The inferior tibiofibular joint is classified as what type of joint, and which ligament is most critical for ankle mortise stability?

• A Synovial plane joint; anterior talofibular ligament
• B Cartilaginous (synchondrosis) joint; deltoid ligament
• C Synovial pivot joint; calcaneofibular ligament
• D Fibrous (syndesmosis) joint; anterior inferior tibiofibular ligament (AITFL) ✓

Explanation

The inferior (distal) tibiofibular joint is a fibrous syndesmosis — united by the interosseous membrane inferiorly, the anterior inferior tibiofibular ligament (AITFL), the posterior inferior tibiofibular ligament (PITFL), and the interosseous ligament. The AITFL is the most commonly injured of these ligaments in a 'high ankle sprain' (syndesmotic injury). The syndesmosis prevents diastasis of the ankle mortise, which would destabilize the talus. The deltoid ligament (medial) and ATFL (lateral) stabilize the ankle but are not part of the tibiofibular syndesmosis.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.