a Department of Orthopedics , Rijnstate , Arnhem.
b Department of Orthopedics , Radboud University Hospital , Nijmegen.
Acta Orthop. 2018 Feb;89(1):59-65. doi: 10.1080/17453674.2017.1376526. Epub 2017 Sep 21.
Background and purpose - Hip resurfacing (HR) is a treatment option promoted for hip arthritis in young and active patients. However, adverse reactions to metal are a concern and the search for non-metallic bearing options proceeds. We present the first clinical study performed in patients using a newly developed hydrophilic polymer-on-polymer hip resurfacing device. Patients and methods - After performing extensive hip simulator tests, biocompatibility testing and animal tests (ISO 14242-1,3; 10993-3,4,5,10,11), approval was obtained from the IRB committee to enroll 15 patients in the first clinical study in humans using this experimental polymer-on-polymer hip resurfacing device. All surgeries were done by 2 experienced hip resurfacing surgeons. Clinical scores and standard radiographs as well as routine MRIs were obtained at regular intervals. Results - The surgical technique proved feasible with successful implantation of the new device using PMMA cement fixation on both sides without complications. Postoperative imaging revealed a well-positioned and well-fixed polymer resurfacing hip arthroplasty in all 4 initial cases. All 4 patients were free of pain and had good function for the first 2 months. However, in all 4 cases early cup loosening occurred between 8 and 11 weeks after surgery, necessitating immediate closure of the study. All 4 patients had a reoperation and were revised to a conventional THA. Retrieval analyses confirmed early cup loosening at the implant-cement interface in all 4 cases. The femoral components remained well attached to the cement. The periprosthetic tissues showed only small amounts of polymeric wear debris and there was only a very mild inflammatory reaction to this. Interpretation - Early cup loosening mandated a premature arrest of this study. After additional laboratory testing this failure mode was found to be the result of a small, yet measurable contraction in the cup size after exposing these implants to biological fluid divalent ion fluctuations in vivo. Currently used preclinical tests had failed to detect this failure mechanism. Modification of the polymer is essential to overcome these problems and before the potential of a polymer-on-polymer resurfacing arthroplasty may be further evaluated in patients.
背景与目的 - 髋关节表面置换术（HR）是一种针对年轻且活跃的髋关节关节炎患者的治疗选择。然而，人们对金属的不良反应表示担忧，因此正在寻找非金属的关节轴承。我们首次报道了使用新开发的亲水聚合物对聚合物髋关节表面置换装置在患者中进行的临床研究。
患者与方法 - 在进行了广泛的髋关节模拟器测试、生物相容性测试和动物试验（ISO 14242-1、3；10993-3、4、5、10、11）后，我们获得了 IRB 委员会的批准，开始在 15 名患者中进行首例使用这种实验性聚合物对聚合物髋关节表面置换装置的人体临床研究。所有手术均由 2 名经验丰富的髋关节表面置换外科医生完成。定期获取临床评分和标准 X 线片以及常规 MRI。
结果 - 手术技术可行，通过在两侧使用 PMMA 水泥固定成功植入新装置，没有出现并发症。术后影像学显示所有 4 例初始病例中聚合物表面置换髋关节置换术位置良好且固定牢固。所有 4 例患者在最初的 2 个月均无疼痛且功能良好。然而，在所有 4 例中，术后 8-11 周时均出现早期杯松动，导致研究立即停止。所有 4 例患者均接受了再次手术，并改为常规全髋关节置换术。取出物分析证实所有 4 例均存在早期杯松动，位于植入物-水泥界面。股骨组件仍与水泥紧密相连。假体周围组织仅显示少量聚合物磨损碎屑，且仅有轻微的炎症反应。
解释 - 早期杯松动要求提前终止该研究。经过进一步的实验室测试，发现这种失效模式是由于这些植入物在体内暴露于生物液二价离子波动后，杯的尺寸出现微小但可测量的收缩所致。目前使用的临床前测试未能检测到这种失效机制。必须对聚合物进行修改，以克服这些问题，然后才能进一步评估聚合物对聚合物表面置换关节置换术在患者中的潜力。
