MRI of Sports Injuries of the Ankle

Imaging Technique

Magnetic resonance imaging techniques for the ankle vary between institutions. We employ a sagittal inversion recovery sequence, which provides homogeneous fat suppression over the curved ankle joint. Additionally, we use an intermediate echo-time, fast-spin-echo proton density technique for cartilage-sensitive imaging in three planes [3].

Articular Cartilage

Osteochondral lesions of the talar dome are usually posttraumatic in origin [4], and can be a source of continued pain, recurrent synovitis, or intra-articular bodies [5]. Modified versions of the grading system described by Clanton and DeLee [6] have been used to describe the appearance of osteochondral talar dome lesions at MR arthrography [7]. More recently, a 5-point grading system has been used with noninvasive, high-resolution MRI to evaluate the articular cartilage of the talar dome [3].

Bones

Common fractures occurring after ankle sprain include avulsion fractures, lateral talar dome fractures, anterior calcaneal process fractures, or fractures at the base of the fifth metatarsal [1]. Many of these may be radiographically occult or subtle [1], and MRI can be useful in making the correct diagnosis.

Some authors have suggested that as many as 50% of all sports injuries are secondary to overuse [11]. Stress fractures are overuse injuries that occur in runners most commonly in the tibia

Lateral Ligaments

The interosseous tibiofibular ligament and anterior and posterior inferior tibiofibular ligaments comprise the distal syndesmosis [18]. On axial MR images, the medial margin of the distal fibula can be used as an anatomic reference. When the medial margin of the distal fibula appears flat, the ligaments in view are the anterior and posterior tibiofibular ligaments (Fig. 6). The tibiofibular ligaments demonstrate an oblique course and may be seen on multiple sequential axial images. The inferior

Anterolateral Impingement

Occasionally patients may develop symptoms of anterolateral impingement after one or more ankle inversion injuries [30], [31]. Chronic ankle pain, particularly with dorsiflexion, is the predominant symptom [31], [32]. Thickening of the anterior talofibular ligament, scar formation, and synovial hypertrophy in the anterolateral gutter are seen at imaging (Fig. 13) [33], [34]. Treatment is typically physical therapy with nonsteroidal anti-inflammatory medications [31]. In those patients whose

Medial Ligaments

The medial collateral ligament, or deltoid ligament, demonstrates some variability in composition [35], [36]. Principal fibers of the superficial deltoid include tibiospring, tibionavicular, tibiocalcaneal, and superficial posterior tibiotalar ligaments [35], [36], [37]. In one anatomic study, only the tibiospring and tibionavicular ligaments were present in all ankles [35]. The deep component of the deltoid includes the anterior tibiotalar and deep posterior tibiotalar ligaments [35], [36].

Posteromedial Impingement

Occasionally after a severe ankle sprain, a thick, confluent scar persists between the medial wall of the talus and the posterior margin of the medial malleolus, causing persistent pain and localized tenderness, particularly with plantar flexion and inversion [43]. Development of this symptomatic local scarring has been referred to as posteromedial impingement, and is thought to result from the deep posterior deltoid ligament being crushed between the talus and the medial malleolus at ankle

Spring and Bifurcate Ligaments

The spring ligament is composed of the superomedial calcaneonavicular ligament and the inferior calcaneonavicular ligament, and functions as a “sling” for the head of the talus (Fig. 16) [37]. Some authors describe a third portion of the spring ligament, with fibers extending from the notch between the calcaneal facets to the navicular tuberosity [44]. The deltoid ligament and posterior tibial tendon have direct attachments to the spring ligament [35], [36], [37]. The superomedial

Peroneal Tendons

The peroneus longus originates from the proximal lateral fibula and inserts on the plantar aspect of the medial cuneiform and the base of the first metatarsal. The peroneus brevis originates from the distal lateral fibula and inserts on the base of the fifth metatarsal. On axial images, the peroneus longus tendon is located posterolateral to the peroneus brevis tendon (Fig. 19). Both are innervated by the superficial peroneal nerve and act to evert the foot. The peroneus longus also inhibits

Flexor Tendons

The flexor tendons that will be discussed in this setting are the posterior tibial tendon (PTT), the flexor digitorum longus tendon (FDL), and the flexor hallucis longus tendon (FHL) (Fig. 27). The PTT originates from the posterior aspect of the interosseous tibiofibular ligament, the tibia, and the fibula, and inserts onto the navicular tuberosity, each of the cuneiforms, and the second through fourth metatarsals. Additional sites of PTT insertion have been found on the spring ligament, the

