Insufficiency Fracture ofthe Talus

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Insufficiency. Fracture ofthe. Talus: Diagnosis with. MR Imaging'. Hilary. Umans,. MD. Helene. Pavlov,. MD. 439. PURPOSE: To describe the clinical setting.
Hilary

Umans,

MD

Helene

Insufficiency Diagnosis

Pavlov,

Fracture ofthe with MR Imaging’

PURPOSE: To describe the clinical setting and pattern of talar insufficiency stress fractures as diagnosed with magnetic resonance (MR) imaging. MATERIALS AND METHODS: The authors retrospectively reviewed the clinical history and MR images from four patients with five talar insufficiency fractures. All patients were women (age range, 30-70 years). Images were evaluated for the location and orientation of fractures and the presence of concomitant osseous and soft-tissue injury. Concomitant fractures were identified in two patients. Only two fractures were typical in location and orientation at the talar neck. Three fractures were atypical in location and orientation. One occurred horizontally in the talar body and two occurred in the posteromedial talus (one was oriented vertically and one horizontally). Two patients had associated concomitant stress fracturesone in the distal tibia and one in the calcaneus. RESULTS:

CONCLUSION:

MD

The

location

and

R

of the orthopedic and radiology literature revealed 11 of talar stress fracture. The talar fracture is classically described

EVIEW

cases stress as

a fatigue

either basic in

stress

increased training.

the

fracture

literature

were

MATERIALS We

retrospectively

history

and

diagnosis and be determined

five talar

and

imaging.

evaluated between

4641.415

Ankle,

#{149}

MR. 4641.1214 #{149}Fractures, insufficiency, 4641.419 #{149} Fractures, MR. 4641.121411, 4641.121413, 4641.121415 . Osteoporosis, 4641.56

Radiology

I

From

1995;

the

197:439-442

Department

of Radiology,

Albert

Einstein College of Medicine and Montefiore Medical Center, 111 E 210th St, Bronx, NY, 10467 (H.U.); and the Department of Radiology, Hospitat for Special Surgery, New York, NY (H.P.). Received April 28, 1995; revision requested May 26; revision received June 15; accepted June 20.

Address RSNA,

reprint 1995

requests

to H.U.

typi-

and

patients. performed performed following spin-echo

fractures.

were gender,

clinical with

Patients teaching hosThe clinical

evaluated to and nature

of symptoms.

nuclear MR

medicine

images

were

bone

obtained

in all

Computed tomography (CT) was in one case. MR imaging was with a i.5-T unit by using the techniques: sagittal Ti-weighted (SE) imaging (repetition time

msec/echo

time

two

acquired)

signals

the patients

at two major i99i and i994.

duration

scans,

Ankle, fractures,

The

on

METHODS

of four

insufficiency

Radiographs, Index terms:

male.

reviewed

images

records of all patients determine their age,

can

dancing, described

AND

recognized.

Specific

to

cal stress fracture is located in the talan neck and parallels the talonaviculan articulation. Atypical stress fractures of the lateral process of the talus have also been reported. The purpose of this study was to describe the clinical setting and pattern of talan insufficiency fracture as diagnosed with magnetic resonance (MR) imaging. Herein, we describe five talar insufficiency fractures, three of which were atypical in location and orientation and all of which occurred in four female patients. All fractures were diagnosed with MR imaging.

were pitals

fractures

related

running, All patients

orientation of talar insufficiency frachires is more variable than previously coexisting with MR

Talus:

msec

sion-recovery (STIR) time msec/echo time msec = i,400/20/i30)

=

and

400-500/i3-i6,

short

tau inver-

imaging (repetition msec/inversion time or fast SE proton-

density-weighted imaging pression (3,500-4,000/i7-i9

with fat [effective

supecho

timel, two signals acquired) and T2-weighted imaging (3,500-4,000/i02 [effective echo timel, two signals acquired); coronal Tiweighted SE imaging (500/i6, one signal acquired) and/or STIR (i,200-1,400/i3-20/ i30-i40) or gradient-echo (450/20, 45#{176} flip

angle, four signals acquired) imaging; and axial Ti-weighted (600/16, one signal acquired) and/or T2-weighted fast SE (4,000-5,250/102-i two signals thickness 0.0-1.0-mm

14 [effective

echo

time],

acquired) imaging. Section varied from 3.0 to 5.0 mm with gap. A 256 x 192 matrix and

12-i4-cm field cases. An insufficiency if a linear area

of view

was

used

fracture of diminished

a a

in all

was diagnosed signal inten-

was seen within the bone with variable surrounding marrow edema, manifesting as ill-defined low signal intensity sity

on

Ti-weighted

intensity pressed

images

and

high

on STIR, T2-weighted, proton-density-weighted

The

location

and

the

and

soft-tissue

and

orientation

presence

signal

or fat-supimages. of fractures

of concomitant injury

was

osseous

noted.

