Oblique Hand
The PA view tells us a lot, but the Oblique Hand is where we find the hidden details. By rotating the hand 45 degrees, we “unlock” the metacarpal heads and phalanges, moving them out of superimposition to reveal fractures and joint misalignments that are invisible on a flat PA image. It’s all about creating that perfect “step” in the anatomy.
The Goal
To demonstrate the phalanges, metacarpals, and carpal bones in a 45° lateral rotation, ensuring the metacarpal heads are separated and the joints are clearly visualized.
Patient Positioning
- The Setup: Seat the patient comfortably at the end of the table. Like the PA view, ensure the shoulder, elbow, and wrist are on the same plane to avoid anatomy distortion.
- The Rotation: From the PA position, rotate the hand laterally (thumb side up) exactly 45 degrees.
- The “OK” Sign: For a “fan” oblique, have the patient touch their thumb and index finger together lightly while the other fingers are stepped out.
- Pro-Tip: Use a 45° foam wedge if the patient is shaky. It is much better to use a sponge for stability than to risk a “fuzzy” image from motion.
Technical Factors
- Central Ray (CR): Perpendicular to the third MCP joint.
- SID: 40″.
- Collimation: Include the entire hand, from the distal fingertips to the distal radius and ulna.
Image Evaluation Criteria (The “Richie” Checklist)
A high-quality Oblique Hand image must pass these checks:
- Proper Rotation: You should see a slight overlap of the second and third metacarpal shafts, but the metacarpal heads (knuckles) should be separated.
- Complete Anatomy: No “piecework” imaging! Ensure you have everything from the soft tissue of the fingertips to the wrist joint.
- Sharp Cortical Margins: You must see sharp trabecular detail. If the bone edges look soft, the patient moved.
- Marker Visibility: Your physical R/L marker must be clear and anatomically correct.
Why the Oblique Matters
We perform the oblique because it profiles the facet joints and metacarpal heads. In cases of trauma, a fracture might be non-displaced on a PA view but show significant displacement once you add that 45-degree shift. This is why a “complete exam” is a legal and ethical requirement—missing a view means potentially missing a diagnosis.
Richie’s Pro-Tips for the Oblique View
Privacy & Safety: Keep the door closed or curtains pulled. Patient privacy is our prime directive, even for a hand x-ray.
Avoid the “Over-Rotate”: It’s easy to let the hand slip into a 60-degree angle. Keep it at a true 45°. If the metacarpals are completely superimposed, you’ve gone too far toward a lateral.
Physical Markers Only: Digital markers are unacceptable for extremity work. Always place your physical marker on the IR before you take the shot to ensure legal and medical accuracy.
Communication: Instruct the patient to “hold perfectly still” just before you step behind the lead glass. A quick 10-second count helps them focus on staying motionless.