(Radiographics. 1999;19:673-683.)
© RSNA, 1999
Collateral Ligaments of the Ankle: High-Resolution MR Imaging with a Local Gradient Coil and Anatomic Correlation in Cadavers1
Claus Muhle, MD,
Lawrence R. Frank, PhD,
Thomas Rand, MD,
LeeRen Yeh, MD,
Eric C. Wong, MD, PhD,
Abdalla Skaf, MD,
Robert W. M. Dantas, MD,
Parviz Haghighi, MD,
Debra Trudell, RA and
Donald Resnick, MD
1 From the Departments of Radiology (C.M., L.R.F., T.R., L.Y., E.C.W., A.S., R.W.M.D., D.T., D.R.) and Pathology (P.H.), Veterans Affairs Medical Center, 3350 La Jolla Village Dr, San Diego, CA 92161; the Department of Pathology, University of California, San Diego (P.H.); and the Department of Diagnostic Radiology, University of Kiel, Kiel, Germany (C.M.). Received May 4, 1998; revision requested May 27 and received June 15; accepted June 23. Supported in part by Veterans Affairs grant SA360 and the Deutsche Forschungsgemeinschaft. Address reprint requests to D.R.
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Abstract
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Findings at high-resolution magnetic resonance (MR) imaging of the lateral and medial collateral ligaments of the ankle were compared with findings in anatomic sections from cadavers. MR imaging of six cadaveric feet was performed with a newly developed local gradient coil and axial and coronal T1-weighted spin-echo sequences. Axial imaging provided optimum views of the anterior and posterior talofibular ligaments, the deep layers of the medial collateral ligament, and the tibionavicular ligament. Coronal imaging allowed complete visualization of the calcaneofibular, posterior talofibular, tibiocalcaneal, and posterior tibiotalar ligaments. In both imaging planes, differentiation of the deep and superficial layers of the medial collateral ligament was possible. Differentiation between the syndesmotic complex and the lateral collateral ligament was accomplished easily; in particular, differentiation of the posterior tibiofibular ligament from the posterior talofibular ligament was not difficult because of the differing insertions of these ligaments. The inhomogeneous appearance of the medial collateral ligament and the posterior talofibular ligament on MR images correlated with areas of fatty tissue on corresponding microscopic sections. High-resolution MR imaging with a newly developed local gradient coil allows excellent visualization of the lateral and medial collateral ligaments of the ankle.
Index Terms: Ankle, anatomy, 46.92 • Ankle, MR, 46.121411 • Ligaments, MR, 46.121411 • Magnetic resonance (MR), coil arrays, 46.121411
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INTRODUCTION
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Important ligaments of the ankle are those that compose the distal tibiofibular syndesmosis and the lateral and medial collateral ligaments (1,2). The lateral collateral ligament consists of three ligaments: the anterior talofibular ligament, the posterior talofibular ligament, and the calcaneofibular ligament. The medial collateral ligament (deltoid ligament) consists of four ligaments: the anterior tibiotalar ligament, the posterior tibiotalar ligament, the tibionavicular ligament, and the tibiocalcaneal ligament. Assessment of the extent of ligamentous injury has been accomplished with routine radiography, stress radiography, arthrography, and tenography (3,4). Owing to the advantage of detailed demonstration of soft-tissue structures and the capability for direct multiplanar demonstration of the ankle ligaments, magnetic resonance (MR) imaging has been increasingly applied to the evaluation of ligamentous injuries of the ankle (5–18).
However, various scientific articles have misidentified the tibiofibular and talofibular ligaments on MR images and misinterpreted the signal intensity characteristics of the lateral and medial collateral ligaments. The purpose of this article is to describe in detail the normal appearances of the lateral and medial ligamentous complexes of the ankle on high-resolution MR images obtained with a newly developed local gradient coil and to correlate these findings with the corresponding macroscopic and microscopic anatomic findings in cadavers.
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MATERIALS AND METHODS
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Six fresh human feet were harvested from nonembalmed cadavers (three male, three female; age range at time of death, 69–86 years; mean age, 79 years). The specimens were derived from legs cut through the distal portion of the tibia and fibula; such cutting allowed preservation of the tibiofibular syndesmosis. The specimens were immediately deep-frozen at -40°C (Bio-Freezer; Forma Scientific, Marietta, Ohio). All specimens were examined with radiography to exclude those with obvious arthritic changes and previous injuries. The specimens were allowed to thaw for 24 hours at room temperature before MR imaging.
