Evidence for the involvement of the hydroxyl radical in the pathogenesis of excessive connective tissue proliferation in patients with tumor-endoprostheses

Extendible Prostheses for Children After Resection of Primary Malignant Bone Tumor

“…Because scar tissue restricting the range of motion is often a factor limiting elongation in children, scar tissue resection is a common procedure in this population. The underlying mechanism still is unknown, although mechanisms leading to the production of highly-cross-linked collagen, which is less susceptible to proteolytic degradation, have been discussed 23 . Currently, surgical resection of scar tissue and muscle release is the only treatment for a severely restricted range of motion.…”

Evidence Linking Elevated Oxidative Stress and Aseptic Loosening of Hip Arthroplasty

“…Because of the inflammatory nature of aseptic loosening of total hip replacement, arthroplasty, it is likely that free radicals play a major role in this condition as well. In the periprosthetic tissues, detection of reactive oxygen species provides evidence for the formation and activity of free radicals (Windhager et al, 1998. Under physiological conditions, ROS are part of normal regulatory circuits, and the cellular redox state is tightly controlled by antioxidants.…”

“…Transition elements like vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), molybdenum (Mo), so-called d-block elements, show variable valence, which allow them to undergo changes in oxidation state involving one electron. If free radicals have a causative role in aseptic loosening than transition metals would have a strong promotional effect (Windhager et al, 1998). Via the Fenton reaction they would greatly stimulate inflammation and loosening.…”

“…H 2 O 2 in the cells can also undergo the Fenton reaction in the presence of metal ions with subsequent formation of highly toxic hydroxyl radical (Lubec, 1996, Sawyer, 1990. Various studies have reported that ROS are connected with tissue damage and fibrosis (Park et al, 2001, Riedle & Kerjaschki, 1997, Wang et al, 2002, Windhager et al, 1998. On the other hand, the effect of submicron wear debris on macrophage production of reactive oxygen species is largely unexplored.…”

“…Connective tissue metabolism is normally characterized by equilibrium between degradation and synthesis of extracellular matrix. Deviation from the equilibrium may lead to the replacement of extracellular matrix by fibrous tissue (Park et al, 2001, Riedle & Kerjaschki, 1997, Wang et al, 2002, Windhager et al, 1998. The fibrous pseudocapsule formed is probably related to high intraarticular pressure and expansion of the effective joint space as well as production of inflammatory substances and subsequent loosening of the implant (El-Warrak et al, 2004.…”