Utility of Intranasal Tapentadol in Redefining Postoperative Pain Management in Total Knee Arthroplasty: A Prospective Observational Study.

Introduction Effective strategies to minimize postoperative pain following total knee arthroplasty (TKA) are essential to improve functional outcomes. This study aimed to evaluate the effectiveness and safety of tapentadol nasal spray as a form of patient-controlled analgesia (PCA) for postoperative pain management after TKA. The intranasal route was chosen for the study as intranasal tapentadol has been shown to have superior pain reduction as compared to intravenous tapentadol. Intranasal instillation of tapentadol is rapid and more effective than the parenteral or oral route. Additional advantages of the intranasal route include enhanced comfort, convenience, and safety. Methods The present study was a single-center prospective observational study including 120 patients undergoing unilateral TKA who were administered tapentadol nasal spray post-surgery (22.5 mg of tapentadol per spray). Pain was objectively assessed using the visual analog scale (VAS) on postoperative days (POD) 1, 2, and 3, before and after spray administration. The pain severity was graded into mild (VAS 1-3), moderate (VAS 4-6), and severe (VAS 7-10) based on the VAS score. The time duration required for the pain severity to become mild from the pre-spray level post-administration of the nasal spray was recorded on all three PODs. The time required in hours for the pain severity to worsen from mild (VAS 1-3) to moderate (VAS 4-6) or severe (VAS 7-10) was also recorded on all three PODs. The statistical analysis plan for this study involved the analysis of VAS scores collected on PODs 1, 2, and 3. Categorical variables were expressed as percentages, while numerical variables were presented as means and standard deviations. The significance of differences between pre and post-treatment VAS scores was analyzed using Student's t-test. Differences between proportions were analyzed using the Chi-square or Fisher's exact test. The Kolmogorov-Smirnov test was used to test the normality of the quantitative data. The Analysis of Variance (ANOVA) test was applied to compare the means across the three PODs. A two-tailed significance level of 0.05 was set for all tests to determine statistical significance. Results The mean pre-spray VAS scores recorded on POD 1, 2, and 3 were 8.07, 7.64, and 7.40 respectively. The mean post-spray VAS scores recorded on POD 1, 2, and 3 were 4.63, 4.71, and 3.95 respectively. There was a statistically significant reduction in the VAS scores on each of the three days when measured before and after spray administration (p<0.001). The average time needed for the pain severity to become mild from the pre-spray level in minutes on POD 1, 2, and 3 was 14.07, 13.36, and 12.34 respectively. Thus, this metric significantly declined (p<0.001) from POD 1 to POD 3. The time taken in hours for the pain severity to worsen from mild to moderate or severe on POD 1, 2, and 3 was 6.57, 6.70, and 6.98 respectively indicating that there was a significant increase in the time till the pain severity worsened from POD 1 to POD 3 (p<0.001)