AJR 2003; 181:223-230
© American Roentgen Ray Society
Comparing Sonography with MR Imaging of Apophyseal Injuries of the Pelvis in Four Boys
Robin Miller Pisacano1 and
Theodore T. Miller
1 Both authors: Department of Radiology, North Shore University Hospital, 825
Northern Blvd., Great Neck, NY 11021.
Received August 7, 2002;
accepted after revision December 6, 2002.
Presented at the annual meeting of the American Roentgen Ray Society,
Atlanta, April–May 2002.
Address correspondence to T. T. Miller.
Abstract
OBJECTIVE. The purpose of this article is to describe the
sonographic appearance of avulsion of the apophyses of the anterosuperior and
anteroinferior iliac spines of the pelvis.
CONCLUSION. Sonography can show apophyseal injuries of the pelvis
and can be used instead of MR imaging.
Introduction
Avulsion injuries of the pelvis, although rare in adults, are common among
adolescents [1]. In the
skeletally immature athlete, the physis is the weakest component of the
muscle-to-tendon-to-bone complex
[2], and the powerful muscular
contraction that occurs in sports such as soccer, gymnastics, or sprinting can
result in avulsion of the attached pelvic apophysis
[1]. Such an avulsion is a
Salter-Harris type I fracture.
Although radiography and MR imaging are often used for the detection of
suspected avulsion of the pelvic apophyses, sonography can also show
apophyseal avulsion and other physeal and epiphyseal injuries
[3–5].
The purpose of this article is to describe the sonographic appearances of
pelvic apophyseal avulsion in four patients.
Subjects and Methods
Four boys, from 13 to 15 years old, experienced acute hip pain during
sports activities. Three were injured while kicking a soccer ball, and the
fourth was injured while sprinting. Radiography was performed in three of the
patients within 2 days of the injury and was not performed in the fourth
patient because the diagnosis of apophyseal avulsion was not considered
clinically. In two of the three patients, the radiographic findings were
normal; in the third patient, the avulsion was apparent but was misinterpreted
as a periosteal reaction at the facility in which radiography was performed,
and the patient was therefore referred to our facility for MR imaging of a
suspected pelvic tumor. The other three patients were referred for MR imaging
of a clinically suspected injury to the muscle or tendon.
MR imaging of the pelvis was performed on a Signa 1.5-T scanner (General
Electric Medical Systems, Milwaukee, WI) in the axial and coronal planes in
all four patients and additionally in the sagittal plane in two of them. A
large flexible wraparound coil, placed around the pelvis, was used in all four
patients. The imaging sequences consisted of spin-echo T1-weighted images
using a TR range/TE range of 450–700/15–16 and fast spin-echo
T2-weighted images using a TR range/TEeff range of
3000–5000/45–56 and an echo-train length of 8 with
frequency-selective fat-suppression. The slice thickness varied from 3.0 to
5.0 mm without an interslice gap; the field of view was 24–38 cm; the
matrix was 256 x 192; and the number of excitations was 1–2.
Gray-scale and power Doppler sonography were performed with parental
consent on an HDI-3000 unit (ATL, Bothel, WA) using either 12-5– or
7-4–MHz linear probes. Sonography was performed before MR imaging in two
patients and afterward in two patients, all by the same radiologist who knew
the patients' clinical histories. Both the symptomatic and contralateral
asymptomatic sides of the pelvis were imaged with gray-scale and power Doppler
sonography in all four patients. The patients were in the supine position, and
the transducer was placed over their site of pain. Longitudinal and transverse
images were obtained, slightly angling the transducer to best show the
relationship of the apophysis to the pelvis. Power Doppler sonography used a
low or medium filter and a pulse repetition frequency of 700–1000 Hz,
and color gain was adjusted to have an absence of flow within normal bone.
Sonography and MR imaging were performed on the same day in each patient,
which was from 4 days to 2 months after the initial injury.
Results
The anteroinferior iliac spine was involved in three patients, and the
anterosuperior iliac spine was involved in one patient
(Table 1). Radiographic
findings in two of the three patients were normal. Avulsions were identified
on both MR imaging and sonography in all patients. Sonographically, the
avulsions were manifest as widening of the physis or frank displacement of the
apophysis compared with the asymptomatic contralateral side, with hypoechoic
or mixed echogenic edema or hemorrhage in the widened space (Figs.
1A,
1B,
1C,
1D,
1E,
1F,
1G,
1H,
2A,
2B,
2C,
2D,
2E,
2F,
2G,
3A,
3B,
3C,
3D,
3E,
3F,
3G). Similar widening or
displacement was visible on MR imaging, with high signal intensity in the
avulsed space on the fat-suppressed T2-weighted sequences. Power Doppler
sonography was performed in all four patients and showed hyperemia compared
with the contralateral side in three of the four patients; the patient who was
imaged 2 months after the initial injury (Figs.
4A,
4B,
4C,
4D,
4E) lacked hyperemia.
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Fig. 1A. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 14 days after injury. Anteroposterior radiograph of
pelvis (A) and coned radiographic view of symptomatic right side
(B) obtained 1 day after injury show no abnormality.
