Lille-Nord-de-France University, 59000 Lille, France.
Orthop Traumatol Surg Res. 2011 Apr;97(2):127-33. doi: 10.1016/j.otsr.2010.12.004. Epub 2011 Mar 5.
Impingement is a factor of failure in total hip replacement (THR), causing instability and early wear. Its true frequency is not known; cup-retrieval series reported rates varying from 27 to 84%.
The hypothesis was that a large continuous series of THR cup removals would help determine the frequency of component impingement.
The hypothesis was tested on a continuous retrospective series of cups removed in a single center, with a secondary objective of identifying risk factors.
[corrected] Macroscopic examination looked for component impingement signs in 416 cups retrieved by a single operator between 1989 and 2004. Risk factors were investigated by uni- and multivariate analyses in the 311 cases for which there were complete demographic data. In these 311 cases, removal was for aseptic loosening (131 cases), infection (43 cases), instability (56 cases), osteolysis (28 cases) or unexplained pain (48 cases); impingement was explicitly implicated in only five cases (1.6%), always with hard-on-hard bearing components.
Impingement was found in 214 of the 416 cups (51.4%) and was severe (notch>1mm) in 130 (31.3%). In the subpopulation of 311 cups, impingement was found in 184 cases (59.2%) and was severe in 109 (35%). Neither duration of implant use nor cup diameter or frontal orientation emerged as risk factors. On univariate analysis, impingement was more frequently associated with revision for instability, young patient age at THR, global hip range of motion >200° or use of an extended femoral head flange (or of an elevated antidislocation rim liner), and was more severe in case of head/neck ratio<2. On multivariate analysis, only use of an extended head flange (RR 3.2) and revision for instability (RR 4.2) remained as independent risk factors for impingement.
Component impingement is frequently observed in cups after removal, but is rarely found as a direct indication for revision, except in case of hard-on-hard friction couples (polyethylene being the most impingement-tolerant material). Systematic use of extended head flanges and elevated antidislocation rims is not to be recommended, especially in case of excessive ROM. A good head/neck ratio should be sought, notably by increasing the head diameter in less impingement-tolerant hard-on-hard friction couples. Although not identified as a risk factor in the present study, implant orientation should be checked; computer-assisted surgery can be useful in this regard, for adaptation to the patient's individual range-of-motion cone.
撞击是全髋关节置换术（THR）失败的一个因素，会导致不稳定和早期磨损。其真正的发生率尚不清楚；从杯取出系列研究报告的发生率从 27%到 84%不等。
假设大量连续的 THR 杯取出系列将有助于确定组件撞击的频率。
该假设在一个连续的回顾性系列中进行了测试，该系列是在一个单一的中心取出的杯，次要目标是确定危险因素。
[已更正]宏观检查在 1989 年至 2004 年间由一名医生取出的 416 个杯中寻找组件撞击的迹象。在 311 例有完整人口统计学数据的病例中，通过单变量和多变量分析调查了危险因素。在这 311 例中，取出的原因是无菌性松动（131 例）、感染（43 例）、不稳定（56 例）、骨溶解（28 例）或不明原因的疼痛（48 例）；只有 5 例（1.6%）明确与撞击有关，始终与硬对硬的轴承组件有关。
在 416 个杯中发现撞击 214 个（51.4%），严重撞击 130 个（31.3%）。在 311 个杯的亚组中，184 个（59.2%）发现撞击，109 个（35%）严重撞击。植入物使用时间、杯直径或额状面方向均未成为危险因素。在单变量分析中，撞击与不稳定的翻修更频繁相关，THR 时年轻患者的年龄、全髋关节活动度>200°或使用扩展股骨头法兰（或升高的防脱位衬里），并且在头/颈比<2 时更严重。在多变量分析中，只有使用扩展的头法兰（RR 3.2）和不稳定的翻修为撞击的独立危险因素（RR 4.2）。
在取出后，杯内经常观察到组件撞击，但很少发现直接作为翻修的指征，除非是硬对硬摩擦组件（聚乙烯是最能耐受撞击的材料）。不建议常规使用扩展的头法兰和升高的防脱位衬里，特别是在活动度过大的情况下。应寻求良好的头/颈比，特别是通过增加在撞击耐受性较差的硬对硬摩擦组件中的头直径。尽管在本研究中未被确定为危险因素，但应检查植入物的方向；计算机辅助手术在此方面很有用，可适应患者的个人活动范围圆锥。
