Lateral Ne Demek
Brie Hoffler
Clinical History: A 52 year-old man presents with history of 10 years of right ankle pain, and clinical suspicion of subtalar arthritis. Sagittal T1- and fat-suppressed T2-weighted (1a,1b), and coronal fat-suppressed proton density-weighted (1c,1d) images are shown below. What are the findings, and what is your diagnosis?
The sagittal T1-weighted image demonstrates extra-articular subcortical cystic changes and bone marrow edema at the lateral talar process and the adjacent calcaneus (arrowheads). Normal fat signal is seen at the sinus tarsi (long arrow).
The sagittal T2-weighted image with fat saturation shows extra-articular subcortical cystic changes and bone marrow edema at the lateral talar process and the adjacent calcaneus (arrowheads). Also demonstrated is unremarkable articular cartilage at the posterior subtalar joint (arrow).
A coronal fat-suppressed proton density-weighted image obtained just anterior to the posterior subtalar joint reveals the extra-articular subcortical bone marrow edema and cystic changes at both the talocalcaneal region (arrowheads), and the calcaneofibular region, with bony remodeling and flat neo-facets at the fibula distally and at the adjacent lateral calcaneus (red arrows). There is peroneal tendinosis (blue arrow), and edema at interposed lateral soft tissues.
A posterior coronal view demonstrates that severe heel valgus is present, with an abnormal, 40 degree angle between the medial calcaneal cortex and the long axis of the tibia, measured just posterior to the sustentaculum at the level of the posterior talus and tibia. As the MR was not obtained during weight-bearing, the measurement may underestimate the extent of functional malalignment.
Lateral hindfoot impingement is characteristically not related to an acute injury, but to chronic hindfoot valgus malalignment. This hindfoot malalignment is often due to posterior tibial tendon insufficiency, as this tendon is crucial in maintaining the longitudinal arch of the foot. The resulting hindfoot valgus malalignment is one of the components of acquired flatfoot deformity (pes planovalgus), and in severe cases a progressive lateral calcaneal subluxation occurs, such that the calcaneus may contact the fibula during weight-bearing.
Posterior hindfoot impingement most commonly occurs in middle-aged and older individuals with a chronic hindfoot valgus deformity. Symptoms often include hindfoot pain on weight-bearing, swelling and tenderness in the region anterior and inferior to the lateral malleolus, and limited subtalar range of motion. These clinical symptoms are not specific and may also be encountered in patients with subtalar degenerative arthritis, sinus tarsi syndrome, and other disorders affecting the hindfoot region.
Posterior tibial tendinopathy is a common cause of hindfoot valgus deformity. The prevalence of lateral hindfoot impingement has been found to increase with higher grades of posterior tibial tendon tear2. Patients with posterior tibial tendon dysfunction experience both pain and disability. The pain is initially located along the medial aspect of the foot, often associated with swelling due to tenosynovitis. With progressive collapse of the longitudinal arch and development of a hindfoot valgus deformity, lateral foot pain develops, found to frequently relate to extra-articular talocalcaneal or calcaneofibular impingement1. The relative frequency of lateral hindfoot impingement, or the severity of hindfoot deformity required before the impingement occurs, are not known1.
Affected patients may also experience subluxation or dislocation of the peroneal tendons, causing a popping sensation at the posterior margin of the lateral malleolus. This instability is not related to the lateral impingement, but rather is caused by severe hindfoot valgus malalignment, and resultant overactivity of the unopposed peroneus brevis in the presence of posterior tibial tendon insufficiency.
A 3D representation of the normal appearance of the structures involved with lateral hindfoot impingement. On the left a lateral view of the ankle shows the normal space between the lateral talar process (asterisk) and the calcaneal angle of Gissane (arrowhead). The image on the right depicts the plane just anterior to the posterior subtalar joint demonstrating normal alignment and spacing between the lateral talus (asterisk), the lateral calcaneus (arrowhead), and the lateral malleolus (arrow).
The sinus tarsi is a non-articular cone-shaped passage between the talus and calcaneus, with a larger opening towards its lateral aspect. The sinus tarsi is located immediately anterior to the posterior subtalar joint, and is separated from this joint by the joint capsule and the short but stout talocalcaneal interosseous ligament. Anteriorly, the sinus tarsi extends to the margin of the talocalcaneal (anterior subtalar) joint, and medially it extends to the middle facet of the subtalar joint. The sinus tarsi contains mostly fat, but also small vascular and nerve branches, the cervical ligament, and the 3 roots combining to form the inferior extensor retinaculum, located towards the anterolateral margin of the sinus tarsi. Normally the sinus tarsi extends into a small space between the apex of the lateral process of the talus and the adjacent calcaneus, just anterior to the posterior subtalar joint margin, and the adjacent talar lateral process is normally rounded or slightly pointed, without a flat facet (8a,9a).