RESULTS All patients were women (age range, 37-70 years). All injuries nepresented insufficiency fractures. Two of the five talar insufficiency fractures were typical in location and orientation, occurring in the talar neck and oriented parallel to the talonavicular joint. Three of the five talar insufficiency fractures were atypical in location and onientation. Two occurred in the posteromedial talus; one was oriented vertically, and one was oriented horizontally. The remaining fracture was oriented horizontally in the body of the talus. A calcaneal stress fracture occurred ipsilateral to one of the two classically oriented talar neck fractures. In the patient with bilateral talar fractures, stress fracture of the distal tibia occurred on the same side as the atypically oriented talar fracture. All four patients had osteoporosis due either to disuse or age. One 37-

a

year-old patient was a housebound agoraphobic who developed left ankle pain exacerbated by ambulation

Abbreviations: tau

inversion

SE

=

spin

echo,

STIR

=

short

recovery.

439

a.

Figure

b.

2.

Atypical orientation and location of an insufficiency fracture in the left talus of the same patient as in Figure 1. (a) Coronal Ti-weighted SE MR image (400/16) demonstrates a horizontally oriented linear fracture of tow signal intensity in the posteromedial talus (arrow). (b) Sagittat T2-weighted fast SE MR image (4,000/102) demonstrates the talar fracture (arrowhead) and a concomitant stress fracture of the distal tibia (arrow) surrounded by high-signalintensity marrow edema.

after successful treatment with antidepressants (Figs 1, 2). Symptoms abated after 2 months of limited weight bearing and nonsteroidal anti-inflammatory therapy. The second patient was 39 years old and presented 3 months postpartum with left ankle discomfort that had been gradually worsening for the previous 10 months (Fig 3). An anthrotomy was performed for resection of subtalar spurs. The third patient was a 44-year-old file clerk who had experienced 2 years of left ankle pain exacerbated after a therapeutic trial of 2 months of non-weight bearing and cast removal. After confirmation of a horizontal insufficiency fracture of the body of the talus (Fig 4), the patient was placed on 8 weeks of bedrest and the symptoms resolved. The last patient was 70 years old and had experienced left foot and ankle pain for 1 month (Fig 5).

DISCUSSION Talar stress fracture (both insufficiency and fatigue) is often a clinically elusive diagnosis owing to its extremely low prevalence, as well as to the fnequently chronic and diffuse nature of the symptoms. The clinical findings often include a variable degree of soft-tissue swelling, erythema, point tenderness, and local pain. These findings are often relieved with rest and exacerbated 440

#{149} Radiology

with

continued

activity.

Limited subtalar motion often accompanies this injury (1). An association between talar stress fracture and pes planovalgus (2) and calcaneonaviculan coalition is recognized (i), although these abnormalities were not present in our series. A review of the literature since 1965 revealed 1 1 previously reported cases in 10 patients (six male patients; the gender in four patients was not specifled). Three typical talan neck fractunes, paralleling the talonavicular joint, were reported in two men (22 and 23 years of age; fracture was bilateral in the 22-year-old patient) during basic training (1) and in a 58-year-old male long-distance runner (3). Two atypical stress fractures of the lateral process were reported: an oblique fracture in a 52-year-old male tennis player (4) and a vertical fracture in a 20-year-old male long-distance runner (5). The French and German literature (6,7) had reports of five cases of talar stress fractures diagnosed with radionuclide bone scanning; the orientation and location in the talus were not identified. One fracture was reported in a male athlete (6), whereas gender was not specified in the nemaining patients (7). Conventional radiographs are usually normal in the acute stage of talar stress fracture (fatigue and insufficiency). In cancellous bone, the earliest plain radiographic sign of stress

b.

c.

Figure 1. MR images in a 37-year-old woman with a typically oriented tatar neck insufficiency fracture parallel to the talonavicular joint. (a) Axial and (b) sagittat TI-weighted SE images (400/16) demonstrate a linear fracture of low signal intensity (arrowhead in a, arrow in b) in the right tatar neck. (c) Sagittat T2-weighted fast SE image (3,500/102 [effective echo time]) demonstrates high-signalintensity marrow edema surrounding the hypointense linear fracture (arrow).

fracture is focal linear sclerosis, typically oriented perpendicular to the trabeculae (8). The linear sclerosis is thought to reflect collapse and condensation of trabeculae, endosteal callus, and osteoblastic new bone formation for the repair of trabecular microfracture, beginning approximately 3-4 weeks after the acute injury (9). Nuclear scintigraphy may demonstrate focal increased radiotracer uptake days to weeks before an November

1995

b. Figure 3. MR images in a 39-year-old woman 3 months posteromedial talus. (a) Coronal proton-density-weighted image (4,000/114), and (c) sagittal Ti-weighted SE image talus (arrowhead in b, arrow in c). The fracture extends

c. postpartum. The patient had a vertically oriented atypical insufficiency fracture fast SE image obtained with fat suppression (4,000/19), (b) axial T2-weighted (400/16) demonstrate the vertical low-signal-intensity fracture at the posteromedial to the subtalar articutar surface (arrow in a).

a.

a.

b.

