Wautier Delphine, Ftaïta Samy, Thienpont Emmanuel
Acta Orthop Belg. 2020 Mar;86(1):82-94.
Aseptic loosening of total knee arthroplasty (TKA) components is one of the frequent reasons for early revision together with infection and instability. Aseptic loosening is usually preceded by the observation of radiolucent lines (RLL) on radiographs. Radiolucent lines have conventionally been considered a sign of osteolysis due to particles disease of either polyethylene or cement wear. However, RLL can be observed quite early after TKA, way before wear and osteolysis can even occur. Immediate postoperative RLL are secondary to surgical technique with either inadequate cement penetration in sclerotic bone, insufficient preparation of the bone or malpositioning of the component relative to the bone cuts. This type of RLL can be observed radiologically but remains often without clinical symptoms. Early development of RLL, on an initially satisfying radiograph, is secondary to changes to the cement-bone interface. These are most often related to micromotion because of constraint, malalignment, remaining mechanical deformity, erroneous bone cuts or osteoporosis. This type of RLL are observed progressively on follow-up radiographs and can be accompanied by pain complaints despite of initial good outcome. Young age, male sex or osteoporotic bones often found in elderly females, are all risk factors. A special form of aseptic loosening is tibial debonding that has been observed for different types of implants and different types of cement. It occurs at the cement-implant interface with cement remaining well attached to the trabecular bone. Probably it is a lack of cement adhesion between the high viscosity cement and the component. Revision is proposed upon diagnosis to avoid component's displacement with secondary destruction of the proximal tibial bone. Finally, RLL can develop over time secondary to polyethylene wear. These lines appear because of osteolysis and bone loss and will lead at the end to aseptic loosening of the components. Symptoms are related to failure of the implant-bone construct. Radiolucent lines without clinical symptoms should be analysed according to their potential reason of development and followed up closely with adequate radiological techniques. If symptoms develop or radiological imaging objectivizes failure and component mobility, revision knee arthroplasty might be necessary.
全膝关节置换术（TKA）组件的无菌性松动是早期翻修的常见原因之一，与感染和不稳定并列。无菌性松动通常先于在X线片上观察到透亮线（RLL）。传统上，透亮线被认为是由于聚乙烯或骨水泥磨损颗粒疾病导致骨溶解的迹象。然而，RLL在TKA后相当早就能观察到，甚至在磨损和骨溶解发生之前。术后即刻出现的RLL继发于手术技术，原因可能是骨水泥在硬化骨中渗透不足、骨准备不充分或组件相对于截骨的位置不当。这种类型的RLL可通过放射学观察到，但通常没有临床症状。在最初令人满意的X线片上，RLL的早期出现继发于骨水泥 - 骨界面的变化。这些变化最常与由于约束、排列不齐、残留机械畸形、错误的骨截骨或骨质疏松导致的微动有关。这种类型的RLL在随访X线片上逐渐观察到，尽管最初结果良好，但可能伴有疼痛主诉。年轻、男性或老年女性中常见的骨质疏松性骨，都是危险因素。一种特殊形式的无菌性松动是胫骨脱粘，已在不同类型的植入物和不同类型的骨水泥中观察到。它发生在骨水泥 - 植入物界面，骨水泥仍与小梁骨紧密附着。可能是高粘度骨水泥与组件之间缺乏骨水泥附着力。诊断后建议进行翻修，以避免组件移位及继发近端胫骨骨破坏。最后，RLL可随着时间推移继发于聚乙烯磨损而出现。这些线因骨溶解和骨质流失而出现，最终将导致组件的无菌性松动。症状与植入物 - 骨结构的失效有关。对于没有临床症状的透亮线，应根据其潜在的发生原因进行分析，并采用适当的放射学技术密切随访。如果出现症状或放射学成像证实失败及组件活动度增加，则可能需要进行膝关节翻修术。