MR images were obtained with a 1.5-T superconducting MR imager (Signa; GE Medical Systems, Milwaukee, Wis) and a specially designed local gradient coil, which was constructed in our laboratory and which has been previously described (19–21). The coil consisted of a symmetric, torque-free, three-axis design built on a cylindric, 22.86-cm-diameter, 40-cm-long form and produced 6 G/cm at 100 A on all three axes with rise times of 100 µsec from zero to full scale. The region of gradient linearity consisted of a 15.24-cm-diameter, 15.24-cm-long cylinder with root-mean-square deviation from linearity of less than 3%. This coil allowed resolution on the order of 100 µm and read periods of approximately 2 msec for conventional imaging. For identical pulse sequence parameters, the coil produced a signal-to-noise ratio 23% higher than that produced by the knee coil (a linear saddle design) available with the imager.
The ankles were taped in 10°–20° dorsiflexion, then placed inside the coil and immobilized with foam pads. The MR imaging protocol consisted of axial and coronal T1-weighted (600/20 [repetition time msec/echo time msec]) spin-echo sequences. The field of view was 8 cm, and the data acquisition matrix was 256 x 256. A section thickness of 3 mm was used with a 0.5-mm intersection gap. Two signals were averaged.
After imaging, the specimens were again frozen for more than 72 hours and subsequently sectioned with a band saw in planes corresponding precisely to those of the MR images.
The MR images were evaluated for demonstration of ligamentous structures and signal intensity characteristics by two radiologists (C.M., T.R.) by means of consensus. The MR imaging findings were correlated with the findings at macroscopic evaluation. Histologic evaluation of four medial collateral ligaments and two posterior talofibular ligaments that contained areas of focal high signal intensity on MR images was performed by an experienced pathologist (P.H.).
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RESULTS
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Axial Plane
Lateral Collateral Ligament.—Owing to the nearly horizontal orientation of the anterior talofibular ligament, this ligament was best visualized on axial images (Figs 1, 2). The anterior talofibular ligament originates from the same level as the posterior counterpart, the posterior talofibular ligament. On MR images and anatomic sections, the anterior talofibular ligament is seen as a triangular or flat band of low signal intensity that arises from the anterior margin of the lateral malleolus and ends in a talar attachment anterior to the fibular articular surface (22,23).
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Figure 2a. Axial sections through the ankle of the cadaver of a 69-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows the anterior talofibular ligament (straight white arrows) as a thin band of homogeneous signal intensity. The posterior talofibular ligament (black arrows) has inhomogeneous signal intensity at the insertion on the concave fibula. Also note the inhomogeneous signal intensity of the anterior (arrowhead) and posterior (curved arrow) tibiotalar ligaments. (b) Photograph of corresponding macroscopic section shows the anterior talofibular ligament (thick arrows) and posterior talofibular ligament (thin arrows). (c) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of corresponding microscopic section shows multiple fascicles (arrowheads) of the posterior talofibular ligament with fatty tissue (arrows) close to the insertion on the fibula (F).
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Figure 2b. Axial sections through the ankle of the cadaver of a 69-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows the anterior talofibular ligament (straight white arrows) as a thin band of homogeneous signal intensity. The posterior talofibular ligament (black arrows) has inhomogeneous signal intensity at the insertion on the concave fibula. Also note the inhomogeneous signal intensity of the anterior (arrowhead) and posterior (curved arrow) tibiotalar ligaments. (b) Photograph of corresponding macroscopic section shows the anterior talofibular ligament (thick arrows) and posterior talofibular ligament (thin arrows). (c) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of corresponding microscopic section shows multiple fascicles (arrowheads) of the posterior talofibular ligament with fatty tissue (arrows) close to the insertion on the fibula (F).
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Figure 2c. Axial sections through the ankle of the cadaver of a 69-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows the anterior talofibular ligament (straight white arrows) as a thin band of homogeneous signal intensity. The posterior talofibular ligament (black arrows) has inhomogeneous signal intensity at the insertion on the concave fibula. Also note the inhomogeneous signal intensity of the anterior (arrowhead) and posterior (curved arrow) tibiotalar ligaments. (b) Photograph of corresponding macroscopic section shows the anterior talofibular ligament (thick arrows) and posterior talofibular ligament (thin arrows). (c) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of corresponding microscopic section shows multiple fascicles (arrowheads) of the posterior talofibular ligament with fatty tissue (arrows) close to the insertion on the fibula (F).