Figure tally body

4.

(a) Sagittal

oriented atypical in a 44-year-old

high-signal-intensity

and

(b) coronal

insufficiency woman. The marrow

STIR MR images fracture fracture

(arrow has low

(1,400/20/130)

in a, arrowhead signal intensity

because capability

not necessarily sensitive for diagnosis. On MR images, a fracture in cancelbus bone manifests as an irregular linear area of low signal intensity with all pulse sequences with variable surrounding bone marrow edema (iO). MR imaging is superior to CT

pattern sclerosis

197

#{149} Number

a horizontalar by

edema.

abnormality is discernible at plain radiography. The sensitivity of scmntignaphy is compromised by a lack of specificity: Similar increased radiotracer uptake may be encountered in entities such as osteomyelitis and neoplasm. In general, targeted thin-section CT (with bone algorithm) may allow specific detection of trabeculan fracture and disorganization but is

Volume

demonstrate

in b) through the and is surrounded

2

it has multiplanar imaging and provides exquisite conspicuity for bone marrow edema and soft-tissue detail. MR imaging may also be more sensitive than bone scmtigraphy in the early diagnosis of fractune, particularly in the setting of severe osteopenia (ii), advanced age or renal insufficiency In the talus, the classic

(12),

of stress fracture perpendicular

(i3). radiographic is a linear to the trabecu-

lan flow (1), paralleling the talonaviculan articulation at the talar neck (Fig 1). This classic pattern, however, was present in only two of our patients. Two case reports describe stress frac-

of the fast SE

tune of the lateral process of the talus in athletes; both cases were diagnosed with CT (4,5). Increased supination of the foot while running was hypothesized to be the reason for a concentration of forces on the lateral process of the talus (4). To our knowledge, vertically and horizontally oriented insufficiency fractures of the medial aspect of the posteroinfenion talus (Figs 2, 3) or transverse (horizontal) fractures of the talar body (Fig 4) have not been previously reported. Five of the previously reported 1 1 cases relied on bone scintigraphy; therefore, the location and orientation of the fracture could not be determined (6,7). These atypically oriented talar insufficiency fractures may remain occult on plain radiographs due to overlap of osseous structures, particularly in the region of the posterior subtalar joint and middle talocalcaneal facet. Coexisting or preexisting stress fractures of the distal tibia and calcaneus

may

occur

in

either

the

ipsi-

lateral or contralateral limb and were observed in half of our patients. Recognition of the various locations and orientation of talar insufficiency fractures is especially important in this era of cost containment, in which patient tion

“throughput” of

imaging

and time

the

(usually

neducby

limit-

ing various planes of evaluation per patient) are emphasized. It is important to perform two sequences in orthogonal planes to diagnose this injury, as the fracture could be missed if the plane of imaging is oriented parallel to the fracture plane. Radiology

e

441

:

.

4i:

;.,

,%

a.

b.

Figure the

5.

(a) Sagittal

tatonavicutar

ture

joint

of the ipsilateral

oriented

calcaneus

talar

TI-weighted (arrowhead).

catcaneus

insufficiency

(arrow).

SE MR image

Both

(b) Sagittat

(arrow).

fracture

fractures

c.

(549/14)

in a 70-year-old

proton-density-weighted

(c) Conventional

(arrowhead)

are linear

Although an atypical appearance of a common entity might not prove diagnostically elusive, an unusual manifestation of an uncommon entity might further delay a correct diagnosis. Clinical familiarity with this often nadiographically occult entity and the use of MR imaging to allow early, specific diagnosis of talan insufficiency fracture and coexisting injuries may prevent delayed diagnosis and unnecessarily prolonged patient morbidity. The pattern of talan insufficiency fractures is more variable than that of previously reported fatigue fractures. The location and orientation of the talar insufficiency fractures described as atypical in this series may actually be a “classic” finding of talar insufficiency fractune that is not yet recognized. #{149}

fast

lateral

parallel

areas

woman

to the

of sclerosis

radiograph

obtained joint

(3,500/19)

6 weeks and

perpendicular

the

5.

Assoc

Motto process Sports Black

the

1983;

concomitant

KP,

Ehlert

KJ.

process

A stress

of the

7.

stellenwert

sketettszintigraphie.

10. 11.

of

in a runner. 13.

Doury P, Pattin R, Granier F, et at. Donn#{233}es nouvelles sur tes fractures de fatigue: a propos d’une observation de fracture de fatigue bilat#{233}rale de l’astragale. Rev Rhum 1984; 51:483-486. Kirschberger R, Henning A, Graff KM. ErmUdnungsbruche bei hochleistungss-

portlern:

Sweet

und indikation

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DE, Altman

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lateral

insufficiency

the MR images

9.

Podiatr 4.

after

talar

demonstrates

to the trabecular

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November

1995