Surg Radiol Anat (2008) 30:361–367 DOI 10.1007/s00276-008-0328-3

A N A T O M I C B A S E S O F M ED I C A L , R A D I O L O G I C A L A N D S U R G I C A L T E C H N I Q U E S

Comparative study of the anatomy, CT and MR images of the lateral collateral ligaments of the ankle joint Jia Hua · Jian Rong Xu · Hai Yan Gu · Wei Li Wang · Wen Jin Wang · Xia Dang · Qing Lu · Wen Long Ding

Received: 22 August 2007 / Accepted: 27 February 2008 / Published online: 21 February 2008 © Springer-Verlag 2008

Abstract Clinical diagnosis of lateral collateral ligamentous injury caused by ankle sprains depends primarily on clinical signs, and X-ray and CT images. None of these, however, provide direct or accurate information about ligamentous injury. MRI has long been testiWed as a useful tool in the demonstration of ligaments due to its good resolution of soft tissues. We conWrmed the appearance of the lateral collateral ligaments of the ankle joints on MR images by comparing MR images with CT images of the ligaments enhanced by coating with contrast medium after dissection of six cadaver feet. Compare study of MR images reveals no diVerence in the natural position and the dorsal position (P > 0.05), whereas, taken into the consideration the long hour of MRI examination, the natural position is regarded as the optimal position for MRI performance. Measured on transverse MR images, lateral ligaments of acutely injured ankles were signiWcantly thicker than those of normal ankles (P < 0.01). According to the MR images of normal and injured ankles, the lateral collateral ligaments injuries were classiWed as type I and type II. Osteal contusion, cartilaginous injury, musculotendinous injury, tenosynovitis, and peritenosynovitis were also observed by MRI in type I and type II acute lateral collateral ligament injury. All these

J. Hua · J. R. Xu · H. Y. Gu · W. L. Wang · X. Dang · Q. Lu Department of Radiology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China W. J. Wang · W. L. Ding (&) Department of Anatomy, Shanghai Jiao Tong University School of Medicine, No. 227 South Chongqing Road, Shanghai 200025, China e-mail: [email protected]

complications have higher incidence in type II than in type I injury (P < 0.05). Thus, by comparing with the CT images and the anatomy we conWrmed the normal appearance of the lateral collateral ligaments on MR images and Wgured out that the natural position is the optimal position for MRI performance. The thickness of the ligaments and incidence of the complications could be regarded as useful cue for the assistant in clinical diagnosis of the lateral collateral ligament injury. Keywords Ankle joint · Lateral collateral ligament · Magnetic resonance imaging · Computed tomography · Ankle sprain

Introduction There are three major lateral collateral ligaments: anterior taloWbular, calcanoWbular, and posterior taloWbular [4, 8, 25]. The ligaments are usually displayed on MR images as Wbrous bands or areas with inhomogeneous signal intensity resulting from the fatty tissues located between the ligamentous Wbers. These ligaments were displayed as bands of low signal intensity in diVerent sequences of MR imaging. Lateral collateral ligament injury is the most common injury caused by ankle sprains [9, 17, 23]. Although general X-ray or CT imaging reveals some injuries, they are inadequate for correct diagnosis due to their limited resolution in soft tissue. MR imaging is a useful tool in the diagnosis of acute or chronical ligamentous injury because it clearly displays abnormalities of injured ligaments as well as those of adjacent tissues caused by various lesions [1, 7, 12, 14, 20, 24]. Therefore, it is valuable to discern the normal structure of lateral collateral ligaments and their adjacent tissues on various MR images in order to diagnose ligamentous injury

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of the ankle joint. We compared the anatomy, CT and MR images of the lateral collateral ligaments, and studied the optimal ankle position for MR imaging on healthy volunteers. Additionally, we measured ligament thickness on MR images and compared these data with that of the acutely injured ligaments secondary to ankle sprains. ClassiWcation of sprained ankle by MR imaging was studied in this study referring to the clinical classiWcation. The characteristics of acute ligamentous injury with ankle sprains on MR images were further evaluated to develop a protocol for the evaluation of ankle joint injury based on MR imaging.