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The posterior talofibular ligament also was optimally visualized in the axial plane (Figs 1, 2). Owing to the transverse course of the posterior talofibular ligament and the origin from the most distal aspect of the fibula with broad attachments to the posterior aspect of the talus, differentiation from the transverse and posterior tibiofibular ligaments was possible. In addition, in all specimens the posterior talofibular ligament originated with a broad base from the concave surface of the fibular fossa, whereas the fibers of the transverse and posterior tibiofibular ligaments originated higher, from the posterior third of the convex-to-flattened surface of the fibula. In five of six specimens, the posterior talofibular ligament had an inhomogeneous appearance on MR images; this appearance correlated with individual fibers separated by fatty tissue on corresponding microscopic sections (Fig 2).
The calcaneofibular ligament was visualized incompletely in the axial plane. This ligament appeared as a homogeneous, thin band of low signal intensity. The band extended deep to the peroneus brevis and peroneus longus tendons, from the apex of the lateral malleolus to a small tubercle on the lateral aspect of the calcaneus.
Medial Collateral Ligament.—The deep and superficial layers of the medial collateral ligament could be differentiated in all specimens on axial images (Figs 1, 3). (The deep layers are the anterior and posterior tibiotalar ligaments; the superficial layers are the tibionavicular and tibiocalcaneal ligaments.) The anterior tibiotalar ligament was evident in two specimens as an inhomogeneous band 2–3 cm in diameter at the insertion on the talar neck (24). However, in four specimens, only a thin band of fibers or no fibers of this ligament were seen on MR images and corresponding anatomic sections (Fig 3). The posterior tibiotalar ligament appeared as a thick, inhomogeneous band with broad attachment to the medial surface of the talus as far posteriorly as the posteromedial talar tubercle (Fig 3) (25). At the attachment site on the medial surface of the talus, this ligament was 5–6 cm thick.
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Figure 3a. Axial sections through the ankle of the cadaver of a 74-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows only thin fibers of the anterior tibiotalar ligament (curved arrow). The posterior tibiotalar ligament (straight arrow) appears as a thick, inhomogeneous band with broad attachment to the medial surface of the talus. (b, c) Corresponding MR images obtained 3 mm (b) and 6 mm (c) below the level of a show thin fibers of the tibionavicular ligament (arrowheads). (d) Photograph of corresponding macroscopic section shows the anterior tibiotalar ligament (curved arrow) and posterior tibiotalar ligament (straight arrow). (e) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of corresponding microscopic section shows areas of fatty tissue (arrows) between the fascicles (arrowheads) of the posterior tibiofibular ligament. These findings correspond to the inhomogeneous signal intensity on T1-weighted spin-echo MR images.
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Figure 3b. Axial sections through the ankle of the cadaver of a 74-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows only thin fibers of the anterior tibiotalar ligament (curved arrow). The posterior tibiotalar ligament (straight arrow) appears as a thick, inhomogeneous band with broad attachment to the medial surface of the talus. (b, c) Corresponding MR images obtained 3 mm (b) and 6 mm (c) below the level of a show thin fibers of the tibionavicular ligament (arrowheads). (d) Photograph of corresponding macroscopic section shows the anterior tibiotalar ligament (curved arrow) and posterior tibiotalar ligament (straight arrow). (e) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of corresponding microscopic section shows areas of fatty tissue (arrows) between the fascicles (arrowheads) of the posterior tibiofibular ligament. These findings correspond to the inhomogeneous signal intensity on T1-weighted spin-echo MR images.
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Figure 3c. Axial sections through the ankle of the cadaver of a 74-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows only thin fibers of the anterior tibiotalar ligament (curved arrow). The posterior tibiotalar ligament (straight arrow) appears as a thick, inhomogeneous band with broad attachment to the medial surface of the talus. (b, c) Corresponding MR images obtained 3 mm (b) and 6 mm (c) below the level of a show thin fibers of the tibionavicular ligament (arrowheads). (d) Photograph of corresponding macroscopic section shows the anterior tibiotalar ligament (curved arrow) and posterior tibiotalar ligament (straight arrow). (e) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of corresponding microscopic section shows areas of fatty tissue (arrows) between the fascicles (arrowheads) of the posterior tibiofibular ligament. These findings correspond to the inhomogeneous signal intensity on T1-weighted spin-echo MR images.
