Rib fractures in infancy, case-series and register case-control study from Sweden

To assess cases with rib fractures in infants under observation for or with an abuse diagnosis, and to compare risk factors with that in infants with fractures but no abuse diagnosis.

Design was case-series and register case-control of infants (aged <1 year) with rib fractures. Data was clinical records for the case-series (n = 26) and from national health registers for the case-controls (n = 28 and n = 31). Outcome measures were maternal and perinatal characteristics, reasons for appointment, examination, diagnoses, blood tests, and radiologic findings.

The case-series had a median age of 70 days. A majority were detected through a skeletal survey for abuse investigation. Sixteen were boys, three were preterm and six were small-for-gestational age. Three carers had noticed popping sound from the chest; no infants showed signs of pain at physical examination. Mean number of fractures was 4.2, and 24 had callus. Bone mineralisation was scarcely reported. Metabolic panel was not uniformly analysed. The register case-control had a median age of 76 days, sharing risk factors such as maternal overweight/obesity, male sex, prematurity, and being small-for-gestational age. Cases more often had subdural haemorrhage, retinal haemorrhage, or long-bone fractures, controls more often had neonatal morbidity, respiratory infection, or a fall accident. Detection of fracture at time of a major surgery (n = 6) and rickets/vitamin D deficiency (n = 5) appeared in both groups, but was delayed among the cases.

Rib fractures in young infants, diagnosed as abuse, are usually asymptomatic and healing. A substantial proportion had metabolic risk factors, suggesting false positive cases.