Lower Extremity Anatomy and Radiographic Positioning: Bones, Joints, and Projections

Phalanges

The bones of the toes, with each toe typically having three phalanges (proximal, middle, and distal) except for the big toe, which has two.

Metatarsals

The five long bones in the foot that connect the tarsal bones to the phalanges.

Tarsals

The seven bones that make up the ankle and the back part of the foot, including the talus, calcaneus, navicular, cuboid, and three cuneiform bones.

Interphalangeal joint (IP)

The joint between the phalanges of the toes.

Distal Interphalangeal joint (DIP)

The joint between the distal and middle phalanges of the toes.

Proximal Interphalangeal joint (PIP)

The joint between the proximal and middle phalanges of the toes.

Talocalcaneal joint

The joint between the talus and calcaneus bones in the ankle.

Talocrural joint

The joint formed between the tibia, fibula, and talus, allowing for ankle movement.

Instep bones

The bones of the foot that form the arch, primarily the metatarsals and tarsals.

Metatarsal parts

Each metatarsal consists of a proximal end, a middle shaft, and a distal end.

Subtalar joint facets

The subtalar joint has three articular surfaces: posterior, middle, and anterior facets.

Largest tarsal bone

The calcaneus, also known as the heel bone.

Second largest tarsal bone

The talus, which sits above the calcaneus.

Most posterior tarsal bone

The calcaneus.

Most proximal tarsal bone

The talus.

Ankle joint bones

The ankle joint is formed by the tibia, fibula, and talus.

Smaller lower leg bone

The fibula.

Laterally located lower leg bone

The fibula.

Distal portion of the fibula

The lateral malleolus.

Distal portion of the tibia

The medial malleolus.

Small round bones near MTP joint

Sesamoid bones.

Dorsum surface

The top surface of the foot.

Posterior surface

The back surface of the foot.

PA projection

Posteroanterior projection, where the X-ray beam enters from the back to the front.

Dorsoplantar projection

An X-ray projection taken from the dorsum to the plantar surface of the foot.

Tri-malleolar fracture

A fracture involving the medial malleolus, lateral malleolus, and posterior malleolus.

Basic projections for ankle in a cast

AP and lateral projections.

Medial malleolus

The bony prominence on the inner side of the ankle, formed by the distal end of the tibia.

Lateral malleolus

The bony prominence on the outer side of the ankle, formed by the distal end of the fibula.

Maisonneuve fracture

A fracture of the fibula at the level of the ankle, often associated with injury to the syndesmosis and the distal tibia.

Tibial spine

The bony protrusion located on the proximal end of the tibia, also known as the intercondylar eminence.

Osgood-Schlatter disease

A condition characterized by pain and swelling at the tibial tuberosity, commonly occurring in adolescents during growth spurts.

Proximal tibiofibular articulation

The joint formed between the proximal ends of the tibia and fibula, allowing for slight movement.

Diarthrodial joint

A type of joint that is freely movable, allowing a wide range of motion.

Amphiarthrodial joint

A type of joint that is slightly movable, providing stability and balance.

Greater trochanter

A large bony prominence located on the lateral side of the femur, near the proximal end.

Lesser trochanter

A smaller bony prominence located on the medial side of the femur, just below the neck.

Intercondylar fossa

The deep depression located between the condyles of the distal femur.

Patella

A small, flat, triangular bone located in front of the knee joint, classified as a sesamoid bone.

Knee joint positioning

To locate the knee joint for positioning, measure 1 inch inferior to the apex of the patella.

Popliteal fossa

The shallow depression located at the back of the knee joint.

Shock absorbers in the knee

Structures such as the menisci that help absorb impact and stabilize the knee joint.

Basic projections for Tib/Fib

AP, LAT, OBL (Lateral), OBL (Medial).

Basic projections for Knee

AP, LAT, OBL (Lateral), Sunrise (Tangential).

Basic projections for Patella

Tangential or Sunrise (Settegast) view.

Basic projections for Femur

AP, LAT, and Intercondylar fossa (PA Axial knee).

Routine knee projections

Should be taken before further positioning to avoid exacerbating injuries.

Internal oblique knee projection

Requires a medial rotation of 45 degrees.

Gonadal shielding

Used during radiography to protect reproductive organs from radiation exposure.

Lateral knee positioning

The knee should be rotated laterally and flexed approximately 20 to 30 degrees.