A. C. Belzarena, M. A. Elalfy, M. A. Yakoub, J. H. Healey, Department of Surgery, Orthopaedic Service, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
Clin Orthop Relat Res. 2021 Jan 1;479(1):95-101. doi: 10.1097/CORR.0000000000001439.
Megaprostheses are commonly used for reconstruction after distal femoral resection in orthopaedic oncology. The polyethylene bearings in these reconstructions experience wear and wear-related complications that may result in revision surgery. Improved manufacturing and processing of polyethylene has increased the durability of components commonly used for routine arthroplasty. Alterations in the manufacture of polyethylene is expected to reduce the revision risk of oncologic megaprostheses, resulting in fewer revision procedures, but this has not been proven.
QUESTIONS/PURPOSES: Is there a difference in the hazard of polyethylene wear or breakage leading to prosthetic revision between differences in polyethylene manufacture and processing based on a competing risk analysis?
This was a single-center, observational, retrospective comparative study of 224 patients who had distal femur megaprostheses with identical rotating hinge articulations and knee kinematics after oncologic surgery from 1993 to 2015. No differences in surgical indications, joint articular components and kinematics, age, sex, diagnosis, BMI, use of chemotherapy, or tumor stage were seen with the patient numbers available. Prosthetic survivorship free from prosthetic revision surgery because of polyethylene wear-related revisions, defined as breakage, increased excursion on varus-valgus stress, or new locking or giving way was compared between two groups of patients: group 1 polyethylene (P1) (66 patients) who had air-sterilized machined ram-extruded bar stock or group 2 polyethylene (P2) (158 patients) molded gamma-radiated argon-processed polyethylene components. The mean follow-up duration for the P1 group (89 ± 55 months) was not different from that of patients with P2 polyethylene (79 ± 63 months; p = 0.24) including 27% (18 of 66) of patients in the P1 group and 25% (40 of 158) of patients in the P2 group followed for more than 10 years. More patients in the P2 group were lost to follow-up (9.2%, 16 of 174) than in the P1 group (5.7%, 4 of 70) but this was not statistically different (chi square; p = 0.37). The hazard of revision because of polyethylene wear or breakage was calculated with a competing risk analysis using the Fine-Gray subdistribution hazard model.
The P1 implants had a higher hazard ratio for revision caused by polyethylene damage at 120 months than did the P2 polyethylene implants (P1 HR 0.24 [95% CI 0.13 to 0.36] versus HR 0.07 [95% CI 0.03 to 0.12]), which represents an estimated absolute risk reduction of 17% (95% CI 6.15 to 27.9).
Polyethylene damage can result in megaprosthetic revisions in patients undergoing oncologic procedures. The hazard of polyethylene failure resulting in revision surgery was lower in patients who received recent polyethylene than in patients with polyethylene produced by previous methods, enhancing the durability of distal femoral megaprosthetic reconstructions. Despite improvements in polyethylene manufacture and clinical results, revision solely because of polyethylene damage still occurs in 7% of patients by the 10-year timepoint; thus, more improvement is needed. Patients who receive these implants should be monitored for signs and symptoms of polyethylene damage.
Level III, therapeutic study.
在骨科肿瘤学中，股骨远端切除后常使用假体进行重建。这些重建中使用的聚乙烯轴承会出现磨损和与磨损相关的并发症，可能需要进行翻修手术。聚乙烯制造和加工的改进提高了常用于常规关节置换的部件的耐用性。预计聚乙烯制造的改变将降低骨肿瘤假体的翻修风险，从而减少翻修手术次数，但这尚未得到证实。
问题/目的：基于竞争风险分析，基于聚乙烯制造和加工的差异，聚乙烯磨损或断裂导致假体翻修的风险是否存在差异？
这是一项单中心、观察性、回顾性比较研究，纳入了 1993 年至 2015 年间因肿瘤接受手术的 224 名患者，他们均接受了远端股骨假体置换，使用了相同的旋转铰链关节和膝关节运动学。可获得的患者数量没有看到手术指征、关节关节组件和运动学、年龄、性别、诊断、BMI、化疗使用或肿瘤分期的差异。比较了两组患者之间因聚乙烯磨损相关翻修（定义为断裂、在内外翻应力下过度活动、或新的锁定或松动）而无需进行假体翻修手术的假体存活率：第 1 组聚乙烯（P1）（66 例）患者接受了空气消毒的机械加工滚压棒料或第 2 组聚乙烯（P2）（158 例）患者接受了伽马辐照氩气处理的聚乙烯组件。P1 组的平均随访时间（89±55 个月）与 P2 聚乙烯组的患者无差异（79±63 个月；p=0.24），包括 P1 组的 27%（18/66）和 P2 组的 25%（40/158）患者随访时间超过 10 年。与 P1 组（5.7%，4/70）相比，P2 组（9.2%，16/174）失访的患者更多，但这无统计学差异（卡方；p=0.37）。使用 Fine-Gray 亚分布风险模型进行竞争风险分析，计算了因聚乙烯磨损而导致翻修的风险比。
在 120 个月时，P1 植入物因聚乙烯损伤导致翻修的风险比 P2 聚乙烯植入物更高（P1 HR 0.24 [95%CI 0.13 至 0.36]与 HR 0.07 [95%CI 0.03 至 0.12]），这意味着估计的绝对风险降低了 17%（95%CI 6.15 至 27.9）。
聚乙烯的损坏会导致接受肿瘤手术的患者进行假体翻修。与接受先前方法生产的聚乙烯的患者相比，接受最近生产的聚乙烯的患者因聚乙烯失效导致翻修手术的风险较低，从而增强了远端股骨假体重建的耐用性。尽管聚乙烯制造和临床结果有所改善，但到 10 年时，仍有 7%的患者因聚乙烯损伤而需要进行翻修手术；因此，仍需要进一步改进。接受这些植入物的患者应密切监测聚乙烯损伤的迹象和症状。
III 级，治疗性研究。
