Delaunay C
Clinique de l'Yvette, 43, route de Corbeil, 91160 Longjumeau.
Rev Chir Orthop Reparatrice Appar Mot. 2000 Dec;86(8):809-24.
Long-term outcome of Charnley low-friction arthroplasty in young active patients is impaired worldwide due to wear of the polyethylene (PE) component and osteolysis. In the late eighties, reports of possible low wear with some former metal on metal total hip arthroplasties led to the reintroduction of metallic bearings. The aims of this work were to examine the rationale for using metal on metal bearings in primary total hip arthroplasty (THA) and report preliminary results obtained with cementless Metasul -Alloclassic hips.
From January 1994 to March 1997, 64 cementless primary Alloclassic-THA (grit-blasted titanium SL stems and CSF treaded cups) with 28 mm Metasul bearings were performed. Mean age at surgery was 60 years (range, 36-73). Diagnoses were usual, mainly primary osteoarthrosis in 70 p. 100 of the hips. Two bearing surfaces were exchanged for late dislocation at 2.6 and 2.9 years. Thus, 62 hips in 58 active patients (4 bilateral) were reviewed after a minimum 2-year follow-up (mean 3.2 years, range 24-66 months).
Clinical results according to the Merle d'Aubigne and Charnley rating system were graded excellent or good in all 62 hips. Radiologically, calcar, atrophy and spot welds were noted in 93 p. 100 and 82 p. 100 of hips respectively. Proximal reactive and lucent lines and mild proximal stress shielding were observed in 8 p. 100 and 4.8 p. 100 of hips respectively. No osteolysis granuloma has thus far been observed in the vicinity of any component. Cobalt blood level remained normal, except in 6 cases due to occupational exposure (n=1), possible impingement (n=1) or an unknown cause (n=4). All elevated cobalt levels (range 7 to 25 microg/l) were nevertheless far below the toxic limit.
Dislocation may be due either to the posterolateral surgical approach and/or early impingement with the first Metasul bearing design (head sleeve). Metasul acetabular component fixation is not restricted to only cementless metal-backing, unlike alumina-ceramic cups. The concern about the toxicity of metallic wear debris dissemination and the hematocarcinogenic risk must be taken into consideration as for any metallic THA. Follow-up is too short for the new polys for significant comparisons.
Metal on metal tribology is well known in vitro and Metasul bearings have functioned in vivo for 12 years (120 000 Metasul hips worldwide) as was expected from laboratory tests. Obviously, this friction couple is not the unique answer to PE-wear and THA longevity, but, in light of current data, appears as a trustworthy solution available today.
在全球范围内，由于聚乙烯（PE）部件的磨损和骨溶解，Charnley低摩擦人工关节置换术在年轻活跃患者中的长期疗效受到影响。在八十年代后期，一些关于早期金属对金属全髋关节置换术可能低磨损的报道促使金属轴承重新被采用。本研究的目的是探讨在初次全髋关节置换术（THA）中使用金属对金属轴承的理论依据，并报告非骨水泥型Metasul - Alloclassic髋关节的初步结果。
从1994年1月至1997年3月，共进行了64例采用28毫米Metasul轴承的非骨水泥初次Alloclassic - THA（喷砂处理的钛制SL柄和CSF螺纹髋臼杯）。手术时的平均年龄为60岁（范围36 - 73岁）。诊断结果常见，主要是70%的髋关节为原发性骨关节炎。有两个关节面因术后2.6年和2.9年的晚期脱位而进行了更换。因此，对58例活跃患者（4例双侧）的62个髋关节进行了至少2年的随访（平均3.2年，范围24 - 66个月）。
根据Merle d'Aubigne和Charnley评分系统，所有62个髋关节的临床结果均为优或良。在影像学上，分别有93%和82%的髋关节出现了股骨距、萎缩和点焊。分别有8%和4.8%的髋关节观察到近端反应性和透亮线以及轻度近端应力遮挡。到目前为止，在任何部件附近均未观察到骨溶解肉芽肿。除6例因职业暴露（n = 1）、可能的撞击（n = 1）或不明原因（n = 4）导致钴血水平升高外，其余患者的钴血水平均保持正常。所有升高的钴水平（范围7至25微克/升）仍远低于毒性极限。
脱位可能是由于后外侧手术入路和/或早期与第一代Metasul轴承设计（头套）发生撞击。与氧化铝陶瓷杯不同，Metasul髋臼部件的固定不限于非骨水泥金属背衬。对于任何金属THA，都必须考虑到金属磨损碎屑传播的毒性和血液致癌风险。由于随访时间过短，无法对新的聚乙烯材料进行有意义的比较。
金属对金属摩擦学在体外是众所周知的，并且正如实验室测试所预期的那样，Metasul轴承在体内已经发挥作用12年（全球有120000个Metasul髋关节）。显然，这种摩擦副并不是解决PE磨损和THA使用寿命问题的唯一答案，但根据目前的数据，它似乎是目前可用的可靠解决方案。
