Biomatlab, Department of Orthopaedic Surgery, Haukeland University Hospital, Bergen, Norway.
The Norwegian Arthroplasty Register, Department of Ortopaedic Surgery, Haukeland University Hospital, Bergen, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway.
Knee. 2024 Aug;49:266-278. doi: 10.1016/j.knee.2024.07.007. Epub 2024 Jul 25.
Approximately 5% of primary total knee arthroplasty patients require revision within 10 years, often due to distal component loosening. Application of a thin layer of PMMA cement as precoating on the tibial component aims to prevent aseptic loosening. This study investigates the impact of precoating and fat contamination on tibial baseplate stability.
Two groups of NexGen® stemmed tibial implants (size 4) were studied: Option implants (N = 12) and PMMA Precoat implants (N = 12). Each implant design was divided into two subgroups, (N = 6), with one subgroup featuring bone marrow fat at the implant-cement interface and the other without contamination. In a mechanical testing machine, the implants underwent uniaxial loading for 20,000 cycles, while recording vertical micromotion and migration of the tibial baseplates. Subsequently, a push-out test assessed fixation strength at the cement interfaces. Results were compared using non-parametric statistics and presented as median and min-to-max ranges.
Option implants exhibited higher micromotion in dry conditions compared to precoated implants (p = 0.03). Under contamination, both designs demonstrated similar micromotion values. Fixation strength did not significantly differ between designs under dry, uncontaminated conditions (p > 0.99). However, under contaminated conditions, the failure load for the non-coated Option implant was nearly half that of the uncontaminated counterparts (3517 N, 2603-4367 N vs 7531 N, 5163-9000 N; p = 0.002). Precoat implants displayed less susceptibility to fat contamination (p = 0.30).
NexGen® implant PMMA precoating might reduce the risk of aseptic loosening and revision surgery in case of eventual bone-marrow fat contamination.
大约 5%的初次全膝关节置换患者在 10 年内需要进行翻修，这通常是由于远端部件松动所致。在胫骨部件上应用一层薄的 PMMA 水泥作为预涂层旨在防止无菌性松动。本研究旨在探讨预涂层和脂肪污染对胫骨基板稳定性的影响。
研究了两种 NexGen® 带柄胫骨植入物（尺寸 4）：Option 植入物（N=12）和 PMMA 预涂层植入物（N=12）。每个植入物设计分为两组（N=6），一组在植入物-水泥界面处有骨髓脂肪，另一组无污染。在机械试验机中，植入物经历了 20000 次的单轴加载，同时记录胫骨基板的垂直微动和迁移。随后，推挤试验评估了水泥界面的固定强度。使用非参数统计方法比较结果，并以中位数和最小到最大范围表示。
在干燥条件下，Option 植入物的微动高于预涂层植入物（p=0.03）。在污染条件下，两种设计的微动值相似。在干燥、无污染条件下，两种设计的固定强度无显著差异（p>0.99）。然而，在污染条件下，未涂层 Option 植入物的失效负荷几乎是无污染植入物的一半（3517 N，2603-4367 N 与 7531 N，5163-9000 N；p=0.002）。预涂层植入物对脂肪污染的敏感性较低（p=0.30）。
NexGen®植入物的 PMMA 预涂层可能会降低无菌性松动的风险，并在发生骨髓脂肪污染时降低翻修手术的风险。