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injury were examined with the ankle in the natural position. Medial and lateral malleolus were placed in the extremity coil. MR imaging was done in transverse, coronal, and sagittal planes: FFE MRI performed on sagittal plane, T1WI, T2WI and PDW MRI on coronal and transverse planes, SPAIR MRI on coronal plane (FOV 130 mm, 2.0/1.0 mm section thickness, matrix 410 £ 512). Ligament thickness was measured on transverse MR images and recorded as the mean value of that measured at the medial, middle, and lateral part of each ligament. CT protocol

Materials and methods The study was approved by the institutional review board. Informed consent was obtained from each volunteer. The ankles were obtained and utilized according to the institutional guidelines and with informed consent of the donors prior to amputation and institutional approval.

CT images were obtained with a 16 row CT machine (GE Lighter Speed, Waukesha, WI, USA) and processed with AW 4.0 workstation. The dissected lateral collateral ligaments of ankles were coated with iodine containing contrast medium for CT scan (1.25 spiral scan section thickness, 120 kv, 280 mA). Images obtained were sent to ADW workstation for transverse, coronal, and sagittal MRP reconstruction.

General information Statistical analysis Transverse, sagittal, and coronal MR imaging was performed on six fresh ankles from amputated legs (volunteer donors underwent amputation of the leg because of primary osteosarcoma or chondroscarcoma in the femoral bone, age range 20–30 years). Lateral collateral ligaments of these ankles were then dissected and coated with iodine containing contrast medium for CT scan and graph reconstruction. The appearances of the lateral collateral ligaments on MR images were ascertained by comparing CT and MR images. Totally, 30 healthy volunteers (15 male, 15 female; age range 25–50 years) underwent MR imaging of the ankle joint in complete dorsal Xexion or in a natural position (20° tarsal Xexion) of the ankle. Of the 33 patients with acute ankle sprains, ligament injury was diagnosed in 27 by MR imaging (17 male, 10 female; age range 21–60 years; mean age 40.2 years). Clinical manifestations included redness and swelling of the ankle joint (more obvious in the lateral malleolus) and tenderness. MRI protocol All MR images were obtained with a 3.0 T MR (Philips Archieva, Amsterdam, the Netherlands) with ankles placed in a SENSE-Xexibility-multiple channel extremity coil (SENSE-Fle-M) and were processed through a View Forum Workstation. Fresh ankles were examined in the natural position (20° tarsal Xexion). The ankles of 30 volunteers were examined in complete dorsal Xexion and natural Xexion (20° tarsal Xexion) with the patient in the supine position. Twenty-seven patients with acute ligamentous

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Data analyses were performed using SPSS, version 11.0. Data were demonstrated as mean § standard deviation. Ankle joint appearances obtained by MR imaging in diVerent positions were analyzed by
2 test. Ligamentous thickness measured on MR images of the lateral ligaments from normal and injured ankles were compared and analyzed by independent-samples T test.

Results Anatomy of the lateral collateral ligaments of the ankle joint There are three major lateral collateral ligaments: (1) anterior taloWbular ligament, which extends from the lateral malleolus, traveling horizontally and anteromedially to the articular facet lateral to the necks of the talus; (2) posterior taloWbular ligament, deep in location and the strongest band of the three ligaments, runs horizontally and posteromedially from the malleolar fossa of the Wbula through posterior to the talus to the lateral tubercle of the talus. The posterior tibiotalar parts of the anterior and posterior ligaments run adjacent to the Xexor hallucis longus tendon and partially fuse with it; (3) calcaneoWbular ligament, a round cord, courses posteroinferiorly from impression below the tip of the lateral malleolus to the tubercle in the middle of the lateral surface of the calcaneus (Fig. 1).

