The comparison effects of intra-articular injection of different opioids on postoperative pain relieve after arthroscopic anterior cruciate ligament reconstruction: A randomized clinical trial study*

BACKGROUND Pain after knee surgery, if not relieved, it would lead to a more severe and prolonged pain that can delay the patients recovery and rehabilitation. The effect of pain relief by some drugs after intra-articular injection has been shown. This study compared the effect of intra-articular injection of opioids (morphine, pethidine, methadone, and tramadol) on postoperative relieving pain after arthroscopic anterior cruciate ligament (ACL) reconstruction. METHODS 150 candidate patients for knee arthroscopic ACL reconstruction were randomly enrolled into five groups. At the end of the procedure, all patients in each group received a joint injection solution including 9.5 millimeters bupivacaine with 1:200,000 epinephrine. The remaining 0.5 milliliters of syringe capacity was filled with one of the five solutions listed below: methadone group I: 5 mg methadone, morphine group II: 5 mg morphine, pethidine group III: 37.5 mg pethidine, tramadol group IV: 100 mg Tramadol, and control group V: 0.5 ml normal saline. Afterwards, any drug further administered to the patients based on need was recorded, and the morphine equivalent for all drugs was calculated. Patients need to narcotic drugs during the first twelve hours of hospitalization and pain scores were recorded. After data gathering, they were analyzed by SPSS 16 software with chi-Square, Kruskal-Wallis and ANOVA statistical tests. RESULTS The highest and the lowest significant pain intensity were seen in placebo and morphine groups, respectively, in the first, second and third 4 hours after surgery. There were significant differences among the groups for need to analgesics. In other words, placebo group needed the highest dosage of analgesics and morphine and methadone groups needed the lowest dosage of analgesics. Morphine and methadone groups had maximum and minimum response to pain, respectively, in the first, second and third 4 hours after surgery. CONCLUSIONS Administering 5 mg intra-articular morphine after arthroscopic ACL reconstruction is a valuable choice and is recommended to be added to other local anesthetics administrated drugs after this procedure.