Ankle Instability


Ankle Instability

  • Ankle sprains are among the most common injuries seen by orthopaedic surgeons.

  • A variety of pathologies can result from an ankle sprain mechanism. These individual pathologies should be actively sought, as the treatment is not the same for all of these different pathologies.

  • The lateral ankle ligaments, as well as the syndesmotic ligaments, can be injured. Medial ankle injuries are less common, although sometimes all of the ankle ligaments can be injured to some degree.

    • The proximal fibula should be palpated so that a Maisonneuve injury is not missed.

  • Fractures of the lateral process of the talus, anterior process of the calcaneus, or the base of the 5th metatarsal can occur. Even Lisfranc and other midfoot injuries can occur, and so all of these places should be palpated.

  • Many, if not most, patients will completely recover without the need for any invasive treatment.

  • If nonoperative treatment is unsuccessful, an MR may be warranted. The MR will typically show ligamentous injury; the chondral surfaces and the peroneal tendons should be closely assessed in these patients.

  • When needed, surgery is often successful, although all pathology must be sought and addressed.

Note the fibular origin of the calcaneofibular ligament (CFL) in this patient without ligamentous pathology. Just inferior to the CFL are the peroneal tendons, and just superior and medial is the posterior talofibular ligament.

A thicker anterior talofibular ligament (ATFL) is seen in this axial MR. Increased thickness can be related to a previous ankle sprain injury, whereas more overt instability can present with discontinuity in the ligament or its complete absence.

The CFL is once again visualized. The coronal MR allows for the best view of the CFL. This patient did not have ligamentous ankle pathology.

Another view of a normal ATFL is shown. This ligament is completely normal with no thickening or other abnormality.


Ankle Sprains and Ankle Instability

  • Ankle sprains are exceedingly common injuries. Virtually every person has sprained his or her ankle at some point. Many of these acute injuries will improve without any specific treatment or without a trip to the doctor. Ankle instability is essentially by its very definition a chronic condition, whereby the static and dynamic stabilizers no longer function to provide adequate stability for the ankle &/or subtalar joint.


  • The ligaments about the ankle are generally broken down into component groups that act together to provide certain components of stability about the ankle and hindfoot. The syndesmotic, or tibiofibular, ligaments provide stability to the syndesmosis, while the lateral ligament complex includes the anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), and lateral subtalar ligaments. The medial side of the ankle is stabilized by the deltoid ligaments in all its component parts.

Syndesmotic Ligaments

  • The syndesmosis, or distal tibiofibular joint, is formed by the articulation of the incisura fibularis tibiae and the corresponding distal medial fibula. It is important to remember that the tibia and fibula come together to make a formal joint in this area.

  • The ligaments stabilizing the tibiofibular syndesmosis include the anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament, and interosseous ligament, in addition to the interosseous membrane and the transverse tibiofibular ligament.

  • The primary motion of the fibula relative to the tibia is primarily rotation in the axial plane, although there is some medial translation with plantarflexion.

Lateral Ankle Ligament Complex

  • This complex is made of the ATFL, CFL, and posterior talofibular ligament (PTFL).

  • The ATFL and CFL are commonly injured, while the PTFL is rarely injured. The ATFL is a condensation of the lateral ankle joint capsule.

  • The ATFL limits anterior translation of the talus, while the CFL limits inversion at both the ankle and subtalar joints, as it also crosses the subtalar joint.

Subtalar Ligament Complex

  • The subtalar joint allows for inversion and eversion of the calcaneus relative to the talus.

  • The lateral subtalar ligaments limit anterior and medial translation as well as inversion at the subtalar joint.

  • There are 3 layers of lateral ligaments: Superficial (calcaneofibular and lateral talocalcaneal ligaments, lateral root of the inferior extensor retinaculum), intermediate (cervical ligament, intermediate root of the inferior extensor retinaculum), and deep (interosseous talocalcaneal ligament and the medial root of the inferior extensor retinaculum).

Deltoid Ligament

  • Deltoid ligament is a large ligament with a deep and superficial component; it is confluent with other medial soft tissue structures and prevents eversion as well as anterior and posterior translation of the talus.

Acute Lateral Ankle Ligament Injuries


  • Patients will typically describe an inversion ankle injury, although it is often difficult for the patient to remember the specifics of the injury.

  • Patients will be variably limited in terms of their ability to ambulate, although some patients may be able to get around well.

Physical Examination

  • Patients typically present with a swollen ankle; the swelling can be somewhat diffuse, extending to areas that may or may not be actually injured.

  • Bruising tends to occur in the most dependent areas and can often often accumulate about the heel or even down the foot in between the toes.

  • Palpation can be very helpful in terms of guiding the examiner as to what exactly is injured. Many structures can be injured with an inversion injury. The surgeon should steadfastly assess the following areas for tenderness to palpation: The proximal fibula (assess for Maisonneuve), distal fibula, 5th metatarsal (assess for Jones or other fracture), tarsometatarsal joints (assess for midfoot or Lisfranc injury), medial ankle (assess for deltoid injury), anterior syndesmosis, over the ATFL and CFL, peroneal tendons, anterior process of the calcaneus, and ankle joint line. An effort should also be made to palpate deep in the sinus tarsi to assess for a fracture of the lateral process of the talus, although palpation in this area is less specific and is often somewhat tender in those with an acute sprain.

  • Range of motion should be assessed, especially in the hindfoot. Some patients, primarily but not exclusively adolescents, may be predisposed to ankle injuries due to a stiff hindfoot, most commonly from a tarsal coalition.


  • Ankle radiographs are appropriate to assess for any fracture; foot radiographs may be warranted in those patients whose physical exam is concerning for foot injury.

  • In the acute setting, further imaging is seldom warranted unless there is concern for a specific injury that is not well visualized on plain radiography. An example would include a patient with pain concerning for a lateral process talus fracture. A CT scan would help to definitively assess whether a fracture was present, and, if so, its dimensions and extension.

  • An MR is rarely needed in the acute ankle sprain, as it will rarely change the initial management. Most often, MRs obtained in this setting do not at all impact decision-making and are entirely extraneous, ultimately making for a poor use of resources.


  • Management of the acute ankle sprain is initially geared toward addressing the acute pain and swelling that accompany these injuries.

  • A controlled ankle motion (CAM) boot can be very helpful for the patient in the initial few days to few weeks, as it simply protects the ankle and makes it easier for the patient to ambulate.

  • Once the acute injury is not so painful, typically in 1-2 weeks, physical therapy is initiated. Physical therapy principally works on peroneal strengthening and balance utilizing a balance board. The return to full eversion strength typically heralds functional recovery.

  • Physical therapy is remarkably successful in this setting with the overwhelming majority of patients getting completely better with no further need for treatment. If patients do not improve despite several months of physical therapy, then further and more aggressive treatment may be warranted.

  • The proportion of patients with acute injury that will develop chronic issues is difficult to define. It is almost certainly overestimated by surgeons. Many patients in the acute phase may never seek formal treatment and are therefore not counted in the denominator of those injured.

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Oct 29, 2019 | Posted by in ORTHOPEDIC | Comments Off on Ankle Instability
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