AJR 2002; 178:423-427
© American Roentgen Ray Society
Nontraumatic Avulsions of the Pelvis
Liem T. Bui-Mansfield1,2,3,
Felix S. Chew2,
Leon Lenchik2,
Mitch J. Kline4 and
Carol A. Boles2
1
Department of Radiology, Keller Army Community Hospital, West Point, NY
10996.
2
Department of Radiology, Wake Forest University School of Medicine, Medical
Center Blvd., Winston-Salem, NC 27157-1088.
3
Department of Radiology, Uniformed Services University of the Health Sciences,
Bethesda, MD 20814-4799.
4
Section of Musculoskeletal Radiology, Diagnostic Radiology/A21, Cleveland
Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195.
Received June 4, 2001;
accepted after revision August 23, 2001.
The opinions and assertions contained herein are those of the authors and
should not be construed as official or as representing the opinions of the
Department of the Army or the Department of Defense.
Address correspondence to L. T. Bui-Mansfield.
ARRS 2002 Annual Meeting provides a forum to report, exchange, and
disseminate new developments in radiology. It will be held April 28-May 3 in
Atlanta. Log on to www.arrs.org for further information.
Abstract
OBJECTIVE. The purpose of this report is to describe the imaging
findings of nontraumatic avulsions of the pelvis.
CONCLUSION. A diagnosis of avulsion fracture of the pelvis in an
adult without appropriate history of substantial trauma must raise the
suspicion of an underlying malignancy. If a patient has not been diagnosed as
having a primary neoplasm, additional imaging evaluation is recommended. Also,
biopsy may be considered in the proper clinical setting.
Introduction
Isolated nontraumatic avulsion fracture of the lesser trochanter in adults
(Fig.
1A,1B,1C)
has been recognized as a pathognomonic sign of metastatic disease
[1,
2]. To our knowledge,
pathologic avulsion of the pelvic bones has not been reported. We present
three cases of pathologic avulsions of the pelvis, involving the
anterosuperior iliac spine, the anteroinferior iliac spine, and the ischial
tuberosity. All three patients had metastatic disease proven histologically or
with additional imaging.
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Fig. 1A. —57-year-old woman with breast cancer, from our case files,
who presented with left hip pain. Oblique radiograph of left hip joint reveals
avulsion fracture (arrow) of lesser trochanter.
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Fig. 1B. —57-year-old woman with breast cancer, from our case files,
who presented with left hip pain. Oblique coronal T1-weighted MR image shows
hypointense lesion (arrowhead) in proximal femur involving lesser
trochanter.
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Fig. 1C. —57-year-old woman with breast cancer, from our case files,
who presented with left hip pain. Oblique coronal T2-weighted MR image shows
abnormal hyperintense lesion (arrow) in proximal femur involving
lesser trochanter, consistent with bony metastasis.
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Materials and Methods
We retrospectively reviewed the medical records of three patients with
pathologic avulsion fracture of the pelvic bones who were seen between July 1,
1999, and June 30, 2000. All patients underwent radiography; two patients
underwent CT and scintigraphy, and one underwent MR imaging.
Our study group included two women and one man, whose average age was 65
years. A 54-year-old woman was diagnosed with adenocarcinoma of the lung with
widespread bony metastases on bone scan (Fig.
2A,2B,2C).
CT of the abdomen and pelvis for routine oncologic follow-up evaluation
revealed that she had an avulsion fracture of the left anterosuperior iliac
spine. An 81-year-old man with adenocarcinoma of the prostate underwent
whole-body bone scanning before surgery that revealed a focal increased uptake
in the right ischial tuberosity (Fig.
3A,3B,3C).
Radiographs of his pelvis showed an avulsion fracture of the right ischium. A
59-year-old woman with non-Hodgkin's lymphoma complained of right hip pain.
Radiographs of the pelvis revealed lytic destructive lesions involving the
right superior and inferior pubic rami and an avulsion fracture of the right
anteroinferior iliac spine (Fig.
4A,4B,4C).
