A medial ankle ligament injury is a serious and uncommon injury. It involves an injury to the ligament on the inside of the ankle.

Ligaments are a specific type of tissue in the body that connects bone to bone. A joint is when at least one bone articulates with another allowing movement to occur. Ligaments provide stability to the joints. The medial ankle ligament is also called the deltoid ligament.

The deltoid ligament is the primary ligamentous stabiliser of the ankle joint. It is composed of a superficial and deep part. The superficial deltoid ligament resists eversion of the hindfoot while the deep deltoid component resists external rotation and lateral displacement of the talus (one of the bones forming the ankle joint).

Please read more about the anatomy of the foot and ankle here.

Medial aspect of foot and ankle illustrating the site of the deltoid ligament

A medial ankle ligament injury (ankle sprain) occurs when the foot and ankle are stressed beyond their normal range of motion and the ligament fibres are stretched or torn. The deltoid is a very large ligament and to injure it requires a high energy force. For that reason it is not commonly injured, unlike the lateral ankle ligaments.

The mechanism of injury is typically an eversion of the ankle (turning/rolling out) with or without an element of twisting.

Deltoid ligament injuries typically occur in association with another injury such as an ankle fracture , high ankle sprain (syndesmotic injury) and spring ligament injury, but occasionally can occur in isolation.

A medial ligament ankle sprain typically presents with pain and swelling of the whole ankle, but worse on the inner (medial) aspect. Bruising may also be present depending on the severity of injury.

Patients often describe difficulty weight bearing immediately after the injury and often have a limp.

 Symptoms following an ankle sprain:

• Popping sensation at the time of the injury
• Pain – exacerbated by weight bearing
• Swelling
• Bruising
• Limp

On clinical examination your foot and ankle surgeon will look for signs of bruising and swelling. Your surgeon will also grade the severity of the injury.

In addition other conditions that can be often associated with or confused for an ankle sprain will be looked for such as:

• Achilles tendon rupture
• Ankle fracture
• Base of 5th metatarsal fracture
• High ankle sprain (syndesmotic injury)
• Osteochondral lesion

With the ankle in neutral the eversion test assesses the superficial deltoid ligament. The external rotation stress test evaluates the deep deltoid ligament and the syndesmosis.

Plain radiograph (x-ray)

Radiographs are always requested in the acute setting of a suspected medial ligament injury. The following maybe evident on a plain radiograph:

• Avulsion fracture distal tibia (medial malleolus)
• Increased medial clear space
• Lateral talar shift
• Syndesmotic widening

MRI

MRI provides excellent high definition static images. It is generally not necessary in the investigation and treatment of routine low grade sprains. In severe injuries it may be necessary to exclude any other pathology in the hindfoot. It is also useful in monitoring healing.

In the setting of a severe ankle sprain an MRI is particularly useful in assessing:

• Cartilage damage – osteochondral lesion
• Reactive bone changes
• Ligament damage – medial ligament involvement
• Syndesmotic injury
• Peroneal tendon pathology (tenosynovitis, tendon tears)
• Any other pathology

MRI of the ankle revealing a torn ATFL