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 c ompared with placebo or no treatment in the control of postoperative pain a fter arthroscopic knee surgery. Methods. Outcome measures were pain scores, supplementary analgesics, and time to first analgesic request. Efficacy wa s 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 patien ts were considered appropriate for analysis. Twelve of these 20 studies sho wed improved pain relief after intra-articular local anesthesia in at least one of the considered pain parameters, whereas the eight other studies wer e without such improvements. In ten of the positive studies, pain scores we re significantly lower in the treatment groups compared with the control gr oups with visual analog scale (VAS) score reductions of between 10 and 35 m m early (1-4 hours) postoperatively. Quantitative analysis with calculation of the weighted mean difference in VAS confirmed a statistically significa nt bur minor clinically important effect on postoperative pain scores. In n ine studies, the consumption of supplementary analgesics was reduced 10-50% during observation periods of up to 4 hours; however, in most cases, the a nalgesic requirements were small to moderate. Only in two of six studies, w here time test analgesic request was evaluated, a significant prolongation of pain relief was observed as lasting between 30 and 50 minutes. Conclusio ns. There is a weak evidence for a reduction of postoperative pain after in tra-articular local anesthesia in patients undergoing arthroscopic knee sur gery, which. although being small to moderate and of short duration, may be of clinical significance in day-case surgery.