Anatomy 

• Why is the 5th metatarsal base a critical landmark?
  It helps confirm correct centering and identifies common avulsion or Jones fractures.
• Why are weight-bearing views useful?
  They demonstrate alignment, joint spacing, and arch integrity under physiological load.
• Why does the longitudinal arch matter clinically?
  Its collapse (pes planus) alters gait mechanics and can cause chronic pain or deformity.
• What type of joints are the tarsometatarsal (TMT) joints?
  Diarthrodial, gliding type.
• What type of joints are the metatarsophalangeal (MTP) joints?
  Diarthrodial, condyloid type.
• What type of joints are the interphalangeal joints?
  Diarthrodial, hinge type.

Positioning

• Why is the CR angled 10° posterior for the AP foot?
  To open joint spaces of the midfoot and reduce foreshortening of metatarsals.
• Why is the foot rotated medially 30–40° for the oblique projection?
  This opens the intertarsal joints, especially between the cuboid and calcaneus, and demonstrates the sinus tarsi.
• Why is the lateral foot performed with the medial side down?
  It provides a more natural position, ensuring the foot’s longitudinal arch is better demonstrated.
• Why should the toes be kept parallel to the IR in AP and oblique foot projections?
  To prevent foreshortening of the phalanges and to open the joint spaces.
• Why is a weight-bearing AP foot sometimes performed?
  To evaluate arches, alignment, and joint spacing under normal load-bearing conditions.
• Why is the plantar surface kept flat on the IR for AP projections?
  To prevent rotation and ensure equal concavity of shafts of phalanges and metatarsals.

Technique & Image Evaluation

• How do you know an AP foot was not rotated?
  Equal concavity of metatarsal and phalangeal shafts on both sides.
• What indicates correct CR angulation on an AP axial foot?
  Open TMT joint spaces and visualization of metatarsal bases without excessive overlap.
• What error is indicated if the tarso-metatarsal joint spaces are not open on an AP foot?
  Insufficient CR angle was used or the plantar surface was not flat against the IR.
• How do you know the oblique foot was rotated the correct 30°–40°?
  The cuboid is demonstrated in profile, the 3rd–5th metatarsal bases are free of superimposition, and the sinus tarsi is well visualized.
• What error is indicated if the sinus tarsi is not visible on an oblique foot?
  The foot was under-rotated.
• What error is indicated if the bases of the 1st and 2nd metatarsals are superimposed on the oblique projection?
  The foot was over-rotated.
• What error is indicated if the 5th metatarsal tuberosity is not well demonstrated on an oblique foot?
  The foot was under-rotated.
• How do you confirm correct positioning on a lateral foot?
  The tibiotalar joint is open, the distal fibula is superimposed over the posterior half of the tibia, and the metatarsals are nearly superimposed.
• What error is indicated if the distal fibula is too far posterior on a lateral foot?
  The foot was rotated externally.
• What error is indicated if the distal fibula is too far anterior on a lateral foot?
  The foot was rotated internally.
• What error is indicated if the distal metatarsals are separated rather than superimposed on a lateral?
  The foot was not in a true lateral position.
• How can you confirm patient cooperation and exposure timing on foot projections?
  Sharp cortical bone and trabecular markings should be visible, with no evidence of motion blur.
• How do you know the arch is well demonstrated on a lateral weight-bearing foot?
  The longitudinal arch is visible with clear joint spacing, showing arch integrity.

Clinical Applications

• Why is the oblique foot important in trauma imaging?
  It demonstrates the 5th metatarsal base, a common site of avulsion fractures.
• Why are weight-bearing projections often ordered?
  They reveal deformities (flatfoot, hallux valgus), fractures, or misalignments not visible in non–weight-bearing studies.
• Why are non-weight-bearing projections still essential?
  They provide controlled positioning for fracture detection and routine evaluation.
• Why might bilateral weight-bearing feet be obtained?
  For comparison of arches and joint alignment between the affected and unaffected sides.