[[File:Subacromial space on outlet view X-ray.jpg|thumb|Supraspinatus outlet view X-ray, showing subacromial space measurement, and an acromial spur (above the arrow).]]
* Measurement of the '''subacromial space'''. This is normally 9–10 mm in shoulder radiographs.<ref name=petersson1984/> It is significantly greater in men, with a slight reduction with age.<ref name=petersson1984/> In middle age, a subacromial space less than 6 mm is pathological.<ref name=petersson1984>{{cite journal|author=Claes J. Petersson & lnga Redlund- Johnell|pmid=6702430|title=The subacromial space in normal shoulder radiographs|journal=Acta Orthop Scanda |year=1984| volume=55 |issue=1 |pages=57–8}}</ref>
* Presence '''Shape''' of the acromion, at least for the presence of any '''acromial spur'''<gallery>File:Flat acromion.jpg|FlatFile:Curved acromion.jpg|CurvedFile:Hooked acromion.jpg|Hooked</gallery>
Also look for common differential diagnoses or worsening factors of shoulder impingement: