Diagnostic ultrasound ( PDFDrive )

904 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
Interdigital (Morton) neuromas, a common cause of forefoot
pain especially in women, have been described at sonography
as hypoechoic masses replacing the normal hyperechoic fat in
the interdigital web spaces. Occasionally a dilated hypoechoic
tubular structure can be seen associated with the neuroma,
relecting the enlarged feeding interdigital nerve. he second
and third web spaces are most oten involved. I generally inject
Morton neuromas using a dorsal approach while imaging the
neuroma in long axis 28 (Fig. 25.12). his approach is well tolerated
by the majority of patients. In certain patients, however, a plantar
approach to injecting the nodule is preferred, such as those with
severe subluxation at the MTP joint. In either case, the needle
is positioned directly within the neuroma and/or adjacent
intermetatarsal bursa (if present) and a small volume of therapeutic
mixture injected, similar to that used for a small joint
injection (0.5-0.75 mL).
Hand and Wrist
In the hand and wrist, de Quervain tendinosis is a frequently
encountered tendinopathy involving the abductor pollicis longus
and extensor pollicis brevis tendons that respond to local
N
calc
FIG. 25.11 Plantar Fascia Injection. The proximal medial band of
the plantar fascia (PF) is thickened and inhomogeneous in a 36-year-old
man with hindfoot pain. calc, Calcaneus. A 25-gauge needle (N) has
been positioned supericial to this plantar fascia and a perifascial injection
performed. The injected material (arrows) loculates along the supericial
margin of the medial band.
PF
administration of antiinlammatory agents (Fig. 25.13). Injections
are also frequently requested for patients with rheumatoid
arthritis or psoriatic arthritis. hese patients typically experience
severe tenosynovitis, which can lead to secondary tendon rupture
and deformity. he approach is similar to that used for supericial
structures in the foot and ankle. A short-axis approach avoids
the surrounding neurovascular structures, and the corresponding
tendon sheaths are injected.
INJECTION OF DEEP TENDONS
Frequently requested deep tendon injections include those for
the bicipital tendon sheath, iliopsoas tendon, gluteal tendon
insertion onto the greater trochanter, and hamstring tendon
origin.
Biceps Tendon
Anterior shoulder pain with radiation into the arm may be
secondary to bicipital tendinitis or tenosynovitis. 29 he biceps
tendon can be palpated, but if nondistended, the sheath may
ofer less than 2 mm of clearance to place a needle. his is
complicated by the caudal extension of the subacromial subdeltoid
bursa, which may overlie the bicipital tendon sheath. A nonimageguided
injection could therefore result in delivery into an
extratendinous synovial space, or possibly result in an intratendinous
injection. Ultrasound guidance enables localization of
therapeutic agent to the biceps tendon sheath. 10
he patient is placed recumbent with the forearm supinated
and the shoulder mildly elevated. he bicipital groove is oriented
anteriorly. A linear transducer, typically 7.5 MHz, is used with
a lateral approach and 25- or 22-gauge needle (Fig. 25.14). he
long head of the biceps tendon is scanned in short axis. When
luid distends the bicipital tendon sheath, the tip is directed into
the luid. Otherwise, the needle is directed along the supericial
margin of the tendon, and a test injection of local anesthetic is
used to conirm local distention of the sheath, which is then
followed by administration of the long-acting corticosteroid. he
PRE-INJECTION
POST-INJECTION
N
A
B
FIG. 25.12 Morton Neuroma Injection. (A) Preinjection image shows 25-gauge needle (N) positioned in a third web space neuroma using a
dorsal approach in 45-year-old woman with forefoot pain. Neuroma appears as a heterogeneous hypoechoic nodule (arrows) within the normal
echogenic fat. (B) After injection and needle removal, the nodule appears expanded and echogenic (arrows). The injected material often decompresses
into an adjacent adventitial bursa, which frequently accompanies these nodules.