Deltoid ligament.

The superficial components include the tibiocalcaneal ligament, tibionavicular ligament, posterior superficial tibiotalar ligament, and tibiospring ligament; the deep layer components include the anterior tibiotalar ligament (ATTL) and the posterior deep tibiotalar ligament (PDTL)

 Anatomically, in general, the superficial components arise from the anterior colliculus of the medial malleolus, and the deep components arise from the intercollicular groove (malleolar groove) and the posterior colliculus of the medial malleolus (3). These ligaments are conveniently named according to their respective distal attachments to the various tarsal bones. The tibiospring portion is the only component without a distal bone attachment because it joins the superomedial oblique band of the spring ligament proper, also known as the plantar calcaneonavicular ligament (2,5). The superomedial oblique band is separated from the overlying tibialis posterior tendon by a gliding zone, composed of fibrocartilaginous tissue with a layer of synovial cells. The gliding zone typically measures 1–3 mm (Fig 2c). The superomedial oblique band typically measures 2–5 mm in thickness.

Normal deltoid ligament. (a) Coronal T1-weighted MR image shows a normal PDTL (arrow) with a striated appearance.

Normal deltoid ligament. (b) Coronal T1-weighted MR image shows a normal ATTL (thin arrow), tibiospring ligament (*), flexor retinaculum (curved arrow), tibialis posterior tendon (thick arrow), and superomedial oblique band (arrowhead). 

Normal deltoid ligament. (c) Axial T1-weighted MR image shows the normal ATTL (arrow) and PDTL (arrowhead).

Normal deltoid ligament. (a) Coronal intermediate-weighted fat-saturated MR image shows a normal ATTL with a minimal striated appearance caused by fat suppression (straight arrow), tibiocalcaneal ligament (curved arrow), and flexor retinaculum (arrowhead).

Normal deltoid ligament. (b) Coronal intermediate-weighted fat-saturated MR image shows a normal PDTL (arrow) with a striated appearance and the flexor retinaculum (arrowhead).

Normal deltoid ligament.  (c) Coronal intermediate-weighted fat-saturated MR image shows the tibiospring ligament (*), flexor retinaculum (curved arrow), tibialis posterior tendon (thick arrow), superomedial oblique band (arrowhead), and fibrocartilaginous gliding zone (thin arrow).

Ankle MR Imaging Protocols at 1.5 and 3 T

At MR imaging, axial and coronal images are most valuable in differentiating various components of the deltoid ligament (1,10). With the high-resolution imaging made possible with 1.5-T and 3-T MR imagers, it is easy to demonstrate the superficial and deep parts of the deltoid ligament. In a recent study by Mengiardi et al (10), the ATTL and tibionavicular ligament were identified in approximately 55% of asymptomatic subjects. The remaining deltoid ligament components, including the tibiospring ligament, were consistently identified in most cases. While taking into account that their study was performed on a 1.5-T imager, we are able to consistently identify all of the components of the deltoid ligament on sequential coronal and axial images at 3-T imaging except the tibionavicular and posterior superficial tibiotalar, which are less frequently well demonstrated. The width of these components varies from the thickest portion, the PDTL (6–11 mm), to the thinnest one, the tibiocalcaneal ligament (1–3 mm) (10). The deep portion of the deltoid ligament (consisting of the anterior and posterior tibiotalar ligaments) demonstrates a striated appearance on T1-weighted and intermediate-weighted images that is caused by interspersed fatty tissue (1,10). This appearance is less well seen on T2-weighted images, especially because of the widespread use of fat-saturated sequences (Figs 1 , 2 ). Also, the striated appearance is less apparent in older subjects, which may be partly attributable to previous subclinical injuries (10). The normal appearance for the remaining components is uniformly low signal intensity on T1-, intermediate-, and T2-weighted MR images.The injuries have also been classified clinically, depending on the craniocaudal extent of involvement of the deltoid ligament, as type I (proximal), type II (intermediate), or type III (distal) injuries of the ligament (12). Type I injuries are most frequent (71%), and type II are the least common (10%), with type III accounting for the rest (19%). Similar to injuries of other ligaments, deltoid ligament injuries are generically classified as grade I sprain (stretching/periligamentous edema), grade II sprain (partial tear), or grade III sprain (complete disruption). Grade I sprain is evident on T1- and intermediate-weighted images as loss of the striated appearance of the deep portion of the deltoid ligament (ATTL and PDTL), with consequent amorphous signal intensity.This abnormal signal intensity is related to hemorrhage and hyperplastic synovial reaction, with hemosiderin deposition in acute injuries and fibrosis/scarring in chronic injuries (Fig 3 ). In higher-grade injuries, abnormal hyperintensity is seen on fat-saturated long-TE MR images as fluid-filled gaps in or complete discontinuity of the ligament (2,4) (Figs 4 –7 ). In our experience, deep deltoid ligament injuries are more frequent than injuries of other components of the ligament. Secondary signs of a widened medial clear space (more than 3–4 mm) and lateral talar shift should also be sought, despite the lack of sensitivity of these signs at radiography (14) (Fig 8 ). With respect to the tibiospring ligament and the superomedial band of the spring ligament, degenerative thickening is more common than frank tears (Figs 6 , 9 ). Coronal and axial MR images nicely depict associated medial malleolar fractures, distal avulsion fractures, osteochondral injuries of the talus, lateral ligament and syndesmosis injuries, and spring ligament and tibialis posterior abnormalities (Fig 9 ).

