Assessing Preoperative Pain Sensitivity Predicts the Postoperative Analgesic Requirement and Recovery after Total Knee Arthroplasty: A Prospective Study of 178 Patients

Background The aim of this article is to study the correlation between preoperative pain sensitivity and postoperative pain and analgesic requirements for patients undergoing primary total knee arthroplasty. Methods Between December 2018 and April 2019, the pain sensitivity of 178 consecutive patients undergoing primary total knee arthroplasty was assessed preoperatively with a digital algometer. The patients reported the VAS (visual analog scale) score at 3 instances of needle prick (phlebotomy, glucometer blood sugar, intradermal antibiotic test dose), during the range of movements and completed the Depression Anxiety Stress Scale score. Postoperative VAS score, analgesic requirement, and physiotherapy milestones were recorded in all these patients on day 0 to day 4. Results The average age of the patients was 64.13 years and 69.1% were females. Females had lower mean algometry values (56.12 ± 12.77 [standard deviation]) compared to males (71.09 ± 18.78 [standard deviation]) (P < .001). Higher Depression Anxiety Stress Scale correlated with lower algometry values (P < .001). The postoperative VAS score was 2.54 ± 0.59 on the day of surgery which increased to 3.27 ± 0.69 on day 1 after mobilization (P < .001) and reduced to 1.67 ± 0.62 on day 4. Low algometer score correlated with higher postoperative VAS score (P < .05), increased analgesic requirement, and opioid utilization (P < .001), delay in achieving an optimum range of movements (P < .001) and independent ambulation (P < .001). Conclusion Preoperative assessment of pain sensitivity predicts postoperative analgesic requirements and recovery. Patients with a lower pain threshold should be counseled preoperatively and also receive a better titration of analgesics perioperatively and prolonged physiotherapy.