Fracture Fixation Technique and Chewing Side Impact Jaw Mechanics in Mandible Fracture Repair

Abraha, Hyab Mehari; Iriarte-Díaz, José; Reid, Russell R.; Ross, Callum F.; Panagiotopoulou, Olga

doi:10.1002/jbm4.10559

Cited by 5 publications

(10 citation statements)

References 56 publications

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“…All macaque data have been previously published [15,17,36,37] and are presented here exclusively for ease of comparison with human models. Note: Coordinate system in our model has the origin in the midpoint between the condyles, x-axis is superior-inferior (SI), y-axis is anterior-posterior (AP), and z-axis is mediolateral (ML).…”

Section: Discussionmentioning

confidence: 99%

“…In addition, given the proposed similarities in deformation regimes between the two species under healthy conditions, we propose that fracture and fixation conditions will have the same effect in both models. As was observed in macaques [ 15 ], we expect that Champy fixation in humans will create larger effects on twisting moments acting about the jaw, increased interfragmentary strain, and global principal strain regimes that differ more from the healthy condition.…”

Section: Introductionmentioning

confidence: 86%

“…However, in a recent study in rhesus macaques, we showed that the less rigid and most commonly used repair technique, the Champy method, results in a biomechanically unfavourable environment in the mandible. This includes greater interfragmentary strain at the fracture plane, higher bone strain magnitudes in the bone-implant interface, and global bone strain regimes that deviate more from the healthy control than the biplanar (more rigid) fixation [ 15 ]. These unfavourable biomechanical environments are exacerbated during contralateral chews (chewing on the opposite side to the fracture).…”

Section: Introductionmentioning

confidence: 99%

“…This partly occurs because the mandible undergoes lateral transverse bending during unilateral post-canine chewing [ 16 , 17 ]. Champy fixation provides minimal resistance against lateral transverse bending, and thus is associated with greater widening of the medial fracture plane during contralateral chews than biplanar fixation [ 15 ]. In addition, under contralateral chewing, Champy fixation reverses the twisting moments acting about the anterior–posterior (AP) axis of the fracture-fixed mandible, such that anterior to the fixation construct the corpus is subjected to negative twisting moments (eversion of the tooth row and inversion of the inferior border).…”

Section: Introductionmentioning

confidence: 99%

“…In addition, under contralateral chewing, Champy fixation reverses the twisting moments acting about the anterior–posterior (AP) axis of the fracture-fixed mandible, such that anterior to the fixation construct the corpus is subjected to negative twisting moments (eversion of the tooth row and inversion of the inferior border). This results in opposite twisting moments occurring on either side of the fracture plane, increasing the strains in the plate construct and in the bone-implant interface [ 15 ]. Together, these findings suggest that chewing contralateral to the fracture side following Champy fixation probably results in biomechanical conditions (high strain, high interfragmentary instability) that inhibit bone healing.…”

Section: Introductionmentioning

confidence: 99%

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Macaca mulattais a good model for human mandibular fixation research

et al. 2022

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Biomechanical and clinical studies have yet to converge on the optimal fixation technique for angle fractures, one of the most common and controversial fractures in terms of fixation approach. Prior pre-clinical studies have used a variety of animal models and shown abnormal strain environments exacerbated by less rigid (single-plate) Champy fixation and chewing on the side opposite the fracture (contralateral chewing). However, morphological differences between species warrant further investigation to ensure that these findings are translational. Here we present the first study to use realistically loaded finite-element models to compare the biomechanical behaviour of human and macaque mandibles pre- and post-fracture and fixation. Our results reveal only small differences in deformation and strain regimes between human and macaque mandibles. In the human model, more rigid biplanar fixation better approximated physiologically healthy global bone strains and moments around the mandible, and also resulted in less interfragmentary strain than less rigid Champy fixation. Contralateral chewing exacerbated deviations in strain, moments and interfragmentary strain, especially under Champy fixation. Our pre- and post-fracture fixation findings are congruent with those from macaques, confirming that rhesus macaques are excellent animal models for biomedical research into mandibular fixation. Furthermore, these findings strengthen the case for rigid biplanar fixation over less rigid one-plate fixation in the treatment of isolated mandibular angle fractures.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Macaca mulattais a good model for human mandibular fixation research

et al. 2022

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The Kinematics of Proal Chewing in Rats

McParland,

Mitchell,

Laurence-Chasen

et al. 2024

Integrative Organismal Biology

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Chewing kinematics are well-documented in several mammal species with fused mandibular symphyses, but relatively understudied in mammals with an unfused symphysis, despite the fact that more than half of extant Mammalia have an unfused mandibular symphysis. The Wistar brown rat (Rattus norvegicus, Berkenhout, 1769) is widely used in human health research, including studies of mastication or neurological studies where mastication is the output behavior. These animals are known to have unfused mandibular symphyses and proal jaw (rostrocaudal) motion during occlusion, but the lack of high resolution, 3-dimensional analysis of rat chewing leaves the functional significance of symphyseal mobility unknown. We used biplanar fluoroscopy and the X-ray Reconstruction Of Moving Morphology (XROMM) workflow (Brainerd et al. 2010; Gatesy et al., 2010) to quantify chewing kinematics in three brown rats, quantifying overall jaw kinematics, including motions about the temporomandibular joint (TMJ) and unfused mandibular symphysis. During occlusion, the teeth and the mandibular condyle translate almost exclusively anteriorly (proal) during occlusion, with little motion in any other degrees of freedom. At the symphysis, we observed minimal flexion throughout the chew cycle. Overall, there are fundamental differences in jaw kinematics between rats and other mammals and therefore rats are not an appropriate proxy for ancestral mammal jaw mechanics. Additionally, differences between humans and rat chewing kinematics must be considered when using rats as a clinical model for pathological feeding research.

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Does the model reflect the system? When two-dimensional biomechanics is not ‘good enough’

Smith

Davis

Panagiotopoulou

et al. 2023

J. R. Soc. Interface.

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Models are mathematical representations of systems, processes or phenomena. In biomechanics, finite-element modelling (FEM) can be a powerful tool, allowing biologists to test form–function relationships in silico , replacing or extending results of in vivo experimentation. Although modelling simplifications and assumptions are necessary, as a minimum modelling requirement the results of the simplified model must reflect the biomechanics of the modelled system. In cases where the three-dimensional mechanics of a structure are important determinants of its performance, simplified two-dimensional modelling approaches are likely to produce inaccurate results. The vertebrate mandible is one among many three-dimensional anatomical structures routinely modelled using two-dimensional FE analysis. We thus compare the stress regimes of our published three-dimensional model of the chimpanzee mandible with a published two-dimensional model of the chimpanzee mandible and identify several fundamental differences. We then present a series of two-dimensional and three-dimensional FE modelling experiments that demonstrate how three key modelling parameters, (i) dimensionality, (ii) symmetric geometry, and (iii) constraints, affect deformation and strain regimes of the models. Our results confirm that, in the case of the primate mandible (at least), two-dimensional FEM fails to meet this minimum modelling requirement and should not be used to draw functional, ecological or evolutionary conclusions.

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Fracture Fixation Technique and Chewing Side Impact Jaw Mechanics in Mandible Fracture Repair

Cited by 5 publications

References 56 publications

Macaca mulattais a good model for human mandibular fixation research

Macaca mulattais a good model for human mandibular fixation research

The Kinematics of Proal Chewing in Rats

Does the model reflect the system? When two-dimensional biomechanics is not ‘good enough’

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