Centre d'orthopédie et traumatologie, hôpital Bellevue, CHU de Saint-Étienne, 42055 Saint-Étienne cedex 2, France.
Centre d'orthopédie et traumatologie, hôpital Bellevue, CHU de Saint-Étienne, 42055 Saint-Étienne cedex 2, France.
Orthop Traumatol Surg Res. 2014 Feb;100(1):85-91. doi: 10.1016/j.otsr.2013.12.011. Epub 2014 Jan 18.
Dual mobility systems with retentive acetabular liners have been used in clinical practice for total hip arthroplasty since 1976. The dual mobility system preserves a wide range of motion while providing greater stability. This study measured wear on the concave and convex surfaces of 40 retrieved polyethylene liners, to evaluate the advantages of this system in relation to wear.
Forty polyethylene inserts that had been removed due to infection or mechanical failure after a mean 8 years were analyzed. The mean age of patients at arthroplasty was 46 years old. Macroscopic analysis was followed by surface analysis with direct measurement of changes in the curvature radii. The internal concave surface was measured in three dimensions using a 4-mm stylus (BNH 706). External convexity was measured by lateral projection. The estimated error was ± 5 μm for both measurement methods. Manufacturers' tolerance for these implants was approximately 50 μm. Linear wear and wear volume was determined by comparing the measured dimensions with the theoretical dimensions of new liners.
Macroscopically, all of the pieces studied had lost the initial machined grooves on the convex surface; 40% of the pieces showed visible wear of the retentive collar. Mean annual convex surface wear was 9 μm (SD 9μm) and 73 μm (SD 69 μm) for the concave surface. Mean total wear, which was the sum of the wear on the convex and concave surfaces was 82 μm (SD 72 μm). Wear volume was 28.9 mm(3)/yr for the convex surface (SD 27.6) and 25.5 for the concave surface (SD 23.2) with a mean annual total wear volume of 54.3 mm(3)/yr (SD 39.6).
Total wear in the 40 dual mobility liners that had functioned in vivo was similar to that reported in metal-polyethylene bearings with 22.2mm femoral heads. The results of wear in both the convex and concave surfaces show that wear with the dual mobility system was not increased compared to conventional metal-polyethylene bearings, while providing better retention and greater stability.
The use of dual mobility acetabular liners is an attractive solution when a metal-polyethylene bearing is needed. The increased joint stability is not associated with increased wear.
自 1976 年以来，带保持髋臼衬垫的双动系统已应用于全髋关节置换术的临床实践中。双动系统在提供更大稳定性的同时保留了更广泛的运动范围。本研究通过测量 40 个回收的聚乙烯衬垫的凹面和凸面的磨损，来评估该系统在磨损方面的优势。
分析了因感染或机械故障而在平均 8 年后取出的 40 个聚乙烯嵌体。患者在关节置换时的平均年龄为 46 岁。在进行宏观分析后，对表面进行分析，并直接测量曲率半径的变化。使用 4 毫米测针（BNH 706）对内部凹面进行三维测量。外部凸面通过侧面投影进行测量。这两种测量方法的估计误差均为±5μm。这些植入物的制造商公差约为 50μm。通过将测量尺寸与新衬垫的理论尺寸进行比较，确定线性磨损和磨损量。
宏观上，所有研究的部件在凸面都失去了初始加工的凹槽；40%的部件显示出保持环的可见磨损。凹面的平均年凸面磨损为 9μm（SD 9μm），73μm（SD 69μm）。凸面的总磨损平均值（凸面和凹面磨损之和）为 82μm（SD 72μm）。凸面的磨损体积为 28.9mm3/yr（SD 27.6），凹面的磨损体积为 25.5mm3/yr（SD 23.2），总磨损体积的平均值为 54.3mm3/yr（SD 39.6）。
40 个在体内功能正常的双动衬垫的总磨损与报告的 22.2mm 股骨头金属-聚乙烯轴承相似。凸面和凹面的磨损结果表明，与传统的金属-聚乙烯轴承相比，双动系统的磨损并没有增加，同时提供了更好的保持力和更大的稳定性。
当需要金属-聚乙烯轴承时，使用双动髋臼衬垫是一种有吸引力的解决方案。关节稳定性的提高与磨损无关。