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Fig. 2A. —54-year-old woman with breast cancer who was recently
diagnosed with adenocarcinoma of lung. Anterior scintigraphic image of pelvis
shows multiple sites of intense focal uptake, consistent with metastases.
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Fig. 2B. —54-year-old woman with breast cancer who was recently
diagnosed with adenocarcinoma of lung. Axial CT image of pelvis reveals
multiple sclerotic bony metastases (thin arrows) involving right half
of sacrum and left anterosuperior iliac spine, which has an avulsion fracture.
Radiolucent defect in left ilium (thick arrow) is site of bone graft
obtained for prior lumbar spine fusion.
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Fig. 2C. —54-year-old woman with breast cancer who was recently
diagnosed with adenocarcinoma of lung. Anteroposterior radiograph of pelvis
obtained 2 weeks after CT of abdomen and pelvis shows pathologic fractures in
left iliac crest extending through anterosuperior iliac spine and right
superior and inferior pubic rami. Additional sclerotic bony metastases can be
seen in right anterior iliac spine, left ilium, and right half of sacrum
(arrowheads). Screws from prior spinal fusion are seen in L4-5 disk
space.
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Fig. 3A. —81-year-old man with elevated serum prostate-specific antigen
whose biopsy of prostate revealed adenocarcinoma. Posterior scintigraphic
image of pelvis reveals focal increased uptake in right ischial tuberosity
(arrowhead).
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Fig. 3B. —81-year-old man with elevated serum prostate-specific antigen
whose biopsy of prostate revealed adenocarcinoma. Anteroposterior radiograph
of pelvis shows avulsion fracture of right ischium (arrow).
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Fig. 3C. —81-year-old man with elevated serum prostate-specific antigen
whose biopsy of prostate revealed adenocarcinoma. Axial CT image of pelvis
reveals sclerotic metastasis in right ischial tuberosity. Lytic area
(arrow) is caused by bony resorption adjacent to avulsion
fracture.
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Fig. 4A. —59-year-old woman with non-Hodgkin's lymphoma who presented
with right hip pain. Anteroposterior radiograph of pelvis shows lytic
destruction of right superior and inferior public rami. The right acetabulum
was sclerotic with cortical irregularity in right anteroinferior iliac spine
(arrow). Surgical staples are from recent surgical biopsy of right
anterosuperior iliac spine.
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Fig. 4B. —59-year-old woman with non-Hodgkin's lymphoma who presented
with right hip pain. Oblique radiograph of right hip reveals avulsion fracture
of right anteroinferior iliac spine (arrow).
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Fig. 4C. —59-year-old woman with non-Hodgkin's lymphoma who presented
with right hip pain. Coronal T1-weighted MR image of pelvis shows tumor
infiltration of entire right pelvic bone and right proximal femur.
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Results
Two of the three patients were symptomatic at the time of diagnosis of
avulsion fracture of the pelvis. The avulsion fractures were found in
different locations in these three patients, including the anterosuperior
iliac spine (n = 1), ischial tuberosity (n = 1), and
anteroinferior iliac spine (n = 1). One patient had histologic
confirmation of metastatic disease. The avulsion fractures were diagnosed by
pelvis radiographs in two patients and found on CT in two patients.
Scintigraphy showed intense focal uptake in these lesions in two patients.
Discussion
Avulsion injuries of the pelvis are common among adolescent participants in
organized sports. In adolescents, muscles and tendons are stronger than the
apophysis. Acute avulsion fractures of the pelvis result from extreme,
unbalanced, and eccentric muscular contractions
[3]. Usually, there is a clear
history because the injury is abrupt, occurring during the activity.
Chronic avulsion fractures are the result of repetitive microtrauma or
overuse of the tendons. Because no history of a specific traumatic event is
present, the radiographic findings of chronic avulsion injuries can be
confusing and may mimic tumors, such as osteochondroma and Ewing's sarcoma, or
infection
[4,5,6].
