An automated system for measuring multi-dimensional, time dependent mechanical properties of a human tibial fracture

• Published in: Medical engineering & physics 2007-12, Vol.29 (10), p.1049-1055
• Main Authors: Ogrodnik, Peter J, Moorcroft, C. Ian, Thomas, Peter B.M
• Format: Article
• Language: English
• Subjects: Automated system; Automation; Biomechanical Phenomena - methods; Creep; Diagnosis, Computer-Assisted - instrumentation; Diagnosis, Computer-Assisted - methods; Elasticity; Equipment Design; Equipment Failure Analysis; Fracture assessment; Fractures, Bone - diagnosis; Fractures, Bone - pathology; Humans; Load-rate; Models, Statistical; Non-linearity; Physical Examination - instrumentation; Physical Examination - methods; Physical Stimulation - instrumentation; Physical Stimulation - methods; Radiology; Stiffness; Stress, Mechanical; Tibia - pathology; Tibial fracture; Tibial Fractures - diagnosis; Tibial Fractures - physiopathology; Time Factors; Viscosity; Weight-Bearing
• ISSN: 1350-4533; 1873-4030
• DOI: 10.1016/j.medengphy.2007.08.001

Abstract An automated loading and measurement device has been developed for assessment of the mechanical properties of a healing human tibial fracture. The characteristics of the device are presented with assessments of errors. This paper constitutes a small part of a long term research project determining a clinically quantifiable end point for fracture healing in humans, hence a sample of results is presented to demonstrate the potential application of the device. A more detailed analysis of the results will be the basis of further publications. The initial results confirm that the non-linear behaviour of callus cannot be ignored in fracture assessment methodologies. They further reinforce the requirement to measure load-rate when measuring fracture stiffness. Polar plots of stiffness demonstrate that when measuring fracture stiffness not only should load-rate be considered, but also the orientation of measurement. The results from this work support the view that fracture stiffness should be measured in at least two planes. A new material property for the assessment of fracture healing, the gamma ratio γ , is examined and preliminary results are shown. The paper also demonstrates how creep properties of a healing tibia can be assessed and proposes that this property may form the basis for future fracture assessment investigations.