Acute left ankle injury and medial pain in a 45-year-old man. (3a) Coronal intermediate-weighted MR image shows loss of fatty striations of the PDTL (arrow), consistent with a grade I sprain injury.

Acute left ankle injury and medial pain in a 45-year-old man.  (b) Coronal intermediate-weighted fat-saturated MR image shows a medial malleolar contusion and minimal hyperintensity of the PDTL (arrow). Note the grade I/II sprained tibiocalcaneal ligament (arrowhead). 

Acute left ankle injury and medial pain in a 45-year-old man.  (c) Axial intermediate-weighted MR image shows amorphous signal intensity of both the ATTL (arrowhead) and the PDTL (arrow), in keeping with a grade I sprain.

Images of a 55-year-old woman with a history of subacute ankle injury. (a) Coronal T2-weighted fat-saturated MR image shows a small osteochondral lesion of the lateral talar dome (arrow) and a grade I/II sprain of the PDTL (arrowhead).  

Images of a 55-year-old woman with a history of subacute ankle injury.  (b) Sagittal T2-weighted fat-saturated MR image shows abnormal high signal intensity in the PDTL (arrow).

Acute ankle injury. (a) Coronal T1-weighted MR image shows amorphous signal intensity in the ATTL (curved arrow) and subcutaneous edema, most prominent medially (straight arrow). 

Acute ankle injury.  (b) Coronal T2-weighted fat-saturated MR image again shows subcutaneous edema (straight arrow), a grade I sprain of the ATTL (curved arrow), and a grade II sprained hyperintense tibiospring ligament (arrowhead).

Images of a 37-year-old man with ankle pain. (a) Coronal T2-weighted fat-saturated MR image shows a hyperintense tibiospring ligament (arrow) and superomedial oblique band (arrowhead). 

Images of a 37-year-old man with ankle pain.  (b) Coronal T1-weighted MR image shows the hyperintense tibiospring ligament (arrow) and superomedial oblique band (arrowhead). 

Images of a 37-year-old man with ankle pain. (c) Axial T2-weighted fat-saturated MR image shows the hyperintense tibiospring ligament (arrow).

Acute left ankle injury with grade II deltoid ligament sprain. (a) Coronal T1-weighted MR image shows loss of normal striations in the deep deltoid ligament (arrow). 

Acute left ankle injury with grade II deltoid ligament sprain. (b) Coronal T2-weighted fat-saturated MR image helps confirm a grade II tear of the ATTL (short thin arrow), calcaneofibular ligament tear (thick straight arrow), anterior talofibular ligament tear (arrowhead), medial malleolar contusion (long thin arrow), and talar contusion (curved arrow). 

Acute left ankle injury with grade II deltoid ligament sprain.  (c) Axial T1-weighted MR image shows thickening and loss of striations of the deep deltoid ligament (arrow). 

Acute left ankle injury with grade II deltoid ligament sprain. (d) Axial T2-weighted fat-saturated MR image shows a grade II deep deltoid ligament tear (arrow) and anterior talofibular ligament tear (arrowhead).