In an early study of avulsion injuries of the pelvis and proximal femur, 19
of 20 patients were men. The one woman was struck by an automobile
[7]. In that study,
distribution of the avulsion fracture by sites in descending order of
frequency was ischium (n = 6), lesser trochanter (n = 5),
anterosuperior iliac spine (n = 4), anteroinferior iliac spine
(n = 4), and iliac crest (n = 1). The iliac crest,
anterosuperior iliac spine, anteroinferior iliac spine, and ischial tuberosity
are the origin of the transverse abdominal and internal oblique abdominal
muscles, sartorius muscle, rectus femoris muscle, and hamstrings muscles,
respectively. The iliac crest, greater trochanter, and lesser trochanter are
the site of insertion of the external oblique abdominal muscle, gluteus medius
muscle, and iliopsoas muscle, respectively
[7].
In a subsequent report of avulsion fractures of the pelvis in children, 33%
of the patients were girls, which may reflect an increased participation by
girls in sports. The children's ages ranged from 11 to 16 years (mean age,
13.8 years). The distribution of the avulsion fracture by sites was ischial
tuberosity (n = 17), anteroinferior iliac spine (n = 8), and
anterosuperior iliac spine (n = 7). Seven patients (28%) had multiple
or bilateral avulsion injuries
[8].
To our knowledge, Bertin et al.
[1] were the first researchers
to recognize that isolated fracture of the lesser trochanter in an adult in
the absence of appropriate trauma was an initial manifestation of metastatic
malignant disease. Phillips et al.
[2] reported additional cases
in adults, supporting the conclusion of Bertin et al. that nontraumatic
avulsion of the lesser trochanter is a pathognomonic sign of metastatic
disease.
Pathologic avulsions of the apophysis of the lesser trochanter, caused by
either infection or tumor, have been reported in children
[9]. The metastatic disease
weakened the bone, resulting in pathologic avulsion fracture of the lesser
trochanter. Identification of this lesion and recognition of its implications
by the radiologist and the referring physician have important bearing on the
selection of proper therapy. A carefully directed nonoperative treatment
program is the therapy of choice for avulsion fractures of the pelvis in
adolescents [10].
In the series of Bertin et al.
[1], the first three patients
developed pathologic subtrochanteric fractures after the diagnosis of isolated
avulsion fracture of the lesser trochanter, requiring open reduction and
internal fixation. The fourth patient underwent prophylactic internal fixation
and had no pathologic fracture on follow-up. If chemotherapy and radiation
therapy cannot achieve local control of the tumor, a total hip replacement may
be required [1]. Another reason
to be aware of this lesion is that a life-threatening hemorrhage can occur
during biopsy or any kind of orthopedic procedure in a patient with a lesion
that is metastatic to bone
[1].
After the vertebral column, the pelvis is the second most common site for
osseous metastasis, and 40% of bony metastases occur in the pelvis
[11]. To our knowledge,
pathologic avulsion fractures of the pelvis have not been previously
described. Our study included patients whose ages ranged from 54 to 81 years
(mean age, 65 years). All had a known diagnosis of malignancy at the time of
diagnosis of avulsion fracture of the pelvis. Two patients were symptomatic,
complaining of pain. One patient had histologic confirmation of tumor
infiltration; the remaining patients had further diagnostic imaging findings
(scintigraphy, MR imaging, and CT) consistent with bony metastases at the site
of avulsion. Similar to an avulsion of the lesser trochanter, metastatic tumor
presumably weakens the involved bone, which is then susceptible to avulsion
fracture under normal stresses. The pathologic avulsion fractures in the cases
we highlight occurred at the origin of the sartorius, rectus femoris, and
hamstring muscles.
In conclusion, a diagnosis of an avulsion fracture of the pelvis in an
adult who has no history of substantial trauma must raise the suspicion of an
underlying malignancy. If a patient has not been diagnosed as having a primary
neoplasm, additional imaging evaluation is recommended. Biopsy may be
considered in the proper clinical setting.
Acknowledgments
We thank Ellen Henson and Debbie Parker for their assistance with the
photographs.
References
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Abstract
Introduction
