Volume 4, Case 2
Rodney B. Boychuk, M.D.
Kapiolani Medical Center For Women And Children
University of Hawaiʻi John A. Burns School of Medicine
This is a 2-month-old female who is brought to an acute care clinic for cough, runny nose, fussiness, and decreased movement of the left arm. The infant has mild nasal congestion, bilateral otitis media, and an angulated tender swelling in the left upper arm with minimal movement of the left arm.
According to the mother, the infant cries a lot when she is dressed and has not been moving her arm for approximately 3 days. The mother also notes swelling, but is uncertain about the day of onset. She said that the father told her that while he was cleaning the house, he tripped over the infant's brother and accidentally stepped on the baby. She did not seek medical attention earlier because she thought the arm was just sore from the incident.
A skeletal survey is done.
View lower extremity:
The left distal femur metaphysis is shown here. Three images are displayed. The top image is taken on the day of presentation to the E.D. Corner fractures on both sides of the distal femur are barely visible. The middle image, taken two days later, shows the two corner fractures more clearly. The bottom image, taken 9 days after presentation shows some periosteal reaction. The pattern of healing shows a bucket handle appearance at the inferior border of the metaphysis.
View upper extremity:
The upper extremity radiograph shows a transverse fracture of the mid-portion of the shaft of the left humerus.
In addition to the fractures displayed above, this patient also has a small bucket handle fracture of the distal humeral metaphysis and a small bucket handle fracture of the distal tibia. Both of these are very hard to see (images not shown). These findings are compatible with child abuse.
A CT scan of the head is normal, and an inpatient ophthalmologic evaluation does not reveal any retinal hemorrhages.
View diagram of fractures.
This diagram illustrates the phenomenon of corner fractures and bucket handle fractures. Corner fractures and bucket handle fractures are similar in etiology despite their different names. A small bucket handle fracture may appear as a corner fracture on the radiograph depending on the angle of the radiograph. A true corner fracture is still similar to a small bucket handle fracture.
This is a 9-month-old who is brought to an acute care clinic after noting something is wrong with the infant's arm after a toy was pulled away from him. The infant was in the care of the baby-sitter at that time. Mother was working at night.
Physical exam reveals a 9-month-old male, approximately 50th percentile for height and weight. A bruise at the lateral edge of the left eye and bruise of the left pinnae are noted. The child is clinging to the mother, quite apprehensively. The right elbow shows 2+ swelling. The child is reluctant to move the right elbow because of pain. The sensation and circulation to the hand appears normal. Above the right elbow, ecchymosis is noted anteriorly and posteriorly. No definite crepitus is detected. The infant holds the right elbow in full extension. Any flexion beyond 10-15 degrees results in pain, with the child crying.
A skeletal survey is obtained.
View right elbow.
Multiple views of the right elbow demonstrate a distal humeral bucket handle type fragment. The thin fragment represents a section of the distal metaphysis. Although the physis (growth plate) cannot be seen radiographically, it is evident that the fracture must go through the physis to splinter off a section of the distal metaphysis as seen. The radius should be pointing at the capitellum in all views. In the oblique lateral view, the radius is not pointing straight at the capitellum indicating that the epiphysis of the humerus (capitellum) is displaced. The AP view shows that the capitellum is displaced medially. This type of fracture is known in the orthopedic literature as a "transepiphyseal" (transphyseal) fracture. This is not a true bucket handle fracture, although it resembles a bucket handle.
A follow-up view of this elbow is taken one month later.
View follow-up view of elbow.
Extensive periosteal reaction and healing are noted in the distal humeral metaphysis. What initially appeared to be a small fracture upon presentation, results in substantial changes associated with healing. Most of the fracture is through the physis, however, this is not ossified and not visible radiographically. These extensive changes are evidence of healing of the "transepiphyseal" fracture.
View patient's tibia.
The lower extremity radiographs demonstrate periosteal new bone formation along the lateral aspect of the shaft of the left tibia, presumably secondary to a healing subperiosteal hematoma. This finding is very subtle and can be best seen on the AP view on the lateral aspect adjacent to the fibula.
