Biomechanical investigation into the torsional failure of immature long bone

Theobald, Peter; Qureshi, Asma; Jones, Michael David

doi:10.1016/j.jcot.2012.02.001

Cited by 8 publications

(13 citation statements)

References 18 publications

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“…The predicted maximum principal strain under torsion was located at the narrowest cross-sectional area of the diaphysis, namely the mid-shaft. This is in agreement with previous experimental studies of long bones under pure torsional loads (Kress et al 1995;Theobald et al 2012).…”

Section: Discussionsupporting

confidence: 93%

Investigating the mechanical response of paediatric bone under bending and torsion using finite element analysis

Altai

Viceconti

Offiah

et al. 2018

Biomech Model Mechanobiol

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Fractures of bone account 25% of all paediatric injuries (Cooper et al. in J Bone Miner Res 19:1976-1981, 2004. https://doi.org/10.1359/JBMR.040902 ). These can be broadly categorised into accidental or inflicted injuries. The current clinical approach to distinguish between these two is based on the clinician's judgment, which can be subjective. Furthermore, there is a lack of studies on paediatric bone to provide evidence-based information on bone strength, mainly due to the difficulties of obtaining paediatric bone samples. There is a need to investigate the behaviour of children's bones under external loading. Such data will critically enhance our understanding of injury tolerance of paediatric bones under various loading conditions, related to injuries, such as bending and torsional loads. The aim of this study is therefore to investigate the response of paediatric femora under two types of loading conditions, bending and torsion, using a CT-based finite element approach, and to determine a relationship between bone strength and age/body mass of the child. Thirty post-mortem CT scans of children aged between 0 and 3 years old were used in this study. Two different boundary conditions were defined to represent four-point bending and pure torsional loads. The principal strain criterion was used to estimate the failure moment for both loading conditions. The results showed that failure moment of the bone increases with the age and mass of the child. The predicted failure moment for bending, external and internal torsions were 0.8-27.9, 1.0-31.4 and 1.0-30.7 Nm, respectively. To the authors' knowledge, this is the first report on infant bone strength in relation to age/mass using models developed from modern medical images. This technology may in future help advance the design of child, car restrain system, and more accurate computer models of children.

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Section: Discussionsupporting

confidence: 93%

Investigating the mechanical response of paediatric bone under bending and torsion using finite element analysis

Altai

Viceconti

Offiah

et al. 2018

Biomech Model Mechanobiol

View full text Add to dashboard Cite

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“…In another laboratory study, using 7-day old calf metacarpal bones, the authors show that an increase in the rate of twist generates a corresponding decrease in normalized fracture angle (inverse of fracture ratio). 7 Furthermore, some material properties of bone, such as the tensile strength and modulus, have been shown to positively correlate with age using both animal models 8 and human bones. 9 This may then influence the pattern of torsional fracture, as a spiral fracture occurs from the combination of tensile and longitudinal shear failure of long bones.…”

Section: Introductionmentioning

confidence: 99%

“…A hypothesis of the study was that the fracture ratio would increase with age, partly because tensile strength of bone has been shown to increase with age in humans 12 and animal models. 8 Secondarily, it was also hypothesized that fracture ratio would increase with the rate of twist, based on the previous study of Theobald et al 7…”

Section: Introductionmentioning

confidence: 99%

Effects of age and rate of twist on torsional fracture patterns in infant porcine femora

Vaughan

Wei

Haut

2020

Journal of Clinical Orthopaedics and Trauma

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Objective: Long bone fractures are a common injury in the pediatric population. Differentiation between abusive, or non-accidental trauma, and accidental trauma in children remains challenging for forensic practitioners. A recent clinical-based study was able to separate pediatric abusive from accidental trauma based on femoral fracture pattern using the ratio of fracture length over bone diameter (fracture ratio), as determined from radiographic analysis of this fractured bone. The forensic literature indicates more cases of abuse in younger pediatric victims than accidental cases. While this was the case in the clinical study, the effect was not shown to be statistically significant. Furthermore, while speed of trauma was not considered in the clinical study, a laboratory study with an immature bovine model indicates rotational speed influences fracture pattern, but specimen age was not varied in that study. Therefore, the objective of the current study was to use immature porcine femora to investigate the effects of age and rate of twist on a modified version of this fracture ratio parameter. Methods: Fifteen pairs of porcine femora with various ages were twisted until observable failure using a custom-built torsional fixture. The left femur of each pair was twisted to failure at a rate of 3 deg/s, while the right femur was twisted at a rate of 90 deg/s. The torque and angle of rotation were recorded at a sampling rate of 10,000 Hz. Fracture ratio was defined as total fracture length divided by bone diameter. Results: Fracture ratio increased with specimen age, with specimens under the low rate of twist yielding a consistently lower fracture ratio than those from specimens under the high rate of twist. The results showed that both specimen age and rate of twist were significant factors influencing fracture ratio. Conclusion:The determination of abusive from accidental trauma in criminal cases, based on the pattern of long bone fracture alone, may need to include additional data on the specific age of the pediatric victim and the potential speed of the traumatic event.

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“…Each bone was tested in torsion to failure, at a rotational rate equal to 90 °/s. This rate was adopted from a previous study, in view of the absence of literature quantifying the rotational rate experienced during equivalent, ‘real-life’ fracture scenarios [ 15 ]. Previous biomechanical studies have shown that testing in torsion is the most valid method for assessing the energy absorbed to failure [ 16 ].…”

Section: Methodsmentioning

confidence: 99%

The change in energy absorbed post removal of metalwork in a simulated paediatric long bone fracture

Howieson

Jones

Theobald

2014

Journal of Children's Orthopaedics

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PurposeThe surgical treatment of paediatric fractures is increasing. Open reduction and internal fixation (ORIF) with plates and screws is long established, whilst the use of elastic stable intramedullary nailing (ESIN) has become increasingly popular. This study quantifies, in terms of the energy required to produce a fracture, the biomechanical sequelae of both techniques post removal of metalwork, to provide clinicians with evidence to guide post-operative advice.MethodsAn immature bovine model was adopted to ascertain whether these techniques exposed the bone to a greater re-fracture risk following removal of the device. Bones were prepared to reflect ORIF or ESIN techniques, or prepared intact for the acquisition of control data. Each bone was tested to failure at 90 °/s, with the absorbed energy then being calculated to determine the relative difference between each technique and versus control data. Data describing peak shear stress and torque were recorded.ResultsAbsorbed energy was reduced by 47 % in the ORIF group compared to both the control (p = 0.011) and ESIN (p = 0.018) groups. The peak shear stress and torque were also significantly different. All ORIF bones failed through drill holes, suggesting stress localisation around the defects.ConclusionThis study suggests that there is a significantly higher re-fracture risk following the removal of ORIF plates when compared to both ESIN and the control environment. Whilst this may reflect the intuitive view of many clinicians, this study provides a quantitative value of the reduction in strength and should help clinicians to appropriately caution patients and parents prior to surgery.

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Biomechanical investigation into the torsional failure of immature long bone

Cited by 8 publications

References 18 publications

Investigating the mechanical response of paediatric bone under bending and torsion using finite element analysis

Investigating the mechanical response of paediatric bone under bending and torsion using finite element analysis

Effects of age and rate of twist on torsional fracture patterns in infant porcine femora

The change in energy absorbed post removal of metalwork in a simulated paediatric long bone fracture

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