Radiographic Procedures · ARRT 2025
Lower Extremity Positioning
Standard projections for the foot, ankle, knee, femur, and hip. Routine views, special projections (Holmblad, Camp-Coventry, Settegast), and common pathology for the ARRT.
Overview
Lower Extremity covers the foot, ankle, lower leg, knee, femur, and pelvis through the hip. As with the upper extremity, this is a high-yield procedures chapter, both because of frequency in the clinic and because the ARRT loves testing specific projection details. Anatomy and pathology are tested side-by-side with central-ray angulation and rotation.
The foot series: AP (axial, 10° posteriorly toward the heel), AP oblique (medial 30–40° rotation), and lateral. The ankle series: AP, AP mortise (15–20° internal rotation to open the mortise joint), and lateral. AP mortise is the only projection that demonstrates the entire ankle mortise (talocrural joint) free of overlap. The knee series: AP, lateral (5–7° cephalic angle to compensate for the slight downward slope of the tibial plateau), and AP oblique. For the intercondylar fossa, use Holmblad (PA with knee flexed 70°, beam perpendicular) or Camp-Coventry (PA with knee flexed 40–50°, beam angled 40–50° caudad). The Settegast (sunrise) demonstrates the patellofemoral joint with the knee flexed.
Hip and pelvis routines: AP pelvis (15–20° internal rotation of the legs to compensate for femoral anteversion, opens up the femoral neck), AP hip with 15–20° internal rotation, and a Danelius-Miller cross-table (axiolateral) lateral when the unaffected leg can be flexed clear of the field. Common pathology: Pott fracture (bimalleolar ankle), Jones fracture (5th metatarsal base), Lisfranc injury (tarsometatarsal), Osgood-Schlatter (tibial tuberosity in adolescents), femoral neck fractures, and slipped capital femoral epiphysis (SCFE).
What you’ll learn in this chapter
The 14 lessons in this chapter break down as follows. The full lesson content is unlocked when you start a free account.
Pelvic & Femoral Anatomy
- The Femur: Foundation of the Lower Limb
- The Pelvic Girdle
- Male vs Female Pelvis
- When the Blueprint Fails
Pelvis & Hip Projections
- Core Positioning Principles for the Lower Limb
- AP Pelvis & Hip Series
Knee, Ankle & Foot
- Knee: AP & Tunnel View
- Ankle Mortise
- Foot: Three Standard Projections
- Common Lower Extremity Pathologies
Knowledge Check
- Question 1 of 4 Quiz
- Question 2 of 4 Quiz
- Question 3 of 4 Quiz
- Question 4 of 4 Quiz
Key terms in this chapter
These are the 7 terms most likely to appear on the ARRT registry from this chapter. Use them as a flashcard pre-quiz.
- AP Mortise
- Ankle projection with 15–20° internal rotation. Opens the talocrural joint space free of overlap.
- Holmblad Method
- PA knee with 70° flexion and perpendicular central ray. Demonstrates the intercondylar fossa.
- Camp-Coventry Method
- PA knee with 40–50° flexion and 40–50° caudad central ray. Alternative for the intercondylar fossa.
- Settegast Method
- Sunrise/skyline projection of the patellofemoral joint with the knee flexed and beam tangential to the patella.
- Danelius-Miller Method
- Cross-table axiolateral hip projection. Used for trauma when the patient cannot rotate the affected leg.
- Jones Fracture
- Transverse fracture at the base of the 5th metatarsal. Distinct from a styloid avulsion fracture.
- Pott Fracture
- Bimalleolar ankle fracture from forced eversion. Both medial and lateral malleoli are involved.
Sample practice question: Extremity
One free sample from the 105-question Extremity bank. See the format, the rationale style, and the difficulty before you sign up.
A patient presents with wrist pain after falling on an outstretched hand. The PA, lateral, and oblique wrist projections appear normal but clinical suspicion for scaphoid fracture remains. What additional projection should be performed?
Show answer and rationale
A, Incorrect: The carpal tunnel projection demonstrates the carpal tunnel itself, not the scaphoid in particular.
B, Correct: Correct. The Stecher method (PA wrist with ulnar deviation, central ray angled 20° proximally toward the elbow) elongates the scaphoid and reveals fractures missed on routine PA. It is the standard supplementary view for suspected scaphoid fracture.
C, Incorrect: AP oblique medial rotation is for the elbow, not the wrist. Wrist obliques are routinely lateral rotation.
D, Incorrect: Radial deviation does not elongate the scaphoid. Ulnar deviation is required for the Stecher.
Hands-on
Practice the positioning
Open the Positioning Lab to drill body position, central ray, anatomy, and common errors for each projection in this chapter.
- Toes AP Foot flat on IR, CR perpendicular to mid-foot. SID 40".
- Toes Lateral Foot in true lateral on IR, CR perpendicular. SID 40".
- Toes AP Oblique Foot rotated medially 45 degrees, CR perpendicular. SID 40".
