The tibionavicular ligament is the most superficial and anterior component of the superficial deltoid ligament complex, running from the anterior medial malleolus to the dorsal surface of the navicular and the plantar calcaneonavicular (spring) ligament. It forms the leading edge of the medial ankle stabilising complex and is the first component stressed in excessive eversion of the foot.
Resists eversion and abduction of the foot at the ankle and subtalar levels, limits talonavicular instability, and is the most superficial visual landmark of the medial ankle ligament complex during surgery.
The tibionavicular ligament is part of the superficial deltoid, which is the first layer injured in progressive stage II adult-acquired flatfoot deformity, preceding spring ligament failure. It is the ligament palpated in the medial ankle soft tissue triangle between the medial malleolus, the navicular, and the sustentaculum tali. In acute eversion ankle sprains, the deltoid is injured; the tibionavicular component produces tenderness directly over the medial ankle anterior to the malleolus.
Forced eversion and abduction sprains injure the superficial deltoid including the tibionavicular component, producing medial ankle pain and swelling with tenderness in the medial ankle triangle; isolated deltoid sprains are less common than lateral ankle sprains but associated with syndesmotic injury in bimalleolar fracture patterns.
