Shoulder (Garth view)

The apical oblique projection or the Garth view of the shoulder is the tangential projection of the shoulder used in trauma ⁴.

Indications

The view is best for evaluating the glenohumeral joint for dislocations and trauma to the glenoid of the scapula; this projection can be used as a replacement to the lateral scapula view in trauma, however, interpretation is difficult. The angle of the beam means it is tangential to the anterior-inferior glenoid rim (great for Bankart fractures) and gives a better view of the posterior humeral head (ideal for Hill-Sachs defect) ^1,3.

Patient position

• the patient is preferably erect, best placed on a seat sitting against the upright bucky (due to the angle of the tube) 
• the midcoronal plane of the patient is parallel to the image receptor, in other words, the patient's back is against the image receptor
• the glenohumeral joint of the affected side is at the center of the image receptor
• the patient is turned toward the affected side to show the glenohumeral joint space; this is achieved by rotating the patient 30-45°
• if possible the patient has the affected side's hand resting on the unaffected shoulder 

Technical factors

• axial oblique projection
• centering point
  • 45° caudal angle of the x-ray tube
  • 2.5 cm inferior to the coracoid process, or 2 cm inferior to the lateral clavicle at the level of the glenohumeral joint
• collimation
  • superior to the skin margins
  • inferior to include one-third of the proximal humerus
  • lateral to include the lateral portion of the humeral head often the skin margins (dependent on body habitus) 
  • medial to 1/3 of the medial clavicle
• orientation  
  • portrait
• detector size
  • 18 cm x 24 cm
• exposure
  • 60-70 kVp
  • 10-18 mAs
• SID
  • 100 cm
• grid
  • yes (this can vary departmentally)

Image technical evaluation

• the humeral head will appear elongated (due to angle) 
• the coracoid process is sometimes projected over the humeral head 
• the AC joint should be superior to the humeral head 
• posterior dislocation
  • the humeral head will be projected superior to the glenoid often obstructed by the acromion
• anterior dislocation
  • in the majority of cases, the humeral head will be projected inferior to the glenoid 

Practical points

• due to the steep angle of the tube, it is advisable to have the patient sitting on a stool for the examination, otherwise, you may hit the ceiling with your x-ray tube
• use of the AEC is not advisable; best to set your own exposures based on the AP shoulder.
• if possible, angle the detector to prevent elongation