Lower Extremity Radiography: Knee and Patella Projections

Vocabulary flashcards covering radiographic positioning, anatomy, and special methods for the knee, patella, intercondylar fossa, and lower extremities.

Medial Oblique Knee Projection

An AP oblique radiograph where the patella rotates toward the medial tibia, opening the lateral joint space and separating the fibular head from the tibia.

Lateral Oblique Knee Projection

An AP oblique radiograph where the patella projects toward the lateral fibular side; excessive lateral rotation results in superimposition of the fibula across the center of the tibia.

Intercondylar Fossa

The deep depression, notch, or tunnel located on the posterior surface of the distal femur between the condyles, visualized on specialized tunnel views.

Holmblad Method

A PA axial tunnel view of the intercondylar fossa requiring the patient to flex the knee $70^\circ$ with the upper body leaning forward, using a perpendicular ($0^\circ$) central ray entering the popliteal fossa.

Camp Coventry Method

A PA axial tunnel view of the intercondylar fossa where the patient is prone with the knee flexed $40^\circ$ to $50^\circ$, and the central ray is angled $40^\circ$ to $50^\circ$ caudad to match the flexion angle, exiting the patellar apex.

Béclère Method

An AP axial tunnel projection of the intercondylar fossa performed supine with the knee flexed $40^\circ$ to $45^\circ$, an elevated image receptor to reduce OID, and a cephalic tube angle directed half an inch below the patellar apex.

PA Patella Projection

A radiograph taken with the patient prone and the heel rotated $5^\circ$ to $10^\circ$ laterally, providing superior spatial detail and reduced magnification compared to an AP projection due to minimized OID.

Lateral Patella Projection

A mediolateral view performed with the knee flexed only $5^\circ$ to $10^\circ$ (unless fracture is suspected) and the central ray directed to the patellofemoral joint space to display the patella in profile.

Intercondylar Sulcus

The anterior groove of the distal femur where the patella glides, into which the patella is drawn when the knee is excessively flexed.

Patellofemoral Joint Space

The joint space between the posterior aspect of the patella and the anterior femur; it narrows or closes if the knee is bent too far during lateral and tangential views.

Settegast Method

A tangential sunrise projection skimming across the patellofemoral joint space with a $15^\circ$ to $20^\circ$ cephalic tube angle, specifically utilized to rule out transverse fractures and assess vertical fractures of the patella.

Merchant Method

A bilateral tangential projection where the patient rests supine with knees flexed $40^\circ$ over the end of the table on a dedicated holder, using a $30^\circ$ caudad central ray angle.

Mortise Projection

An oblique view of the ankle obtained by rotating the entire lower extremity $15^\circ$ to $20^\circ$ medially, which opens all three borders of the ankle mortise joint space.

Talus

The specific tarsal bone that articulates with the distal tibia and fibula to form the ankle joint.

Calcaneus

The largest of the tarsal bones in the human foot.

Tuberosity of the Fifth Metatarsal

The prominent bony process located at the lateral proximal base of the fifth metatarsal, clearly visualized on a medial oblique foot radiograph.