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Figure 3d. Axial sections through the ankle of the cadaver of a 74-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows only thin fibers of the anterior tibiotalar ligament (curved arrow). The posterior tibiotalar ligament (straight arrow) appears as a thick, inhomogeneous band with broad attachment to the medial surface of the talus. (b, c) Corresponding MR images obtained 3 mm (b) and 6 mm (c) below the level of a show thin fibers of the tibionavicular ligament (arrowheads). (d) Photograph of corresponding macroscopic section shows the anterior tibiotalar ligament (curved arrow) and posterior tibiotalar ligament (straight arrow). (e) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of corresponding microscopic section shows areas of fatty tissue (arrows) between the fascicles (arrowheads) of the posterior tibiofibular ligament. These findings correspond to the inhomogeneous signal intensity on T1-weighted spin-echo MR images.
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Figure 3e. Axial sections through the ankle of the cadaver of a 74-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows only thin fibers of the anterior tibiotalar ligament (curved arrow). The posterior tibiotalar ligament (straight arrow) appears as a thick, inhomogeneous band with broad attachment to the medial surface of the talus. (b, c) Corresponding MR images obtained 3 mm (b) and 6 mm (c) below the level of a show thin fibers of the tibionavicular ligament (arrowheads). (d) Photograph of corresponding macroscopic section shows the anterior tibiotalar ligament (curved arrow) and posterior tibiotalar ligament (straight arrow). (e) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of corresponding microscopic section shows areas of fatty tissue (arrows) between the fascicles (arrowheads) of the posterior tibiofibular ligament. These findings correspond to the inhomogeneous signal intensity on T1-weighted spin-echo MR images.
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The superficial tibionavicular ligament was well visualized as a thin, homogeneous band of low signal intensity approximately 0.5–1 cm wide that inserted on the navicular tuberosity (Fig 3).
Coronal Plane
Lateral Collateral Ligament.—The calcaneofibular ligament was demonstrated best in the coronal plane (Fig 4). In all specimens, the full length of this ligament was visualized on one or two images. The fibers of the posterior talofibular and calcaneofibular ligaments were visualized together on at least one image in all specimens. The calcaneofibular ligament consisted of thinner fibers than the posterior talofibular ligament (Fig 4). With regard to differentiation of the posterior talofibular ligament and the transverse and posterior tibiofibular ligaments, the posterior talofibular ligament was well separated from the distal posterior tibiofibular syndesmosis on coronal images.
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Figure 4a. Coronal sections through the ankle of the cadaver of a 67-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows the posterior talofibular ligament (arrowhead), which originates from the concave surface of the fossa of the lateral malleolus and extends to the insertion on the talus. The calcaneofibular ligament (arrow) appears as a thin band of homogeneous signal intensity, which extends from the apex of the lateral malleolus to the lateral aspect of the calcaneus. Pb = peroneus brevis tendon, Pl = peroneus longus tendon. (b) Photograph of corresponding macroscopic section shows the posterior talofibular ligament (arrowhead) and calcaneofibular ligament (arrow). The inhomogeneous signal intensity of the posterior talofibular ligament on the MR image (a) corresponds to multiple fascicles with areas of interspersed fatty tissue. (c) Corresponding MR image obtained 6 mm posterior to a shows the transverse ligament (arrowheads) and posterior tibiofibular ligament (arrow) of the distal tibiofibular syndesmosis. The transverse ligament appears as a thin band of homogeneous signal intensity below the posterior tibiofibular ligament that extends obliquely to the tibia.
