The disuse-related bone loss that results from immobilisation following injury shares characteristics with osteoporosis in post-menopausal women and the aged, with decreases in bone mineral density leading to weakening of the bone and increased risk of fracture. The aim of this study was to use the finite element method to: (i) calculate the mechanical response of the tibia under mechanical load and (ii) estimate of the risk of fracture; comparing between two groups, an able-bodied group and spinal cord injury patients group suffering from varying degrees of bone loss. The tibiae of eight male subjects with chronic spinal cord injury and those of four able-bodied age-matched controls were scanned using multi-slice peripheral quantitative computed tomography. Images were used to develop full three-dimensional models of the tibiae in Mimics (Materialise) and exported into Abaqus (Simulia) for calculation of stress distribution and fracture risk in response to specified loading conditions - compression, bending and torsion. The percentage of elements that exceeded a calculated value of the ultimate stress provided an estimate of the risk of fracture for each subject, which differed between spinal cord injury subjects and their controls. The differences in bone mineral density distribution along the tibia in different subjects resulted in different regions of the bone being at high risk of fracture under set loading conditions, illustrating the benefit of creating individual material distribution models. A predictive tool can be developed based on these models, to enable clinicians to estimate the amount of loading that can be safely allowed onto the skeletal frame of individual patients who suffer from extensive musculoskeletal degeneration (including spinal cord injury, multiple sclerosis and the ageing population). The ultimate aim is to reduce fracture occurrence in these vulnerable groups.
|Number of pages
|Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
|Published - Feb 2014
Bibliographical noteFunding Information:
Funding was provided by the Scottish Funding Council’s Glasgow Research Partnership in Engineering for Dr Coupaud and Prof Tanner, the Royal Society of Edinburgh’s International Exchange Programme for an initial short visit from Dr Sasagawa to Glasgow and Niigata Engineering Promotion Society's scheme for supporting a subsequent 1-year secondment for Dr Sasagawa to continue his research at the University of Glasgow.
- Disuse osteoporosis
- Finite element model
- Fracture risk
- Spinal cord injury