Wang J P, Pan Z G, Wang Y Q, et al.Error analysis of knee joint motion measurement contour based on RSA[J].Journal of Henan Polytechnic University(Natural Science) ,2026,45(6):108-116.

doi:10.16186/j.cnki.1673-9787.2025030004

Received:2025/03/03

Revised:2025/05/23

Published:2026/10/09

Error analysis of knee joint motion measurement contour based on RSA

Wang Jianping1, Pan Zhiguang1, Wang Yanqing2, Shao Peixuan3, Ma Suxia4, Zhang Yang5, Zhang Mingjun1, Song Mengjie6, Chen Xu7, Guo Dong8, Zeng Xi9, Tan Jianxin10, Hu Hai11

1.School of Mechanical and Power Engineering， Henan Polytechnic University， Jiaozuo  454003， Henan， China；2.School of Radiation Medicine and Protection， Soochow University， Suzhou  215006， Jiangsu， China；3.School of Internet of Things Engineering， Wuxi University， Wuxi  214105， Jiangsu， China；4.Department of Stomatology， The Second People’s Hospital of Jiaozuo， Jiaozuo  454003， Henan， China；5.Shanghai Qilan Industrial Co.， Ltd.， Shanghai  201306， China；6.Xin’gang Medical Equipment Co.， Ltd.， Jiaozuo  454000， Henan， China；7.Department of Orthopedics， The Second People’s Hospital of Jiaozuo， Jiaozuo  454003， Henan， China；8.School of Intelligent Manufacturing， Hebi Campus， Henan Polytechnic University， Hebi  458000， Henan， China；9.Department of Rehabilitation Medicine， The First Affiliated Hospital of Zhengzhou University， Zhengzhou  450052， Henan， China；10.Department of Rehabilitation Medicine， Jiaozuo Traditional Chinese Medicine Hospital， Jiaozuo  454000， Henan， China；11.Department of Orthopedics， Shanghai Sixth People’s Hospital， Shanghai  200233， China

Abstract: Objectives To systematically analyze the contour errors in knee joint motion measurement using radiostereometric analysis （RSA） technology， clarify the magnitude and sources of these errors， and propose effective error reduction methods. The aim is to optimize the knee joint motion measurement workflow， improve measurement accuracy， and provide both theoretical support and practical guidance for the accurate assessment of knee joint biomechanical performance.  Methods Thirty healthy volunteers were selected. CT scans of their knee joints were performed to establish three-dimensional bone models， and dynamic fluoroscopic images were acquired using a C-arm X-ray machine. Six operators manually drew contour lines in Rhino software and aligned the 3D models with the contour lines through multi-phase registration techniques. A segmentation approximation method combined with the fminunc optimization function in MATLAB was employed for iterative computation to determine the contour errors. The effects of image quality， operator proficiency， CT data accuracy， and knee joint model complexity on the contour errors were analyzed， and corresponding optimization methods were proposed.  Results The results showed that the mean contour errors of the femoral and tibial contours drawn by the six operators were 0.960 mm and 0.896 mm， respectively， measured as the normal distance from the measurement points on the contour to the theoretical contour. Error sources including image quality， operator proficiency， CT data accuracy， and knee joint model complexity were analyzed， and methods such as image grayscale and contrast adjustment were proposed to reduce the errors.  Conclusions The findings provide both theoretical support and practical guidance for optimizing the knee joint motion measurement workflow， contributing to more accurate assessment of knee joint biomechanical performance and offering valuable references for related medical research and clinical applications.

Key words: RSA technology; knee joint motion measurement; contour line error; segmentation approximation method;2D-3D registration; error source analysis