[Effectiveness of morphine by periarticular injections after shoulder arthroscopy]

Peripheral opioid receptors have been found in inflamed synovia and the analgesic effect of intra-articularly administered morphine after arthroscopic knee surgery has been proven. There is controversy about efficacy of intraarticular morphine after shoulder arthroscopy. Thirty-two patients with impingement syndrome underwent subacromial decompression in the course of arthroscopic shoulder surgery. At the end of the operation morphine (5 mg) or saline was injected periarticularly. Pain intensity (rest and passive mobilisation) was recorded after recovery and after 1,2,4, and 24 hours (Numeric Rating Scale); the use of rescue medication (piritramide by patient controlled analgesia) was noted. No relevant pain reduction was apparent in the morphine group. Piritramide consumption was identical in both groups (19.7 +/- 16 mg vs. 19.8 +/- 19 mg). We conclude that periarticularly administered morphine in arthroscopic subacromial decompression in the dosage applied in this study does exert no relevant analgesic effect. This is possibly due to the fact that either subacromial tissue, despite of chronic inflammation, does not show the same reagibility as synovia or it is a problem of the nearly complete resection of the subacromial bursa.