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Fig. 1 Lateral part of freshly dissected left ankle (a). The thick arrow shows the anterior taloWbular ligament, the arrow head shows the calcanoWbular ligament. Posterolateral part of freshly dissected left ankle (b). The arrow shows the posterior taloWbular ligament, the arrow head shows the calcanoWbular ligament

Comparison of reconstructed CT and MR images of the lateral collateral ligaments In the transverse plane (plane crossing the neck of the talus) CT images displayed the anterior taloWbular ligament as a band traveling transversely from the anterior border of the lateral part of the lateral malleolus, and then coursing posterior. The posterior taloWbular ligament was displayed as a cord running posterior to the talus from the malleolar fossa of the Wbula to the lateral tubercle of the talus (Fig. 2a). MR images clearly displayed the anterior part of the extramalleolar articular capsule around the anterior taloWbular ligament, the Wbularis longus and brevis tendon left and posterior to the posterior taloWbular ligament, and the Xexor hallucis longus tendon right and posterior to this ligament (Fig. 2b).

Fig. 2 Transverse images of the taloWbular ligament of the left ankle. Anterior (arrow) and posterior (arrow head) taloWbular ligaments showed on CT transverse reconstructed Wlm (a). Anterior taloWbular ligament (thick arrow), posterior taloWbular ligament (arrow head), Wbularis longus and brevis tendon (thin arrow) and Xexor hallucis longus tendon (star) showed on transverse PDW MR image (b). Complete

In the talocalcaneous plane, CT images displayed the calcanoWbular ligament as a cord coursing obliquely and medioposteriorly from the tip of the lateral malleolus to the middle of the lateral calcaneus (Fig. 3a). MR imaging displayed the same ligament and the Wbularis longus and brevis tendon close and lateral to this ligament (Fig. 3b). In the coronal plane, CT images displayed the posterior taloWbular ligament as a band running transversely, and the calcanoWbular ligament as a cord passing obliquely and vertically (Fig. 4a). MR imaging displayed the posterior taloWbular ligament, calcanoWbular ligament, and the Wbularis longus and brevis muscle tendon adjacent to these structures on the same plane (Fig. 4b). In all instances, besides the anatomical location, morphology, and adjacent tissues of the ligament, MR imaging fully displayed the inner structure of ligaments on both

rupture of anterior taloWbular ligament showed on transverse T2WI MR image. The ruptured ligament is more clearly displayed close to the attach point of the talus on T2WI MR image due to the contrast of the Xuidity in the articular capsule demonstrating high signal intensity (arrow) (c)

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Fig. 3 The calcaneoWbular ligament (thick arrow) of the left ankle showed on CT transverse reconstructed Wlm (a). CalcaneoWbular ligament (thick arrow) and the Wbularis longus and brevis tendon (thin arrow) lateral to the ligament coursing parallel with it showed on transverse PDW MR image (b). Partial tear of calcaneoWbular ligament

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(thick arrow) showed on transverse T2WI MR image, displayed as ruZed edge, inhomogeneous inner signal intensity, vague surrounding fatty gaps. The Wbularis tendon was surrounded by areas of annuliform high signal intensity, indicating Xuidity of the tendinous sheath (thin arrow) (c)

Fig. 4 The posterior taloWbular ligament (arrow head) and calcaneoWbular ligament (thick arrow) of the left ankle showed on CT coronal reconstructed Wlm (a). Posterior taloWbular ligament (arrow head) and calcanoWbular ligament (thick arrow) showed on coronal PDW MR image (b)

transverse and coronal planes as thin bands of ligamentous Wbers with areas of fatty tissue located between the ligamentous Wbers. This is most typical seen in the images of taloWbular ligaments (Fig. 4b). In the sagittal plane, neither CT image reconstruction nor MR imaging was able to adequately display the lateral collateral ligaments of the ankle joint. Therefore, transverse and coronal MR imaging planes are two most useful in observing the lateral collateral ligaments and surrounding tissues. The posterior taloWbular ligament and calcanoWbular ligament are primarily observed

