title: Design, validation, and utilization of an articular cartilage impact instrument.
abstract: This paper describes the development and use of an instrument mechanically to impact bovine articular cartilage and record the event using a piezoelectric accelerometer, as well as to carry out post-impact characterization of the tissue. Two levels of impact (low: 6 cm drop height, 18.4 N tup; high: 10 cm drop height, 27.8 N tup) were chosen such that the former did not show gross damage upon inspection, while the latter showed substantial gross damage. Peak stress, time to peak stress, and impact duration were taken from data recorded by the instrument. Three cartilage biomechanical properties (aggregate modulus, Poisson's ratio, and permeability) were acquired by creep indentation, and tissue morphology rated on a standardized scale was also determined. When subjected to the high level of impact, articular cartilage showed statistically significant (p < 0.05) differences in all three impact metrics and morphology. This high level of impact also resulted in a 37 per cent decrease in the aggregate modulus of the tissue. Lower drop heights resulted in more consistent impact curves, demonstrated less standard deviation, and did not change the biomechanical properties of the tissues. With the instrument and techniques described in this study, articular cartilage can be subjected to specific levels of impact in order to study injury biomechanics of the tissue at specific levels of mechanical damage.
authors.affiliation: Department of Bioengineering, Rice University, 6100 Main St, Keck Hall, Suite 116, Houston, Texas 77584, USA.
authors.forename: C C
authors.initials: CC
authors.lastname: Scott
authors.forename: K A
authors.initials: KA
authors.lastname: Athanasiou
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000295:instrumentation* / Q000379:methods; D002358:Cartilage, Articular / Q000166:cytology* / Q000502:physiology*; D002417:Cattle; D004548:Elasticity; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006244:Hardness; D006245:Hardness Tests / Q000295:instrumentation* / Q000379:methods; D066298:In Vitro Techniques; D010812:Physical Stimulation / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014783:Viscosity