A comparison of healthy human and swine articular cartilage dynamic indentation mechanics

Abstract

Articular cartilage is a multicomponent, poroviscoelastic tissue with nonlinear mechanical properties vital to its function. A consequent goal of repair or replacement of injured cartilage is to achieve mechanical properties in the repair tissue similar to healthy native cartilage. Since fresh healthy human articular cartilage (HC) is not readily available, we tested whether swine cartilage (SC) could serve as a suitable substitute for mechanical comparisons. To a first approximation, cartilage tissue and surgical substitutes can be evaluated mechanically as viscoelastic materials. Stiffness measurements (dynamic modulus, loss angle) are vital to function and are also a non-destructive means of evaluation. Since viscoelastic material stiffness is strongly strain rate dependent, stiffness was tested under different loading conditions related to function. Stiffness of healthy HC and SC specimens was determined and compared using two non-destructive, mm-scale indentation test modes: fast impact and slow sinusoidal deformation. Deformation resistance (dynamic modulus) and energy handling (loss angle) were determined. For equivalent anatomic locations, there was no difference in dynamic modulus. However, the HC loss angle was ~35% lower in fast impact and ~12% higher in slow sinusoidal mode. Differences seem attributable to age (young SC, older HC) but also to species anatomy and biology. Test mode-related differences in human-swine loss angle support use of multiple function-related test modes. Keeping loss angle differences in mind, swine specimens could serve as a standard of comparison for mechanical evaluation of e.g. engineered cartilage or synthetic repair materials.

A tracheal scaffold of gelatin-chondroitin sulfate-hyaluronan-polyvinyl alcohol with orientated porous structure

“…This result suggested that PVA incorporation can enhance the elasticity of the composite scaffolds when they were stressed under high frequency. The value of loss tangent of human articular cartilage tissue was about 0.25 (Ronken, Arnold, Garcia, Jeger, Daniels & Wirz, 2012). Such a small value of loss tangent indicated a small viscous response in cartilage tissue at the frequencies reported.…”

“…In general, the cartilage tissue has an energy dissipation of 50%-80% (Varga et al, 2007), which can assure stable mechanical reaction to cyclic compression. The articular cartilage tissue shows a small loss tangent (0.25) (Ronken, Arnold, Garcia, Jeger, Daniels & Wirz, 2012), which gives the information about viscoelasticity.…”

Influence of medial meniscectomy on stress distribution of the femoral cartilage in porcine knees: a 3D reconstructed T2 mapping study

“…In some previous studies, knee kinematics and in situ force in the reconstruction technique of anterior cruciate ligament were assessed using porcine knee joint 33,34 , or compressive stresses in the subchondral bone, epiphysis, and diaphysis of the tibia in porcine knees were measured under static and impact load with various knee alignments 35 . Ronken et al assessed stiffness of human and porcine articular knee cartilage under different loading conditions, and reported that porcine cartilage has mechanical properties similar to the human cartilage 36 . We believe that this model allowed investigation of the load response of cartilage by T2 mapping.…”

Repair of Osteochondral Defects with Rehydrated Freeze-Dried Oligo[Poly(Ethylene Glycol) Fumarate] Hydrogels Seeded with Bone Marrow Mesenchymal Stem Cells in a Porcine Model

“…This is a significant outcome as the porcine joint simulates the biomechanical rigors experienced in the human joints. 54 Thirdly, we cannot conclude if the cell number seeded is optimal for repair, as the amount was determined from our own groups' cartilage experience. Further studies would be required in this aspect.…”