- Sesamoids Tangential, Lewis Method Patient prone, toe flexed back on IR. CR perpendicular and tangential. SID 40".
- Foot AP Axial Foot dorsiflexed on IR, CR angled 10° cephalad toward heel. SID 40".
- Foot Medial Oblique Foot rotated medially 30-45 degrees, CR perpendicular. SID 40".
- Calcaneus Axial (Plantodorsal) Foot dorsiflexed, CR angled 40° cephalad through plantar surface. SID 40".
- Calcaneus Lateral (Mediolateral) Patient lateral recumbent on affected side, CR perpendicular to calcaneus. SID 40".
- Ankle AP Foot vertical on IR, CR perpendicular to ankle joint. SID 40".
- Ankle Lateral (Mediolateral) Patient lateral recumbent on affected side, CR perpendicular to ankle. SID 40".
- Ankle Medial (Lateromedial) Patient lateral on non-affected side, medial ankle on IR. CR perpendicular. SID 40".
- AP Medial Oblique Ankle Supine, ankle internally rotated 45 degrees. SID 40".
- AP Medial Oblique Mortise Ankle Supine, leg internally rotated 15-20°. Talus between malleoli. SID 40".
- AP Weight-Bearing Ankle Upright standing on low platform, feet slightly apart. SID 40".
- AP Leg (Tibia & Fibula) Supine, leg extended on IR, foot true AP. SID 40".
- Lateral Leg (Tibia & Fibula) Supine, turn toward affected side, knee and ankle flexed 45 degrees. SID 40".
- AP Knee Supine, leg fully extended on IR. SID 40".
- Lateral Knee Supine rotated lateral, knee flexed 20-30 degrees. SID 40".
- AP Weight-Bearing Knees Upright standing, both feet flat, knees extended. SID 40".
- PA Axial Intercondylar Fossa Standing Holmblad Standing facing IR, knee flexed ~70 degrees, CR perpendicular to lower leg. SID 40".
- PA Axial Intercondylar Fossa Camp-Coventry Prone, knee flexed 40-50 degrees, CR 40-50 degrees caudad. SID 40".
- AP Axial Intercondylar Fossa Beclere Supine, knee flexed 60 degrees, CR 40 degrees cephalad. SID 40".
- PA Patella Prone, knee flexed 45 degrees with lateral rotation. SID 40".
- Lateral Patella Supine rotated lateral, knee flexed 5-10 degrees. SID 40".
- Tangential Patella Settegast Prone, knee flexed 45-90 degrees, CR perpendicular to patella underside. SID 40".
- AP Proximal Femur Supine, leg internally rotated 15-20 degrees. Hip joint included.
- AP Distal Femur Supine, leg extended in true AP. Knee joint included.
- Lateral Proximal Femur Lateral recumbent on affected side. Hip joint included.
- Lateral Distal Femur Lateral recumbent on affected side. Knee joint included.
- Hip AP Supine, legs extended and internally rotated 15-20 degrees. SID 40".
- Hip Lateral Supine, affected leg flexed 45 degrees at hip and knee. SID 40".
- Hip Axiolateral Supine, affected leg extended, opposite leg raised out of the field. Horizontal cross-table CR. SID 40".
- Pelvis AP Supine, legs extended and internally rotated 15-20 degrees. SID 40".
- Femoral Neck AP Oblique (Modified Cleaves) Supine, hips flexed 40-45 degrees, knees flexed 60 degrees, feet together. SID 40".
- Sacrum AP Axial Axial view of sacrum. CR 15° cephalad. SID 40".
- Sacrum Lateral True lateral sacrum. SID 40". CR perpendicular to IR.
- Coccyx AP Axial Axial view of coccyx. CR 10° caudad. SID 40".
- Coccyx Lateral True lateral coccyx. SID 40". CR perpendicular to IR.
- SI Joints AP Axial AP axial bilateral SI joints. CR 30-35° cephalad. SID 40".
- SI Joints AP Oblique (RPO) AP oblique SI joints, RPO. SID 40". CR perpendicular to IR.
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Frequently asked questions
What does the ARRT Radiography Radiographic Procedures category cover?
Lower Extremity covers the foot, ankle, lower leg, knee, femur, and pelvis through the hip. As with the upper extremity, this is a high-yield procedures chapter, both because of frequency in the clinic and because the ARRT loves testing specific projection details. Anatomy and pathology are tested side-by-side with central-ray angulation and rotation.
How many lessons are in the Lower Extremity Positioning chapter?
This chapter contains 14 lessons across 4 sections, plus a knowledge-check quiz at the end. The full lesson content is unlocked with a Premium subscription. The free tier includes the first chapter complete.
Is this chapter aligned with the ARRT 2025 Content Specifications?
Yes. Every chapter on this site maps directly to the ARRT Radiography Content Specifications effective 2025. This chapter falls under the Radiographic Procedures domain of the official ARRT exam blueprint.