Pediatr Radiol DOI 10.1007/s00247-014-2960-x

CASE REPORT

Ischial apophyseal fracture in an abused infant Sarah D. Bixby & Celeste R. Wilson & Ignasi Barber & Paul K. Kleinman

Received: 11 October 2013 / Revised: 29 January 2014 / Accepted: 28 February 2014 # Springer-Verlag Berlin Heidelberg 2014

Abstract We report a previously healthy 4-month-old who presented to the hospital with leg pain and swelling and no history of trauma. Radiographs demonstrated a comminuted left femur fracture. Given the concern for child abuse, skeletal survey was performed and revealed four vertebral compression deformities. Although abuse was suspected, the possibility of a lytic lesion associated with the femur fracture and multiple spinal abnormalities raised the possibility of an underlying process such as Langerhans cell histiocytosis. Subsequently 18F-NaF positron emission tomographic (PET) scintigraphy revealed increased tracer activity in the ischium, and MRI confirmed an ischial apophyseal fracture. Pelvic fractures, particularly ischial fractures, are extremely rare in the setting of child abuse. This case report describes the multimodality imaging findings of an ischial fracture in an abused infant. Keywords Ischial apophysis . Magnetic resonance imaging . Positron emission tomography . Radiography . Fracture . Child abuse . Infant

Introduction Pelvic fractures rarely occur in the setting of child abuse. A review of the literature revealed only sporadic reports of pelvic fractures in children related to abuse [1–4]. In infants S. D. Bixby (*) : P. K. Kleinman Department of Radiology, Boston Children’s Hospital, 300 Longwood Ave., Boston, MA 02115, USA e-mail: [email protected] C. R. Wilson Child Protection Program, Department of Pediatrics, Boston Children’s Hospital, Boston, MA, USA I. Barber Department of Pediatric Radiology, Hospital Vall d’Hebrόn, Barcelona, Spain

the imaging findings are often subtle and usually involve the superior pubic ramus [1]. In older children abusive pelvic fractures are usually caused by high-force blunt trauma, sometimes in association with sexual assaults, and the injuries tend to be gross and varied in location [1, 4]. The ischium is an extremely uncommon location for abusive injury [1, 2, 5]. We report the imaging findings of a rare ischial apophyseal fracture in an abused infant.

Case report A 4-month-old girl was brought to the Emergency Department with concern for left lower extremity pain and swelling. According to the mother, the baby grew fussy 1 day earlier, though no witnessed traumatic event was described. The fussiness continued, and the left thigh appeared swollen the next day. The baby also had vomiting and diarrhea attributed to a “GI bug,” but there was no history of fever. Physical examination revealed a sleeping but easily aroused infant. The girl was afebrile and vital signs were normal. The most notable finding was swelling of the left thigh with tenderness to palpation and passive movement. The right lower extremity was without tenderness or limitations in range of motion. The remainder of the physical exam was within normal limits. Anteroposterior (AP) and lateral radiographs of the left femur revealed a severely comminuted, displaced left femur fracture (Fig. 1). Laboratory studies including complete blood count, liver enzymes, calcium, phosphate, and vitamin D were all normal except for mildly elevated white blood cell count (18.8 K cells/μL; normal 6.8–12.8). Because multiple other fractures were found in the infant and there was also a maternal history of 11 fractures, a genetics consult was requested to exclude conditions that increase fracture risk. Serum COL1A1/2 genetic testing revealed no mutations that would suggest either osteogenesis imperfecta or Ehlers–Danlos syndrome type VII,

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Fig. 1 Radiography in a 4-month-old girl who presented with leg pain and swelling. Anteroposterior radiograph of the left femur (cropped to the distal femur only) demonstrates a comminuted fracture of the distal left femoral metaphysis. The femoral shaft has telescoped into the metaphysis. There is the suggestion of an underlying intramedullary lucency, raising concerns of a pathological fracture (arrows)

and the consulting geneticist found no clinical stigmata of osteogenesis imperfecta. In addition to the left femoral fracture, a skeletal survey performed in accordance with American College of Radiology guidelines revealed compression deformities of the T8, T9, T11 and T12 vertebral bodies. Of note, the right ischium appeared normal on initial skeletal survey (Fig. 2). Apparent medullary radiolucency adjacent to the femoral fracture site and the multiple spinal deformities raised concern for an underlying pathological process such as Langerhans cell histiocytosis. In light of this concern dedicated CT of the distal left femur was performed; it showed no evidence of a lytic lesion. A head CT was normal. Given the strong clinical concern for inflicted trauma, an MRI of the brain was

