Acid Attack and Cathepsin K in Bone Resorption Around Total Hip Replacement Prosthesis

• DOI: 10.1359/jbmr.2001.16.10.1780
• Publication Date: 2006-04-27T03:14:25Z
• Authors: Yrjö T. Konttinen; Michiaki Takagi; Jami Mandelin; Jan Lassus; Jari Salo; Mari Ainola; Tian-Fang Li; Ismo Virtanen; Mikko Liljeström; Hideaki Sakai; Yasuhiro Kobayashi; Timo Sorsa; Reijo Lappalainen; Anne Demulder; Seppo Santavirta
• Keywords: Cathepsin K; Osteoid; Bone remodeling

Normal bone remodeling and pathological destruction have been considered to be osteoclast-driven. Osteoclasts are able attach bare surface produce an acidic subcellular space. This leads acid dissolution of hydroxyapatite, allowing cathepsin K degrade the organic type I collagen-rich osteoid matrix under condition prevailing in Howship lacunae. Using a sting pH electrode, interface membrane around loosened total hip replacement prosthesis was found acidic. Confocal laser scanning disclosed irregular demineralization contact with interface. Cathepsin K, collagenolytic enzyme, tissue macrophages/giant cells pseudosynovial fluid. Tissue extracts contained high levels messenger RNA (mRNA) protein. These observations suggest presence acid- K-driven mechanism resorption, mediated not by osteoclasts subosteoclastic space, but rather uncontrolled activity macrophages extracellular