperative days 1, 3, 5, and 7. We compared random-effect structures before fitting mixed-effects models and treated APAIS as a continuous exposure. Hospital for Special Surgery (HSS) knee-score trajectories, restricted cubic spline (RCS) analyses, and propensity score-weighted generalized estimating equation (GEE) models were used for exploratory or sensitivity analyses. Results Of the 236 patients, 100 underwent TKA without a tourniquet and 136 underwent TKA with a tourniquet. In the adjusted random-intercept model, tourniquet use was associated with higher postoperative VAS (β = 1.256, 95% CI 1.037 to 1.476; P &lt; 0.001). Each one-point increase in APAIS was also associated with higher VAS (β = 0.151, 95% CI 0.110 to 0.191; P &lt; 0.001). The APAIS-by-tourniquet interaction was not significant (β=-0.030, 95% CI -0.109 to 0.049; P = 0.459), and neither was the time-by-APAIS-by-tourniquet interaction (β=-0.009, 95% CI -0.027 to 0.008; P = 0.291). HSS improved during follow-up. Tourniquet use was associated with lower HSS (β=-3.552, 95% CI -4.180 to -2.924; P &lt; 0.001), whereas APAIS was not (β=-0.012, 95% CI -0.126 to 0.102; P = 0.836). Conclusions In this real-world TKA cohort, higher preoperative APAIS and tourniquet use marked patients with higher early postoperative pain. APAIS did not appear to modify the tourniquet-pain association, and it was not related to HSS recovery. These findings support anxiety-informed perioperative pain planning and trajectory-based pain assessment, while the observational design limits causal interpretation.</p>