Focal cartilage defect compromises fluid‐pressure dependent load support in the knee joint

Abstract

A focal cartilage defect involves tissue loss or rupture. Altered mechanics in the affected joint may play an essential role in the onset and progression of osteoarthritis. The objective of the present study was to determine the compromised load support in the human knee joint during defect progression from the cartilage surface to the cartilage-bone interface. Ten normal and defect cases were simulated with a previously tested 3D finite element model of the knee. The focal defects were considered in both condyles within high load-bearing regions. Fluid pressurization, anisotropic fibril-reinforcement, and depth-dependent mechanical properties were considered for the articular cartilages and menisci. The results showed that a small cartilage defect could cause 25% reduction in the load support of the knee joint due to a reduced capacity of fluid pressurization in the defect cartilage. A partial-thickness defect could cause a fluid pressure decrease or increase in the remaining underlying cartilage depending on the defect depth. A cartilage defect also increased the shear strain at the cartilage-bone interface, which was more significant with a full-thickness defect. The effect of cartilage defect on the fluid pressurization also depended on the defect sites and contact conditions. In conclusion, a focal cartilage defect causes a fluid-pressure dependent load reallocation and a compromised load support in the joint, which depend on the defect depth, site, and contact condition.

Computational evaluation of altered biomechanics related to articular cartilage lesions observed in vivo

“…Previously, the prevalence and progression of chondral lesions as well as alterations in cartilage biomechanics in in vitro models of cartilage lesions have been investigated . In vitro models and strain‐based degeneration algorithm have, for example, been able to reproduce experimentally found cartilage degeneration in terms of proteoglycan loss under similar levels of strain as reported here .…”

Quantitative Evaluation of the Mechanical Risks Caused by Focal Cartilage Defects in the Knee

“…Previously, the effects of focal defects on the mechanical environment of articular cartilage have been analyzed experimentally in in vitro systems478 and theoretically with whole joint finite element (FE) models including artificially introduced cartilage defects121314. However, in vivo characterization of changes in the local mechanical response of cartilage in the vicinity of a clinically observed focal defect could improve understanding of the underlying biomechanical response and mechanobiology at the damaged region.…”

Assessment of fracture risk in proximal tibia with tumorous bone defects by a finite element method

“…It is believed by some scholars that there is no association between the preoperative bone fracture and the size of the tumorous lesions (Hirn et al, 2009;Keene, Sellinger, McBeath, & Engber, 1986). In the established 3D model of the bone defects, certain factors, such as notch (Dabiri & Li, 2015;Elias, Frassica, & Chao, 2000), segments (Chen et al, 2014;Duda et al, 2002), circular type (Alexander et al, 2013), and cylindrical type (Karunratanakul et al, 2013;Rennick et al, 2013), are considered. Because of the differences in these factors that have been found, it is difficult to compare the findings of finite element studies regarding fracture risk due to defect level, shape, and load, along with various other reasons (Liu et al, 2013).…”