Development of a Sequence of Mechanical Tests for Articular Cartilage at a Single Location

Sim S; Chartrand A; Lavallee AP; Tessier J; Garon M; Quenneville E; Buschmann MD
Orthopeadic Research Society Annual Meeting in Orlando, 2016

Les titres, résumés et légendes des publications sont présentés en anglais.

In a recent study, our group has highlighted the importance of considering the natural topographic variability of the mechanical properties over the articular surface, particularly in the context of cartilage repair, where it can screen the effect of a treatment [1]. Moreover, the availability of test sample is limited in those repair studies since the regions of interest are often limited in size. A solution to overcome this problematic is to perform multiple tests at a single location over the articular surface. Therefore, the objective of this study was to develop such a sequence of mechanical tests to characterize articular cartilage at a single location.

METHODS: Five distal femurs from healthy cadaveric human distal femurs provided by a tissue bank (RTI Surgical, Florida) were used. All mechanical tests were performed using a multiaxial mechanical tester, Mach-1 v500css (Biomomentum Inc., Canada). Initially, an automated indentation mapping followed by a thickness mapping was performed on entire distal femurs in order to calculate the instantaneous modulus (IM) using an elastic indentation model [2]. Osteochondral cores (3.5 mm diameter) were then extracted from distal femurs where six cores were randomly chosen for this study. From the maps, the IM and cartilage thickness corresponding to each core was calculated as the average of all values measured within 6 mm from the core center location. Cartilage thickness was remeasured using a dissection microscope and a 10 minute wait was allowed between each test. On each core, a 20% equilibrium strain was applied and then a friction test was executed following a 5 mm circular path (1440° rotation) in order to extract the coefficient of friction at equilibrium μeq.

Utilisation des équipements

Le Mach-1 réalisait la séquence d’essais mécaniques sur le cartilage articulaire humain, comprenant la cartographie par indentation et la mesure d’épaisseur.