Lippert F G, Harrington R M, Veress S A, Fraser C, Green D, Bahniuk E
J Biomech. 1982;15(9):677-82. doi: 10.1016/0021-9290(82)90022-7.
X-ray photogrammetry is an accurate method of measuring structural displacements within the musculoskeletal system. Total joint implant alignment, migration and loosening are important clinical parameters which can be measured by X-ray photogrammetry. The purpose of this paper is to compare two different X-ray photogrammetry systems which are being used to study total joint parameters. The Seattle system uses a convergent geometry and the Cleveland system a bi-plane geometry. The accuracy of the two systems was compared by individually measuring the relative motion produced in an articulated plastic model. The model was designed to simulate the relative motion which can take place between the bone and a loose implant. The displacements of the model components were determined physically and photogrammetrically, and the error in the measurements was calculated for several conditions. Both systems measured relative component motion in the model with a root mean square error of 0.1 mm or less. In clinical use stainless steel markers are implanted in human subjects, and both systems measure distances with a r.m.s. error of 0.2 mm or less. The ease of usage, efficiency and flexibility of the two systems based on actual clinical experience reveals strengths and weaknesses in each which should be recognized when selecting a particular system.
X射线摄影测量法是一种测量肌肉骨骼系统内部结构位移的精确方法。全关节植入物的对线、移位和松动是重要的临床参数，可通过X射线摄影测量法进行测量。本文的目的是比较两种用于研究全关节参数的不同X射线摄影测量系统。西雅图系统采用会聚几何学，而克利夫兰系统采用双平面几何学。通过分别测量铰接塑料模型中产生的相对运动来比较这两种系统的精度。该模型旨在模拟骨骼与松动植入物之间可能发生的相对运动。通过物理方法和摄影测量法确定模型组件的位移，并计算几种情况下测量的误差。两种系统测量模型中组件的相对运动时，均方根误差均在0.1毫米或更小。在临床应用中，将不锈钢标记物植入人体受试者体内，两种系统测量距离的均方根误差均在0.2毫米或更小。基于实际临床经验，这两种系统的易用性、效率和灵活性揭示了各自的优缺点，在选择特定系统时应予以认识。