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on coronal MR images, while the anterior and posterior taloWbular ligaments and the calcanoWbular ligament are mainly observed on transverse MR images. Sagittal MR imaging is much less useful in ligament identiWcation. Assessment of normal ankle appearance on MR images in diVerent positions MR images taken in normal and dorsal positions were studied. Comparison of MR images in the two positions reveals no signiWcant diVerences with P < 0.05. The appearance of

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Table 1 MRI of the ankles in natural position and complete dorsal position (n = 30) Ligament

Anterior taloWbular ligament

Posterior taloWbular ligament

Degree of demonstration

C

P

N

C

P

CalcanoWbular ligament N

C

P

N 0

Natural position (T)

26 (86.7%)

4 (3.3%)

0

18 (60.0%)

12 (40.0%)

0

25 (83.3%)

5 (16.7%)

Dorsal Xexion (T)

26 (86.7%)

4 (3.3%)

0

19 (63.3%)

11 (36.7%)

0

24 (80.0%)

6 (20.0%)

0

Natural position (F)

0

0

30 (100%)

28 (93.3%)

2 (6.7%)

0

16 (53.3%)

14 (46.7%)

0

Dorsal Xexion (F)

0

0

30 (100%)

27 (90.0%)

3 (10.0%)

0

14 (46.7%)

16 (53.7%)

0


2 test revealed insigniWcant diVerences between the two groups (P < 0.05) T transverse plane, F frontal plane, C all ligaments were displayed on the same plane, P the course of the ligament was displayed on several planes instead of one, N the ligament could hardly or not be displayed

the anterior or posterior taloWbular ligaments and the calcanoWbular ligament as displayed by transverse or coronal MR imaging were categorized as complete (C), partial (P), or none (N). Results are summarized in Table 1. MRI appearance of lateral collateral ligaments of normal and injured ankles Thickness of the lateral collateral ligaments of 30 ankles was measured on transverse MR images (Table 2). MR images of acute lateral collateral ligament injury of the ankle demonstrated thicker ligaments, rough edges, inhomogeneous signal intensity, vague fatty interspaces surrounding the ligaments, and arthroedema in each injured ankle. TaloWbular ligaments in eight cases and calcanoWbular ligaments in three cases were completely disrupted and displayed as a loss of continuity on MR images (Fig. 2c). Areas between the disrupted ligaments were displayed as areas of increased high-signal intensity and blurred borders on T2W1 MR imaging, and hemorrhage and edema were observed in surrounding soft tissues. The thickness of 19 anterior taloWbular ligaments and 11 calcanoWbular ligaments was measured. The injured ligaments are signiWcantly thicker than the normal ligaments. A comparison of ligament thickness between injured and normal ligaments is shown in Table 2. The diVerences were statistically signiWcant with P < 0.01. Of the 13 cases with type I ligamentous injury, osteal contusion coexisted in 3, epitendinous Xuidity of Wbularis

Table 2 Comparison of the ligament thickness between normal and injured anterior taloWbular and calcanoWbular ligaments (mean § standard deviation) Thickness of ligament

Normal (n = 30)

Injury

Anterior taloWbular ligament

1.462 § 0.214

2.712 § 0.498# (n = 19)

CalcanoWbular ligament

1.522 § 0.211

2.318 § 0.172# (n = 11)

# P < 0.01 (vs. normal ligament)

Table 3 Complications in type I and II ligament injury Injury types

Type I (n = 13)

Type II (n = 14)

Osteal contusion

3 (23.1%)

12 (85.7%)*

Chondral injury

0 (00.0%)

4 (28.6%)*

Fibular longus and brevis tendon injury

1 (7.7%)

4 (28.6%)

Fluidity of Wbular longus and brevis tendon sheath

5 (38.5%)

