Metaphyseal fractures and the diagnosis of non-accidental injury
- Firstly it is necessary to distinguish between fractures occurring at the dia-metaphyseal junction, and the classic metaphyseal lesions CML’S (corner fractures, chip fractures, bucket handle fractures) that occur through the growth plate. The former, although occurring in cases of non-accidental injury also commonly occur accidentally, and are less specific for NAI than the CML’S. I believe the issue being addressed in the correspondence refers to the CML.
- Before making a diagnosis of classic metaphysical lesions, it is essential that other causes of abnormal metaphases be considered. It is for this reason that a skeletal survey should be reported by a radiologist with sufficient experience in the reporting of general paediatric radiographs including those of accidentally and non-accidentally injured children. Beaking of the metaphyses may be a normal appearance i.e. a normal variant, and beaking alone does not necessarily imply the presence of a CML. Follow up radiographs will usually remain unchanged and may be helpful in difficult cases. A number of metabolic and genetic disorders may give rise to abnormalities of the metaphysis which may cause initial concern about the presence of a metaphyseal fracture. However, careful enquiry into the family history, a thorough clinical examination, and a full skeletal survey will identify the presence of an underlying disorder of he metaphyses in almost all cases.
- For many years it has been taught that CML are highly specific for injuries caused non-accidentally. However, the scientific basis for this is largely based on descriptive studies highlighting the frequency of the CML in abused infants compared to the rarity of these injuries following well documented accidents and the association of these lesions with other unexplained injuries in infants particularly rib fractures and subdural haemorrhages. A systematic review of the world literature has been performed by the Welsh Child Protection Systematic Review Group led by Professor S Maguire of Cardiff University and supported by The NSPCC (web site http://core-info.cf.ac.uk/fractures/cofs_isit/key_metaphyseal.htm.) This study indicated that there were insufficient reports specifically addressing metaphyseal lesions in abused and non-abused children to derive a probability of abuse for metaphyseal fractures. However, it was noted that the literature review did indicate that:
· Metaphysical fractures are more commonly described in physical child abuse than in non-abuse
· Metaphysical fractures are one of the commonest fractures in fatal abuse
The report quotes a number of references to support these statements.
4. Although the classic metaphysical lesions are said to have a high specificity for injuries occurring non- –accidentally, it must be stressed that these lesions may also occur accidentally, although they are uncommon. When associated with accidental injury there is usually a well documented history of trauma. There are several reports in the literature documenting the accidental occurrence of classic metaphyseal lesions.
Helfer, R. E., Scheurer, S. L., Alexander, R., Reed, J., & Slovis, T. L. (1984). Trauma to the bones of small infants from passive exercise: a factor in the aetiology of child abuse. Journal of Pediatric Orthopaedics, 104(1), 47-50
Grayev, A. M., Boal, D. K. B., Wallach, D. M., & Segal, L. S. (2001). Metaphyseal fractures mimicking abuse during treatment for clubfoot. Pediatric Radiology, 31(8), 559-563
Altman, D. H., & Smith, R. L. (1960). Unrecognised trauma in infants and children. Journal of Bone and Joint Surgery, 42(3), 407-413
When accidental there is usually a clear history of a shearing (twisting/gripping) mechanism, supporting the studies by Kleinmann who demonstrated the histologic/ radiologic correlation of the classic metaphyseal injury indicating a shearing mechanism.
Kleinman, P. K., & Marks, S. C., Jr. (1998). A regional approach to the classic metaphyseal lesion in abused infants: the distal femur. American Journal of Roentgenology, 170(1), 43-47
Kleinman, P. K., Marks, S. C., Jr., Richmond, J. M., & Blackbourne, B. D. (1995). Inflicted skeletal injury: A postmortem radiologic-histopathologic study in 31 infants. American Journal of Roentgenology, 165(3), 647-650
Thus in summary although the current literature on CML does not conclusively indicate that the CML is highly indicative of child abuse, there is no doubt that the CML is frequently seen in abuse, and is a most uncommon finding as a result of well documented accidental trauma unless accompanied by a strong history e.g. difficult delivery. The diagnosis of child abuse is rarely made on the basis of a single metaphyseal fracture, and it is important that all the clinical, radiological and social aspects are taken into account before arriving at the diagnosis. Every effort has to be made prior to this to ascertain from the parents/ carers of any possible mechanism, accidental or unintentional, that could account for the injury. Clearly one has to be certain that the observation truly represents a metaphyseal injury.
Child abuse by its very nature makes the performance of controlled studies very difficult. It must be stressed that child abuse is a significant problem and failure to diagnose abuse may result in further abuse and possibly the death of the infant.