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Fig. 1B. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 14 days after injury. Anteroposterior radiograph of
pelvis (A) and coned radiographic view of symptomatic right side
(B) obtained 1 day after injury show no abnormality.
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Fig. 1C. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 14 days after injury. Sagittal fat-suppressed fast
spin-echo T2-weighted MR image (TR/TE, 4400/52; echo train length, 8) of
asymptomatic side shows normal anteroinferior iliac spine (large
arrow) and rectus femoris tendon (small arrow).
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Fig. 1D. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 14 days after injury. Sagittal fat-suppressed fast
spin-echo T2-weighted MR image (4400/52; echo-train length, 8) of symptomatic
side shows widening of physis (large arrow). Note
high-signal-intensity edema and hemorrhage (small arrows) in gap and
surrounding soft tissues.
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Fig. 1E. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 14 days after injury. Longitudinal sonogram of
asymptomatic side shows rectus femoris tendon (R) arising from normal
anteroinferior iliac spine (S), apophysis of which is thin echogenic line
(curved arrow) closely apposed to anteroinferior iliac spine.
Hypoechoic region between tendon and apophysis is due to anisotropy of tendon.
Note echogenic cortex (straight arrow) of femoral head.
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Fig. 1F. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 14 days after injury. Longitudinal sonogram of
symptomatic side shows widening of physis with heterogeneous echogenicity
(arrow) in gap.
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Fig. 1G. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 14 days after injury. Power Doppler sonogram
obtained through left anteroinferior iliac spine shows normal background
flow.
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Fig. 1H. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 14 days after injury. Power Doppler sonogram
obtained through avulsed right anteroinferior iliac spine shows marked
hyperemia in widened apophysis and surrounding soft tissues.
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Fig. 2A. —14-year-old boy injured while sprinting. MR imaging and
sonography were performed 4 days after injury. Anteroposterior radiograph of
pelvis (A) and coned radiographic view of symptomatic left side
(B) obtained 2 days after injury show ill-defined density adjacent to
anterosuperior iliac spine (arrows, B), which was
misinterpreted as periosteal reaction, for which patient was referred for
additional imaging.
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Fig. 2B. —14-year-old boy injured while sprinting. MR imaging and
sonography were performed 4 days after injury. Anteroposterior radiograph of
pelvis (A) and coned radiographic view of symptomatic left side
(B) obtained 2 days after injury show ill-defined density adjacent to
anterosuperior iliac spine (arrows, B), which was
misinterpreted as periosteal reaction, for which patient was referred for
additional imaging.
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Fig. 2C. —14-year-old boy injured while sprinting. MR imaging and
sonography were performed 4 days after injury. Axial fat-suppressed fast
spin-echo T2-weighted MR image (TR/TE, 3200/52; echo-train length, 8) obtained
through pelvis at level of anterosuperior iliac spine shows normal right side
(curved solid arrow), avulsed and laterally displaced left
anterosuperior iliac spine, and attached sartorius tendon (curved open
arrow) with marked edema and hemorrhage (straight arrow) in
surrounding soft tissues.
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Fig. 2D. —14-year-old boy injured while sprinting. MR imaging and
sonography were performed 4 days after injury. Transverse sonogram of
asymptomatic right side shows normal apophysis (arrow) and
anterosuperior iliac spine (S).
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Fig. 2E. —14-year-old boy injured while sprinting. MR imaging and
sonography were performed 4 days after injury. Transverse sonogram of left
symptomatic side shows avulsed and displaced left apophysis (arrow).
S = anterosuperior iliac spine.
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Fig. 2F. —14-year-old boy injured while sprinting. MR imaging and
sonography were performed 4 days after injury. Power Doppler sonogram of
normal anterosuperior iliac spine shows normal background flow.
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Fig. 2G. —14-year-old boy injured while sprinting. MR imaging and
sonography were performed 4 days after injury. Power Doppler sonogram of
affected side shows hyperemia surrounding avulsed apophysis.
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Fig. 3A. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 4 days after injury. Anteroposterior radiograph of
pelvis (A) and coned radiographic view of symptomatic right side
(B) obtained 1 day after injury show no abnormality.
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Fig. 3B. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 4 days after injury. Anteroposterior radiograph of
pelvis (A) and coned radiographic view of symptomatic right side
(B) obtained 1 day after injury show no abnormality.
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Fig. 3C. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 4 days after injury. Axial fat-suppressed fast
spin-echo T2-weighted MR image (TR/TE, 4500/52, echo-train length, 8) obtained
through pelvis at level of anteroinferior iliac spine shows widening
(arrow) of avulsed right side.
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Fig. 3D. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 4 days after injury. Longitudinal sonogram of
asymptomatic left side shows normal apophysis (curved arrow)
overlying anteroinferior iliac spine (S). Note echogenic cortex (straight
arrow) of femoral head.
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Fig. 3E. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 4 days after injury. Longitudinal sonogram of right
symptomatic side shows displacement of avulsed apophysis (white
arrow) from underlying anteroinferior iliac spine (S) and widening of
physis (black arrow).