14 (100.0%)#

* P < 0.05, versus type I injury, # P < 0.01, versus type II injury

longus and brevis tendon in 5, and tendinous injury in 1. No chondral injury was observed. Of the 14 cases suVering from type II (for ankle injury classiWcation see “Discussion”) ligamentous injury, osteal contusion coexisted in 12, chondral injury in 4, tendinous injury of Wbularis longus and brevis tendon in 4, and epitendon Xuidity of Wbularis longus and brevis tendon (Fig. 3c) in all 14 cases. Statistical analysis demonstrated statistically signiWcant diVerences in all complications between the two types of ligamentous injury except for the tendinous injury of the Wbularis longus and brevis tendon (P < 0.05). The diVerence of epitendon Xuidity of Wbularis longus and brevis tendon between the two types of injury is signiWcant (P < 0.01) (Table 3).

Discussion Comparison of the anatomy, and CT and MR images of the lateral collateral ligaments of the ankles We dissected the ankle joint to study the location and adjacent tissues of the lateral collateral ligaments. The lateral collateral ligaments were dissected and coated with iodine containing contrast medium for CT imaging in order to overcome the poor CT resolution of soft tissue. The anatomy of the ankles and the CT and MR images of the ligaments of the ankles were complementary to each other and

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help to ascertain the appearance of the lateral collateral ligaments of the ankle joints on the MR images of various planes. Thus, CT images based on the dissection were compared to the MR images to support the identiWcation of the appearance of the lateral collateral ligaments displayed by MR images. Our results indicate that CT transverse image reconstruction is adequate in displaying the anterior and posterior taloWbular ligaments and the calcanoWbular ligament, while CT coronal image reconstruction is good for imaging the posterior taloWbular ligament and the calcanoWbular ligament. MR images displayed soft tissue better than other modalities [3, 18, 21, 26]. We chose the PDW sequence for MR imaging in this study because this sequence displays the lateral collateral ligaments as intermediate to low signal intensity, the adjacent tendon as low signal intensity, the Xuid inside the capsule and the surrounding fatty tissue as intermediate to high signal and high signal intensity, respectively. In order to adequately display lateral collateral ligaments and their adjacent tissues, it is very important to choose the correct plane for MR imaging due to its varying resolution on diVerent tissues. Based on reconstructed CT images, the transverse and coronal planes are regarded as primary planes for MR imaging, not only to display the course of the lateral collateral ligaments, but also to clearly display the detailed ligament structures and adjacent tissues. Measurement and comparison of lateral collateral ligaments on MR images obtained in diVerent ankle positions Some scholars regard the natural position of the ankle position (20° tarsal Xexion) in the supine position as the ideal position for MR imaging of the lateral collateral ligaments, whereas others prefer the complete dorsal Xexion position [2, 11]. We desired to Wnd an optimal position not only to fully display the ligaments and adjacent tissues, but also to make imaging easier for patients. No signiWcant diVerences between complete dorsal Xexion and the natural position were found. Thus the natural position was considered to be the optimal position for MR imaging of the ankles, especially due to the fact that it takes approximately 1 h to perform high-resolution MR imaging and it is diYcult and uncomfortable for patients with injured ankles to remain still for such a long time. Therefore, all the 27 cases with acute ligamentous injury of the ankle underwent MR imaging with the ankle in natural position. Ligament thickness is usually altered when injured [22, 23]. Concrete measurement data, however, have not been conWrmed by literature. The ligament thickness measured on transverse MR images of 30 normal volunteers in this study provides important indications for clinical diagnosis.

