Adhesive capsulitis; evaluation of a recently introduced MRI criterion

Introduction: Adhesive capsulitis is a common disorder, defined as the painful limitation of glenohumeral range of motion due to capsular hyperplasia and fibrosis. Magnetic resonance imaging (MRI) – as the gold standard of shoulder imaging- plays a critical role in diagnosis of adhesive capsulitis, in the early stages. The anterior predominance of pathologic and arthroscopic abnormalities suggest that the thickness of anterior joint capsule may be a more reliable diagnostic criterion on MRI; however, to our knowledge, only one study has evaluated the significance of this parameter up to now, the results of which, may be subject to substantial bias, due to small sample size. Objectives: To evaluate the anterior capsule of glenohumeral joint, in terms of thickness and signal intensity, and also to conduct a comparison between adhesive capsulitis subjects and control individuals. Materials and Methods: This is a case-control study. Cases were all patients with the final diagnosis of adhesive capsulitis, based on history, physical examination and imaging. Controls were all patients who underwent shoulder MRI, because of another reason. Anterior capsular thickness, and other qualitative and quantitative criteria were evaluated on the MRIs, by two musculoskeletal radiologists, with three and 10 years experience respectively. Results: All of the evaluated criteria showed significant difference, between cases and controls. Considering the cut-off point equal to 1.3 mm, "anterior capsular thickness" had 86.7% sensitivity, 96.7% specificity, 96.3% positive and 87.9% negative predictive values respectively, which posed an acceptable position among MRI criteria of adhesive capsulitis. Of note, was the near perfect inter-observer agreement of this criterion between the two radiologists, implicating its practicality. Conclusion: The anterior capsule signal and thickness are valuable criteria for diagnosis of adhesive capsulitis on MRI. Future studies with large sample volumes, clinical sub-categorization of the patients and multivariate analysis are recommended to more accurately define its role in MRI-based diagnosis of adhesive capsulitis.