Intra-synovial, compared to intra-articular morphine provides better pain relief following knee arthroscopy...

To evaluate the analgesic effect of morphine 1 mg administered into the synovial tissue and the outer third of the meniscus after knee arthroscopy.

In a prospective, double-blind, randomized study, 60 patients who required elective knee arthroscopy were assigned to two groups: Group A consisted of 30 patients who received a direct injection of morphine 1 mg into either the synovial tissue or the outer third of the meniscus following menisectomy. Group B consisted of 30 patients who received a direct injection of NaCl 0.9% 1 mL into the synovial tissue or the outer third of the meniscus following menisectomy. At the end of the operation Group A received an intra-articular injection of NaCl 0.9% 1 mL and bupivacaine 0.5% 10 mL and Group B received an intra-articular injection of morphine 1 mg and bupivacaine 0.5% 10 mL. Analgesic effect was evaluated by pain intensity (visual analogue scale; VAS) and analgesic requirements (paracetamol) during the first one, three, six, 12, 24, and 48 hr postoperatively.

There was no significant difference between the two groups within the first six hours and after 24 hr following the operation regarding VAS score and analgesic requirements. At 12 and 24 hr following the operation, the VAS score and the analgesic requirements were significantly higher in Group B compared to Group A (P <0.01 and P <0.01, respectively). No patient developed side effects.

We conclude that direct morphine injection into the synovia or the outer third of the meniscus provided better pain relief than intra-articular morphine after knee arthroscopy.