Molecular basis of osteoarthritis: biomechanical aspects

Abstract

The unique biomechanical properties of healthy cartilage ensure that articular cartilage is able to transmit force between the joints while maintaining almost friction-free limb movement. In osteoarthritis, the biomechanical properties are compromised, but we still do not understood whether this precedes the onset of the disease or is a result of it. This review focuses on the physical changes to cartilage with age, disease, and mechanical loading, with specific reference to the increased collagen cross-linking that occurs with age (nonenzymatic glycation), and the response of chondrocytes to physiological and pathological loads. In addition, the biomechanical properties and matrix biosynthesis of cartilage from various joint surfaces of the knee and ankle are compared to elucidate reasons why the ankle is less affected by progressive osteoarthritis than the knee.

A driving force for change: interstitial flow as a morphoregulator

“…In cartilage, where lymphatics are absent and intercellular distances are large, interstitial fluid flow is driven by mechanical loading and is necessary for nutrient transport and cell-cell communication when diffusion is inadequate [24][25][26]. Also, interstitial flow rather than solid stress is responsible for at least some of the mechanical stress-induced matrix production in cartilage [27], because dynamic rather than static compression was found to promote proteoglycan and collagen synthesis [28] and increase chondrocyte metabolism [29] (interstitial flow is always present in tissues undergoing dynamic compression). Dynamic compression stimulates directional deposition of proteoglycans and matrix fiber compaction in the direction of flow [26] and directs remodeling by enhancing the transport of tissue inhibitor of metalloproteinase-1 (TIMP-1) [30].…”

Estudo morfoquantitativo e imunohistoquímico da cartilagem articular do joelho de ratos Wistar submetidos à restrição calórica no envelhecimento

“…Segundo Kerin et al (2002), áreas nas articulações que sofrem grandes forças durante a locomoção, geralmente tem maior quantidade de proteoglicanas comparado com a cartilagem adjacente com menor estresse, porém, segundo Arokoski et al (2000), locais que apenas suportam descarga de peso, como por exemplo o platô tibial, são ricos em proteoglicanas.…”

“…Pode ser causada por diversos fatores como a pós-menopausa, ocasionada por baixos níveis de estrógeno (WLUKA et al, 2004;FONTINELE, 2008), hereditariedade (SAXON et al, 1999;WLUKA et al, 2004;GOLDRING;GOLDRING, 2007), trabalhos que envolvam movimentos repetitivos (SAXON et al, 1999), envelhecimento (FELSON et al, 1988;BEAUPRÉ et al, 2000;KERIN, 2002;GUERRA et al, 2004;WANG et al, 2006;GOLDRING;GOLDRING, 2007) e obesidade que afeta principalmente o joelho (FELSON et al, 1988;SAXON et al, 1999;KERIN et al, 2002;KEAN, 2012).…”

“…As cartilagens articulares que mais sofrem com a osteoartrose são a proximal da tíbia, distal do fêmur e superfície patelofemoral (KERIN, et al, 2002). Outros locais mais comumente afetados são as mãos, quadris e coluna (GOLDRING;GOLDRING, 2007).…”

“…A excessiva ingestão calórica é um fator de risco para diversas doenças crônicas (HURSTING et al, 2003;FONTANA;KLEIN, 2007), incluindo diabetes, hipertensão, acidente vascular cerebral, infarto do miocárdio, Alzheimer (LOGROSCINO et al, 2007) e osteoartrose (SAXON et al, 1999;KERIN et al, 2002), diminuindo a expectativa de vida (FONTANA; KLEIN, 2007), sendo as maiores causas de incapacidade e morte nos países industrializados (MATTSON, 2005).…”