The effect of a postoperative local anaesthetic pain pump in anterior total hip arthroplasty: a randomised control trial

Abstract

Introduction: This project aims to determine if an addition of a local anaesthetic pain pump for 48 hours postoperatively effects verbal pain scores (VRS), opioid usage and length of stay (LOS) after anterior approach total hip arthroplasty (THA). Methods: This was a single-centre, single-surgeon, randomised, parallel-group study with balanced randomisation involving 108 patients. Randomisation and blinding were computer generated into 2 groups: local infiltration anaesthetic (LIA) only (Control Group) and LIA+ continuous postoperative infusion of local anaesthetic for 48 hours via a pain pump (Intervention Group). Postoperatively VRS (first 30 minutes, 1 hour, 2 hours and every 4 hours postoperatively up to 48 hours), opioid consumption, length of hospital admission, antiemetic and laxative usage were recorded. Statistical analysis utilised independent sample t-tests and repeated ANOVA. Results: Demographics and duration of surgery were similar across both cohorts. On average, compared to the control group, the intervention group required 2 mg less of opioid consumption over 48 hours ( p = 0.41). VRS between the 2 groups showed no statistically significant difference. Scores ranged from 0 to 7, with an average of 1.28 in the intervention group and 1.29 in the control group ( p = 0.31). 9 patients in the intervention group and 10 in the control group required antiemetics. There was no difference in the LOS or postoperative constipation. No complications or adverse events occurred. Conclusions: Our study has shown the addition of a continuous postoperative infusion of local anaesthetic for 48 hours post an anterior THA had no effect on VRS, opioid consumption, LOS and antiemetic usage.