Hemiarthroplasty is a surgical procedure that replaces the injured half of a diarthrodial joint (such as the hip or shoulder) with a smooth impermeable metal surface, leaving the apposing healthy cartilage layer intact. In 2006, more than 260,000 hip and shoulder hemiarthroplasties were performed in the United States alone. Hemiarthroplasties are often revised to total arthroplasties, due in part to premature erosion of the intact, initially healthy cartilage. Recent theoretical and experimental studies have shown that the low friction and wear of healthy diarthrodial joints depend critically upon sustained, elevated pressure of the interstitial water within the porous cartilage. Because this fluid pressure is continuous across the porous-permeable cartilage contact interface, the impermeable bearing surface implanted in hemiarthroplasty may substantially disrupt the natural lubrication of the apposing healthy cartilage. Motivated by the established clinical success of implanting glutaraldehyde-treated porcine and bovine heart valves and pericardial grafts in humans, the objective of this study was to investigate whether a novel bioprosthetic hemiarthroplasty, utilizing a glutaraldehyde-treated cartilage xenograft, can reproduce the sustained low friction of a healthy natural diarthrodial joint. The specific aim of this study was to measure and compare the 24 h in-vitro frictional response of a bovine shoulder joint with that of a bioprosthetic hemiarthroplasty consisting of a glutaraldehyde-treated humeral head and an untreated, native cartilage glenoid.
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