View focused view of tibia.
This focused view of the patient's tibia points to the area of periosteal reaction.
A technetium bone scan is recommended to determine if there are any other skeletal injuries, which cannot be visualized radiographically. A radionuclide bone scan with vascular flow scan is performed.
View bone scan.
Delayed static images of the bone scan showed increased tracer localization in multiple sites, including the left clavicle, both humeri (R>L), both ulnae (not shown), and both tibiae (L>R). Findings were felt to be most likely traumatic in etiology.
Images obtained soon after injection ("blood pool"), are mainly a function of blood flow and the degree of soft tissue hyperemia. The early images are useful in the diagnosis of infectious and traumatic lesions, as well as malignant bone tumors. After a delay of 2-4 hours, the concentration of the phosphate compound by the bone is a function of its osteogenic activity and blood flow. Since many conditions can alter the degree of tracer localization, it is particularly important to correlate the abnormalities in bone scan with detailed radiographic views of the involved areas and with the clinical situation to come to an accurate diagnostic impression.
Discussion: Child Abuse Fractures
1. Epiphyseal-Metaphyseal Fractures
Injuries at the epiphyseal-metaphyseal junction are highly suggestive of abuse. The periosteum surrounding the growing long bones is thick and tightly anchored at both ends by heavy extensions into the epiphyseal cartilages. In contrast, the highly vascularized, loosely attached young periosteum of the diaphysis is easily torn from its underlying cortex. The resultant subperiosteal bleeding lifts the periosteum, forming layers of periosteal new bone away from the cortex to form an external shell of new bone.
This extremely strong periosteum that is tightly anchored by heavy extensions into the epiphyseal cartilages can easily explain the dynamics of epiphyseal-metaphyseal fractures. Axial ligament and periosteal traction or torsion forces are generated by sudden traction on the extremity, such as occurs when the arms or legs are pulled or swung violently upward or forward. This results in the typical traction "corner" fracture pathognomonic of child abuse. These are well-visualized in the cases described above.
2. Metaphyseal Fractures
Metaphyseal fractures were first described by Caffey in 1972, who felt they represented an indirect avulsion injury to the metaphysis by the pull of the periosteum when the child was severely shaken. In 1983, Kleinman and Zito showed these to be transverse fractures through the metaphysis and only appeared to be avulsion injuries because of the radiographic projection views. If the metaphysis is tipped or simply projected obliquely to the X-ray beam, the margin of the resultant fragment is projected with a bucket-handle appearance. If the peripheral fragment is substantially thicker than the central fragment, and the plane of injury is viewed tangentially, a corner fracture appearance results. Note the potential radiographic appearance of the injuries diagrammed earlier.
View diagram of these injures.
These authors believed that metaphyseal fractures were most suggestive of abuse. Reed has pointed out that these metaphyseal fractures can be seen in other orthopedic conditions, including rickets, scurvy, multiple congenital contractures, and kinky-hair syndrome.
3. Diaphyseal Fractures
Diaphyseal fractures can be grouped into three broad categories: 1) Transverse, spiral, and oblique shaft fractures. 2) Multiple fractures in various stages of healing. 3) Bony deformity.
A spiral or oblique fracture is produced by a twisting mechanism, while a transverse fracture is caused by a direct blow.
Technetium 99 bone scanning has been shown to be highly sensitive when used to assess skeletal injury, particularly in occult areas not easily accessible to clinical examination. The scan is frequently "hot" for many weeks during healing. The bone scan can be especially useful in identifying fractures of flat bones, such as the skull, ribs and scapulae, which may be missed on radiographic films.
In summary, radiographic findings indicating child abuse include epiphyseal-metaphyseal fractures, such as "corner" / "bucket-handle" fractures, and subperiosteal hematoma bone formation as described above. Consultation with an experienced radiologist will often be helpful in determining the etiology of the injury.
References