Title: Mechanical characterisation of a scaffold under monotonic and cyclic loading conditions

Authors: Yu-Hsiu Hsu; Colin Lupton; Jie Tong; Andy Cossey; Ada Au

Addresses: Mechanical Behaviour of Materials Laboratory, School of Engineering, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth, PO1 3DJ, UK ' Mechanical Behaviour of Materials Laboratory, School of Engineering, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth, PO1 3DJ, UK ' Mechanical Behaviour of Materials Laboratory, School of Engineering, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth, PO1 3DJ, UK ' Queen Alexandra Hospital, Southwick Hill Rd, Portsmouth, Hampshire PO6 3LY, UK ' Advanced Surgical Devices, Smith & Nephew, 150 Minuteman Rd, Andover, MA 01810, USA

Abstract: Loading from daily activities or from intensive exercise can lead to increased risk of fracture. Implants designed for load bearing purposes, such as repair of articular cartilage and underlying subchondral bone in knees must have the necessary mechanical competence under long term physiological loadings. In this study, the mechanical behaviour of a polymer-based osteochondral scaffold was examined under monotonic and cyclic loading conditions in a phosphate buffered saline solution at 37°. Monotonic compression tests at selected strain rates were performed in both confined and unconfined conditions to investigate the influence of confinement. The effects of strain rate and sample composition on mechanical properties were also studied. Multi-step cyclic tests were carried out with increasing compressive loads. Changes in secant modulus and residual strain accumulation are monitored. The secant modulus and the number of cycles to failure of the scaffold are obtained and compared with those of human trabecular bone (Topolinski et al., 2011).

Keywords: articular cartilage; subchondral bone; osteochondral scaffolds; compression tests; mechanical properties; monotonic loading; fatigue damage; stepwise load; fracture; physiological loadings; strain rates; confinement; compressive loads; secant modulus; residual strain accumulation; knee implants; bone repair.

DOI: 10.1504/IJECB.2014.066091

International Journal of Experimental and Computational Biomechanics, 2014 Vol.2 No.4, pp.359 - 375

Received: 08 Mar 2014
Accepted: 02 Jun 2014
Published online: 17 Dec 2014 *

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