Fig. 2 Radiography of the femur and pelvis area in a 4-month-old girl. a Anteroposterior (AP) radiograph of the right femur (cropped to the right hip) from the initial skeletal survey demonstrates a normal right ischium.

performed to exclude neurological injury. It revealed mild asymmetry of the lateral ventricles and slight enlargement of the bifrontal arachnoid spaces, which was within normal variation. MRI of the spine performed to evaluate for spinal cord compromise and pathological vertebral lesions confirmed the vertebral compression fractures noted radiographically and also identified bone marrow edema within L1, L2, L3, S3 and S4. Two days after the infant was admitted an 18F-NaF PET whole-body bone scan was performed. The study demonstrated minimally increased uptake at the site of distal left femur fracture, increased activity in four thoracic vertebral bodies corresponding to the radiographically evident compression fractures, and increased bone turnover in the right ischium (Fig. 3). Five days after presentation an MRI of the lower extremities was performed to rule out concerns for a pathological marrow process that could explain the left femur fracture. No underlying process was identified, though a fracture was detected in the right ischial tuberosity abutting the cartilaginous apophysis with surrounding marrow and soft-tissue edema (Fig. 4). Evolving sclerosis at the site of the healing ischial fracture could be seen on 2-week follow-up skeletal survey (Fig. 1). A mandated report was filed with state child protective services (CPS). In the CPS investigation it was disclosed that the father, who did not live in the home, had visited on the evening before presentation and was caring for the child while the mother slept. CPS assumed emergency custody and the infant was placed in kinship foster care.

Discussion This case demonstrates a rare ischial apophyseal fracture in an infant with multiple other abusive injuries. Review of the literature reveals only sporadic cases of pelvic fractures in abused children. A large study of 930 children undergoing skeletal surveys for suspected abuse identified only one pelvic

b Cropped AP radiograph of the pelvis from 2-week follow-up skeletal survey reveals interval sclerosis at the right ischium (arrow), consistent with fracture healing

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Fig. 3 Positron emission tomography (PET) in a 4-month-old girl. Two days after the girl presented with leg pain and swelling, 18F-NaF PET bone scan demonstrates areas of increased bone turnover in the right ischium (short arrow) and within four thoracic vertebral bodies corresponding to T8, T9, T11 and T12. Only mildly increased activity is noted at the site of the known comminuted femur fracture (long arrow). There is mildly increased activity within the left femoral diaphysis proximal to the fracture (likely secondary to hyperemia or stress changes) Fig. 4 MRI of the pelvis and bilateral femurs in the same 4month-old girl. a Axial T2weighted fat-suppressed image of the bilateral femurs demonstrates increased signal intensity within the right ischial apophysis (arrow) as well as the adjacent bone marrow and soft tissues (arrowhead). b Sagittal STIR image of the right pelvis demonstrates increased signal intensity within the ischium and soft tissues adjacent to the ischial apophysis (arrowhead). There is mild posterior and caudal displacement of the ischial apophysis (arrow). Bl denotes the bladder. c Sagittal STIR image through the left pelvis demonstrates a normally situated ischial apophysis with intact cortex and normal surrounding marrow signal (arrow). There is mild subcutaneous soft-tissue edema within the adjacent buttock (arrowhead). STIR short tau inversion recovery

fracture in a child younger than 2 years [2], while a multicenter study reviewing 2,049 skeletal surveys in children younger than 10 years identified ten pelvic fractures [3]. In older children pelvic fractures might be associated with sexual abuse and are often related to physical restraint applied in the area of fracture [4]. We have been unable to find any report of an ischial apophyseal injury in an abused infant. The infant described in this case report presented to the Emergency Department with a severely comminuted fracture of the distal femoral shaft, without a history of witnessed traumatic event. The initial skeletal survey identified four vertebral compression fractures in addition to the known left femur fracture, further supporting the clinical suspicion for abuse. However, the question of a pathological basis of the femoral fracture, with vertebral collapse at multiple levels, raised the possibility of an underlying process such as Langerhans cell histiocytosis. The ischial fracture was not detected on the initial survey, even in retrospect. At the authors’ institution 18F-NaF PET bone scan is preferred over 99Tc-labeled diphosphonate imaging when scintigraphy is employed to complement the radiographic survey done for suspected abuse. The 18F-NaF PET bone scan performed in this case drew attention to the ischium in light of increased bone turnover in this region. The subsequent MRI confirmed the presence of an injury to the right ischium. MRI studies of

