However, despite its frequency and significance, there is little understanding of the response of a child's head to injurious loading.
Off-loading cartilage causes thinning, while excessive or injurious loading leads to degeneration.
Thus, conditions such as obesity or trauma that represent excessive or injurious loading will increase catabolic activities and accelerate matrix damage [ 48, 62, 63].
However, conditions such as obesity or trauma that represent excessive or injurious loading will increase catabolic activities and accelerate matrix damage mediated by abnormal integrin signals [ 43, 44].
Painful IVD degeneration is therefore complex and multifactorial, likely involving larger changes to the IVD than the loss of NCs such as injurious loading and altered microenvironment conditions occurring in the context of genetic susceptibility.
However, we cannot know whether the imbalance of PG and type II collagen is a consequence or cause of OA. Cell death by injurious mechanical load has been observed in both in vivo and in vitro studies, although some of these studies have reported that apoptosis did not appear to be the cause [ 2, 47].
However, injurious mechanical loading has also been observed to significantly increase the number of apoptotic cells [ 48, 49].
However, in abnormal or injurious joint loading the balance between cartilage matrix synthesis and degradation is disturbed [ 7], resulting in tissue breakdown and the risk of progression of OA.
Literature data indicate that excessive injurious single-impact loading causes acute cartilage damage with increasing chondrocyte death and extracellular matrix damage.
Although 'poor' unloaded standing posture has been related to spinal pain, there is little evidence of whether, and how much, exposure to posterior load produces injurious effects on spinal tissue.