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Figure 4b. Coronal sections through the ankle of the cadaver of a 67-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows the posterior talofibular ligament (arrowhead), which originates from the concave surface of the fossa of the lateral malleolus and extends to the insertion on the talus. The calcaneofibular ligament (arrow) appears as a thin band of homogeneous signal intensity, which extends from the apex of the lateral malleolus to the lateral aspect of the calcaneus. Pb = peroneus brevis tendon, Pl = peroneus longus tendon. (b) Photograph of corresponding macroscopic section shows the posterior talofibular ligament (arrowhead) and calcaneofibular ligament (arrow). The inhomogeneous signal intensity of the posterior talofibular ligament on the MR image (a) corresponds to multiple fascicles with areas of interspersed fatty tissue. (c) Corresponding MR image obtained 6 mm posterior to a shows the transverse ligament (arrowheads) and posterior tibiofibular ligament (arrow) of the distal tibiofibular syndesmosis. The transverse ligament appears as a thin band of homogeneous signal intensity below the posterior tibiofibular ligament that extends obliquely to the tibia.
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Figure 4c. Coronal sections through the ankle of the cadaver of a 67-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows the posterior talofibular ligament (arrowhead), which originates from the concave surface of the fossa of the lateral malleolus and extends to the insertion on the talus. The calcaneofibular ligament (arrow) appears as a thin band of homogeneous signal intensity, which extends from the apex of the lateral malleolus to the lateral aspect of the calcaneus. Pb = peroneus brevis tendon, Pl = peroneus longus tendon. (b) Photograph of corresponding macroscopic section shows the posterior talofibular ligament (arrowhead) and calcaneofibular ligament (arrow). The inhomogeneous signal intensity of the posterior talofibular ligament on the MR image (a) corresponds to multiple fascicles with areas of interspersed fatty tissue. (c) Corresponding MR image obtained 6 mm posterior to a shows the transverse ligament (arrowheads) and posterior tibiofibular ligament (arrow) of the distal tibiofibular syndesmosis. The transverse ligament appears as a thin band of homogeneous signal intensity below the posterior tibiofibular ligament that extends obliquely to the tibia.
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Medial Collateral Ligament.—On coronal images, the deep layers of the medial collateral ligament could be well differentiated from the superficial layers (Figs 5, 6). The anterior and posterior tibiotalar ligaments were identified as short, obliquely oriented fibers extending from the tip of the medial malleolus to the medial talar surface (Fig 5). Both of these ligaments were seen as thin fibers surrounded by areas of high signal intensity, which correlated with fatty tissue on macroscopic sections (Fig 6).
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Figure 5a. Coronal sections through the ankle of the cadaver of a 76-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows the posterior tibiotalar ligament (arrows) as a short, thick band that extends from the tip of the medial malleolus to the medial talar surface. (b) Photograph of corresponding macroscopic section shows the posterior tibiotalar ligament (arrows).
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Figure 5b. Coronal sections through the ankle of the cadaver of a 76-year-old woman. (a) T1-weighted spin-echo MR image (600/20) shows the posterior tibiotalar ligament (arrows) as a short, thick band that extends from the tip of the medial malleolus to the medial talar surface. (b) Photograph of corresponding macroscopic section shows the posterior tibiotalar ligament (arrows).
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Figure 6a. Coronal sections through the ankle of the cadaver of an 86-year-old woman. D = flexor digitorum longus tendon, S = sustentaculum tali of the calcaneus, T = tibialis posterior tendon. (a) T1-weighted spin-echo MR image (600/20) shows multiple fascicles of the posterior tibiotalar ligament (black arrow) with hyperintense layers (white arrow) of fatty tissue between the fascicles. The superficial layer of the medial collateral ligament, the tibiocalcaneal ligament (arrowhead), is shown as a small, homogeneous band of low signal intensity lateral to the posterior tibiotalar ligament (deep layer of the medial collateral ligament). (b) Corresponding MR image obtained 3 mm posterior to a shows the posterior tibiotalar ligament (arrow) and tibiocalcaneal ligament (arrowheads), which extends to the sustentaculum tali of the calcaneus. The tibiocalcaneal ligament can be easily differentiated from the tibialis posterior and flexor digitorum longus tendons. (c) Photograph of corresponding macroscopic section shows the posterior tibiotalar ligament (arrow) and tibiocalcaneal ligament (arrowheads).
