Ankle and Foot 47 - Department of Radiology - University of ...

47 Ankle and Foot 2221 47
Figure 47-19. Complete Achilles tendon rupture at
the musculotendinous junction in a 52-year-old. A, An
initial set of sagittal images was obtained with the
extremity coil centered on the heel, which was too low
to include the proximal end of the tear. B, The coil was
repositioned proximal to the ankle joint to include the
musculotendinous junction. The marker (m) is at the
palpable defect.
A
B
Figure 47-20. Intrasubstance tear of the Achilles
tendon in a 54-year-old with a history of rheumatoid
arthritis and several months of persistent heel pain.
T2-weighted fat-suppressed images in the sagittal (A)
and axial (B) planes reveal that the distal Achilles
tendon is abnormally swollen with increased
intrasubstance signal (black arrow). An incidental
finding is an abnormal amount of fluid in the posterior
tibial tendon sheath (white arrow in B).
A
B
to retain its thickened fusiform shape. However, unlike the
acute intrasubstance tear, a healed Achilles tendon does
not contain internal signal (Fig. 47-22).
• Medial Tendons
Normal Anatomy
The classic mnemonic “Tom, Dick, and Harry” is useful for
remembering the order of the medial ankle tendons; T
represents the posterior tibial tendon, D the flexor digitorum
longus tendon, and H the flexor hallucis longus
tendon. By changing the emphasis to “Tom, Dick, ANd
Harry,” with the AN standing for the posterior tibial artery
and nerve, it is easier to remember the neurovascular
bundle that runs between the flexor digitorum longus
and flexor hallucis longus tendons (see Figs. 47-10 and
47-11).
The posterior tibial tendon runs directly behind and
under the medial malleolus, proceeds medial to the talus,
and inserts on the medial pole of the navicular (see Fig.
47-10D). At this insertion site there is a focal osseous
prominence, called the navicular tubercle. The bulk of the
posterior tibial tendon inserts on the navicular tubercle,
although smaller slips of tendon pass under the navicular
(see Fig. 47-11C) to insert on the plantar aspects of all three
cuneiforms as well as the bases of the second through
fourth metatarsals.
The flexor digitorum longus tendon runs directly
behind the posterior tibial tendon, although these two
tendons maintain individual tendon sheaths. The flexor
digitorum longus tendon extends plantar to the bones of
the midfoot, crossing superficially to the flexor hallucis
longus tendon. This crossover point has been called the
master knot of Henry, 24 and the sheaths of these two flexor
tendons communicate at this point. Distally, the flexor
digitorum longus divides into separate tendon slips that
insert on the plantar bases of the second through fifth
distal phalanges.
Ch047-A05375.indd 2221
9/9/2008 5:33:45 PM