Lingaraj Krishna, Morris Hayden, Bartlett John
Department of Orthopaedic Surgery, National University Health System, 5 Lower Kent Ridge Road, Singapore 119074, Singapore.
Knee. 2011 Jun;18(3):165-7. doi: 10.1016/j.knee.2010.04.012. Epub 2010 May 26.
Inadequate polyethylene thickness is a risk factor in the development of polyethylene wear in unicompartmental knee arthroplasty (UKA). The labelled thickness of polyethylene inserts often refers to the combined thickness of the insert and its metal backing. However specific information regarding the actual minimum thickness of the polyethylene is seldom available. We sought to determine the actual minimum thickness of polyethylene inserts used in five contemporary metal-backed UKA designs. The thinnest available insert from each of these designs was identified and measured at the lowest point of its concave articulating surface with a Kincrome electronic digital micrometer. The minimum thickness of the inserts ranged from 3.702 mm to 7.859 mm (mean values). In two of the inserts, the minimum thickness was found to be less than the recommended minimum thickness of 6mm. Implant manufacturers should clearly indicate the actual minimum thickness of polyethylene inserts on their product labels.
聚乙烯厚度不足是单髁膝关节置换术（UKA）中聚乙烯磨损发展的一个风险因素。聚乙烯植入物的标记厚度通常指的是植入物及其金属背衬的总厚度。然而，关于聚乙烯实际最小厚度的具体信息却很少能获取到。我们试图确定五种当代金属背衬UKA设计中所使用的聚乙烯植入物的实际最小厚度。从每种这些设计中找出最薄的可用植入物，并使用金铬电子数字千分尺在其凹形关节表面的最低点进行测量。植入物的最小厚度范围为3.702毫米至7.859毫米（平均值）。在其中两个植入物中，发现最小厚度小于推荐的最小厚度6毫米。植入物制造商应在其产品标签上明确标明聚乙烯植入物的实际最小厚度。
