Introduction Characterising the shapes, dimensions and overall numbers of fragments produced by explosive devices is important for determining methods of potential mitigation, such as personal armour. The aim of this investigation was to compare the mass of excised fragments with that predicted from CT to ascertain the validity of using such an approach to measure retained fragments for multiple body areas using CT alone.
Method 27 retained fragments excised from consecutive patients treated at a US Role 3 Medical Treatment Facility in Afghanistan were examined. Each fragment was measured in three dimensions and the mass was obtained to estimate the density and thereby probable composition. These same excised fragments were identified radiologically and their predicted masses calculated and compared with the known masses with a paired t-test. The total numbers of retained fragments in each of four body areas for 20 casualties were determined radiographically and the mass of the largest fragment in each body region estimated.
Results Excised fragments were most commonly metallic (17/27, 63%), with masses ranging from 0.008 to 37.6 g. Mean mass predicted from CT was significantly different from than that measured (p=0.133), with CT underestimating true mass by 5%–17%. 889/958 (93%) retained fragments appeared metallic on imaging, with the most commonly affected body areas being the torso and upper extremity (45% of casualties).
Conclusions Predicting the mass of metallic fragments from CT was possible with an error margin of up to 5%, but was less accurate for non-metallic fragments such as stone. Only 3% of fragments were removed through debridement or purposeful excision; these were not just the largest or most superficial. This suggests that future retrospective analysis of the dimensions and predicted masses of retained fragments in larger casualty cohorts of service personnel is potentially feasible within a small margin of error.
- orthopaedic & trauma surgery
- diagnostic radiology
- computed tomography
Data availability statement
Data may be obtained from a third party and are not publicly available. N/A.
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Contributors JB: conceptualisation, data collection, data analysis, project administration, writing. CJS: data collection, data analysis, writing. AS: data collection, data analysis, writing. KMS: data collection, data analysis, writing.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Disclaimer The views expressed are solely those of the authors and do not reflect the official policy or position of the US Air Force, the Department of Defense or the US Government. Permission to publish has been granted by the US Department of Defense (DOPSR case number DOPSR 21-S-0719). The views expressed do not reflect the official policy or position of the British Army, the Ministry of Defence or Her Majesty’s Government. Permission to publish was granted by the UK Ministry of Defence (reference CC1-20210027).
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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