Presumed Primary Frozen Shoulder - Clinical Characteristics and Findings of Magnetic Resonance Imaging

Purpose: To determine rotator cuff pathologies in patients with painful and stiff shoulder using plain magnetic resonance imaging, and to assess differences in patients' characteristics and patterns of fluid collection in and around the shoulder joint. Methods: Magnetic resonance imaging studies were performed on 130 shoulders of 126 patients who were 40 years or older with passive flexion 120 degrees or less, and no history of trauma. The patients' characteristics at the initial visit, the supraspinatus tendon insertion and fluid collection in and around the shoulder joint were studied. Results: Patients were diagnosed as showing complete-thickness tear (n=15, 12%), incomplete-thickness tear (n=54, 42%), tendinopathy (n=36, 27%), or primary frozen shoulder (n=25, 19%). Age at an initial visit was significantly older in the complete-thickness group than in the other two groups. The complete-thickness group showed significantly wider passive internal rotation than the other two groups, and could be differentiated with a probability of 96%, if the internal rotation restriction was set at L5 or more caudal. The incomplete-thickness group showed fluid collection in the subacromial bursa significantly more frequently than the primary frozen shoulder group. Conclusion: Almost all patients with stiff shoulder had minor cuff pathologies or frozen shoulder, if the internal rotation restriction was severe.