Objective: To study the acromial type, acromial angle, acromial tilt and subacromial distances which known as extrinsic factors of subacromial impingement syndrome in groups of subacromial impingement syndrome and normal control.

Method: The radiography of shoulder named shoulder series composed of AP view, arch view and impingement view was performed in thirty patients with subacromial impingement syndrome and ninety persons with normal adult and we measured the acromial type, acromial angle, acromial tilt, subacromial distances and subacromial spur.

Results: Mean subacromial distances of impingement group were 11.3⁑2.4 mm in AP view, 11.1⁑2.5 mm in arch view and those of normal control group were 11.1⁑2.2 mm in AP view, 10.4⁑1.9 mm in arch view. Incidences of acromial type I,II,III in impingement group were 15 (50%), 10 (33.3%), 5 (16.7%) respectively and those in normal control group were 20 (22.2%), 46 (51.1%), 24 (26.7%) respectively. Incidence of subacromial spur was 19 (63.3%) in impingement group and 52 (57.8%) in normal control group.

Mean subacromial spur size was 10.0⁑5.4 mm in impingement group and 12.4⁑4.5 mm in normal control group. Mean acromial angle was 27.1⁑8.3 degree in impingement group and 29.1⁑8.7 degree in normal control group. Mean acromial tilt was 28.0⁑6.39 degree in impingement group and 31.8⁑3.4 degree in normal control group.

Conclusion: No significant statistical difference between subacromial impingement syndrome group and normal control group in acromial type, acromial angle, acromial tilt and subacromial distance known as extinsic factors of subacromial impingement syndrome

Keywords :Subacromial impingement syndrome, Extrinsic factors, Shoulder series