Factors influencing preoperative outcome expectations in patients undergoing total knee arthroplasty: a cross-sectional observational study

Preoperative outcome expectations are closely associated with postoperative satisfaction and recovery in patients undergoing total knee arthroplasty (TKA). However, the relationships among knee function, psychological factors, and outcome expectations remain insufficiently understood. This study aimed to examine the associations among knee function, pain catastrophizing, anxiety/depression, and preoperative outcome expectations in patients undergoing TKA using structural equation modeling (SEM). A cross-sectional study was conducted among patients with severe osteoarthritis undergoing primary TKA at three tertiary hospitals in Changsha, China, between September 2023 and May 2024. Participants completed the Hospital for Special Surgery Total Knee Replacement Expectations Survey (HSS-TKRES), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Pain Catastrophizing Scale (PCS), and Hospital Anxiety and Depression Scale (HADS). SEM was used to evaluate direct and indirect associations among variables. A total of 203 participants were included. The mean preoperative outcome expectations score was 63.58 ± 9.98, indicating a moderate level of expectation. HSS-TKRES scores were positively correlated with WOMAC scores ( r = 0.229, P < 0.01) and negatively correlated with PCS ( r = − 0.338, P < 0.001) and HADS scores ( r = − 0.362, P < 0.001). In the SEM, WOMAC was positively associated with HSS-TKRES ( β = 0.398), whereas HADS ( β = −0.362) and PCS ( β = −0.193) were negatively associated with HSS-TKRES. WOMAC also showed significant indirect associations with HSS-TKRES through PCS, HADS, and the sequential pathway WOMAC → PCS → HADS → HSS-TKRES. Preoperative outcome expectations among patients undergoing TKA were associated with symptom severity and psychological distress. Worse knee function was associated with higher expectations, whereas greater anxiety/depression and pain catastrophizing were associated with lower expectations. Given the cross-sectional design, these findings should be interpreted as associational rather than causal. Comprehensive preoperative assessment and expectation-focused communication may help support more realistic and adaptive expectations before TKA.