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Figure 6b. Coronal sections through the ankle of the cadaver of an 86-year-old woman. D = flexor digitorum longus tendon, S = sustentaculum tali of the calcaneus, T = tibialis posterior tendon. (a) T1-weighted spin-echo MR image (600/20) shows multiple fascicles of the posterior tibiotalar ligament (black arrow) with hyperintense layers (white arrow) of fatty tissue between the fascicles. The superficial layer of the medial collateral ligament, the tibiocalcaneal ligament (arrowhead), is shown as a small, homogeneous band of low signal intensity lateral to the posterior tibiotalar ligament (deep layer of the medial collateral ligament). (b) Corresponding MR image obtained 3 mm posterior to a shows the posterior tibiotalar ligament (arrow) and tibiocalcaneal ligament (arrowheads), which extends to the sustentaculum tali of the calcaneus. The tibiocalcaneal ligament can be easily differentiated from the tibialis posterior and flexor digitorum longus tendons. (c) Photograph of corresponding macroscopic section shows the posterior tibiotalar ligament (arrow) and tibiocalcaneal ligament (arrowheads).
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Figure 6c. Coronal sections through the ankle of the cadaver of an 86-year-old woman. D = flexor digitorum longus tendon, S = sustentaculum tali of the calcaneus, T = tibialis posterior tendon. (a) T1-weighted spin-echo MR image (600/20) shows multiple fascicles of the posterior tibiotalar ligament (black arrow) with hyperintense layers (white arrow) of fatty tissue between the fascicles. The superficial layer of the medial collateral ligament, the tibiocalcaneal ligament (arrowhead), is shown as a small, homogeneous band of low signal intensity lateral to the posterior tibiotalar ligament (deep layer of the medial collateral ligament). (b) Corresponding MR image obtained 3 mm posterior to a shows the posterior tibiotalar ligament (arrow) and tibiocalcaneal ligament (arrowheads), which extends to the sustentaculum tali of the calcaneus. The tibiocalcaneal ligament can be easily differentiated from the tibialis posterior and flexor digitorum longus tendons. (c) Photograph of corresponding macroscopic section shows the posterior tibiotalar ligament (arrow) and tibiocalcaneal ligament (arrowheads).
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On coronal images, demonstration of only a portion of the tibionavicular ligament was possible. The tibiocalcaneal ligament appeared as a small, homogeneous band of low signal intensity that attached to the sustentaculum tali of the calcaneus. The fibers of this ligament were easily differentiated from those of the posterior tibiotalar ligament and the tibialis posterior and flexor digitorum longus tendons (Fig 6).
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DISCUSSION
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Different MR imaging protocols and ankle positions have been used in the evaluation of normal ligaments and ligamentous injuries of the ankle (6,9,10,12,14,15,26). Previous reports have recommended that the ankle be taped in dorsiflexion when imaged and then imaged again with the ankle taped in full plantar flexion to evaluate specific ligaments of the lateral and medial collateral complexes of the ankle (12,15,27). In addition, reformatted three-dimensional gradient-echo images have been emphasized in the evaluation of portions of the obliquely oriented medial collateral ligament (12). Our results, derived from close correlation of MR imaging and anatomic findings, suggest that the anatomy of the lateral and medial collateral ligaments can be demonstrated in detail on axial and coronal high-resolution MR images obtained with the ankle taped in 10°–20° dorsiflexion (Figs 2– 6).
The posterior talofibular ligament appears as an inhomogeneous band on MR images (Figs 2, 4) (2,5,15,26). Contrary to previous reports, in which the inhomogeneous signal intensity within some portions of the medial collateral ligament and posterior talofibular ligament was explained as due to partial volume averaging created by periligamentous collections of fatty or fibrocartilaginous tissue, macroscopic and microscopic evaluation of anatomic sections from cadavers reliably showed areas of fatty tissue within both ligaments and thereby allowed accurate judgment of ligamentous integrity (Fig 2c) (2,5,26). The MR imaging appearance of a parallel arrangement of individual fibers separated by fatty tissue is similar to that of the anterior cruciate ligament of the knee (2,8,17).
Various scientific publications have misidentified the tibiofibular and talofibular ligaments on MR images (2,7,10,26,28,29). The most frequent error has been to label the posterior tibiofibular ligament and occasionally the anterior tibiofibular ligament as the talofibular ligaments. However, in our series, differentiation between the syndesmotic complex and the lateral collateral ligament was accomplished easily (Table 1). The anterior tibiofibular ligament courses obliquely from the anterior aspect of the distal portion of the tibia to the anterior aspect of the fibula above the joint line. The lateral insertion is more distal than the medial insertion. In addition, the anterior tibiofibular ligament has a multilaminar appearance on axial and coronal high-resolution MR images, whereas the anterior talofibular ligament appears as a single band. Differentiation of the posterior tibiofibular ligament and the posterior talofibular ligament is also not difficult (2,5). On axial images, the fibers of the posterior tibiofibular ligament extend from the posterior third of the convex-to-flattened shaft of the fibula (Fig 4c). On coronal images, the fibers of the posterior tibiofibular ligament originate above the fibular fossa. In contrast, the posterior talofibular ligament extends from the anterior to posterior thirds of the concave surface of the fibular fossa on axial images (Figs 2, 4a, 4b). On coronal images, the posterior talofibular ligament extends from the most distal aspect of the fibula.
