Smith S L, Unsworth A
Centre for Biomedical Engineering, University of Durham, UK.
Proc Inst Mech Eng H. 2000;214(3):233-8. doi: 10.1243/0954411001535723.
Two wear tests were conducted using the Durham Hip Joint Wear Simulator to investigate the effects of simplified motion and loading on ultra-high molecular weight polyethylene (UHMWPE) acetabular cup wear rates. Bovine serum was used as a lubricant and a gravimetric technique was used to measure wear. The first wear test duration was 7.1 x 10(6) cycles and investigated the effect of simplified loading. This was achieved by using full physiological motion and loading for the first 5 x 10(6) cycles of the test, then physiological motion with simplified loading for the final 2.1 x 10(6) cycles of the wear test. The UHMWPE acetabular cup wear rates using full physiological motion and loading were 32.2 and 51.7 mm3/10(6) cycles against zirconia and CoCrMo femoral heads respectively. Using simplified loading the cup wear rates were 30.1 and 49.2 mm3/10(6) cycles against zirconia and CoCrMo respectively which was not significantly different from wear rates with physiological loading. The effect of simplified motion was investigated in a second wear test of 5.0 x 10(6) cycles duration. Physiological loading was applied across the prosthesis with physiological motion in the flexion/extension plane only. Mean wear of the acetabular component dropped to 0.197 mm3/10(6) cycles. The surfaces of all the acetabular cups were subject to gross examination, optical microscopy and scanning electron microscopy. No notable difference was observed between the cups subjected to physiological motion and loading and those subjected to simplified loading. The cups worn with a single plane of motion had a much smaller worn area and a notable difference in surface features to the other cups. Simplifed loading is therefore an acceptable simplification in simulator testing but simplifying motion to the flexion/extension plane axis only is unacceptable.
使用达勒姆髋关节磨损模拟器进行了两项磨损试验，以研究简化运动和加载对超高分子量聚乙烯（UHMWPE）髋臼杯磨损率的影响。使用牛血清作为润滑剂，并采用重量法测量磨损。第一次磨损试验持续时间为7.1×10⁶次循环，研究了简化加载的影响。这是通过在试验的前5×10⁶次循环中使用完全生理运动和加载，然后在磨损试验的最后2.1×10⁶次循环中使用简化加载的生理运动来实现的。在使用完全生理运动和加载时，UHMWPE髋臼杯相对于氧化锆和钴铬钼股骨头的磨损率分别为32.2和51.7立方毫米/10⁶次循环。使用简化加载时，髋臼杯相对于氧化锆和钴铬钼的磨损率分别为30.1和49.2立方毫米/10⁶次循环，与生理加载时的磨损率没有显著差异。在持续时间为5.0×10⁶次循环的第二次磨损试验中研究了简化运动的影响。仅在屈伸平面内以生理运动对假体施加生理载荷。髋臼部件的平均磨损降至0.197立方毫米/10⁶次循环。对所有髋臼杯的表面进行了肉眼检查、光学显微镜检查和扫描电子显微镜检查。在经受生理运动和加载的髋臼杯与经受简化加载的髋臼杯之间未观察到明显差异。仅在一个运动平面磨损的髋臼杯磨损面积小得多，并且与其他髋臼杯在表面特征上有明显差异。因此，简化加载在模拟器测试中是可接受的简化方式，但仅将运动简化为屈伸平面轴是不可接受的。
