Implants clinical performance

Hydrophobic coatings composed of silicon- and fluorine-containing polymeric materials as well as polyurethanes have been studied because of the relatively good clinical performances of Silastic , Teflon , and polyurethane polymers in cardiovascular implants and devices. Polymeric fluorocarbon coatings deposited from a tetrafluoroethylene gas discharge have been found to greatly enhance resistance to both acute thrombotic occlusion and embolization in small diameter Dacron grafts. 

On the other hand, survivorship alone does not fully capture the clinical performance of UHMWPE in the knee. Surface damage and wear of the UHMWPE insert are also important measures of clinical performance of knee arfhroplasty. If a knee prosthesis survives the first 10 years of implantation, wear behavior... 

Snyder G. 1996. Shoulder implant system. In Clinical performance of skeletal prostheses. L. Hench and J. Wilson, Eds. London, Chapman Hall. 

Clinical performance of implants is challenging to interrogate through randomized clinical trials and these efforts are typically reserved for those implants for which there is not an acceptable predicate device. More often, acceptable clinical performance is predicted through preclinical in vitro and animal studies. Whenever possible, implants... 

Because there are always potential risks associated with any implantable device, before any new biotextile product can be distributed, sold and implanted clinically in a human patient in the United States, its properties and performance are required by law to be carefully reviewed and evaluated by the federal Food and Drug Administration. Its role is to ensure the safety and efficacy of all implantable devices before they are made available for surgical use in the United States. Other countries and jurisdictions have similar regulatory bodies that require all biotextile products to comply with their regulatory process (Chapter 7). 

Harding, A. F., Cook, S. D., and Thomas, K. A., Orthopaedic Implant Retrieval Clinical Performance, Metallurgical Characteristics and Tissue Reaction in 250 Internal Fixation Devices, Proceedings of the 5th Southern Biomedical Engineering Conference, Petgamon Phess, NY, 1985, pp. 282-288. 

Kurtz SM, Austin M, Azzam K, Sharkey P, MacDonald D, Medel FJ, Hozack WJ. Mechanical properties, oxidation and clinical performance of retrieved highly cross-linked crossfire liners after intermediate-term implantation. J Arthroplasty 2008. (In Press). 

The clinical use of Poly II persisted into the 1980s until it was eventually abandoned, but no studies have documented its long-term performance. Surprisingly, some of these CFR-UHMWPE tibial components have managed to survive long-term implantation in patients (Figitre 17.4). These observations prompted the author and colleagues at Drexel University to revisit the clinical performance of Poly n. 

UHMWPE wear continues to be an important factor in the long-term survivability of orthopedic implants [1-3]. As established in Chapter 23, periprosthetic osteolysis occurs secondary to the generation of UHMWPE wear debris in total hip arthroplasty (THA) [1, 2, 4]. In the last decade, efforts have been made to increase the wear resistance of UHMWPE [1, 5, 6], Highly crosslinked UHMWPE (Chapters 13 and 14) was introduced in THA 10 years ago and more recently in total knee arthroplasty. UHMWPE wear volume and wear patterns must be fiiUy evaluated to understand historic UHMWPE wear processes to evaluate the efficacy of highly crosslinked UHMWPE and to analyze future UHMWPE formulations that attempt to improve the clinical performance of UHMWPE. 

Clinical evaluation is underway to test transvenous electrodes. Transvenous leads permit pacemakers to be implanted under local anesthesia while the patient is awake, greatly reducing recovery time and risk. As of 1996, the generation of implantable defibrillators requires a thoracotomy, a surgical opening of the chest, in order to attach electrodes to the outside of the heart. Transvenous electrodes would allow cardiologists to perform pacemaker procedures without a hospital or the use of general anesthesia. 

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