In both imaging planes, differentiation of the deep and superficial layers of the medial collateral ligament is possible (Figs 2, 3, 5, 6) (Table 2). The two deep layers of the medial collateral ligament, the anterior and posterior tibiotalar ligaments, are visualized completely on axial and coronal images, although the anterior tibiotalar ligament can be markedly thin or absent (Figs 2, 3, 5). This finding confirms findings in previous reports that described anatomic variations of this ligament (12,15,22,23,27). When the anterior and posterior tibiotalar ligaments are both present, both ligaments may demonstrate multiple thin fibers surrounded by fatty tissue, which corresponds to the inhomogeneous appearance on MR images (Fig 3e). The tibionavicular ligament is visualized incompletely on coronal images and is better identified on multiple axial images as a thin, homogeneous band of low signal intensity (Fig 3). Owing to the almost vertical course of the tibiocalcaneal ligament with fibers inserting on the sustentaculum tali of the calcaneus, this ligament can be best demonstrated on coronal images, although it can also be seen in part on axial images (Fig 6).
Our study had several limitations. First, the study was performed in cadavers rather than in living subjects, a situation that is not entirely analogous to examination of patients. Second, artifacts produced by anatomic sectioning or freezing may have influenced the observations, although such artifacts appeared to be a minor problem. Third, because only a small number of specimens from the cadavers of elderly subjects were included in the study, it is difficult to determine the prevalence of the MR imaging findings in the general population. However, our findings are in agreement with the observations of Noto et al (26), who found similar signal intensity characteristics of the medial collateral and posterior talofibular ligaments in a group of healthy volunteers. Fourth, the MR images were obtained with a local gradient coil that is not yet available commercially. However, high-performance gradient systems with capabilities similar to those of our coil are rapidly becoming available.
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CONCLUSIONS
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High-resolution MR imaging allows excellent visualization of the lateral and medial collateral ligaments of the ankle. The inhomogeneous appearance of the medial collateral and posterior talofibular ligaments on T1-weighted spin-echo images corresponds to areas of fatty tissue located between ligamentous fibers and should not be mistaken for evidence of a ligamentous tear.
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References
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Kannus P, Renstrom P. Treatment of ankle sprains in young athletes. J Bone Joint Surg [Am] 1991; 73:305-312.[Free Full Text]
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Mink JH. Ligaments of the ankle. In: Deutsch AL, Mink JH, Kerr R, eds. MRI of the foot and ankle. New York, NY: Raven, 1992; 173-197.
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Raatikainen T, Putkonen M, Puranen J. Arthrography, clinical examination, and stress radiographs in the diagnosis of acute injury to the lateral ligaments of the ankle. Am J Sports Med 1992; 20:2-6.[Abstract/Free Full Text]
-
Haller J, Resnick D, Sartoris D, et al. Arthrography, tenography, and bursography of the ankle and foot. Clin Podiatr Med Surg 1988; 5:893-908.[Medline]
-
Resnick D. Ankle and foot. In: Resnick D, Kang HS, eds. Internal derangements of joints: emphasis on MR imaging. Philadelphia, Pa: Saunders, 1997; 823-838.
-
Beltran J, Noto AM, Mosure JC, Shamam OM, Weiss KL, Zuelzer WA. Ankle: surface coil MR imaging at 1.5 T. Radiology 1986; 161:203-209.[Abstract/Free Full Text]
-
Chan WP, Peterfy C, Erickson SJ, Helms CA. The ankle and foot. In: Chan WP, Lang PL, Genant HK, eds. MRI of the musculoskeletal system. Philadelphia, Pa: Saunders, 1995; 351-385.
