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The lesson of temporary brittle bone disease: all bones are not created equal
Insights
Temporary brittle bone disease (TBBD) involves unexplained fractures in infants due to fetal immobilization. This condition, caused by reduced fetal bone loading, leads to transient osteopenia and increased fracture risk with normal handling.
Area of Science:
- Pediatrics
- Orthopedics
- Developmental Biology
Background:
- Temporary brittle bone disease (TBBD) is a recently identified condition characterized by multiple unexplained fractures in infants, primarily within the first six months of life.
- This phenotype often lacks other signs of trauma like bruising or internal injuries, and standard evaluations reveal no underlying radiographic or biochemical abnormalities.
- The medical community, particularly in child abuse and pediatric radiology, has been skeptical, often mistaking TBBD for non-accidental trauma.
Discussion:
- The mechanostat/bone loading theory suggests TBBD results from fetal immobilization leading to bone unloading and relative osteopenia.
- Fractures in TBBD infants can occur with routine handling, mimicking patterns historically associated with child abuse.
- This review critiques the diagnostic approach to child abuse in infants with multiple unexplained fractures.
Key Insights:
- Normal fetal movement is crucial for developing adequate fetal bone strength.
- Infants with TBBD exhibit a fracture pattern that can be misattributed to child abuse.
- Evidence suggests child abuse is unlikely in infants diagnosed with TBBD.
Outlook:
- Further research into fetal bone development and loading is warranted.
- Developing refined diagnostic criteria for TBBD is essential to differentiate it from non-accidental trauma.
- Improved understanding can lead to accurate diagnosis and appropriate management for infants with unexplained fractures.
Abstract:
Temporary brittle bone disease (TBBD) is a recently described phenotype of multiple, unexplained fractures in the first year of life and predominantly in the first 6 months of life. There is usually no other injury such as bruising, subdural hematomas, retinal hemorrhages, or other internal organ injury. The susceptibility to fracture is transient, and there are no other radiographic or biochemical abnormalities noted in the standard evaluation that might suggest an underlying cause. The child abuse and pediatric radiology communities have, for the most part, been unwilling to accept this as a real condition, for they believe it is a ruse for child abuse. This review describes the experience of the author in evaluating infants with multiple unexplained fractures and the hypothesis that has emerged for explaining TBBD. The hypothesis is a prenatal application of the mechanostat/bone loading theory of bone formation and states that TBBD is caused by fetal immobilization which leads to fetal bone unloading and transient, relative osteopenia. Such susceptible infants can fracture with routine handling and present with a pattern of fractures that is similar to that which has been thought to be highly specific for child abuse. The review presents: (a) the evidence that indicates that normal fetal movement is important for normal fetal bone strength, (b) a critique of the radiologic approach in the diagnosis of child abuse in infants with multiple unexplained fractures, (c) observations that would indicate that child abuse is unlikely in infants with TBBD, and (d) new approaches to the infant with multiple unexplained fractures that would assist in accurate diagnosis.