Urquhart A G, D'Lima D D, Venn-Watson E, Colwell C W, Walker R H
Division of Orthopaedic Surgery, Scripps Clinic, La Jolla, California 92037, USA.
J Bone Joint Surg Am. 1998 Nov;80(11):1641-7.
The use of modular components in total hip arthroplasty has been thought to contribute to accelerated polyethylene wear. Specifically, a modular femoral head with a flange extension and a longer neck may cause increased wear. The purpose of the current study was to evaluate the effect of a flange extension on polyethylene wear. Ninety-one patients who had had a total of 100 primary total hip arthroplasties were evaluated after an intermediate duration of follow-up. All of the acetabular components consisted of a hemispherical titanium-alloy fiber-mesh porous-coated shell with a nonelevated modular polyethylene liner; they were inserted without cement and with use of supplemental screws through the dome after so-called line-to-line reaming. All of the femoral components consisted of a modular head with a diameter of twenty-eight millimeters and either a long neck (with a flange extension) or a short or medium neck (without a flange extension). The study group comprised sixty-two patients (sixty-six hips) who had had radiographic evaluation that was adequate to allow the valid measurement of polyethylene wear. Thirty-two hips were in men, and thirty-four were in women. The mean age of the patients was fifty-six years, the mean weight was seventy-three kilograms, and the mean duration of follow-up was 6.1 years (range, four to eight years). The rate of polyethylene wear in the eleven hips in which the femoral component had a flange extension was significantly greater than that in the fifty-five in which the femoral component did not have a flange extension (mean, 0.17 compared with 0.11 millimeter per year; p = 0.009). Multivariate analysis showed that the presence of a flange extension was associated with increased polyethylene wear to a greater degree (F = 2.86) than were all other variables that were measured, including a younger age (F = 1.72), a more vertical angle of the acetabular component (F = 0.49), a heavier weight (F = 0.14), male gender (F = 0.11), and a smaller initial thickness of the polyethylene (F = 0.02). These data support an association between the presence of a modular femoral head with a flange extension and an accelerated rate of polyethylene wear. The presumed mechanism is an increase in peripheral, or so-called rim, impingement of the flange-reinforced neck on the acetabulum due to a decrease in the ratio between the diameters of the femoral head and neck.
全髋关节置换术中使用模块化组件被认为会导致聚乙烯磨损加速。具体而言，带有凸缘延伸和较长颈部的模块化股骨头可能会导致磨损增加。本研究的目的是评估凸缘延伸对聚乙烯磨损的影响。对91例共接受100次初次全髋关节置换术的患者进行了中期随访评估。所有髋臼组件均由半球形钛合金纤维网多孔涂层壳和未抬高的模块化聚乙烯内衬组成；在所谓的线对线扩孔后，不使用骨水泥并通过髋臼顶使用辅助螺钉将其植入。所有股骨组件均由直径为28毫米的模块化股骨头和长颈部（带有凸缘延伸）或短或中颈部（无凸缘延伸）组成。研究组包括62例患者（66髋），其影像学评估足以进行聚乙烯磨损的有效测量。32髋为男性，34髋为女性。患者的平均年龄为56岁，平均体重为73千克，平均随访时间为6.1年（范围为4至8年）。股骨组件有凸缘延伸的11髋中聚乙烯磨损率明显高于股骨组件无凸缘延伸的55髋（平均每年分别为0.17毫米和0.11毫米；p = 0.009）。多变量分析显示，与所有其他测量变量相比，凸缘延伸的存在与聚乙烯磨损增加的关联程度更大（F = 2.86），这些变量包括年龄较小（F = 1.72）、髋臼组件角度更垂直（F = 0.49）、体重较重（F = 0.14）、男性（F = 0.11）以及聚乙烯初始厚度较小（F = 0.02）。这些数据支持了带有凸缘延伸的模块化股骨头的存在与聚乙烯磨损加速之间的关联。推测的机制是由于股骨头与颈部直径之比减小，凸缘加强的颈部对髋臼的周边（即所谓的边缘）撞击增加。
