RADIOGRAPHIC ANATOMY, PATHOLOGY & POSITIONING REVIEWER

SECTION 1: RADIOGRAPHIC ANATOMY & PATHOLOGY

1. Bones & Important Landmarks

Foot (26 bones total): Divided into 14 Phalanges (Digits 1–5), 5 Metatarsals, and 7 Tarsals[span_0](start_span)[span_0](end_span)[span_1](start_span)[span_1](end_span).
- Tarsal Mnemonic: Come To Colorado Next 3 Christmases → Calcaneus, Talus, Cuboid, Navicular, 1st, 2nd, 3rd Cuneiforms[span_2](start_span)[span_2](end_span).
- Calcaneus (Os Calcis): Largest/strongest tarsal bone[span_3](start_span)[span_3](end_span). Features the tuberosity (attachment for Achilles tendon), sustentaculum tali (medial support for talus), and calcaneal sulcus (forms part of the sinus tarsi)[span_4](start_span)[span_4](end_span).
- Talus (Astragalus): 2nd largest tarsal; transmits body weight from the leg to the foot[span_5](start_span)[span_5](end_span). Articulates with 4 bones: tibia, fibula, calcaneus, and navicular[span_6](start_span)[span_6](end_span).
- Sesamoid Bones: Embedded in tendons near joints; largest is the patella[span_7](start_span)[span_7](end_span). Two prominent sesamoids (tibial and fibular) are located on the plantar surface of the 1st MTP joint[span_8](start_span)[span_8](end_span).
Leg:
- Tibia (Shinbone): Weight-bearing, medial bone[span_9](start_span)[span_9](end_span)[span_10](start_span)[span_10](end_span). Key landmarks include the medial/lateral condyles, tibial plateau (slopes posteriorly 10°–20°), intercondylar eminence, tibial tuberosity, anterior crest, and medial malleolus[span_11](start_span)[span_11](end_span)[span_12](start_span)[span_12](end_span).
- Fibula: Lateral and slightly posterior bone[span_13](start_span)[span_13](end_span)[span_14](start_span)[span_14](end_span). Key landmarks include the apex/head, neck, body, and lateral malleolus (extends ~1 cm more distal and ~1 cm more posterior than the medial malleolus)[span_15](start_span)[span_15](end_span)[span_16](start_span)[span_16](end_span).

2. Ankle Joint & Mortise

True Ankle Joint: Hinge-type synovial joint formed by the tibia, fibula, and talus[span_17](start_span)[span_17](end_span)[span_18](start_span)[span_18](end_span).
Ankle Mortise: Deep 3-sided socket formed by the inferior tibia and malleoli into which the talus fits[span_19](start_span)[span_19](end_span).
Intermalleolar Line: Forms a 15°–20° angle with the coronal plane[span_20](start_span)[span_20](end_span). A 15°–20° medial rotation (Mortise Projection) is required to open all 3 sides of the mortise joint space[span_21](start_span)[span_21](end_span)[span_22](start_span)[span_22](end_span).

3. Pathology Quick-Reference

Bone Cysts: Benign fluid-filled lesions near knee joint in children; lucent areas with thin cortex[span_23](start_span)[span_23](end_span).
Chondromalacia Patellae: Softening/wearing of cartilage under patella ("runner's knee")[span_24](start_span)[span_24](end_span).
Ewing's Sarcoma: Primary malignant bone tumor in children/young adults; "onion peel" look on radiographs[span_25](start_span)[span_25](end_span).
Exostosis (Osteochondroma): Benign bone outgrowth at a joint[span_26](start_span)[span_26](end_span).
Gout: Uric acid deposits in joints; commonly starts at the 1st MTP joint[span_27](start_span)[span_27](end_span).
Lisfranc Injury: Injury/sprain to Lisfranc ligament between medial cuneiform and 1st/2nd metatarsal bases; best seen on weight-bearing AP/lateral foot projections[span_28](start_span)[span_28](end_span).
Osgood-Schlatter Disease: Inflammation/separation of the tibial tuberosity at the patellar tendon attachment (common in active boys aged 10–15)[span_29](start_span)[span_29](end_span)[span_30](start_span)[span_30](end_span).
Paget's Disease (Osteitis Deformans): Dense yet soft bone overproduction resulting in a "cotton wool" appearance[span_31](start_span)[span_31](end_span).
Reiter's Syndrome: Asymmetrical arthritis/erosion at the Achilles tendon insertion on the calcaneus[span_32](start_span)[span_32](end_span).

