El magnesio intra-articular es efectivo para la analgesia postoperatoria…(I)

"El magnesio intra-articular es efectivo para la analgesia postoperatoria en la cirugía artroscópica de rodilla."

R. S. Bondok1,* and A. M. Abd El-Hady2

1 Department of Anaesthesiology and Intensive Care, Ain-Shams University Hospitals Cairo, Egypt 2 Department of Orthopaedic Surgery, Ain-Shams University Hospitals Cairo, Egypt

*Corresponding author: Department of Anaesthesiology, Ain-Shams University Hospital, Ramses Street, Abbassia, Cairo, Egypt. E-mail: bondokrsa@hotmail.com

Background. Several medications are commonly injected intra-articularly for postoperative analgesia after arthroscopic knee surgery. Among the potentially efficient substances, magnesium could be of particular interest through its NMDA-receptor blocking properties.

Methods. A total of 60 patients undergoing arthroscopic knee surgery were randomly and double-blindly assigned to two groups to receive intra-articular injection of either 10 ml of magnesium sulphate (MgSO4) (50 mg ml–1) (Group M) or 10 ml of normal saline (Group C). Analgesic effect was evaluated by measuring pain intensity (visual analogue scale; VAS) 1, 2, 6, 8, 12, 18 and 24 h after operation and the time delay between MgSO4 or saline administration and the first requirement of supplementary analgesic medication by the patient (diclofenac).

Results. Intra-articular magnesium administration resulted in a significant reduction in pain scores in Group M compared with Group C 1, 2, 6 and 8 h after the end of surgery [1.7 (0.59), 2.2 (0.69), 2.8 (1.01) and 3.5 (1.10) in Group M; 8.0 (1.25), 5.9 (1.12), 4.4 (0.67) and 4.5 (1.13) in Group C, respectively]. A longer delay between intra-articular injection of the study medication and first administration of diclofenac was observed in Group M [667 (198) min] as compared with Group C [49 (13) min]. Total diclofenac consumption was significantly lower in Group M [37.5 (38.14) mg] than in Group C [117.5 (46.95) mg]. No early side-effects were noted.

Conclusion. Intra-articular magnesium is effective for postoperative analgesia in arthroscopic knee surgery.

British Journal of Anaesthesia 2006 97(3):389-392.