Hip replacement devices

Bundy, K J. and Collier, J. P., "Mechanistic Studies of Corrosion of Galvanically Coupled Alloys Used in Modular Total Hip Replacement Devices, Transactions of the Implant Retrieval Symposium, 1992, Pheasant Run, IL, p. 55. 

Shown here is a hip replacement device with an alumina ceramic joint head. 

Sulzer Hip Joints. At the machine shop where the Sulzer Company manufactured hip replacement devices, lubricating oil leaked from the machinery into many of the artificial hip sockets, thereby preventing them from adhering to the pelvic bones of the patients into which they were inserted. After receiving many reports of malfunctioning devices, the company recalled 17,500 devices, about 350 of which had to be removed at great pain and expense to the patients. ... 

The success of hip replacements has been greatly advanced by major development in the biomaterials for orthopedic devices. What aspects of chemistry must be considered in designing an effective artificial hip ... 

An interesting finding regarding potentially toxic chromium (and cobalt) in the body is elevated blood and urine levels of these metals in patients who have undergone total hip replacement.5 The conclusion of the study was that devices such as prosthetic hips that involve metal-to-metal contact may result in potentially toxic levels of metals in biological fluids. 

Elevated levels of chromium in blood, serum, urine, and other tissues and organs have been observed in patients with cobalt-chromium knee and hip arthroplasts (Michel et al. 1987 Sunderman et al. 1989). Whether corrosion or wear of the implant can release chromium (or other metal components) into the systemic circulation depends on the nature of the device. In one study, the mean postoperative blood and urine levels of chromium of nine patients with total hip replacements made from a cast cobalt-chromium-molybdenum alloy were 3.9 and 6.2 pg/F, respectively, compared with preoperative blood and urine levels of 1.4 and 0.4 pg/F, respectively. High blood and urinary levels of chromium persisted when measured at intervals over a year or more after surgery. These data suggest significant wear or corrosion... 

HPI AF is a 55-year-old woman who is scheduled to undergo left hip replacement surgery. While in the operating room and postanesthesia care unit (PACU), she has on thromboembolic deterrent (TED) stockings and sequential compression devices (SCDs). On postoperative day 1, the SCDs are discontinued, and she is started on enoxaparin for deep vein thrombosis (DVT) prophylaxis. On postoperative day 7, as AF is getting ready for discharge, she becomes acutely short of breath and develops a painful and swollen left leg. 

Saikko VO, Ahlroos T. Wear simulation of UHMWPE for total hip replacement with a multidirectional pin-on-disk device effects of counterface material, contact area and lubricant. J Biomed Mater Res 2000 49 147-54. 

Regulatory guidelines instruct that implant leachates should not produce adverse local, systemic, tumorigenic, reproductive, or developmental effects to be approved. Evaluations of biocompatibility, which are described in these standards, are all part of the overall safety and efficacy assessment of medical devices and advanced therapy medical products, for example, scaffolds for tissue engineering, tissue adhesives, hip replacements, and surgical meshes for tissue support. 

Biomaterials which are used to repair the body need to last as long as the patient does. At present this is not the case and some people may face several hip replacement operations, for example, each time there being less bone material (or less healthy bone material) for incorporation of devices. The current life expectancy of such replacements is on the order of 10 years at present. This needs to be doubled on tripled in the future. None of the materials described above is able to address the problem of tissue alteration with age and disease. The skeletal system has the capacity to repair itself, this ability diminishing with age and disease state of the material. The ideal solution to the problem is to use biomaterials to augment the body s own reparative process. Certain of the resorbable implants such as tricalcium phosphate and some bioactive glasses are based on this concept. Problems which exist with the development of resorbable materials are (a) the products of resorption must be compatible with cellular metabolic processes and (b) the rate of resorption must also be matched by the capacities of the body to process and transport the products of this process. In addition, as the material is resorbed and new material formed, the properties of both phases will alter and compatibility must be maintained at all times. This is difficult to achieve. 

If yon want to design hip replacements or artificial limbs, work on robotic snrgeiy devices, or engineer mobility assistance for the disabled, then you are interested in biomedical engineering. You might also work on dialysis machines, artificial hearts or nuclear magnetic resonance (NMR) scanners. 

Walter A. Wear-screening of ceramic-to-ceramic components for total hip replacements by ring-on-disc device and joint simulator test. In High tech ceramics. Amsterdam Elsevier Science Publishers B.V. 1987. 

HDPE by itself is a safe plastic material on account of its chemical inertness and lack of toxicity. Consequently, film and containers made from HDPE are used on a large scale in food and dmg packaging. Moreover, HDPE has been used in prosthetic devices including hip and knee joint replacements (122). 

EC Reclassifies hip, knee and shoulder joint replacements as Class 111 devices by way of derogation from the general classification rules... 

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