SECTION 2: RADIOGRAPHIC POSITIONING & PROCEDURES

Projection / Method	Image Receptor (IR)	Patient & Part Position	Central Ray (CR) & Angle	Key Demonstration
Subtalar Joint (AP Lateral Rotation)	8x10 in (18x24 cm)[span_33](start_span)[span_33](end_span)	Affected side lateral; heel elevated 1.5 in (3.8 cm); foot angled 25° forward[span_34](start_span)[span_34](end_span)	Double angle: 5° anterior & 23° caudal; centered 1–1.5 in distal to ankle joint[span_35](start_span)[span_35](end_span)	Open subtalar joint, sinus tarsi, lateral malleolus in profile[span_36](start_span)[span_36](end_span)
Subtalar Joint (AP Medial Rotation)	8x10 in (18x24 cm)[span_37](start_span)[span_37](end_span)	Supine; IR under leg/heel; lower edge 1 in distal to plantar surface[span_38](start_span)[span_38](end_span)	4 separate exposures: 40°, 30°, 20°, 10° cephalad; 2–3 cm caudoanterior to lateral malleolus[span_39](start_span)[span_39](end_span)	40° = anterior facet; 20°–30° = middle facet; 10° = posterior facet[span_40](start_span)[span_40](end_span)
Subtalar Joint (Lateromedial Oblique - Isherwood)	8x10 in (18x24 cm)[span_41](start_span)[span_41](end_span)	Semi-supine/seated; ankle in right-angle flexion; leg/foot leaned medially onto foam wedge[span_42](start_span)[span_42](end_span)	Perpendicular to a point 1 inch distal and 1 inch anterior to lateral malleolus[span_43](start_span)[span_43](end_span)	Anterior subtalar articular surface, middle subtalar articulation, sinus tarsi[span_44](start_span)[span_44](end_span)
Ankle (AP Projection)	8x10 in (18x24 cm)[span_45](start_span)[span_45](end_span)	Supine; ankle/foot in anatomical position (vertical/flexed)[span_46](start_span)[span_46](end_span)	Perpendicular to ankle joint, midway between malleoli[span_47](start_span)[span_47](end_span)	Tibiotalar joint space, medial talomalleolar space open (normal overlap of distal tib/fib)[span_48](start_span)[span_48](end_span)
Ankle (45° Medial Oblique)	8x10 in (18x24 cm)[span_49](start_span)[span_49](end_span)	Supine; dorsiflex foot; rotate entire leg and foot medially 45°[span_50](start_span)[span_50](end_span)	Perpendicular to ankle joint, midway between malleoli[span_51](start_span)[span_51](end_span)	Distal tibia, fibula, talus, and distal tibiofibular articulation[span_52](start_span)[span_52](end_span)
Ankle Mortise (15°–20° Medial Oblique)	8x10 in (18x24 cm)[span_53](start_span)[span_53](end_span)	Supine; internally rotate entire leg and foot 15°–20° until intermalleolar plane is parallel to IR[span_54](start_span)[span_54](end_span)	Perpendicular to ankle joint, midway between malleoli[span_55](start_span)[span_55](end_span)	Entire 3-sided ankle mortise joint space open without superimposition[span_56](start_span)[span_56](end_span)
Ankle (45° Lateral Oblique)	8x10 in (18x24 cm)[span_57](start_span)[span_57](end_span)	Seated/supine; laterally rotate leg and foot 45° outward[span_58](start_span)[span_58](end_span)	Perpendicular to ankle joint, midway between malleoli[span_59](start_span)[span_59](end_span)	Subtalar joint and calcaneal sulcus[span_60](start_span)[span_60](end_span)
Ankle (Mediolateral Lateral)	8x10 in (18x24 cm)[span_61](start_span)[span_61](end_span)	Supine; turned toward affected side until leg is lateral; patella perpendicular to table[span_62](start_span)[span_62](end_span)	Perpendicular through ankle joint (1/2 inch / 1.3 cm superior to lateral malleolus)[span_63](start_span)[span_63](end_span)	True lateral ankle; tibiotalar joint; fibula superimposed over posterior half of tibia[span_64](start_span)[span_64](end_span)
Leg / Tib-Fib (AP Projection)	18x43 cm / 35x43 cm[span_65](start_span)[span_65](end_span)	Supine; femoral condyles parallel to IR; foot dorsiflexed vertical[span_66](start_span)[span_66](end_span)	Perpendicular to midpoint of leg[span_67](start_span)[span_67](end_span)	Entire tibia and fibula including both knee and ankle joints[span_68](start_span)[span_68](end_span)
Leg / Tib-Fib (Mediolateral Lateral)	18x43 cm / 35x43 cm[span_69](start_span)[span_69](end_span)	Turned toward affected side; patella perpendicular to IR[span_70](start_span)[span_70](end_span)	Perpendicular to midpoint of leg[span_71](start_span)[span_71](end_span)	Lateral tibia/fibula; fibula overlapping posterior half of tibia; both joints shown[span_72](start_span)[span_72](end_span)
Leg (45° Medial Oblique)	18x43 cm / 35x43 cm[span_73](start_span)[span_73](end_span)	Supine; rotate entire leg medially 45°[span_74](start_span)[span_74](end_span)	Perpendicular to midpoint of IR[span_75](start_span)[span_75](end_span)	Maximum interosseous space; proximal/distal tibiofibular articulations open[span_76](start_span)[span_76](end_span)
Leg (45° Lateral Oblique)	18x43 cm / 35x43 cm[span_77](start_span)[span_77](end_span)	Supine; rotate entire leg laterally 45°[span_78](start_span)[span_78](end_span)	Perpendicular to midpoint of IR[span_79](start_span)[span_79](end_span)	Fibula superimposed over lateral portion of tibia[span_80](start_span)[span_80](end_span)

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