Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan.
Department of Bone and Joint Biomaterial Research, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan.
Arch Orthop Trauma Surg. 2023 Dec;143(12):7195-7203. doi: 10.1007/s00402-023-04972-1. Epub 2023 Jul 12.
An acetabular liner thickness of around 6 mm remains the "gold standard" in total hip arthroplasty. Some surgeons have been recommending the use of the thickest possible liner because contact stress and strain in articulating surfaces decrease with increasing the wall thickness. The purpose of this study was to determine whether in vivo creep and wear performance could be enhanced using a thicker liner over the standard thickness in vitamin-E-diffused highly crosslinked polyethylene (HXLPE).
One hundred and twenty-two hips were allocated to age-matched, sex-matched, and body mass index-matched two subgroups implanted either with a 6.8- or 8.9-mm-thick vitamin-E-diffused HXLPE liner against 28-mm cobalt-chrome femoral head, and followed-up for 7 years. Linear and volumetric penetration of femoral head into the liners attributed to creep and wear were analyzed for each group.
Compressive creep strain generated at the initial 6 months was significantly larger in the 6.8-mm group (2.6%) than in the 8.9-mm group (2.2%). The linear steady-state wear observed after 2 years was 0.0019 and 0.0015 mm/year, whereas the volumetric steady-state wear was 0.54 and 0.45 mm/years in the 6.8- and 8.9-mm-thick groups, respectively. Although less strain in the thicker group resulted in a slightly less wear, it did not reach significant differences in the steady-state wear rates between the groups.
No clinical significance for using a thicker liner over the standard thickness (6.8 mm → 8.9 mm) was confirmed in the vitamin-E-diffused HXLPE according to the 7-year follow-up. The wear rates for both thicknesses were very low enough to prevent osteolysis, and no mechanical failure was observed at any follow-up interval. Nevertheless, since the significantly higher strain was seen in the thinner liner, further follow-up is needed to compare the longer term wear and the incidence of osteolysis and component fracture.
在全髋关节置换术中，髋臼衬垫厚度约为 6 毫米仍然是“金标准”。一些外科医生建议使用尽可能厚的衬垫，因为在关节表面中，接触压力和应变随着壁厚的增加而减小。本研究的目的是确定在维生素 E 弥散的高交联聚乙烯（HXLPE）中使用比标准厚度更厚的衬垫是否可以提高体内的蠕变和磨损性能。
将 122 髋患者按年龄、性别和体重指数匹配，分为两组，分别植入 6.8 或 8.9 毫米厚的维生素 E 弥散的 HXLPE 衬垫，与 28 毫米钴铬股骨头匹配，随访 7 年。分析每组股骨头上的线性和体积穿透衬垫归因于蠕变和磨损的情况。
在最初的 6 个月内，6.8 毫米组的压缩蠕变应变（2.6%）明显大于 8.9 毫米组（2.2%）。2 年后观察到的线性稳态磨损率分别为 0.0019 和 0.0015mm/年，而 6.8 和 8.9 毫米厚组的体积稳态磨损率分别为 0.54 和 0.45mm/年。尽管较厚组的应变较小导致磨损略少，但在两组的稳态磨损率之间未达到显著差异。
根据 7 年的随访结果，在维生素 E 弥散的 HXLPE 中，使用比标准厚度（6.8mm→8.9mm）更厚的衬垫没有临床意义。两种厚度的磨损率都非常低，足以防止骨溶解，并且在任何随访间隔都没有观察到机械故障。然而，由于较薄的衬垫中存在明显更高的应变，需要进一步随访来比较长期的磨损和骨溶解以及组件骨折的发生率。
