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. 2019 Jul-Aug;10(4):744-749.
doi: 10.1016/j.jcot.2018.10.001. Epub 2018 Oct 13.

An in-vitro animal bone model study to predict spiral fracture strength of long bones in the young infant

S S Malik  1 , S Malik  1 , R Shenoy  2 , M D Jones  1 , P S Theobald  1
Affiliations

An in-vitro animal bone model study to predict spiral fracture strength of long bones in the young infant

S S Malik et al. J Clin Orthop Trauma. 2019 Jul-Aug.

Erratum in

  • Erratum regarding previously published articles.
    [No authors listed] [No authors listed] J Clin Orthop Trauma. 2020 Nov-Dec;11(6):1169-1171. doi: 10.1016/j.jcot.2020.09.032. Epub 2020 Sep 26. J Clin Orthop Trauma. 2020. PMID: 33013141 Free PMC article.

Abstract

Introduction: The risk of fracture from a non-accidental injury is highest in the infant age group. A spiral fracture of the long bone can occur equally from accidental and non-accidental causes, meaning the clinical judgement of non-accidental injury in an infant is particularly challenging. This study aimed to assist in differentiating accidental, from non-accidental, injury in infants, by establishing whether correlation exists between geometry and torsional strength in the immature long bone.

Methods: Immature porcine third and fourth metacarpals (n = 21) were imaged with a dual energy x-ray absorptiometry (DEXA) scanner to measure their linear bone mineral content (BMCL), bone mineral density (BMD) and section modulus (Z). The specimens were then subjected to a torque of one degree per second until failure. The failure strength and the three DEXA measures were analyzed for a correlation.

Results: The mean failure strength of 11 successful tests was 13.71Nm (+/-SD 2.42Nm), with correlation to BMCL, BMD and Z described by r2 = 0.81, 0.283 and 0.75 respectively.

Conclusion: This study is a novel attempt at estimating torsional strength of long bones in a specific paediatric age group using a size-matched animal bone model. It found a strong correlation between bone and fracture strength parameters over the BMCL range of 0.59-0.77 g/cm.

Keywords: Infant; Long bones; Non-accidental injury; Spiral fracture; Torsional fracture strength.

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Figures

Fig. 1
Fig. 1
A drawing of a typical porcine third and fourth metacarpal with DEXA measurements indicated. A 1.5 cm height ROI centred over the mid-diaphysis was analysed for projected area and BMC.
Fig. 2
Fig. 2
A specimen embedded in the steel jigs and positioned in the test machine.
Fig. 3
Fig. 3
Load deformation curve for specimen 1.
Fig. 4
Fig. 4
The correlation of BMC L with maximum torque.
Fig. 5
Fig. 5
The correlation of Z with maximum torque.
Fig. 6
Fig. 6
The correlation of BMD with maximum torque.
Fig. 7
Fig. 7
A computed tomographic image at the mid-diaphysis of the porcine metacarpal bone.
See this image and copyright information in PMC

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