SPR: Dating fractures critical in suspected infant abuse cases
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Michele Walters, MD, of the department of radiology at Children’s Hospital Boston said that dating fractures is critical in cases of suspected infant abuse. “There are little scientific data to guide radiologists, and dating is generally based on personal experience and conventional wisdom. Since birth-related clavical fractures are not immobilized and their age is unknown, we proposed that an assessment of these injuries and healing patterns may serve as a guide for dating inflicted fractures,” she said.
For the retrospective study, which took place over a 12-year period at two institutions, Walters and colleagues selected 108 radiographs of presumed birth-related clavicular fractures in infants between the ages of zero and three months. The radiographs were reviewed by two pediatric radiologists with 30 and 15 years experience, respectively. The authors limited their study to birth-related clavicular fractures and readers were blinded to infant age, wrote the authors.
The readers were each asked to evaluate the images for the presence of two parameters of fracture healing, subperiosteal new bone formation (SPNBF) and callus formation, and the reader’s responses were correlated with known fracture ages. Walters noted that SPNBF was looked at in regard to presence on a four-point scale of thickness from tip to shaft width and whether it was single-layered or solid and multi-layered. Callus was also looked at on a four point scale, and whether it had a soft, intermediate or hard matrix.
According to the researchers, SPNBF was first observed at eight days of age and the overwhelming majority of cases demonstrated this finding by day ten. Callus was first observed at 10 days of age and all cases demonstrated callus by day 16. Only one case of an 18-day-old fracture was read as presenting no new bone and no callus by both readers, said Walters, but she attributed this finding to the fact that the infant had been in the NICU since birth.
Walters explained that as fracture age advances the thickness of the new bone increases and as new bone ages, it goes from single-layered to multi-layered. In addition, as fracture age advances, callus thickness decreases and callus matrix goes from soft, to intermediate and then to hard. Each finding supported this and were found to be statistically significant, she said.
The authors wrote that fractures in young infants without SPNBF are likely to be less than 10 days of age and those with SPNBF are probably more than seven days old. Fractures without callus are likely less than 16 days of age and those with callus are likely to be at least 10 days old.
Citing several limitations of this research, Walters noted that the study was retrospective and the researchers utilized limited quality chest and clavical radiographs. In addition, fractures were presumed to be birth-related, but this cannot be determined for certain, she said.
“Our results suggest that early stages of fracture healing in young infants follow a predictable, radiographically evident time course with regard to the development and character of SPNBF and callus formations,” said Walters.
Healing patterns of clavicular birth injuries may be used as a guide to fracture dating in cases of possible infant abuse, concluded the researchers.