Mellon Stephen J, Grammatopoulos George, Andersen Michael S, Pegg Elise C, Pandit Hemant G, Murray David W, Gill Harinderjit S
Nuffield Orthopaedic Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK.
Proc Inst Mech Eng H. 2013 Jul;227(7):799-810. doi: 10.1177/0954411913483639. Epub 2013 Apr 16.
The occurrence of pseudotumours (soft tissue masses relating to the hip joint) following metal-on-metal hip resurfacing arthroplasty has been associated with higher than normal bearing wear and high serum metal ion levels although both these findings do not necessarily coexist. The purpose of this study was to examine patient activity patterns and their influence on acetabular component edge loading in a group of subjects with known serum metal ion levels. Fifteen subjects with metal-on-metal hip resurfacing arthroplasty (eight males and seven females) were recruited for motion analysis followed by computed tomography scans. They were divided into three groups based on their serum metal ion levels and the orientation of their acetabular component: well-positioned acetabular component with low metal ions, mal-positioned acetabular component with low metal ions and mal-positioned acetabular component with high ions. A combination of motion analysis, subject-specific modelling (AnyBody Modeling System, Aalborg, Denmark) and computed tomography measurements was used to calculate dynamically the contact patch-to-rim distance for each subject during gait and sit-to-stand. The contact-pitch-to-rim distance for the high ion group was significantly lower (p<0.001) than for the two low ion groups (well-positioned and mal-positioned) during the stance phase of gait (0%-60%) and loading phase of sit-to-stand (20%-80%). The results of this study, in particular, the significant difference between the two mal-positioned groups, suggest that wear of metal-on-metal hip resurfacing arthroplasty is not only affected by acetabular cup orientation but also influenced by individual patient activity patterns.
金属对金属髋关节表面置换术后假瘤（与髋关节相关的软组织肿块）的出现与高于正常水平的轴承磨损及高血清金属离子水平有关，尽管这两个发现不一定同时存在。本研究的目的是在一组已知血清金属离子水平的受试者中，检查患者的活动模式及其对髋臼组件边缘负荷的影响。招募了15名接受金属对金属髋关节表面置换术的受试者（8名男性和7名女性）进行运动分析，随后进行计算机断层扫描。根据他们的血清金属离子水平和髋臼组件的方向，将他们分为三组：金属离子水平低且髋臼组件位置良好组、金属离子水平低且髋臼组件位置不良组、金属离子水平高且髋臼组件位置不良组。结合运动分析、个体特异性建模（丹麦奥尔堡的AnyBody建模系统）和计算机断层扫描测量，动态计算每个受试者在步态和从坐到站过程中的接触斑到边缘的距离。在步态的站立阶段（0%-60%）和从坐到站的负重阶段（20%-80%），高离子组的接触斑到边缘的距离显著低于两个低离子组（位置良好组和位置不良组）（p<0.001）。本研究的结果，特别是两个位置不良组之间的显著差异，表明金属对金属髋关节表面置换术的磨损不仅受髋臼杯方向的影响，还受个体患者活动模式的影响。
