Sudden thigh swelling in a 6 week old

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This 6-week old male was well until two days prior to presenting to the ED when his left thigh suddenly became swollen.

His mother, who cares for him both day and night, states that there is no history of trauma. She denies any rough play, shaking, or any chance of trauma, such as rolling off the bed or the couch. Further questioning reveals that sometimes the infant’s father, paternal grandmother, paternal grandfather, and paternal aunt, all living in the same household, also care for the infant. There is also a one-year old female sibling a 2-year old female cousin, and great grandparents all living in the same house, who sometimes play with the infant. Both mother and father are 18 years of age.

This infant was born full-term with a birth weight of 3.4 kg. Immunizations are up to date (hepatitis B vaccine X2). No allergies are noted. He is on no medications and has had no illnesses, hospitalizations or surgery since birth.

His mother states that the thigh swelling is somewhat less that the day prior, but the child still will not move his leg, which is her greatest concern.

Exam findings

T37.4 (rectal), HR 160, R30, weight 4.2 kg. Quiet, well developed, well nourished, active and alert. His anterior fontanelle is flat and soft. Pupils are equal and reactive to light. The red reflex is present, and the fundi (exam with difficulty) appear clear. There are no bruises noted anywhere on the head or elsewhere on the body.

Tympanic membranes appear normal. Chest reveals no bony deformity, with good aeration bilaterally. Heart regular with a grade 2/6 vibratory systolic murmur present at the left sternal border. The abdomen is soft. Active bowel sounds are noted. No masses are evident, and no bruising is noted. Normal male external genitalia are noted. Except for an abnormal left lower extremity, other extremities appear normal.

The left thigh is very swollen, with the foot being somewhat externally rotated. Pedal pulses are good, and capillary refill time is less than 2 seconds. The thigh is very firm and warm, but not discolored. No spontaneous movement is present in the left leg, and the leg is tender to touch (baby cries when the leg is touched). Radiographs of the left lower extremity are done.

thigh

This radiograph shows an obvious oblique fracture of the proximal shaft of the left femur, with superior and anterior displacement of the distal fracture fragment. There is also a hairline fracture component involving the middle and distal shaft of the left femur.

On the lateral view (left image), this can be seen as a faint oblique linear lucency over the distal 1/3 of the femur. On the AP view (right image), this can be seen as a faint linear lucency extending from the obvious fracture above, downward and through the mid femur and continuing obliquely into the distal 1/3 of the femur. The left knee, tibia and fibula are unremarkable.

Because of the strong suspicion of intentional trauma (child abuse), the infant is hospitalized and a skeletal survey is done. The following radiographs are shown:

arm

 The upper extremity radiograph (left image) reveals an old fracture of the right proximal radius. There is some periosteal elevation surrounding the fracture indicating that the fracture did not occur recently. The lower extremity radiograph (right image) reveals a healing fracture of the right tibia with periosteal reaction along the entire shaft of the right tibia. The fracture line itself is not easily identified.

chest

The vertebral body of T12 appears much flatter than the other thoracic vertebra. T10 and L2 may also be slightly flattened. Because of the difficulty in diagnosing these as vertebral body compression fractures, a bone scan is done for correlation.

bone scan

This bone scan confirms the long bone fractures. There is an obvious hot spot in the right radius. The entire left femur and right tibia are hot. There is also a hot spot over the occiput suggesting a fracture or a subperiosteal contusion. There are no obvious vertebral hot spots suggesting that the flattened vertebral bodies may not represent fractures.

This study is a “planar” bone scan. More conventional bone scanners utilizing the SPECT (single photon emission computed tomography) method are more accurate in identifying such fractures. The remainder of the skeletal survey was negative. The skull radiographs were not able to identify any fractures. A CT scan of the head was negative for fracture or brain injury. An ophthalmology examination found no retinal hemorrhages.

Progress

The infant remained medically stable. He was feeding well and gaining weight. After being fitted with an orthopedic Pavlik harness, child protective services placed the infant in a foster home. The young children living in the household were also removed and placed in foster homes.

Discussion

Physical abuse is any non-accidental injury to a child caused by a parent or caretaker. This might be shaking, beating, burning, scalding, poisoning, or other trauma. Physicians must maintain a high index of suspicion, particularly when the history of an injury is inconsistent with physical findings. Excessive delay in seeking medical treatment, trauma inconsistent with age-related injury, unexplained or multiple trauma, or sibling-inflicted injuries must raise suspicion of abuse.

Physical abuse most often is a pattern of repeated behavior, with bruises and welts being the most frequent evidence of such. Typical sites for inflicted bruises include the neck (choke marks), upper lip and frenulum (forceful feeding), ear lobe (pinch or slap marks), cheeks (slap marks), buttocks and lower back (paddling), the genital area and inner thighs. Human bite marks leave concentric bruises that contain individual teeth marks.

Patterns of injuries

Child abuse is a common cause of burns. Scald or immersion burns are the most common, bearing the characteristic glove or stocking pattern that is observed on physical examination. With a water temperature of 145 degrees or greater, an almost instantaneous full-thickness burn will occur. With a water temperature of 130 degrees, it takes approximately 30-45 seconds. Contact burns from a hot metal object or cigarette are another type of burn seen with child abuse.