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the spine and lower extremities and the CT of the left femur did not demonstrate any underlying pathology or systemic process. The ischial fracture was confirmatory evidence of severe inflicted trauma. The mechanism of this type of injury is uncertain, but based upon experience with accidental ischial fractures it is likely related to a high-energy force delivered to the pelvis. The associated vertebral compression fractures suggest an axial loading mechanism in this case, perhaps with an impact on the buttocks [6]. Ischial avulsion fractures are more commonly seen in adolescent patients as a result of a sudden and forceful contraction of the attached hamstrings tendons related to athletic activity, rather than a direct pelvic trauma. In infancy the ischial apophysis is unossified, presenting a diagnostic challenge on initial radiographs. It has been suggested that, in light of the low incidence of fractures of the pelvis in infants and children undergoing skeletal survey for suspected abuse, the customary view of the pelvis should be omitted to decrease radiation exposure [2, 7]. Although exclusion of this view appears reasonable in light of the rarity of abusive pelvic fractures, it should be acknowledged that such an approach could compromise diagnostic yield of the imaging assessment in abused infants who have bony pelvic injuries. It is not uncommon for centers to selectively perform bone scans in addition to skeletal surveys in cases of suspected child abuse, because these complementary techniques increase detection of unsuspected skeletal injuries. Although bone scans entail additional radiation exposure, the risks may be outweighed by the benefit of detecting injuries that are not visible on initial plain radiographs. In one series, 20% of children would have had no confirmation of bony injury had a bone scan not been performed in addition to a skeletal survey [5]. The image contrast and spatial resolution of the 18F-NaF whole-body bone scan is superior to imaging performed with traditional 99Tc-labeled diphosphonate compounds, despite having essentially equivalent absorbed

radiation dose [8]. The 18F-NaF PET scan in this case allowed for detection of the additional pelvic fracture, which provided compelling evidence that abuse was the underlying mechanism for all of the injuries. As illustrated by our case, the selective use of advanced imaging techniques may increase detection of fractures with a potential positive impact on the care and protection of children at risk for abuse.

Conflict of interest None

References 1. Ablin DS, Greenspan A, Reinhart MA (1992) Pelvic injuries in child abuse. Pediatr Radiol 22:454–457 2. Karmazyn B, Lewis ME, Jennings SG et al (2011) The prevalence of uncommon fractures on skeletal surveys performed to evaluate for suspected abuse in 930 children: should practice guidelines change? AJR Am J Roentgenol 197:W159–W163 3. Lindberg DM, Harper NS, Laskey AL et al (2013) Prevalence of abusive fractures of the hands, feet, spine, or pelvis on skeletal survey. Pediatr Emerg Care 29:26–29 4. Johnson K, Chapman S, Hall CM (2004) Skeletal injuries associated with sexual abuse. Pediatr Radiol 34:620–623 5. Mandelstam SA, Cook D, Fitzgerald M et al (2003) Complementary use of radiological skeletal survey and bone scintigraphy in detection of bony injuries in suspected child abuse. Arch Dis Child 88:387–390 6. Tran B, Silvera M, Newton A et al (2007) Inflicted T12 fracturedislocation: CT/MRI correlation and mechanistic implications. Pediatr Radiol 37:1171–1173 7. Sonik A, Stein-Wexler R, Rogers KK et al (2010) Follow-up skeletal surveys for suspected non-accidental trauma: can a more limited survey be performed without compromising diagnostic information? Child Abuse Negl 34:804–806 8. Drubach LA, Connolly SA, Palmer EL 3rd (2011) Skeletal scintigraphy with 18F-NaF PET for the evaluation of bone pain in children. AJR Am J Roentgenol 197:713–719

Ischial apophyseal fracture in an abused infant.

We report a previously healthy 4-month-old who presented to the hospital with leg pain and swelling and no history of trauma. Radiographs demonstrated...
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