British Journal of Radiology (2004) 77, 532-537
© 2004 British Institute of Radiology
doi: 10.1259/bjr/60447506
MRI features of foot and ankle injuries in ballet dancers
J C Hillier, FRCR
1
K Peace, FRCR
1
A Hulme, FRCS
2 and
J C Healy, FRCR
1
Departments of 1 Radiology and 2 Orthopaedics, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK
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Abstract
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Foot and ankle pain is common in ballet dancers. Although clinical examination often points to the underlying cause, imaging is often necessary to confirm the diagnosis and thus ensure appropriate future management. Factors predisposing to the increased incidence of injuries in this population include the classical position in which ballet dancers stand, which is on the tips of the toes in the en pointe position or on the balls of the feet in the demi-pointe position. Furthermore, the repetitious nature of ballet and the long hours spent rehearsing cause over-use injuries. The causes of foot and ankle pain can be thought of in four different groups: the impingement syndromes; tendon abnormalities; osseous pathology; and ligament abnormalities. These will be discussed and illustrated.
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Impingement syndromes
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The impingement syndromes of the ankle are a group of painful disorders that limit full range of movement. Symptoms are due to compression of soft tissues or osseous structures during particular movements [1]. The most commonly described are posterior and anterolateral impingement.
Posterior impingement syndrome
This presents with pain and swelling at the back of the ankle in plantar flexion. It is common in ballet dancers due to the forced plantar flexion associated with the en pointe position (on the tips of the toes). Symptoms are due to compression of structures between the calcaneus and the posterior plafond of the tibia [2].
The presence of a Steida process (prominent lateral tubercle of talus) or an os trigonum can contribute to the problem (Figure 1
). The tissues are repetitively compressed, leading to bone contusions and a local synovitis involving the posterior recess of both the tibiotalar and subtalar joints (Figure 2) [3, 4]. The flexor hallucis longus (FHL) tendon often becomes involved as it courses between the medial and lateral tubercles of the posterior talus, leading to a tenosynovitis.
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Figure 1. 17-year-old male ballet dancer. (a) Sagittal spin echo T1 weighted MR (TR/TE, 722/20) image demonstrating an os trigonum posterior to the talus, between the posterior plafond of the tibia and the calcanium. Excess soft tissue (arrow) indicating a synovitis is seen in this interval. (b) Sagittal short tau inversion recovery (TR/TE/TI, 4655/30/130) demonstrates high signal within the os trigonum and the talus (arrows).
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Figure 2. 16-year-old female ballet dancer. (a) Sagittal spin echo T1 weighted MR image (TR/TE, 722/20) shows an os trigonum with excess soft tissue being compressed between the calcaneum and the posterior plafond of the talus, in keeping with posterior ankle impingement syndrome. (b) Sagittal short tau inversion recovery (TR/TE/TI, 4655/30/130) shows the localized oedema in the os trigonum, adjacent talus and the soft tissues in keeping with posterior ankle impingement syndrome.
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Anterolateral impingement
This presents with pain and limitation of movement in dorsiflexion with intermittent swelling. The symptoms are due to excess soft tissue in the anterolateral gutter, the space bounded by the anterior talofibular (ATF) ligament, the anteromedial aspect of the fibula, the anterolateral aspect of the tibia and the anterolateral aspect of the talus (Figure 3) [5]. The abnormal soft tissue occurs due to scarring and synovitis as a result of repetitive injury to the lateral ligament complex.
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Figure 3. 17-year-old female ballet dancer. Axial fast spin echo T2 weighted MR image (TR/TE, 4500/95) shows loss of clarity of the anterior talofibular ligament, together with soft tissue in the anterolateral gutter (arrow) in keeping with anterolateral impingement. The posterior talofibular ligament is intact.
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Tendon abnormalities
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Flexor hallucis longus tendon pathology
The FHL tendon passes within a fibro-osseous tunnel between the medial and lateral tubercles of the posterior talus. More inferiorly it passes around the back of the medial malleolus, occupies a shallow groove on the posterior of the sustentaculum tali, and passes between the two sesamoids to the great toe terminal phalanx. These are all sites of impingement [6].
Thickening of the tendon and patchy high signal on T2 weighted or short tau inversion recovery (STIR) images within the tendon are features of tendonitis. Fluid around the tendon often indicates tenosynovitis (Figure 4). However the FHL tendon sheath communicates with the ankle joint in 20% of the population, therefore simple ankle effusions can extend into the FHL tendon sheath mimicking a tenosynovitis. The location of the fluid can help to differentiate between the two. The fluid is normally located proximal to the talar fibro-osseous tunnel [7] when the fluid is due to a tenosynovitis. Often the most helpful feature is the relative absence of fluid within the ankle joint when compared with the FHL tendon sheath in FHL tenosynovitis.
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Figure 4. 21-year-old female ballet dancer. Axial fast spin echo T2 weighted MR image (TR/TE, 4500/95) shows high signal around flexor hallucis longus (arrow) in keeping with tenosynovitis. Note the tendon itself returns normal low signal.
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Peroneal tendons
Subluxation and dislocation of the peroneal tendons have been reported in ballet dancers. In our experience these injuries are rare. Peritendonitis and tenosynovitis are seen due to long periods spent in the demi-pointe position [8]. Clinically, swelling and tenderness along the course of the tendons are apparent.
