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

• Published in: British journal of anaesthesia : BJA Vol. 97; no. 3; pp. 389 - 392
• Main Authors: Bondok, R.S., Abd El-Hady, A.M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2006; Oxford University Press; Oxford Publishing Limited (England)
• Subjects: Adult; analgesia; analgesia, knee surgery; analgesia, postoperative; Analgesics - administration & dosage; Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Anti-Inflammatory Agents, Non-Steroidal - administration & dosage; Arthroscopy; Biological and medical sciences; Diclofenac - administration & dosage; Double-Blind Method; Drug Administration Schedule; Humans; Injections, Intra-Articular; intra-articular; knee; Knee Joint - surgery; knee surgery; magnesium; Magnesium Sulfate - administration & dosage; magnesium, intra-articular; Male; Medical sciences; NMDA; Pain Measurement; Pain, Postoperative - prevention & control; postoperative; receptor; receptor, NMDA; surgery; surgery, knee; receptor, NMDA; analgesia, knee surgery; surgery, knee; magnesium, intra-articular; analgesia, postoperative; Knee; Prostaglandin-endoperoxide synthase; knee surgery; analgesia; Visual analogue scale; postoperative; magnesium; Inorganic element; Diclofenac; Pain; Surgery; NMDA; Anesthesia; Delay time; Magnesium; Delayed time; Human; Postoperative; NMDA; surgery; Enzyme; Enzyme inhibitor; Non steroidal antiinflammatory agent; Analgesia; Arylacetic acid derivatives; Analgesic; Antipyretic; Oxidoreductases; NMDA receptor; intra-articular; receptor
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/ael176

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