Differences in the relationship between pain and anxiety in total knee and hip arthroplasty: a longitudinal cross-lagged analysis mediated by depression and pain catastrophizing.

Acute postsurgical pain (APSP) is an important risk factor for pain chronification, with reports of being more intense after total knee arthroplasty (TKA) than after total hip arthroplasty (THA). Psychological variables have been associated with differences in postsurgical pain experience. This study aimed to analyse the longitudinal reciprocal association between pain and anxiety levels in patients undergoing TKA or THA, to investigate the moderator role of the type of surgery and to explore psychological mediators in the anxiety - pain association. Patients undergoing TKA (n = 120) or THA (n = 109) were evaluated before surgery and in the acute postsurgical period (48 h postsurgery). Presurgical assessment comprised sociodemographic, pain-related and psychological variables (anxiety, depression, pain catastrophizing, self-efficacy, optimism and satisfaction with life). Postsurgical assessment focused on pain frequency, pain intensity and anxiety. Longitudinal associations were explored using cross-lagged panel models that included the indirect effect paths through possible mediators (pain catastrophizing and depression). Multigroup analyses compared TKA and THA. In the global sample, higher APSP was predicted by higher presurgical pain and worse presurgical anxiety. Multigroup analyses revealed that worse APSP was predicted by higher presurgical anxiety in patients undergoing TKA and by higher presurgical pain in patients undergoing THA. Furthermore, there was a positive significant indirect effect of pain catastrophizing, but not depressive symptoms, in the relationship between presurgical anxiety and APSP in THA. Anxiety and APSP are differently interrelated in TKA and THA. Psychological characteristics could be managed before surgery to favour better APSP control and potentially prevent pain chronification after total joint arthroplasty.