Macroscopic assessment of cartilage shear: Effects of counter-surface roughness, synovial fluid lubricant, and compression offset

Abstract

During joint articulation, cartilage is subjected to compression, shear, and sliding, mechanical factors that regulate and affect cartilage metabolism. The objective of this study was to use an in vitro material-on-cartilage shear test to elucidate the effects of counter-surface roughness (Polished, Mildly rough, and Rough), lubricants (phosphate buffered saline (PBS) and bovine synovial fluid (bSF)), and compression offset on the shearing and sliding of normal human talar cartilage under dynamic lateral displacement. Peak shear stress (σ xz,m ) and strain (E xz,m ) increased with increasing platen roughness and compression offset, and were 30% higher with PBS than with bSF. Compared to PBS, bSF was more effective as a lubricant for P than for M and R platens as indicated by the higher reduction in kinetic friction coefficient (−60% vs. − 20% and −19%, respectively), σ xz,m (−50% vs. −14% and −17%) and E xz,m (−54% vs. −19% and − 17%). Cartilage shear and sliding were evident for all counter-surfaces either at low compression offset (10%) or with high lateral displacement (70%), regardless of lubricant. An increase in tissue shear occurred with either increased compression offset or increased surface roughness. This material and biomechanical test system allow control of cartilage σ xz,m and E xz,m , and hence, sliding magnitude, for an imposed lateral displacement. It therefore can facilitate study of cartilage mechanobiological responses to distinct regimes of cartilage loading and articulation, such as shear with variable amounts of sliding.

The Relationship of Autophagy Defects to Cartilage Damage During Joint Aging in a Mouse Model

“…In old mice there is a significant reduction in the level of constitutive autophagy with a reduction in size and number of autophagosomes. The defect in autophagy is most profound in the superficial and upper middle zones where the earliest OA structural defects occur (29, 30). We also observed a similar aging-related decrease in the number and size of autophagosomes in subchondral bone.…”

TargetedIn SituBiosynthetic Transcriptional Activation in Native Surface-Level Human Articular Chondrocytes during Lesion Stabilization

“… 70 - 79 This physiochemical loading of accessible surface-based diseased tissue can alter the relative ratio of tension compression nonlinearity toward a state amenable to gentle shear deformation mechanical debridement of tissue already characterized by the deteriorating surface-layered shear properties of collagen fibril disruption and orientation changes, weak collagen-to-proteoglycan bonds, proteoglycan and lipid depletion, aberrant water content, and decreased fixed charge density. 80 - 84 Optimizing the surface shear properties of early articular cartilage damage through cleavage plane stabilization is an important parameter for overall lesion stabilization relative to perturbation specificity 58 particularly because these mechanisms do not impair residual chondrocyte viability. 2 , 3 , 85 These layered surface properties exploited for cleavage plane shear stabilization have been observed in other tissue types and locales requiring shear mitigation during surface degeneration and normally represent a back-up mechanism to boundary lubrication regime failures associated with perturbation exceeding homeostasis and tissue repair for reversible lesions.…”

Effect of Surface Modification of Acetabular Cup with Embedded Micro-Pits on Friction Properties

“…This raises the importance of the density of embedded micro-pits, and the need to reevaluate the parameters, in order to negate potential loosening of the hip implant, even though a low level of friction is achieved.. Furthermore, the friction between the femoral head and the acetabular cup may be reduced by using other potential lubricants [6,7,19]. However, surface modification of the acetabular cup with micro-pitting, does play a role in reducing friction.…”

“…The main problem in the acetabular and femoral head is damage caused by friction and wear [2,4,5]. In hip implant tribology, a reduction of synovial fluid to lubricate the hip prosthesis leads to unsatisfactory outcomes, and even failure of the implant [6,7]. Undergoing a total hip arthroplasty (THA) operation can be traumatic for the patient and, in general, is a very expensive intervention [8,9,10,11].…”