ANALGESIA FOLLOWING ARTHROSCOPY - A COMPARISON OF INTRAARTICULAR MORPHINE, PETHIDINE AND FENTANYL

It has recently been reported that morphine given in low doses intra-a rticularly can produce significant analgesia in patients undergoing ar throscopic knee joint surgery. Data are lacking on the effect of other opioids using a local approach for drug delivery. We studied the anal gesic effect of intra-articular opioids in 70 patients, divided into 7 groups, subjected to arthroscopic knee surgery in general anesthesia. The dimension of the study was based on a power of 0.8 to detect a 25 % difference in pain intensity between those receiving opioids locally versus systemically (alpha=0.05 and beta=0.20). Following surgery but before terminating anesthesia, the patients received one of the follo wing combinations: 1 mg morphine intra-articularly (i.art.) + saline i ntramuscularly (i.m.), 10 mg pethidine i.art + saline i.m., or 10 mu g fentanyl i.art + saline i.m. In three additional groups the three opi oids were given i.m. and saline given i.art. An additional control gro up received saline i.art. + i.m. We did not find any significant diffe rence between the groups considering postoperative pain intensity, nee d for analgesics or considering time to standing/walking or to dischar ge, analysing each opioid independently. There was, however, a tendenc y for pethidine i.art. to produce the lowest pain scores both at rest and during movement (P=0.06). If analysing the results with regards to if opioids were given intraarticularly or systemically, not consideri ng the type of opioid given, we did however, find a significantly lowe r total sum of pain scores at movement following local administration (P<0.05). No specific side-effects were detected. We conclude that pet hidine given intra-articularly merits further investigation with respe ct to postoperative analgesia following the activation of peripheral o pioid mechanisms.