Original Report. Nontraumatic Avulsions of the Pelvis. Liem T. Bui-Mansfield 1 3 Felix S. Chew 2 Leon Lenchik 2 Mitch J. Kline 4 Carol A.

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1 Downloaded from by on 05/12/18 from IP address opyright RRS. For personal use only; all rights reserved Liem T. ui-mansfield 1 3 Felix S. hew 2 Leon Lenchik 2 Mitch J. Kline 4 arol. oles 2 Received June 4, 2001; accepted after revision ugust 23, 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 rmy or the Department of Defense. 1 Department of Radiology, Keller rmy ommunity Hospital, West Point, NY ddress correspondence to L. T. ui-mansfield. 2 Department of Radiology, Wake Forest University School of Medicine, Medical enter lvd., Winston-Salem, N Department of Radiology, Uniformed Services University of the Health Sciences, ethesda, MD Section of Musculoskeletal Radiology, Diagnostic Radiology/21, leveland linic Foundation, 9500 Euclid ve., leveland, OH JR 2002;178: X/02/ merican Roentgen Ray Society Original Report Nontraumatic vulsions of the Pelvis OJETIVE. The purpose of this report is to describe the imaging findings of nontraumatic avulsions of the pelvis. ONLUSION. 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. lso, biopsy may be considered in the proper clinical setting. I solated nontraumatic avulsion fracture of the lesser trochanter in adults (Fig. 1) 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. ll three patients had metastatic disease proven histologically or with additional imaging. 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, ll patients underwent radiography; two patients underwent T and scintigraphy, and one underwent MR imaging. Our study group included two women and one man, whose average age was 65 years. 54-yearold woman was diagnosed with adenocarcinoma of the lung with widespread bony metastases on bone scan (Fig. 2). T of the abdomen and pelvis for routine oncologic follow-up evaluation revealed that she had an avulsion fracture of the left anterosuperior iliac spine. n 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. 3). Radiographs of his pelvis showed an avulsion fracture of the right ischium. 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. 4). 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 T in two patients. Scintigraphy showed intense focal uptake in these lesions in two patients. Discussion vulsion injuries of the pelvis are common among adolescent participants in organized sports. In adolescents, muscles and tendons are stronger than the apophysis. cute 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. JR:178, February

2 ui-mansfield et al. Downloaded from by on 05/12/18 from IP address opyright RRS. For personal use only; all rights reserved Fig 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., Oblique coronal T1-weighted MR image shows hypointense lesion (arrowhead ) in proximal femur involving lesser trochanter., Oblique coronal T2-weighted MR image shows abnormal hyperintense lesion (arrow) in proximal femur involving lesser trochanter, consistent with bony metastasis. Fig year-old woman with breast cancer who was recently diagnosed with adenocarcinoma of lung., nterior scintigraphic image of pelvis shows multiple sites of intense focal uptake, consistent with metastases., xial T 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., nteroposterior radiograph of pelvis obtained 2 weeks after T of abdomen and pelvis shows pathologic fractures in left iliac crest extending through anterosuperior iliac spine and right superior and inferior pubic rami. dditional 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. 424 JR:178, February 2002

3 Nontraumatic vulsions of the Pelvis Downloaded from by on 05/12/18 from IP address opyright RRS. For personal use only; all rights reserved Fig 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)., nteroposterior radiograph of pelvis shows avulsion fracture of right ischium (arrow)., xial T image of pelvis reveals sclerotic metastasis in right ischial tuberosity. Lytic area (arrow) is caused by bony resorption adjacent to avulsion fracture. hronic avulsion fractures are the result of repetitive microtrauma or overuse of the tendons. ecause 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 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, ertin 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 ertin 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. carefully directed nonoperative treatment program is the therapy of choice for avulsion fractures of the pelvis in adolescents [10]. In the series of ertin 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 re- JR:178, February

4 ui-mansfield et al. Downloaded from by on 05/12/18 from IP address opyright RRS. For personal use only; all rights reserved Fig year-old woman with non-hodgkin s lymphoma who presented with right hip pain., nteroposterior radiograph of pelvis shows lytic destruction of right superior and inferior pubic 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., Oblique radiograph of right hip reveals avulsion fracture of right anteroinferior iliac spine (arrow)., oronal T1-weighted MR image of pelvis shows tumor infiltration of entire right pelvic bone and right proximal femur. quired [1]. nother 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]. fter 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). ll 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 T) 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. 426 JR:178, February 2002

5 Nontraumatic vulsions of the Pelvis Downloaded from by on 05/12/18 from IP address opyright RRS. For personal use only; all rights reserved 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. iopsy may be considered in the proper clinical setting. cknowledgments We thank Ellen Henson and Debbie Parker for their assistance with the photographs. References 1. ertin K, Horstman J, oleman SS. Isolated fracture of the lesser trochanter in adults: an initial manifestation of metastatic malignant disease. J one Joint Surg m 1984;66: Phillips D, Pope TL Jr, Jones JE, Keats TE, MacMillan RH 3rd. Nontraumatic avulsion of the lesser trochanter: a pathognomonic sign of metastatic disease? Skeletal Radiol 1988;17: Stevens M, El-Khoury GY, Kathol MH, randser E, how S. Imaging features of avulsion injuries. RadioGraphics 1999;19: arnes ST, Hinds R. Pseudotumor of the ischium. late manifestation of avulsion of the ischial epiphysis. J one Joint Surg m 1972;54: Finby N, egg F. Traumatic avulsion of ischial epiphysis simulating neoplasm. NY State J Med 1967;67: Rogge E, Romano RL. vulsion of the ischial apophysis. J one Joint Surg m 1956;38: Fernbach SK, Wilkinson RH. vulsion injuries of the pelvis and proximal femur. JR 1981;137: Sundar M, arty H. vulsion fractures of the pelvis in children: a report of 32 fractures and their outcome. Skeletal Radiol 1994;23: Wilkinson RH. vulsion injuries of the lesser trochanter. Skeletal Radiol 1979;4: Metzmaker JN, Pappas M. ase report 90: avulsion fractures of the pelvis. m J Sports Med 1985; 13: Sim FH. Metastatic bone disease of the pelvis and femur. Instr ourse Lect 1992;41: RRS 2002 nnual Meeting provides a forum to report, exchange, and disseminate new developments in radiology. It will be held pril 28-May 3 in tlanta. Log on to for further information. JR:178, February