Achilles tendon
These are not uncommon in ballet dancers accounting for 9% of ballet injuries. Tendonitis, paratendonitis and retrocalcaneal bursitis are all encountered.
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Osseous pathology
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Bone marrow oedema
Patchy high signal on T2 weighted or STIR images within the bone marrow of the tarsal bones is a common finding and appears to represent a stress response. This is commonly seen in the talus, calcaneus and second metatarsal. This is often asymptomatic.
High T2 signal is often seen within the sesamoid bones, indicating a sesamoiditis (Figure 5). Dancers may develop sesamoiditis as a result of landing incorrectly after a jump. Traumatic fractures of the sesamoids occur less commonly and should be distinguished from bipartite sesamoids by their sharply defined irregular edge (Figure 6).
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Figure 5. 18-year-old female ballet dancer. (a) Coronal spin echo T1 weighted MR image (TR/TE, 722/20) showing low signal in the medial sesamoid (arrow). (b) Coronal short tau inversion recovery MR image (TR/TE/TI, 4655/30/130) showing high signal within the medial sesamoid in keeping with sesamoiditis.
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Figure 6. 17-year-old female ballet dancer. (a) Sagittal spin echo T1 weighted MR image (TR/TE, 722/20) shows low T1 signal within the medial sesamoid. In addition there is a smooth break in the cortex of the sesamoid (arrow), in keeping with a bipartite sesamoid. (b) Sagittal short tau inversion recovery MR image (TR/TE/TI, 4655/30/130) shows high signal in the medial bipartite sesamoid (arrow) in keeping with sesamoiditis.
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Stress fracture
Stress fractures occur in bone subjected to multiple episodes of low level stress. The most common site for stress fractures in the foot is the second metatarsal. This is the longest metatarsal and is weight bearing when the foot is in the demi-pointe position. An area of high T2 signal associated with a low T1 signal line is characteristic (Figure 7) [9]. The Steida process can also be fractured.
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Figure 7. 18-year-old female ballet dancer. (a) Sagittal spin echo T1 weighted MR image (TR/TE, 501/20) shows a low signal line (arrow) extending from the cortex of the second metatarsal into the metaphysis characteristic of a stress fracture. (b) Sagittal short tau inversion recovery MR image (TR/TE, 5640/30/130) shows marked marrow oedema and the stress fracture.
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Osteochondral injury
The talar dome is a common site for development of osteochondritis dissecans. Repeated subchondral stress during plantar flexion and dorsiflexion are aetiological factors in ballet dancers (Figure 8) [9].
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Figure 8. 35-year-old female ballet dancer. Sagittal spin echo T1 weighted MR image (TR/TE, 501/20) shows a well defined low signal crescent in the talar dome. This does not involve the articular cartilage and is in keeping with an early osteochondral injury.
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Ligamentous injury
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These are the most common traumatic injuries encountered in ballet. Disruption of the lateral ligament complex is caused by inversion injuries and accounts for the vast majority of ligament injuries. Injury to the medial (deltoid) ligament is rare in ballet dancers.
The lateral ligament complex is composed of the ATF ligament, the calcaneofibular (CF) ligament and the posterior talofibular (PTF) ligament. The ATF ligament is best demonstrated on axial T2 weighted images as a structure of uniform low signal extending from the anterior aspect of the fibula to the talus. The PTF ligament is best demonstrated on the same sequences, as a low signal structure (often somewhat striated) extending from the inner surface of the distal fibula to the posterior aspect of the talus (Figure 9). The CF ligament runs in an oblique plane, and can be more difficult to delineate. It can be demonstrated either on coronal or axial images as a low signal structure deep to the peroneal ligaments running from the calcaneus to the tip of the fibula (Figure 10).
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Figure 9. 18-year-old male ballet dancer. Axial fast spin echo T2 weighted MR image (TR/TE, 4500/95) demonstrates the low signal anterior talofibular ligament (long arrow) extending from the anterior aspect of the fibula to the talus. The posterior talofibular ligament is seen as a striated structure (short arrow) extending from the inner surface of the distal fibula to the posterior aspect of the talus.
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Figure 10. 16-year-old male ballet dancer. Axial fast spin echo T2 weighted MR image (TR/TE, 4500/95) shows the calcaneofibular ligament (arrow) at its calcaneal insertion just deep to the peroneal ligaments.
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The ATF ligament is the weakest and therefore is injured first. The CF ligament is the next to be injured, and injury to the CF ligament is only seen in conjunction with injury to the ATF ligament. The PTF ligament is rarely damaged. A partial or complete tear of the ATF ligament is seen most commonly. Partial tears are demonstrated as areas of high signal intensity with thickening on T2 weighted images. Complete tears are seen as discontinuity of the ligament with high signal intensity between the torn segments. Chronic tears are often only evident by non-visualization of the ligament in its anticipated location, or thickening of the ligament (Figure 11) [10].
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Figure 11. 18-year-old female ballet dancer. Axial fast spin echo T2 weighted MR image (TR/TE, 4500/95) shows a thickened anterior talofibular ligament (arrow) in keeping with a chronic partial tear.
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Received for publication April 11, 2003.
Revision received December 15, 2003.
Accepted for publication February 11, 2004.
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Abstract
Impingement syndromes
