骨水泥型人工髋关节置换后假体柄的无菌性松动:36例翻修标本分析

背景:无菌性松动是骨水泥型人工髋关节置换后失败的主要原因,探讨其发病机制对于预防松动具有重要意义.目的:通过对髋关节翻修手术中取出的假体柄及骨水泥外壳的磨损进行观察,结合临床及X射线资料,探讨骨水泥型人工髋关节置换后假体柄无菌性松动的机制.设计、时间及地点:观察性实验,于2002-07/2003-11在美国休斯敦贝勒医学院骨科研究所完成.对象:选择休斯敦卫理公会医院(Methodist Hospital at Houston)骨科收治的行骨水泥型人工髋关节置换患者36例,男20例,女16例;年龄38～92岁.包括无菌性松动24例,感染10例,脱位1例,骨折1例.方法:36例髋关节翻修手术中取出的骨水泥型似体柄及完整的骨水泥外壳,利用立体光学显微镜对骨水泥外壳内外两面及假体柄进行观察分析,按照Grone分区记录其表面磨损位置及磨损程度和骨水泥开裂区域.将主要的假体微动模式分为扭转应力,内翻屈曲应力,柄末端应力,柄领应力.主要观察指标:骨水泥外壳内外两面磨损位置及磨损程度和骨水泥开裂区域,以及与其相匹配假体柄的磨损位置及磨损程度.结果:除2例外所有假体柄及与其相匹配的骨水泥内面部宵磨损,与假体置入时间无明显关联性.全部无菌性松动翻修取出的标本,其骨水泥外壳表面都有抛光区,只有1例非松动翻修取出的标本骨水泥表面有抛光.根据骨水泥外壳表面磨损大于其内面与假体柄间的磨损,推测骨水泥在髓腔中的微动多于骨水泥与假体柄间的微动.无菌性松动翻修取出的标本中13例发生骨水泥开裂,而因其他原因翻修的标本末发生骨水泥开裂.结论:早期骨水泥开脱及骨水泥与假体柄微动是骨水泥型假体柄普遍存在的特征.骨水泥外壳表面磨损产生的微粒引起骨溶解进一步加速骨水泥表面的磨损.

Aseptic loosening of cemented stem following cemented hip arthroplasty Analysis of 36 revised specimens

BACKGROUND: Aseptic loosening is the main complication after cemented hip arthroplasty. Therefore, it is very important to explore its pathogenesis so as to prevent the aseptic loosening.OBJECTIVE: To observe the prosthesis stem and cement mantles retrieved at revision surgery, in combination with clinical and radiographic data, to explore the pathogenesis of aseptic loosening following hip arthroplasty.DESIGN, TIME AND SETTING: Observation experiment. The study was performed at Baylor College of Medicine and the Institute of Orthopedic Research, Houston, USA between July 2002 and November 2003.PARTICIPANTS: Thirty six patients undergoing cemented hip arthroplasty in Department of Orthopedics, Methodist Hospital at Houston were selected, including 20 males, 16 females, aged 38-92 years. There were 24 cases of aseptic loosening, 10 cases of infection, 1 of dislocation and 1 of fracture.METHODS: The cemented femoral stems with complete cement mantles from the revision surgery of 36 cases were observed. The outer and inner surfaces of the cement mantle and the surface of the femoral component were carefully examined with stereo microscopy. The area, location and degree of surface abrasion and cement cracking were recorded by Gruen zone. The predominant displacement mode of each implant was classified as torsional, varus-bending, end-loading and/or collar loading.MAIN OUTCOME MEASURES: The area, location and degree of surface abrasion and cement cracking. RESULTS: Wearing of the stem and the matching surface of the cement mantle were found in all patients except two, independent of the duration of implantation. Regions of polishing of the outer surface of the cement mantle were observed in all implants revised for aseptic loosening, but only one of the components revised for other causes. The volume of cement removed by external abrasion of mantle was greater than that removed through stem contact by at least an order of magnitude. Cracks were visible within 13 cases of the mantles revised secondary to loosening, but none was found in infected or dislocated cases.CONCLUSION: Early debonding and stem/cement motion appear to be a universal charactedstic of cemented femoral stems. The osteolysis caused by particles generated from abrasive wearing of the outer surface of the cement mantle further accelerates wearing of cement mantle.