The Craniomaxillofacial Skeleton: New Approaches in Computational Biomechanics and Fracture Stabilization

The mechanical behaviour of the craniomaxillofacial skeleton (CMFS) under physiological loads is among the least understood in the field of musculoskeletal biomechanics. The highly complex structure of the CMFS defies reduction to analogous or simpler components. Its modelling demands a holistic and inte- grated approach in order to gain insight into its structural function. As such, the biomechanical foundations upon which the practises for open-reduction internal-fixation are developed are controversial. A systematic and quantitative biomechanical framework is needed to guide the treatment of CMFS injuries and pathologies. This research aims to address these issues on two fronts: through characterization of the loading patterns of the CMFS derived from computational modelling, as well as the development of an innovative internal stabilization device for the CMFS. This thesis first addresses the challenges through a practical and novel approach whereby a deblurring algorithm is applied to clinical CT images which restores the geometry and intensity of the thin cortical bone structures. Using these restored images a biomechanical framework was further developed to produce high fidelity subject-specific finite element models of the CMFS. Validation of this approach was demonstrated through strong correlation with multi-subject in vitro experiments (r = 0.93, regression slope of unity). These models elucidated the patterns of stress and strain on the CMFS subject to a simulated physiological masticatory bite load. The observed patterns invite a critical re-analysis of the classic CMFS buttress hypothesis. Finally, a pilot experimental investigation into the mechanical efficiency of“Bone Tape”, a bioresorbable polymer- ceramic composite device for internal fixation of CMFS fractures, was conducted. In vitro experiments demonstrated an initial flexibility which conferred an ability to conform to complex 3-D bone topologies and a potential to equate the strength of commercially available bioresorbable systems. A prototype concept for its use was deployed in an in vivo rabbit model. The structural biomechanics knowledge gained based on the validated computational biomechanical framework will ultimately provide a robust platform which will enable the rational design and optimization of new treatment hardware and practises, such as Bone Tape, toward improved outcomes in reconstruction of the CMFS.

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Year

Entry

2007

Anderson AE, Ellis BJ, Weiss JA. Verification, validation and sensitivity studies in computational biomechanics. Comput Methods Biomech Biomed Eng. June 2007;10(3):171-184.

2006

Taddei F, Cristofolini L, Martelli S, Gill HS, Viceconti M. Subject-specific finite element models of long bones: an in vitro evaluation of the overall accuracy. J Biomech. 2006;39(13):2457-2467.

2005

Anderson AE, Peters CL, Tuttle BD, Weiss JA. Subject-specific finite element model of the pelvis: development, validation and sensitivity studies. J Biomech Eng. June 2005;127(3):365-373.

1994

Silva MJ, Wang C, Keaveny TM, Hayes WC. Direct and computed tomography thickness measurements of the human, lumbar vertebral shell and endplate. Bone. July 8, 1994;15(4):409-414.

1993

Dalstra M, Huiskes R, Odgaard A, van Erning L. Mechanical and textural properties of pelvic trabecular bone. J Biomech. April–May 1993;26(4-5):523-535.