The measurement of subacromial contact pressure in patients with impingement syndrome

This study presents the subacromial contact pressure findings in 25 patient s who underwent an arthroscopic acromioplasty for impingement syndrome. All patients failed a course of conservative management before surgery. Patien ts were evaluated, both before and after acromioplasty, by examination, UCL A functional score, and radiographic assessment of acromial morphology. At the time of surgery, a 4 X 10 mm air-filled catheter was placed beneath the anterior aspect of the acromion under arthroscopic visualization. Subacrom ial contact pressures were recorded throughout an are of shoulder motion. M ean pressure and standard deviation were derived from three trials. This pr otocol was performed on all patients and the results were statistically eva luated. The mean subacromial pressure before acromioplasty was 11.7, 35.6, 50.1, 51.1, and 57.4 mm Hg at abduction arcs of 0 degrees, 90 degrees, and 180 degrees, hyperabduction (forced passive limit of abduction), and cross- reach (arm adducted across the patient's chest with the shoulder internally rotated), respectively. The pressure after acromioplasty decreased to 1.6, 7.8, 15.9, 22.8, and 16.5 mm Hg, respectively. This decrease was significa nt in all positions (P = .016 at 0 degrees and <.001 in all other positions ). At 90 degrees of abduction, pressure always decreased in internal rotati on and increased in external rotation. Maximal contact pressure developed i n either hyperabduction or cross-reach in all patients except two. Preopera tive testing for the position of maximum impingement pain generally correla ted with the position of maximum contact pressure.