A systematic review of intra-articular local anesthesia for postoperative pain relief after arthroscopic knee surgery

BACKGROUND AND OBJECTIVES: In a systematic review, we have evaluated double-blind, randomized, controlled trials of intra-articular local anesthesia compared with placebo or no treatment in the control of postoperative pain after arthroscopic knee surgery.

METHODS: Outcome measures were pain scores, supplementary analgesics, and time to first analgesic request. Efficacy was estimated by significant difference (P < .05) as reported in the original reports and by calculation of the weighted mean difference of pain scores between treatment groups.

RESULTS: Twenty studies with data from 895 patients were considered appropriate for analysis. Twelve of these 20 studies showed improved pain relief after intra-articular local anesthesia in at least one of the considered pain parameters, whereas the eight other studies were without such improvements. In ten of the positive studies, pain scores were significantly lower in the treatment groups compared with the control groups with visual analog scale (VAS) score reductions of between 10 and 35 mm early (1-4 hours) postoperatively. Quantitative analysis with calculation of the weighted mean difference in VAS confirmed a statistically significant but minor clinically important effect on postoperative pain scores. In nine studies, the consumption of supplementary analgesics was reduced 10-50% during observation periods of up to 4 hours; however, in most cases, the analgesic requirements were small to moderate. Only in two of six studies, where time to first analgesic request was evaluated, a significant prolongation of pain relief was observed as lasting between 30 and 50 minutes.

CONCLUSIONS: There is a weak evidence for a reduction of postoperative pain after intra-articular local anesthesia in patients undergoing arthroscopic knee surgery, which although being sinall to moderate and of short duration, may be of clinical significance in day-case surgery.