Ankle and Foot 47 - Department of Radiology - University of ...
Ankle and Foot 47 - Department of Radiology - University of ... Ankle and Foot 47 - Department of Radiology - University of ...
2224 VII Imaging of the Musculoskeletal System A B C Figure 47-24. Longitudinal split in the posterior tibial tendon (PT) in a 39-year-old. Shown are the same straight axial images obtained through the tip of the medial malleolus (MM). A, T1-weighted image well demonstrates the anatomy of the tendons as well as the neurovascular bundle (dotted oval). B, Proton-density–weighted image shows what appears to be four medial tendons, the four-tendon sign, where 1 and 2 are the two halves of the split PT, and 3 and 4 are the normal flexor digitorum longus (FDL) and flexor hallucis longus (FHL) tendons. C, T2-weighted image demonstrates not bright fluid but gray scar (gray arrowhead) around the split PT, suggesting that this is chronic stenosing tenosynovitis. There is an abnormal amount of fluid in the FDL sheath (black arrowhead), suggesting active tenosynovitis here. The fluid in the FHL sheath (white arrowhead) is within normal limits for this tendon only. A B Figure 47-25. Active posterior tibial tenosynovitis in a 46-year-old with chronic pain in the distribution of the posterior tibial tendon (PT). A, Straight axial proton-density–weighted image demonstrates that the PT is intact and contains no abnormal internal signal. The PT is slightly larger in cross section than the normal anterior tibial tendon, and there is loss of the normal fat signal around the tendon (gray arrowhead). B, Straight axial T2-weighted image at the same level reveals an abnormal amount of fluid in the posterior tibial tendon sheath (black arrowhead), indicating active tenosynovitis. Ch047-A05375.indd 2224 9/9/2008 5:33:51 PM
47 Ankle and Foot 2225 47 A B C Figure 47-26. Chronic posterior tibial stenosing tenosynovitis in a 57-year-old with chronic pain in the distribution of the posterior tibial tendon (PT). (This is the same patient as in Fig. 47-16; these straight axial images are two slices distal to those.) T1-weighted (A), proton-density–weighted (B), and T2-weighted (C) images all show abnormally dark signal (gray arrowhead) around the PT. women than men, particularly workers who are on their feet all day, such as waitresses and sales clerks. In the ankle, tenosynovitis most frequently occurs in the posterior tibial tendon and in the two peroneal tendons. Even when these tendons are intact, their tendon sheaths and surrounding soft tissues should be carefully examined. An abnormal amount of fluid in the tendon sheath indicates active tenosynovitis (Fig. 47-25). Dark, fibrous tissue around the tendon suggests chronic scarring or stenosing tenosynovitis (Fig. 47-26). Rheumatoid pannus can also be demonstrated by MRI (see Fig. 47-55) and should enhance if intravenous contrast is administered. It has been suggested that these inflammatory conditions of the tendon sheath can be ameliorated by therapeutic tenography. 40 • Lateral Tendons Laterally, the peroneus brevis and longus tendons share a common sheath as they pass under the lateral malleolus. Distal to the lateral malleolus, the tendons are enveloped with individual sheaths. The peroneus brevis tendon extends along the lateral aspect of the midfoot and inserts on the tuberosity at the lateral base of the fifth metatarsal. The peroneus longus tendon passes through a groove in the plantar surface of the cuboid, crosses under the midfoot deep to the master knot of Henry, and extends medially to insert on the plantar aspect of the medial cuneiform and the base of the first metatarsal, just lateral to the anterior tibial tendon insertion site. A trick for identifying the peroneal tendons is to think of the lateral malleolus as a race track (Fig. 47-27). The peroneus brevis, being the shortest, hugs the inside curve and is thus closest to the fibula. The peroneus longus follows the outside of the curve, running posterior and inferior to the peroneus brevis. Unlike the medial ankle tendons, which are normally round or oval in axial cross section, the peroneus brevis Figure 47-27. Coronal MRI (left) and graphic representation in the sagittal plane (right) demonstrate the relationship of the peroneal tendons to the lateral malleolus (LM); the peroneus brevis (PB) is closer to the distal fibula than is the peroneus longus (PL). can normally appear flattened as it passes around the lateral malleolus. The presence of increased signal in the substance of the tendon, or the presence of fluid in the surrounding sheath, aids in the diagnosis of pathology of the peroneal tendons. It is often helpful to examine the peroneal tendons over multiple slices, using several imaging planes and sequences (Fig. 47-28). Ch047-A05375.indd 2225 9/9/2008 5:33:52 PM
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2224 VII Imaging <strong>of</strong> the Musculoskeletal System<br />
A B C<br />
Figure <strong>47</strong>-24. Longitudinal split in the posterior tibial tendon (PT) in a 39-year-old. Shown are the same straight axial images obtained through<br />
the tip <strong>of</strong> the medial malleolus (MM). A, T1-weighted image well demonstrates the anatomy <strong>of</strong> the tendons as well as the neurovascular bundle<br />
(dotted oval). B, Proton-density–weighted image shows what appears to be four medial tendons, the four-tendon sign, where 1 <strong>and</strong> 2 are the two<br />
halves <strong>of</strong> the split PT, <strong>and</strong> 3 <strong>and</strong> 4 are the normal flexor digitorum longus (FDL) <strong>and</strong> flexor hallucis longus (FHL) tendons. C, T2-weighted image<br />
demonstrates not bright fluid but gray scar (gray arrowhead) around the split PT, suggesting that this is chronic stenosing tenosynovitis. There is<br />
an abnormal amount <strong>of</strong> fluid in the FDL sheath (black arrowhead), suggesting active tenosynovitis here. The fluid in the FHL sheath (white<br />
arrowhead) is within normal limits for this tendon only.<br />
A<br />
B<br />
Figure <strong>47</strong>-25. Active posterior tibial tenosynovitis in a 46-year-old with chronic pain in the distribution <strong>of</strong> the posterior tibial tendon (PT).<br />
A, Straight axial proton-density–weighted image demonstrates that the PT is intact <strong>and</strong> contains no abnormal internal signal. The PT is slightly<br />
larger in cross section than the normal anterior tibial tendon, <strong>and</strong> there is loss <strong>of</strong> the normal fat signal around the tendon (gray arrowhead).<br />
B, Straight axial T2-weighted image at the same level reveals an abnormal amount <strong>of</strong> fluid in the posterior tibial tendon sheath (black arrowhead),<br />
indicating active tenosynovitis.<br />
Ch0<strong>47</strong>-A05375.indd 2224<br />
9/9/2008 5:33:51 PM
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