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MRI manifestation of acute lateral collateral ligamentous injury of the ankle The posterior taloWbular ligament, the deepest and strongest, is rarely aVected in ankle injuries [6]. Injury to the posterior taloWbular ligament occurred in only 1 of 27 cases of ankle sprains in this study. According to MR imaging ligamentous injury can be classiWed into two types. Type I injury is equal to the clinically classiWed degree one, and type II includes clinically classiWed degree two and three [4, 23]. Morphological changes such as increased thickness, abnormal course, ruZed edges and discontinuity, abnormal signal intensity of the ligament and surrounding tissues, abnormal structure of the surrounding tissues, including the articular cavity and the fatty tissue located between ligament Wbers, were observed in 27 cases to varying degrees. Injured anterior taloWbular ligaments were clearly observed on transverse T2WI MR images due to the contrast between the surrounding articular capsule and the arthroedema. Injured ligaments were thicker than normal ones (P < 0.01), indicating that an increase in ligament thickness may be an important indicator of acute ligament injury. Besides the lateral collateral ligaments injury, acute ankle joints sprain might cause a series of abnormalities of adjacent tissues and structures. Injury of the adjacent tissues, including fracture, osteal contusion, chondral injury, tendinous injury, and peritendinitis, may occur in acute ankle sprain. Of these, fracture is readily diagnosed with Xray or CT imaging, whereas the others can only be identiWed by MR imaging [5, 6, 10, 13, 15, 16, 19]. All these signs developed concomitantly with type I and type II lateral collateral ligament injury and a compare study reveals higher incidence of these signs in type II than type I injury, especially the Xuidity of the Wbularis longus and brevis tendinous sheath (P < 0.05). Therefore, compound ligamentous injury results in much more severe pathological alterations of adjacent tissues. The calcanoWbular ligamentous injury might lead to injury of the Wbularis longus and brevis tendinous sheath because of the anatomical closeness of these two structures. Thus, Xuidity of the Wbularis tendinous sheath may be an indication of calcanoWbular ligament injury.

Conclusion The appearance of the lateral collateral ligaments on MR images was identiWed by compare with the enhanced CT images based on the dissection of the ankles. The natural position (20° tarsal Xexion) of the ankle with the patient in the supine position is the optimal position for MR imaging of the lateral collateral ligaments of the ankle. Ligament thickness measured through transverse MR imaging

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demonstrated thicker ligaments in acute ankle sprains than in normal ankles (P < 0.01). This could be helpful in the clinical diagnosis of lateral collateral ligament injury of the ankles. A higher incidence of complications is seen in type II ligamentous injury. The Xuidity of the Wbularis tendinous sheath may be an indicator of calcanoWbular ligament injury. MR imaging is a superior tool in the diagnosis of lateral ligamentous injury of ankle, not only by clearly demonstrating morphological alterations of the ligament, but also by clearly demonstrating adjacent tissues; thus greatly facilitating the diagnosis and treatment of injury to the lateral ligaments of the ankle joint.

References 1. Antonio GE, GriYth JF, Yeung DK (2004) Small-Weld-of-view MRI of the knee and ankle. Am J Roentgenol 183(1):24–28 2. Beltran J, Munchow AM, Khabiri H, Magee DG, McGhee RB, Grossman SB (1990) Ligaments of the lateral aspect of the ankle and sinus tarsi: an MR imaging study. Radiol 177(2):455–458 3. Breitenseher MJ (2007) Injury of the ankle joint ligaments. Radiol 47(3):216–223 4. Brown KW, Morrison WB, Schweitzer ME, Parellada JA, Nothnagel H (2004) MRI Wndings associated with distal tibioWbular syndesmosis injury. Am J Roentgenol 182(1):131–136 5. Bureau NJ, Cardinal E, Hobden R, Aubin B (2000) Posterior ankle impingement syndrome: MR imaging Wndings in seven patients. Radiol 215(2):497–503 6. Cheung Y, Rosenberg ZS (2001) MR imaging of ligamentous abnormalities of the ankle and foot. Magn Reson Imaging Clin N Am 9(3):507–531 7. De Smet AA, Graf BK (1994) Meniscal tears missed on MR imaging: relationship to meniscal tear patterns and anterior cruciate ligament tears. Am J Roentgenol 162(4):905–911 8. Dong WJ, Ma ZL, Yang YX, Yang GF, Liu GQ, Gong HL, Feng GF, Zhang FC (2004) A study on the sectional and imaging anatomy of the human ankle joints. Chin J Clin Anat 22(1):63– 66 9. Farooki S, Yao L, Seeger LL (1998) Anterolateral impingement of the ankle: eVectiveness of MR imaging. Radiol 207(2):357–360 10. Flick AB, Gould N (1985) Osteochondritis dissecans of the talus (transchondral fractures of the talus): review of the literature and new surgical approach for medial dome lesions. Foot Ankle 5(4):165–185

