Medial Ankle Sprains

Medial Ankle Sprains is less common than lateral ankle sprain, it involves injury to the medial ankle ligament that is called the deltoid ligament.

Deltoid ligament sprains accounts for 3% to 15% of all ankle sprains. And the anterior fibers of the deltoid ligament tend to be most frequently involved in medial ankle sprains

The strength of the deltoid ligament and the mechanical advantage of the longer lateral malleolus limit eversion. Because of the small amount of eversion (i.e., 5°) normally associated with the subtalar joint, the primary mechanism Deltoid ligament sprains is external rotation of the talus in the ankle mortise.

See Also: Lateral Ankle Sprains

Related Anatomy

Collectively, the medial collateral ligaments form a triangular shaped ligamentous structure known as the deltoid ligament of the ankle . Wide variations have been noted in the anatomic description of the deltoid ligament of the ankle but is generally agreed that it consists of both superficial and deep fibers.

The superficial fibers consist of the following:

1. Tibionavicular fibers: These fibers extend from the medial malleolus to the tuberosity of the navicular and serve to resist lateral translation and external rotation of the talus.
2. Posterior talotibial fibers: These fibers travel in a posterolateral direction from the medial malleolus to the medial side of the talus and medial tuberosity of the talus. These fibers resist ankle dorsiflexion and lateral translation and external rotation of the talus.
3. Calcaneotibial fibers: These thin fibers extend from the medial malleolus to the sustentaculum tali. The fibers are oriented in such a way that they resist abduction of the talus, calcaneus, and navicular, when the foot and ankle are positioned in plantar flexion and eversion.

The deep fibers consist of the following:

Anterior talotibial fibers: The fibers of this strong ligament extend from the tip of the medial malleolus to the anterior aspect of the medial surface of the talus. These fibers are oriented in such a way that they resist abduction of the talus, when it is in plantar flexion and eversion. Such is the strength of these fibers that an injury to this ligament is often associated with an avulsion fracture.

Although the calcaneotibial ligament is very thin and supports only negligible forces before failing, the talotibial ligaments are very strong.

Rasmussen et al. found that the superficial fibers of the deltoid ligament of the ankle specifically limited talar abduction or negative talar tilt and that the deep layers of the deltoid ligament of the ankle ruptured with external rotation of the leg, without the superficial portion being involved.

See Also: Ankle Anatomy

Clinical Evaluation

Deltoid ligament ankle sprain are frequently associated with other ankle pathology including syndesmotic sprains and malleolar fractures.

Because of its close association with the spring ligament, the stability of the medial longitudinal arch requires evaluation when a sprain of the deltoid ligament is suspected.

Physical examination findings can identify trauma to the ankle medial ligaments. Pain is present along the medial joint line, especially the anterior portion, and swelling tends to be more localized than that associated with lateral ankle sprains.

If an eversion mechanism is described in Medial Ankle Sprains, the lateral malleolus should be carefully evaluated for the presence of a “knock-off” fracture. Eversion may also cause an avulsion of the medial malleolus.

A similar mechanism may cause bimalleolar fracture (Pott’s fracture) and carries with it the increased potential complication of a nonunion of the medial malleolus unless surgery is performed. Intra-articular trauma to the talus and tibia may also be present.

Radiology

Radiographs are used to rule out bony trauma and evaluate the width of the ankle mortise.

Stress radiographs are indicated if the anteroposterior radiographs are negative for mortise disruption (less than 4 mm distance between medial malleolus and talus, the medial clear space).

MRI may be ordered to ascertain soft tissue trauma.

Medial Ankle Sprain Treatment

As with lateral ankle sprain, the initial treatment of deltoid ligament sprains includes the RICE protocol:

1. Rest,
2. Ice,
3. Compression,
4. Elevation.

Early functional rehabilitation programs should begin with a focus on restoring range of motion, following by proprioception and neuromuscular training, and strength training.

References

1. Lynch SA. Assessment of the Injured Ankle in the Athlete. J Athl Train. 2002 Dec;37(4):406-412. PMID: 12937562; PMCID: PMC164372.
2. Stufkens SA, van den Bekerom MP, Knupp M, Hintermann B, van Dijk CN. The diagnosis and treatment of deltoid ligament lesions in supination-external rotation ankle fractures: a review. Strategies Trauma Limb Reconstr. 2012 Aug;7(2):73-85. doi: 10.1007/s11751-012-0140-9. Epub 2012 Jul 6. PMID: 22767333; PMCID: PMC3535131.
3. Melanson SW, Shuman VL. Acute Ankle Sprain. [Updated 2021 Jul 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459212/