Identification of important interactions between subchondral bone ...
Identification of important interactions between subchondral bone ...
Identification of important interactions between subchondral bone ...
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2.3 The pathology <strong>of</strong> Osteoarthritis<br />
CHAPTER 2: Introduction<br />
OA is a complex disease <strong>of</strong> the entire joint. It is mainly characterized by the progressive<br />
degradation <strong>of</strong> articular cartilage, formation <strong>of</strong> osteophytes (<strong>bone</strong> outgrowths) and alterations and<br />
thickening <strong>of</strong> the <strong>subchondral</strong> <strong>bone</strong> (fig. 8) 60,61 . The main focus in the past decades has been on<br />
the articular cartilage as the affected tissue and biomechanics as the causative agent. The<br />
alterations in <strong>subchondral</strong> <strong>bone</strong> were believed to be secondary to the enforced inactivity.<br />
However, several studies have shown that normal cartilage turnover is dependent on a healthy<br />
<strong>subchondral</strong> <strong>bone</strong> 62,63 . Today, it is openly debated whether the pathogenesis <strong>of</strong> OA originates in<br />
the <strong>bone</strong> or in the cartilage compartment, and it is not clear to which extend these two<br />
compartments drives disease progression. An increased amount <strong>of</strong> evidence suggests a strong<br />
coupling <strong>between</strong> the <strong>subchondral</strong> <strong>bone</strong> and the articular cartilage turnover with pathological<br />
processes occurring concurrently in both compartments. Therefore, an optimal intervention<br />
strategy for OA likely includes the targeting <strong>of</strong> both <strong>bone</strong> and cartilage compartments that affects<br />
the pathophysiology <strong>of</strong> the whole joint by modulating and altering the <strong>interactions</strong> <strong>between</strong> the<br />
different cell types.<br />
Fig. 8. Illustration <strong>of</strong> a knee with severe osteoarthritis.<br />
A severe chronic osteoarthritic knee, with eroded cartilage,<br />
eroded meniscus, exposed <strong>bone</strong> and osteophytes (<strong>bone</strong><br />
outgrowths). Adapted with few modifications 64 .<br />
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