367 11. Grasel RP, Schweitzer ME, Kovalovich AM, Karasick D, Wapner K, Hecht P, Wander D (1999) MR imaging of plantar fasciitis: edema, tears, and occult marrow abnormalities correlated with outcome. Am J Roentgenol 173(3):699–701 12. Hardy CJ, Katzberg RW, Frey RL, Szumowski J, Totterman S, Mueller OM (1988) Switched surface coil system for bilateral MR imaging. Radiol 167(3):835–838 13. Hillier JC, Peace K, Hulme A, Healy JC (2004) Pictorial review: MRI features of foot and ankle injuries in ballet dancers. Br J Radiol 77(918):532–537 14. Kneeland JB, Hyde JS (1989) High-resolution MR imaging with local coils. Radiol 171(1):1–7 15. Mabit C, Boncoeur-Martel MP, Chaudruc JM, Valleix D, Descottes B, Caix M (1997) Anatomic and MRI study of the subtalar ligamentous support. Surg Radiol Anat 19(2):111–117 16. Masala S, Fiori R, Marinetti A, Uccioli L, Giurato L, Simonetti G (2003) Imaging the ankle and foot and using magnetic resonance imaging. Int J Low Extrem Wounds 2(4):217–232 17. Muhle C, Frank LR, Rand T, Yeh L, Wong EC, Skaf A, Dantas RW, Haghighi P, Trudell D, Resnick D (1999) Collateral ligaments of the ankle: high-resolution MR imaging with a local gradient coil and anatomic correlation in cadavers. Radiographics 19(3):673–683 18. NierhoV CE, Ludwig K (2006) Magnetic resonance imaging of the ankle. Radiologe 46(11):1005–1018 19. Oae K, Takao M, Naito K, Uchio Y, Kono T, Ishida J, Ochi M (2003) Injury of the tibioWbular syndesmosis: value of MR imaging for diagnosis. Radiol 227(1):155–161 20. Peterfy CG, Linares R, Steinbach LS (1994) Recent advances in magnetic resonance imaging of the musculoskeletal system. Radiol Clin North Am 32(2):291–311 21. Riley GM (2007) Magnetic resonance imaging in the evaluation of sports injuries of the foot and ankle: a pictorial essay. J Am Podiatr Med Assoc 97(1):59–67 22. Robinson P, White LM (2002) Soft-tissue and osseous impingement syndromes of the ankle: role of imaging in diagnosis and management. Radiographics 22(6):1457–1471 23. Rosenberg ZS, Beltran J, Bencardino JT (2000) From the RSNA refresher courses. Radiological society of North America. MR imaging of the ankle and foot. Radiographics 20:153–179 24. Rosenberg ZS, Bencardino J, Astion D, Schweitzer ME, Rokito A, Sheskier S (2003) MRI features of chronic injuries of the superior peroneal retinaculum. Am J Roentgenol 181(6):1551–1557 25. Sha Y, Zhang SX (2000) Comparative study between the sectional anatomy and MRI of the lateral ligaments of the ankle subtalar joints. Chin J Clin Anat 18(4):289–293 26. Taser F, ShaWq Q, Ebraheim NA (2006) Anatomy of lateral ankle ligaments and their relationship to bony landmarks. Surg Radiol Anat 28(4):391–397

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