Tarsal Tunnel Syndrome

Located between the FDL and FHL tendons at the posteromedial aspect of the ankle is the neurovascular bundle consisting of posterior tibial artery and vein, and tibial nerve (Fig. 32). Symptoms of pain or numbness in the distribution of the medial or lateral plantar nerves may be caused by compression of the tibial nerve or plantar nerves, and have been referred to as tarsal tunnel syndrome [73]. There are multiple possible etiologies for tarsal tunnel syndrome, including fracture [74], flexor

Posterior Impingement

Posterior impingement is a clinical disorder manifested by pain at the posterior aspect of the ankle in plantarflexion [79]. This may be a result of acute injury or chronic repetitive stress, and is common in ballet dancers [79]. An os trigonum is present in about two of three cases (Fig. 36) [80]. Common MRI findings in posterior ankle impingement include increased T2 signal intensity posterior to the subtalar joint from synovitis, tenosynovitis of the FHL tendon sheath, and thickening of the

Extensor Tendons

The anterior tibial tendon (ATT) originates from the lateral tibia and the anterior aspect of the interosseous tibiofibular ligament, and inserts onto the medial cuneiform and base of the first metatarsal. The ATT (Fig. 37) acts to dorsiflex and invert the foot. The extensor hallucis longus tendon originates from the medial fibula and interosseous ligament, and inserts onto the base of the great toe distal phalanx, acting to dorsiflex and extend the great toe. The extensor digitorum longus

Sinus Tarsi

The sinus tarsi is a cone-shaped area bounded by the talus superiorly and the calcaneus inferiorly, located at the anterolateral aspect of the subtalar joint. Within the sinus tarsi are the interosseous talocalcaneal ligament (Fig. 39); the cervical ligament (Fig. 40); nerve branches from the deep peroneal nerve [86]; arterial branches arising from the anterior lateral malleolar artery and the lateral tarsal artery [87]; a venous plexus; and the medial, intermediate, and lateral roots of the

Anterior Impingement

Osteophytes at the anterior margin of the distal tibia (Fig. 44), and at the dorsum of the talus have been implicated in symptoms of anterior impingement [94]. The soft tissues at the anterior aspect of the ankle may be compressed between the tibia and talus in dorsiflexion, causing pain [95]. MRI demonstrates the osteophyte and often-associated osseous and soft-tissue edema [96]. Surgical excision of bone spurs and debridement of impinging soft tissues is effective in relieving pain and

Lisfranc Ligament

The Lisfranc ligament extends from the medial cuneiform to the medial base of the second metatarsal, and is biomechanically the strongest and stiffest stabilizing ligament of the medial tarsometatarsal joint [98], [99]. The Lisfranc ligament is composed of dorsal, plantar, and interosseous components (Fig. 45) [100], [101]. Injury to the Lisfranc ligament occurs after midfoot trauma, and is common in athletes [98]. When radiographs show diastasis at the second tarsometatarsal joint, MRI is

Achilles Tendon

The Achilles tendon (Fig. 47) represents the conjoined tendon of the gastrocnemius and soleus muscles, and may have a small contribution from the plantaris [103]. Located in the superficial, posterior compartment of the calf, the Achilles tendon is subjected to the highest loads of any tendon in the body [103]. Plantarflexion during running or jumping may subject the tendon to loads up to 10 times body weight [103]. Chronic degeneration of the Achilles tendon is an overuse syndrome thought to

Plantar Fascia

The plantar fascia is a fibrous aponeurosis attaching to the plantar anterior aspect of the calcaneus, coursing adjacent to the plantar margin of the flexor digitorum brevis muscle, and sending digital slips to each toe. Interconnecting transverse fasciculi are present between the digital slips. The superficial transverse metatarsal ligaments and the flexor digitorum brevis tendons also have attachments to the plantar fascia. A smaller lateral band of the plantar fascia is present, extending

Summary

MRI provides accurate evaluation of the articular cartilage, bones, ligaments, tendons, nerves, and vessels of the ankle. A thorough understanding of the anatomy and imaging manifestations of ankle injury is necessary for adequate evaluation. MRI is useful in treatment planning by evaluating the extent of injury and the presence of associated injuries.