Jacobs J J, Skipor A K, Patterson L M, Hallab N J, Paprosky W G, Black J, Galante J O
Department of Orthopedic Surgery, Rush Arthritis and Orthopedics Institute, Rush Medical College, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA.
J Bone Joint Surg Am. 1998 Oct;80(10):1447-58. doi: 10.2106/00004623-199810000-00006.
There is an increasing recognition that, in the long term, total joint replacement may be associated with adverse local and remote tissue responses that are mediated by the degradation products of prosthetic materials. Particular interest has centered on the metal-degradation products of total joint replacements because of the known toxicities of the metal elements that make up the alloys used in the implants. We measured the concentrations of titanium, aluminum, cobalt, and chromium in the serum and the concentration of chromium in the urine of seventy-five patients during a three-year prospective, longitudinal study. Twenty patients had had a so-called hybrid total hip replacement (insertion of a modular cobalt-alloy femoral stem and head with cement and a titanium acetabular cup without cement), fifteen had had insertion of an extensively porous-coated cobalt-alloy stem with a cobalt-alloy head and a titanium-alloy socket without cement, and twenty had had insertion of a proximally porous-coated titanium-alloy stem with a cobalt-alloy head and a titanium socket without cement. The remaining twenty patients did not have an implant and served as controls. The results of our study showed that, thirty-six months postoperatively, patients who have a well functioning prosthesis with components containing titanium have as much as a threefold increase in the concentration of titanium in the serum and those who have a well functioning prosthesis with cobalt-alloy components have as much as a fivefold and an eightfold increase in the concentrations of chromium in the serum and urine, respectively. The predominant source of the disseminated chromium-degradation products is probably the modular head-neck junction and may be a function of the geometry of the coupling. Passive dissolution of extensively porous-coated cobalt-alloy stems was not found to be a dominant mode of metal release.
Increased concentrations of circulating metal-degradation products derived from orthopaedic implants may have deleterious biological effects over the long term that warrant investigation. This is a particularly timely concern because of recent clinical trends, including the reintroduction of metal-on-metal bearing surfaces and the increasing popularity of extensively porous-coated devices with large surface areas of exposed metal. Accurate monitoring of the concentrations of metal in the serum and urine after total hip replacement also can provide insights into the mechanisms of metal release. Our findings suggest that fretting corrosion at the head-neck coupling is an important source of metal release that can lead to increased concentrations of chromium in the serum. Determinations of the concentrations of metal in the serum and urine may be useful in the diagnosis of patients who are symptomatic after a total joint replacement as increased levels are indicative of at least one mode of mechanical dysfunction (for example, fretting corrosion) of the device.
人们越来越认识到，从长远来看，全关节置换可能与由假体材料降解产物介导的局部和远处不良组织反应相关。由于构成植入物所用合金的金属元素具有已知毒性，全关节置换的金属降解产物尤其受到关注。在一项为期三年的前瞻性纵向研究中，我们测量了75例患者血清中钛、铝、钴和铬的浓度以及尿液中铬的浓度。20例患者接受了所谓的混合式全髋关节置换（植入带骨水泥的模块化钴合金股骨干和股骨头以及无骨水泥的钛髋臼杯），15例患者植入了带钴合金头和钛合金臼杯的广泛多孔涂层钴合金柄且无骨水泥，20例患者植入了带钴合金头和钛臼杯的近端多孔涂层钛合金柄且无骨水泥。其余20例患者未植入假体，作为对照。我们的研究结果表明，术后36个月，假体功能良好且部件含钛的患者血清中钛浓度增加了两倍之多，假体功能良好且部件为钴合金的患者血清和尿液中铬浓度分别增加了五倍和八倍之多。扩散的铬降解产物的主要来源可能是模块化头颈交界处，可能与连接的几何形状有关。未发现广泛多孔涂层钴合金柄的被动溶解是金属释放的主要方式。
源自骨科植入物的循环金属降解产物浓度增加可能长期产生有害的生物学效应，值得研究。由于近期的临床趋势，包括重新引入金属对金属的关节面以及具有大面积暴露金属的广泛多孔涂层装置越来越受欢迎，这一问题尤为及时。全髋关节置换术后准确监测血清和尿液中的金属浓度也有助于深入了解金属释放机制。我们的研究结果表明，头颈连接处的微动腐蚀是金属释放的一个重要来源，可导致血清中铬浓度升高。测定血清和尿液中的金属浓度可能有助于诊断全关节置换术后出现症状的患者，因为浓度升高表明装置至少存在一种机械功能障碍模式（例如微动腐蚀）。