-
Erickson SJ, Smith JW, Ruiz ME, et al. MR imaging of the lateral collateral ligament of the ankle. AJR 1991; 156:131-136.[Abstract/Free Full Text]
-
Schweitzer ME. Magnetic resonance imaging of the foot and ankle. Magn Reson Q 1993; 9:214-234.[Medline]
-
Mitchell M, Sartoris DJ. Magnetic resonance imaging of the foot and ankle: an updated pictorial review. J Foot Ankle Surg 1993; 32:311-342.[Medline]
-
Kerr R, Forrester DM, Kingston S. Magnetic resonance imaging of foot and ankle trauma. Orthop Clin North Am 1990; 21:591-601.[Medline]
-
Klein MA. MR imaging of the ankle: normal and abnormal findings in the medial collateral ligament. AJR 1994; 162:377-383.[Abstract/Free Full Text]
-
Miller CD, Shelton WR, Barrett GR, Savoie FH, Dukes AD. Deltoid and syndesmosis ligament injury of the ankle without fracture. Am J Sports Med 1995; 23:746-750.[Abstract/Free Full Text]
-
Beltran J, Munchow AM, Khabiri H, Magee DG, McGhee RB, Grossman SB. Ligaments of the lateral aspect of the ankle and sinus tarsi: an MR imaging study. Radiology 1990; 177:455-458.[Abstract/Free Full Text]
-
Schneck CD, Mesgarzadeh M, Bonakdarpour A. MR imaging of the most commonly injured ankle ligaments. II. Ligament injuries. Radiology 1992; 184:507-512.
-
Rijke AM, Goitz HT, McCue FC, Dee PM. Magnetic resonance imaging of injury to the lateral ankle ligaments. Am J Sports Med 1993; 21:528-534.[Abstract/Free Full Text]
-
Kier R, McCarthy S, Dietz M, et al. MR appearance of painful conditions of the ankle. RadioGraphics 1991; 11:401-414.[Abstract]
-
Chandnani VP, Harper MT, Ficke JR, et al. Chronic ankle instability: evaluation with MR arthrography, MR imaging, and stress radiography. Radiology 1994; 192:189-194.[Abstract/Free Full Text]
-
Wong EC, Jesmanowicz A, Hyde JS. Coil optimization for MRI by conjugate gradient descent. Magn Reson Med 1991; 21:39-48.[Medline]
-
Wong EC, Jesmanowicz A, Hyde JS. High-resolution, short echo time MR imaging of the fingers and wrist with a local gradient coil. Radiology 1991; 181:393-397.[Abstract/Free Full Text]
-
Frank LR, Wong EC, Luh WM, Ahn JM, Resnick D. Articular cartilage in the knee: mapping of the physiologic parameters at MR imaging with a local gradient coil—preliminary results. Radiology 1999; 210:241-246.[Abstract/Free Full Text]
-
Sarrafian SK. Anatomy of the foot and ankle 2nd ed. Philadelphia, Pa: Lippincott, 1993; 159-217.
-
Kelikian H, Kelikian AS. Disorders of the ankle Philadelphia, Pa: Saunders, 1985; 1-39.
-
Gray H, Williams PL, Warwick R, eds. Gray's anatomy of the human body 36th ed. Philadelphia, Pa: Saunders, 1980; 720-722.
-
Pankovich AM, Shivaram MS. Anatomical basis of variability in injuries of the medial malleolus and the deltoid ligament. I. Anatomical studies. Acta Orthop Scand 1979; 50:217-223.
-
Noto AM, Cheung Y, Rosenberg ZS, Norman A, Leeds NE. MR imaging of the ankle: normal variants. Radiology 1989; 170:121-124.[Abstract/Free Full Text]
-
Schneck CD, Mesgarzadeh M, Bonakdarpour A, Ross GJ. MR imaging of the most commonly injured ankle ligaments. I. Normal anatomy. Radiology 1992; 184:499-506.[Abstract/Free Full Text]
-
Rosenberg ZS, Cheung Y. Diagnostic imaging of the ankle and foot In: Jahss MH. Disorders of the foot and ankle. Philadelphia, Pa: Saunders, 1991; 109-154.
-
Vogl TJ, Hochmuth K, Diebold T, et al. Magnetic resonance imaging in the diagnosis of acute injured distal tibiofibular syndesmosis. Invest Radiol 1997; 32:401-409.[Medline]
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Abstract
INTRODUCTION