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Fig. 3F. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 4 days after injury. Power Doppler sonogram of
normal anteroinferior iliac spine shows normal background flow.
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Fig. 3G. —13-year-old boy injured while playing soccer. MR imaging and
sonography were performed 4 days after injury. Power Doppler sonogram of
avulsed anteroinferior iliac spine shows hyperemia in apophysis and
surrounding soft tissues.
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Fig. 4A. —15-year-old boy injured while playing soccer. MR imaging and
sonography were performed 60 days after injury. Axial fat-suppressed fast
spin-echo T2-weighted MR image (TR/TE, 4000/56; echo-train length, 8) obtained
through pelvis at level of anteroinferior iliac spine shows widening
(arrow) of avulsed right side.
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Fig. 4B. —15-year-old boy injured while playing soccer. MR imaging and
sonography were performed 60 days after injury. Sagittal fat-suppressed fast
spin-echo T2-weighted MR image (400/48; echo-train length, 8) of symptomatic
side shows widening of physis (arrow). Note absence of edema and
hemorrhage in adjacent soft tissues.
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Fig. 4C. —15-year-old boy injured while playing soccer. MR imaging and
sonography were performed 60 days after injury. Longitudinal sonogram of
asymptomatic left side shows normal apophysis (arrow) overlying
anteroinferior iliac spine (S).
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Fig. 4D. —15-year-old boy injured while playing soccer. MR imaging and
sonography were performed 60 days after injury. Longitudinal sonogram of right
symptomatic side shows displacement of avulsed apophysis (curved
arrow) from underlying anteroinferior iliac spine (S) and widening of
physis (straight arrow).
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Fig. 4E. —15-year-old boy injured while playing soccer. MR imaging and
sonography were performed 60 days after injury. Power Doppler sonogram of
avulsed anteroinferior iliac spine shows no hyperemia.
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Discussion
A combination of decreased elasticity of physeal cartilage, hormonal
influence, and variation in apophyseal ossification results in the apophysis
being most susceptible to injury in patients between puberty and 25 years old
[2,
3]. During this time, a sudden
strong contraction of the attached musculotendinous unit can result in
avulsion of the apophysis [1,
3]. The rectus femoris muscle
originates from the anteroinferior iliac spine, whereas the tensor fascia lata
and the sartorius muscles originate from the anterosuperior iliac spine.
Sports activities such as sprinting and soccer that involve forceful
contraction of these hip flexors predispose adolescent patients to avulsion
injuries of the anterosuperior iliac spine and the anteroinferior iliac spine
[6].
The anteroinferior iliac spine was the site of injury in three of our four
patients and the anterosuperior iliac spine, in one patient. Rossi and Dragoni
[1] reported 203 pelvic
avulsion fractures in 198 individuals with an average age of 14 years and
found the ischial tuberosity to be the most commonly injured site, followed by
the anteroinferior iliac spine and the anterosuperior iliac spine. In
contrast, the anterosuperior iliac spine was the most common site affected in
62 cases of pelvic avulsion reported by Lazovic et al.
[3], followed by the
anteroinferior iliac spine and the ischial tuberosity. Soccer was responsible
in all three patients for injury of the anteroinferior iliac spine in our
series, paralleling the findings of Rossi and Dragoni.
A conventional anteroposterior radiograph of the pelvis should be the first
imaging study for patients suspected of having these injuries because the
diagnosis of avulsion injury may be determined without further imaging.
However, apophyseal avulsions may be radiographically occult if the apophysis
is not ossified or only minimally so. Even a displaced ossified apophysis may
be obscured by the underlying bony pelvis
[3,
7]. Conventional radiographs
were obtained in three of the four patients but showed the abnormality in one
patient only. Hence, the radiographic findings can be negligible despite the
fact that an avulsion has occurred. Although MR imaging can reveal these
injuries, sonography is advantageous because of its faster examination time
and decreased cost. Sonography showed the apophyseal injuries in all four of
our patients.
Although this is a small series, our findings are consistent with those of
Lazovic et al. [3], who
described the use of sonography for showing apophyseal injuries, 62 of which
occurred in the pelvis, in 243 individuals. Our study used three of the four
criteria that Lazovic et al. used, including a hypoechoic zone in the region
of the apophysis extending to the surrounding soft tissue, representing edema
or hemorrhage; widening of the normally hypoechoic physis between the
apophysis and the pelvis; and tilting and dislocation of the apophysis.
Although these authors also used mobility of the apophysis on dynamic imaging
as a fourth criterion, we instead used power Doppler sonography and found
hyperemia in the affected region in the three acute cases. Hyperemia was not
present in the patient who underwent imaging 2 months after injury, suggesting
that power Doppler sonography may not be helpful in chronic injuries. However,
a larger number of subjects with chronic injury would be needed to confirm
this observation. Furthermore, if the sonographic findings are normal or
equivocal and the patient continues to have symptoms, MR imaging may be
required for additional evaluation.
In conclusion, sonography can show apophyseal injuries of the pelvis.
Sonography should be considered an alternative imaging modality to MR imaging
in patients in whom conventional radiography fails to reveal a clinically
suspected avulsion.
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Abstract
Introduction
