Acceptance and Commitment Therapy for Prevention of Chronic Pain After Total Knee Arthroplasty

Objective: The aims of this study are to assess the preliminary outcomes of the NOPAIN treatment, which is an ACT-based treatment performed in the early postoperative period after Total Knee Arthroplasty (TKA), aimed to prevent the onset of chronic postsurgical pain, as well as to evaluate the predictors of the presence of moderate-to-severe pain after three months. Design: Non-controlled preliminary trial. Setting: Division of Rehabilitation Medicine within an Italian tertiary care hospital. Subjects: Eighty patients undergoing postoperative rehabilitation after TKA. Methods: Before the treatment, patients underwent a baseline assessment of pain intensity (Numeric Rating Scale), knee pain, stiffness and function (WOMAC), as well as of potential predictors of the effects of the treatment, namely sex, age, pain duration, catastrophizing (Pain Catastrophizing Scale), psychological distress (Hospital Anxiety and Depression Scale), presence of central sensitization (Central Sensitization Inventory), cognitive flexibility (Wisconsin Card Sorting Test) and heart rate variability. Then, all patients underwent the NOPAIN treatment. Pain intensity, knee pain, stiffness and function, catastrophizing and psychological distress were also assessed after three months. Results: Participation rate was 72% and retention was high, with 81.3% of participants completing all four sessions of the NOPAIN treatment. Pain intensity (p < 0.01), knee pain (p < 0.01), knee stiffness (p < 0.01) and knee function (p < 0.01) improved over time. Female sex and age were associated with lower odds of moderate-to-severe pain at three months, whereas presence of central sensitization, baseline pain intensity, rumination, helplessness and changes in helplessness were associated with higher odds. Conclusion: This study shows that the NOPAIN treatment is feasible, that it can be integrated into standard rehabilitative care, and that it might contribute to the prevention of chronic post-surgical pain. The results of this preliminary study will be the basis for the improvement of the intervention.