Lateral Patella is a radiography positioning projection of the Lower Extremity. Supine rotated lateral, knee flexed 5-10 degrees. SID 40". The centering point is located center of patella in lateral position.. The central ray is perpendicular to the patella in true lateral.. Image-quality criteria include patella in true lateral profile, not rotated., patellar outline clear and distinct from femur.. Standard exposure ranges from 60 to 70 kVp, 4 to 7 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Patella in true lateral profile.
- Femoral condyles superimposed posteriorly.
- Patellofemoral joint space.
- Articular facets of patella.
- Anterior femoral cortex.
- Tibia anterior ridge.
Patient preparation
- Verify patient identity using two identifiers.
- Remove shoes and any radiopaque items from the leg.
- Position patient supine, rotate toward affected knee side.
- Flex knee 5 to 10 degrees and place on IR in true lateral.
- Ensure pelvis and hips are aligned.
Position & centering point
Center of patella in lateral position.
Central ray
Perpendicular to the patella in true lateral.
Exposure / technique
- kVp
- 60–70
- mAs
- 4–7
- SID
- 40" (102 cm)
- Notes
- Slight knee flexion (5-10 degrees) positions patella in true lateral.
Image-quality criteria
- Patella in true lateral profile, not rotated.
- Patellar outline clear and distinct from femur.
- Femoral condyles superimposed and visible behind patella.
- Patellofemoral joint space open.
- No superimposition of tibia over patella.
- Collimation 1.5 inches anterior and posterior, 1 inch on sides.
Common errors / ARRT traps
- 1 Knee flexion beyond 10 degrees draws the patella into the patellofemoral joint.
- 2 Insufficient flexion rotates patella into oblique view.
- 3 Tibia overlaps patella if knee insufficiently flexed.
- 4 Off-centered CR clips patella anteriorly or posteriorly.
Clinical indications
- Patellar fracture evaluation in lateral plane.
- Assessment of patellar position and tracking.
- Patellofemoral arthritis and cartilage loss.
- Post-operative fixation alignment check.
Aligned to the 2025 ARRT Content Specifications.