Automatic Lower Limb Critical Angle Assessment System for Patients with Robot-based Knee Replacement

This article introduces an automatic evaluation system identifying the critical angles that are closely related to human locomotion functionalities. The current measurement method is selecting the target point on the digital X-ray film to measure the indicators by doctor manually. Whole lower limb X-ray films were preprocessed by histogram equalization, linear filtering and morphological transformation. Edge detection algorithm and Hough transform were used to extract valuable pixel points and then to construct the lower limb force line. Results showed that the proposed system successfully identified the two angles and demonstrated high robustness.