ABFAS ABFAS Surgical Anatomy and Biomechanics 2 — Questions and Answers
Question 1: The sinus tarsi is located between which two bones?
- Tibia and talus
- Talus and calcaneus (Correct answer)
- Calcaneus and cuboid
- Navicular and cuboid
Correct answer: Talus and calcaneus
The sinus tarsi is the cone-shaped space located between the talus superiorly and calcaneus inferiorly, containing the interosseous talocalcaneal ligament.
Question 2: Which of the following describes the normal foot pronation-supination axis of the subtalar joint?
- Purely vertical axis
- Oblique axis passing medially, anteriorly, and superiorly (Correct answer)
- Horizontal transverse axis
- Purely sagittal axis
Correct answer: Oblique axis passing medially, anteriorly, and superiorly
The subtalar joint axis is oblique, passing medially, anteriorly, and superiorly at approximately 16° from vertical and 42° from horizontal.
Question 3: Hallux valgus deformity is primarily associated with which biomechanical finding?
- Forefoot supinatus
- Increased intermetatarsal angle between the first and second metatarsals (Correct answer)
- Cavus foot type
- Tibial varum
Correct answer: Increased intermetatarsal angle between the first and second metatarsals
Hallux valgus is radiographically characterized by an increased first-second intermetatarsal angle (normal ≤9°) along with an increased hallux abductus angle.
Question 4: Which blood supply is most critical to the talus and most commonly disrupted in talar neck fractures?
- Anterior tibial artery
- Peroneal artery
- Artery of the tarsal canal (branch of posterior tibial artery) (Correct answer)
- Dorsalis pedis artery
Correct answer: Artery of the tarsal canal (branch of posterior tibial artery)
The artery of the tarsal canal, a branch of the posterior tibial artery, is the primary blood supply to the talar body and is frequently disrupted in talar neck fractures, risking avascular necrosis.
Question 5: The Lisfranc ligament connects which two structures?
- First and second metatarsal bases
- Medial cuneiform to second metatarsal base (Correct answer)
- Navicular to first metatarsal
- Cuboid to fourth metatarsal
Correct answer: Medial cuneiform to second metatarsal base
The Lisfranc ligament runs from the medial cuneiform to the base of the second metatarsal and is the primary stabilizer of the Lisfranc (tarsometatarsal) joint complex.
Question 6: Which term describes the triplanar motion of the foot combining dorsiflexion, eversion, and abduction?
- Supination
- Inversion
- Pronation (Correct answer)
- Adduction
Correct answer: Pronation
Pronation is the triplanar motion combining dorsiflexion, eversion, and abduction, occurring primarily at the subtalar and midtarsal joints.
ABFAS ABFAS Surgical Anatomy and Biomechanics 2
The sinus tarsi is located between which two bones?