CASE 153
BY: Dr. Nizar Al-Nakshabandi MD, FRCPC
HISTORY: 27-year-old female with history of twisting her ankle.
What are your findings?
What is the differential diagnosis?
What are the causes?
FINDINGS:
Axial T2-weighted images at the level of the anterior talofibular ligament demonstrate an absent anterior talofibular ligament. Instead, only fluid is seen at the site of attachment of the anterior talofibular ligament as well as torn anterior inferior tibiofibular ligament.
DIFFERENTIAL DIAGNOSIS:
· Anterior talofibular ligament tear.
· Anterolateral impingement syndrome of the ankle.
DIAGNOSIS:
Complete tear of the anterior talofibular ligament associated with anterior inferior tibiofibular ligament tear.
PEARLS AND DISCUSSION:
Ankle Ligaments:
Lateral complex:
· Anterior talofibular ligament.
· Posterior talofibular ligament.
· Calcaneofibular ligament.
Medial complex (deltoid):
· Tibionavicular ligament.
· Tibiospring ligament.
· Tibiocalcaneal ligament.
· Anterior tibiotalar ligament.
· Posterior tibiotalar ligament.
Ankle syndesmosis:
· Anterior inferior tibiofibular ligament.
· Posterior inferior tibiofibular ligament.
· Inferior transverse ligament Distal interosseous ligament or membrane.
Spring ligament complex (calcaneonavicular ligament):
· Superomedial calcaneonavicular ligament.
· Medioplantar oblique calcaneonavicular ligament.
· Inferoplantar longitudinal calcaneonavicular ligament.
Lateral ligament complex is the most commonly injured group of ankle ligaments and is often associated with other ligamentous injuries in the ankle. The lateral complex compromising the anterior talofibular ligament, calcaneofibular ligament, and posterior talofibular ligament is adequately managed with routine axial MRI.
Grading
The severity of ligamentous injury can be classified into 3 grades:
· grade I: injury without macroscopic tears.
· grade II:
o partial tear.
o mild to moderate joint instability may be present.
· grade III:
o complete tear.
o inability to weight-bear.
o associated with significant joint instability.
Mechanism of injury is usually inversion with plantar flexion to the ankle.
Two thirds of injuries are isolated to the ATFL.
FURTHER READING:
1. Haraguchi N, Toga H, Shiba N et-al. Avulsion fracture of the lateral ankle ligament complex in severe inversion injury: incidence and clinical outcome. Am J Sports Med. 2007;35 (7): 1144-52. doi:10.1177/0363546507299531 - Pubmed citation
2. Kumai T, Takakura Y, Rufai A et-al. The functional anatomy of the human anterior talofibular ligament in relation to ankle sprains. J. Ana
3. Lee MH, Cha JG, Lee YK et-al. The bright rim sign on MRI for anterior talofibular ligament injury with arthroscopic correlation. AJR Am J Roentgenol. 2012;198 (4): 885-90.
