PA Axial Intercondylar Fossa Camp-Coventry is a radiography positioning projection of the Lower Extremity. Prone, knee flexed 40-50 degrees, CR 40-50 degrees caudad to match. SID 40". The centering point is located midpopliteal crease with patient prone and knee flexed 40-50 degrees. The central ray is 40 to 50 degrees caudad to match the knee flexion, perpendicular to the lower leg. Image-quality criteria include intercondylar eminence clearly visualized in axial view, intercondylar fossa in profile and open, not superimposed by the patella. A sample technique is 70 kVp with DR 2.5 or CR 5 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Intercondylar eminence in axial projection.
- Intercondylar fossa and notch.
- Posteroinferior articular surfaces of the femoral condyles.
- Tibial plateau in axial relationship.
- Medial and lateral intercondylar tubercles.
Patient preparation
- Verify patient identity using two identifiers.
- Remove shoes and any radiopaque items from the leg.
- Position patient prone on table with leg extended initially.
- Flex affected knee 40 to 50 degrees, rest the foot on a support.
- Ensure pelvis is level and not rotated.
Position & centering point
Midpopliteal crease with patient prone and knee flexed 40-50 degrees.
Central ray
40 to 50 degrees caudad to match the knee flexion, perpendicular to the lower leg.
Exposure / technique
- kVp
- 70
- mAs
- DR 2.5 / CR 5
- SID
- 40" (102 cm)
- Notes
- CR angle matches knee flexion (40-50°) so beam is perpendicular to the lower leg. Bontrager prints a grid and digital 75 +/- 5 kV; the sample is Merrill's nongrid tabletop row. Sample technique: DR 2.5 / CR 5 mAs at 70 kVp, 40 in SID, for a 14 cm part. Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Intercondylar eminence clearly visualized in axial view.
- Intercondylar fossa in profile and open, not superimposed by the patella.
- No rotation: posterior femoral condyles symmetric, about half the fibular head behind the tibia.
- Tibial plateau included in axial projection.
- Medial and lateral intercondylar tubercles differentiated.
- Collimation: four sides to the knee joint area (Bontrager); 1 inch beyond the sides (Merrill's).
Common errors
- 1 Knee not flexed the 40 to 50 degrees the CR matches.
- 2 CR not perpendicular to the lower leg.
Clinical indications
- Bony or cartilaginous pathology, osteochondral defects, or joint space narrowing.
- Intercondylar fossa loose body detection.