Bilateral Arm-Abduction Shoulder Radiography to Determine the Involvement of the Scapulothoracic Motion in Frozen Shoulder

Background: We hypothesize that there is no difference in the motion of the scapula with respect to the thoracic wall (scapulothoracic interface) between the affected versus non-affected shoulder on 0° and 90° standard arm abduction radiography. Methods: We enrolled 30 patients with the diagnosis of unilateral frozen shoulder after ruling out of other pathologies. Bilateral standard shoulder radiography was done in two position of 0° and 90° of arm abduction. Non-affected side was used as a control group. Results: The mean scapulothoracic angle of the affected side was significantly larger than the non-affected side in both 0° and 90°of abduction in spite that the scapulohumeral angles were comparable in 0°, indicating potential alteration in scapular positioning. Conclusion: Scapulothoracic motion and position can be affected in frozen shoulder along with other areas. All treatment modalities should be applied to this area as well if substantial difference was detected between the two sides. Level of evidence: I