Elbow AP Oblique (Medial Rotation) is a radiography positioning projection of the Upper Extremity. Arm extended, hand internally rotated 45 degrees from true AP. The centering point is located mid-elbow joint with the hand internally rotated 45 degrees from a true ap start.. The central ray is perpendicular to the mid-elbow joint.. Image-quality criteria include coronoid process of the ulna in profile, free of the radial head., radial head and neck superimposed by the proximal ulna.. Standard exposure ranges from 60 to 75 kVp, 3 to 6 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Coronoid process of the ulna in profile.
- Trochlea of the humerus in profile.
- Medial epicondyle.
- Open humeroulnar joint.
- Distal third of the humerus.
- Proximal radius (overlapped by the ulna).
Patient preparation
- Verify patient identity using two identifiers.
- Remove watches, bracelets, and radiopaque items from the arm.
- Seat the patient at the end of the table.
- Extend the arm over the IR, palm up, in true AP first.
- Internally rotate the hand 45 degrees from true AP.
Position & centering point
Mid-elbow joint with the hand internally rotated 45 degrees from a true AP start.
Central ray
Perpendicular to the mid-elbow joint.
Exposure / technique
- kVp
- 60–75
- mAs
- 3–6
- SID
- 40" (102 cm)
- Notes
- Medial rotation projects the coronoid process free of the radius.
Image-quality criteria
- Coronoid process of the ulna in profile, free of the radial head.
- Radial head and neck superimposed by the proximal ulna.
- Trochlea visible in profile.
- Open elbow joint space.
- Distal humerus and proximal forearm both included.
- Collimation: 3 inches proximal and distal to the joint.
Common errors / ARRT traps
- 1 Rotation under 45 degrees leaves the coronoid overlapped by the radius.
- 2 Rotation past 45 degrees foreshortens the coronoid.
- 3 Failure to keep the humerus on the same plane closes the joint.
- 4 Rotating only the wrist instead of the whole forearm gives a partial oblique.
Clinical indications
- Suspected coronoid process fracture.
- Evaluation of the medial elbow joint.
- Post-trauma assessment of the trochlea.
- Follow-up of coronoid fixation.
Aligned to the 2025 ARRT Content Specifications.