Images of a 55-year-old man with chronic ankle pain. (a) Coronal intermediate-weighted MR image shows posterolateral talar subluxation and tilt, with tibiotalar spurs in the medial clear space (arrow). 

Images of a 55-year-old man with chronic ankle pain.  (b) Coronal intermediate-weighted fat-saturated MR image shows tibiotalar osteoarthritis with subchondral edema (circled area). Also note amorphous signal intensity of the ATTL (arrowhead). 

Images of a 55-year-old man with chronic ankle pain.(c) Coronal intermediate-weighted fat-saturated MR image obtained posterior to b shows thickened and remodeled tibiocalcaneal ligament (arrow) related to the chronic/old injury.

Images of a 45-year-old woman with medial ankle pain and findings of an old partial tear of the deltoid ligament and tibialis posterior dysfunction.(d) Axial intermediate-weighted fat-saturated MR image shows a thickened tibialis posterior tendon with mild tenosynovitis (arrowhead) and a hyperintense anterior talofibular ligament related to an old partial tear (arrow).

Anteromedial ankle impingement in a 55-year-old woman with previous ankle injuries and recurrent medial ankle pain. (a) Coronal intermediate-weighted MR image shows amorphous signal intensity in the ATTL with heterotopic bone formation (arrow). 

Anteromedial ankle impingement in a 55-year-old woman with previous ankle injuries and recurrent medial ankle pain. (b)Coronal intermediate-weighted fat-saturated MR image shows amorphous signal intensity in the ATTL and heterotopic bone formation (arrow).  

Anteromedial ankle impingement in a 55-year-old woman with previous ankle injuries and recurrent medial ankle pain. (c) Axial T1-weighted MR image helps confirm involvement of the ATTL (arrow) and shows a normal-appearing PDTL (arrowhead). 

Anteromedial ankle impingement in a 55-year-old woman with previous ankle injuries and recurrent medial ankle pain.  (d) Axial intermediate-weighted fat-saturated MR image shows fibrosis and synovial proliferation of the ATTL (arrow).

Predominantly anteromedial impingement in a 39-year-old man with recalcitrant medial ankle pain and instability. (a)Anteroposterior radiograph of the ankle shows heterotopic bone formation (arrow) in the medial tibiotalar space. 

Predominantly anteromedial impingement in a 39-year-old man with recalcitrant medial ankle pain and instability.  (b) Coronal intermediate-weighted MR image shows heterotopic bone formation in relation to the ATTL (arrow), with amorphous signal intensity.

Predominantly anteromedial impingement in a 39-year-old man with recalcitrant medial ankle pain and instability. (c) Coronal T2-weighted fat-saturated MR image shows abnormal high signal intensity (arrow) in the region of the ATTL that is due to synovial proliferation and fibrosis. 

Predominantly anteromedial impingement in a 39-year-old man with recalcitrant medial ankle pain and instability.(d) Axial intermediate-weighted MR image shows amorphous signal intensity in both the ATTL and the PDTL, with heterotopic bone formation (arrow) in relation to the ATTL.

Posteromedial impingement in a 46-year-old man with previous ankle injury and posteromedial pain. (a) Coronal intermediate-weighted MR image shows a normal striated appearance of the ATTL (arrow).

Posteromedial impingement in a 46-year-old man with previous ankle injury and posteromedial pain. (b) Axial intermediate-weighted MR image shows amorphous signal intensity in the PDTL, with heterotopic bone formation in the posterior and central medial clear space (thin arrow). Also note the osteochondral lesion of the posterior medial talus (thick arrow).

Posteromedial impingement in a 46-year-old man with previous ankle injury and posteromedial pain.(c) Axial intermediate-weighted fat-saturated MR image shows amorphous signal intensity in the PDTL (thin arrow) and the osteochondral lesion of the posterior medial talus (thick arrow). 

Posteromedial impingement in a 46-year-old man with previous ankle injury and posteromedial pain. (d) Axial intermediate-weighted MR image obtained caudad to b shows similar findings: amorphous signal intensity in the PDTL and heterotopic bone formation in the medial clear space (arrow).  

Posteromedial impingement in a 46-year-old man with previous ankle injury and posteromedial pain. (e) Axial intermediate-weighted fat-saturated MR image obtained caudad to c shows abnormal high signal intensity in the PDTL (arrow), resulting from synovial proliferation and fibrocartilaginous metaplasia.

Reference