Abstract:

Acetabular reamer is one of the most important surgical tools in hip replacement surgery. The milling quality of acetabular reamer on acetabulum is affected by the dimension change of cutting edges. The wear of acetabular reamer can be examined by processing 3D point cloud of acetabular reamer， so a dimensional analysis algorithm for the cutting edges of acetabular reamer based on 3D point cloud processing was proposed. Frist， an algorithm with tangency plane and maximum angle criterion were introduced in the proposed algorithm to obtain the boundary point cloud of acetabular reamer based on boundary characteristics of the tooth holes. Second， the boundary point cloud was partitioned into individual tooth hole point clouds by K-means clustering algorithm， and then the point cloud of each tooth hole boundary was searched by radius nearest neighbor search algorithm to obtain the point cloud of cutting edges belonging to different tooth holes. Finally， RANSAC （RANdom SAmple Consensus） algorithm was used to fit the point cloud of acetabular reamer to a sphere， and Euclidean distance from the point cloud of cutting edges to the center of the fitted sphere was calculated to analyze cutting edge dimensions of acetabular reamer. PCL （Point Cloud Library） was used as a development framework to process the point cloud of acetabular reamer. The accuracy of hole segmentation of the point cloud of acetabular reamer is 100%， and the accuracy of spherical fitting radius of the point cloud of the acetabular reamer is 0.004 mm. Experimental results show that the proposed algorithm has a good effect on the point cloud processing of acetabular reamer， and can effectively realize the dimensional analysis of the cutting edges of acetabular reamer.

Key words: 3D point cloud, acetabular reamer, point cloud boundary extraction, point cloud segmentation, point cloud surface fitting

摘要：

髋臼锉是髋关节置换手术中最重要的手术刀具之一，髋臼锉锉齿的尺寸变化会影响髋臼锉对髋臼的铣削质量。通过处理髋臼锉三维点云可以检验髋臼锉的磨损情况，为此提出基于三维点云处理的髋臼锉锉齿尺寸分析的算法。首先结合锉齿孔洞具有点云的边界特征引入微切面法，利用最大夹角准则获取髋臼锉点云的边界；然后通过K-means聚类算法分割点云边界以标记不同齿孔位置，并对分割出的各个齿孔边界点云进行半径最近邻搜索获取隶属不同的锉齿孔的齿刃点云；最后通过RANSAC（RANandom SAample Consensus）算法对髋臼锉三维点云进行球面拟合，计算各齿孔上的齿刃点云到拟合球心的欧氏距离来分析髋臼锉的切削齿尺寸。以PCL（Point Cloud Library）为框架，实现了对髋臼锉锉齿点云的处理，其中髋臼锉点云的齿孔分割准确度达到100%，髋臼锉点云球面拟合半径精度达到0.004 mm；并对各个锉齿点云尺寸范围进行了分析。实验结果表明，所提算法对髋臼锉点云处理效果好，能有效地实现髋臼锉锉齿尺寸分析。

关键词: 三维点云, 髋臼锉, 点云边界提取, 点云分割, 点云曲面拟合