The fibula normally does not extend distally to near the lateral cortex of the calcaneus in the plane of the lateral process of the talus. With valgus malalignment the calcaneus may sublux and rotate laterally, resulting in direct osseous contact with the fibula.
3D representation in the coronal plane just anterior to the posterior subtalar joint demonstrates changes of lateral hindfoot impingement. On the left the lateral talus impacts the lateral calcaneus. With more severe hindfoot valgus and lateral calcaneal subluxation additional impingement may occur between the lateral malleolus and lateral calcaneus as depicted on the right.
A sagittal T1-weighted image of the ankle in a 54 year-old woman demonstrates normal talocalcaneal alignment, with a normal small interval between the apex of the lateral talar process and the calcaneus at apex of the angle of Gissane (blue lines). Dotted red lines demonstrate the landmarks for measuring the angle of Gissane. An unremarkable cervical ligament at the sinus tarsi, with adjacent normal fat signal is indicated (arrowhead).
The corresponding fat-suppressed T2-weighted image demonstrates the normal rounded to slightly pointed apex of the lateral talar process (arrow), and the unremarkable cervical ligament (arrowhead). Normal minimal fluid is present at the posterior subtalar joint, without capsular distension into the sinus tarsi.
A fat-suppressed proton density-weighted image, obtained coronal to the apex of the angle of Gissane in a 54 year-old woman showing normal talocalcaneal alignment, with a normal interval between the lateral malleolar tip and the lateral calcaneus (arrow), and normal position of the peroneal tendons (arrowheads).
Subluxation at the talocalcaneal joint has been shown to occur in symptomatic adults with acquired flat foot, involving a lateral translocation of the calcaneus into valgus malalignment, with the subluxation greater at the anterior and middle talocalcaneal articular facets than at the posterior facet, leading to reduction of articular contact surfaces at these joints6. This subluxation causes a change in the overall shape of the foot, with flattening of the longitudinal arch, valgus of the hindfoot, and abduction of the forefoot6. With a significant hindfoot valgus deformity, there will be a lateral shift of the main weightbearing forces at the ankle and hindfoot, from the talar dome towards the lateral talus and also to the fibula7. If excessive, this can result in subtalar pathology including degenerative arthritis, sinus tarsi syndrome, or extra-articular bony contact as with lateral hindfoot impingement.
Regarding the frequent association with posterior tibial tendinopathy, it should be emphasized that an acquired flat foot deformity may develop without a complete tendon tear and distraction, as functional insufficiency may present at earlier stages such as with a grade 1 interstitial tear (11a).
An axial T1-weighted image in a 71 year-old woman with left ankle pain, swelling and difficulty with weight-bearing, showing a longitudinal split tear of the posterior tibial tendon (arrows). The MR examination also showed characteristic features of lateral hindfoot impingement.
Osseous findings of lateral hindfoot impingement include extra-articular subcortical bone marrow edema at specific locations at the talus, calcaneus or fibula. Also frequently present are cystic changes at the bone marrow at these same locations, and subcortical sclerosis at bony contact surfaces.
In reported cases, the incidence of calcaneofibular impingement was somewhat lower than talocalcaneal impingement, with calcaneofibular impingement present almost exclusively in individuals who also had talocalcaneal impingement, suggesting that the talocalcaneal osseous changes occur before the calcaneofibular changes.
Subcortical bone marrow edema characteristically involves both opposing aspects of the talus, calcaneus, or fibula (3a). The location of the bone marrow edema is characteristic, at the extra-articular region at the inferior apex of the lateral talar process and at the immediately subjacent aspect of the calcaneus at the apex of the angle of Gissane (12a). The bony changes sometimes are seen to also involve the adjacent subcortical region of the anterosuperior calcaneal process (13a), however if bone marrow edema is present all along the cortex around the margins of the sinus tarsi, this would not be characteristic and would instead suggest a diagnosis of sinus tarsi syndrome.
A fat-suppressed T2-weighted image in a 52 year-old patient with lateral hindfoot impingement demonstrates characteristic bone marrow edema at the inferior apex of the lateral talar process (asterisk) as well as at the subjacent angle of Gissane (arrowhead).
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