Head injuries are the most common cause of death from child abuse. In 1946, Dr. John Caffey reported six children who had chronic subdural hematomas in association with multiple fractures of the peripheral skeleton. In 1974, Caffey described a syndrome of severe central nervous system injury caused by “the shaken infant syndrome.” Shaking produces a whiplash injury to the brain tissue, causing injury to the axons and bridging vessels that leads to subdural hematoma and/or subarachnoid hemorrhage. Retinal hemorrhages and changes in sensorium are characteristic findings resulting in a clinical picture of coma, apnea, seizures, sepsis or other non-specific neurological signs.

Abdominal injury is the second most common cause of death among battered children. Ruptures of the spleen, liver or bowel caused by a punch or kick can result in the above with no visible bruises or marks on the abdomen in over half the cases. Rupture of the bladder may also occur.

Epiphyseal-metaphyseal injury is virtually diagnostic of physical abuse in an infant, since an infant cannot generate enough force to fracture a bone at the epiphysis. Fractures secondary to abuse are more commonly seen in children less than 3 years of age. Conversely, less than 10% of children over 5 years of age who are abused sustain fractures.

In general, a complete skeletal survey should be done on all children less than 2 years of age who are possible abuse victims. A spiral or oblique fracture of long bones is produced by a twisting mechanism. Whether accidental or non-accidental, a large amount of force is required to produce a fracture of the femur. A direct blow causing a transverse fracture can also be seen with major violence. Young children who are not ambulatory cannot produce enough force to fracture their femur. A history of getting his/her leg “caught in the crib” should be viewed with suspicion.

Rib fractures are highly suggestive of abuse in infants and young children. Squeezing usually produces fractures of the posterolateral aspects of the ribs. Shaking or choking a child has been shown to produce fractures anteriorly in the first or second ribs. Rib fractures secondary to trauma that is NOT child abuse tend to occur in the middle or anterior part of the rib cage.

Spinal fractures are infrequently seen in child abuse cases. The mechanism is usually one of compression, as a child is forcibly seated into a chair or onto a tabletop. A skeletal survey is often diagnostic of the child abuse syndrome. The survey should include, at a minimum, two views of the skull, lateral view of the thoracolumbar spine, and anterior-posterior views of both upper extremities, hands, pelvis, and both lower extremities, including the feet.

Radiological signs of abuse

There are several radiologic signs suggestive of abuse. These include healing fractures, multiple fractures, fractures of unusual locations, and metaphyseal fractures.

The typical radiographic appearances have been described as: a) “corner fractures”, b) “bucket handle” fractures, and c) subperiosteal hematoma with new bone formation.

Other radiographic findings suggestive of abuse include posterior rib fractures, spinous process fractures, sternal fractures, complex skull fractures, and diaphyseal spiral and oblique fractures.

Fractures showing different stages of healing are almost pathognomonic of abuse. Any fracture which already shows signs of healing suggests that the fracture is at least ten days old.

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 exam. This scan is frequently “hot” for many weeks during healing. American law requires the reporting of any suspected abuse.

A report of suspected abuse is a responsible attempt to protect a child. A significant number of children may be further abused if not protected and may even die from further injury. Physicians must consider abuse as a potential diagnosis and maintain a high index of suspicion in order to prevent further morbidity and mortality in children unable to speak for themselves.

References

1. Gibson G, Block R. Child Abuse. In: Surpure JS (ed). Synopsis of Pediatric Emergency Care, 1993, Boston, Andover Medical Publishers, pp. 367-372.

2. Black GB. Child Abuse Fractures. In: Letts RM. Management of Pediatric Fractures, 1994, New York, Churchill Livingstone, pp. 931-944.

3. Caffey J. Multiple Fractures in Long Bones of Infants Suffering from Chronic Subdural Hematoma. American Journal of Radiology 1946:56;163.

4. Caffey J. On the Theory and Practice of Shaking Infants. American Journal of Disease in Children 1972:124;161.

5. O’Conner JF, Cohn J. Diagnostic Imaging of Child Abuse. In: Kleinman PK (ed). Diagnostic Imaging of Child Abuse, 1987, Baltimore, Williams & Wilkins, 1987, p.112.

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Tessa Davis is a paediatric emergency registrar from Glasgow and Sydney, but currently living in London. Tessa tries to spend time with her 3 kids in between shifts. @tessardavis | + Tessa Davis | Tessa's DFTB posts

2 Responses to "Sudden thigh swelling in a 6 week old"

  1. Chris Bidder
    Chris Bidder 3 years ago .Reply

    This is a good educational case, but it seems incomplete. Before diagnosing NAI, one needs to consider possible medical explanations for multiple fractures in a baby, e.g. metabolic bone disease like OI. I accept this is rare, but it does happen and ought to have a mention

    • Tessa Davis
      Tessa Davis 3 years ago .Reply

      Yes, agreed. A medical work-up would be a routine part of any NAI investigation.

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