Arthroscopic acromioplasty: extravasation of fluid into the deltoid muscle.

We studied 25 patients who underwent an arthroscopic examination of the shoulder and in whom 20 had an arthroscopic acromioplasty. In all patients there was extravasation of fluid due to the use of pressure irrigation. The pressures rose from a baseline of 12 mm up as high as 120 mm of mercury. Within 4 min of the procedure, the pressures had returned to the baseline. No patients showed evidence of muscle damage during electromyograms done at 4-6 weeks postoperatively. Pressure irrigation appears to be safe for subacromial decompression.