MRI shoulder without contrast is unreliable method to explain prolonged morbidity after subacromial decompression

Abstract

IntroductionSubacromial decompression is a common surgical procedure in patients with subacromial impingement. The results are often good, although some patients develop prolonged morbidity with postoperative pain and stiffness. The main aim of the present study was to analyze the reaction of the joint capsule 3 months after subacromial decompression using MRI without contrast. We also wanted to study if there was a relation between the capsular reaction and the Constant score (CS) or the subjective shoulder value (SSV). Materials and methodsForty-eight patients with a mean age of fifty-six years underwent subacromial decompression. They were investigated with a standard x ray and MRI before surgery and at three months after surgery. The CS and SSV were measured preoperatively and at three months, six months, and two years postoperatively. Two musculoskeletal radiologists independently evaluated the MRI images and used a scoring system from 0 to 7 to evaluate capsular changes. ResultsThe inter-rater reliability was fair. Spearman's correlation was calculated between CS scores at baseline, 3 months and 6 months with MRI score rater 1, MRI score rater 2. None of the relationships were significant. Spearman's correlation was also calculated for those with a CS score <60 and none were significant. The improvement in the CS from baseline to three- and six months postoperative was significant. The subjective shoulder value improved at three, six and 24 months after surgery. ConclusionsThe persistent pain and stiffness in some patients after subacromial decompression cannot be explained by the development of capsular changes shown by non-arthrographic MRI, which seems to be unreliable method due to high subjectivity in the assessment between the radiologists.