Digits 2-5 Lateral is a radiography positioning projection of the Upper Extremity. Seated, affected digit in true lateral with adjacent fingers flexed away. SID 40". The centering point is located PIP joint of the affected digit, in true lateral. The central ray is perpendicular to the PIP joint of the affected digit. Image-quality criteria include affected digit shown in true lateral with no rotation or overlap, all three phalanges and the distal metacarpal included. A sample technique is 63 kVp with DR 0.6 or CR 1.6 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Distal, middle, and proximal phalanges of digits 2-5.
- Distal portion of the adjoining metacarpal.
- IP and MCP joint spaces (Bontrager; Merrill's criterion lists the IP joints).
Patient preparation
- WARNING: with possible spinal injury or severe trauma, do not attempt to move the patient; do not rotate a severely injured part or remove splints (Bontrager). Merrill's: do not attempt true AP or lateral positioning of a severely injured limb; take two projections 90 degrees apart, moving it as little as possible, and move the IR and tube if the patient cannot reach the position.
- Verify patient identity using two identifiers.
- Remove rings, bracelets, and radiopaque items from the hand.
- Seat the patient at the end of the table.
- Flex the elbow about 90 degrees and flex the adjacent fingers away from the affected digit.
- Extend the affected digit and support it parallel to the IR.
Position & centering point
PIP joint of the affected digit, in true lateral.
Central ray
Perpendicular to the PIP joint of the affected digit.
Exposure / technique
- kVp
- 63
- mAs
- DR 0.6 / CR 1.6
- SID
- 40" (102 cm)
- Notes
- Tabletop technique. Bontrager: 2nd digit mediolateral (radial side down) if the patient can assume it, digits 3-5 lateromedial (thumb side up, ulnar side down). Merrill's rests the 2nd and 3rd digits radial side down and the 4th and 5th ulnar side down. Sample technique: DR 0.6 / CR 1.6 mAs at 63 kVp, 40 in SID, for a 1.5 cm part. Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Affected digit shown in true lateral with no rotation or overlap.
- All three phalanges and the distal metacarpal included.
- Joint spaces open and clearly visible.
- Soft tissue and bone trabeculae sharp, no motion blur.
- Collimation: 1 inch on all sides, 1 inch proximal to MCP joint.
Common errors
- 1 Finger not in true lateral: the anterior surface of the phalangeal shafts should look concave.
- 2 Affected digit flexed or overlapped by adjacent fingers obscures joint spaces.
- 3 CR not at the PIP joint of the affected digit.
- 4 2nd digit not mediolateral when the patient can assume it: less OID improves definition.
Clinical indications
- Fractures and dislocations of the phalanges, distal metacarpal and associated joints (routine with the PA and oblique).
- Pathologic processes such as osteoporosis and osteoarthritis.