Objective To explore the influence of different factors on the safe screw placement of the ulnar coronoid process based on the DR imaging measurement of the ulnar coronoid process.Methods During the period from July 2020 to November 2021,102 normal adult elbow joint DR films were randomly included from Yunnan Provincial Hospital of Traditional Chinese Medicine.Standard elbow joint DR films were selected as the measurement objects,with the apex of the coronoid process as the vertex and two straight lines parallel to the elbow joint space along both sides of the coronoid process.The length of the line segment from the apex of the coronoid process to the intersection of the radius and ulnar cortex of the ulna was the safe distance to place the nail on the coronal surface of the ulna coronoid process;The standard lateral DR film of the elbow joint was selected as the measurement image,and the apex of the coronoid process was used as a point to draw out two safety lines intersecting with the ulnar cortex at the proximal and distal ends.The length of the safety lines at the proximal and distal ends of the coronoid process was the safe nail placement distance on the sagittal plane of the ulnar coronoid process.The differences in safe nail placement distance between different genders,left and right sides,were compared and the correlation between safe nail placement distances on different cross-sections was analyzed.Results There was a statistically significant difference in the safe placement distance of the ulnar coronoid process between males and females(P＜0.05);On the coronal plane,there was a correlation between the safe nail placement distance on the radial and ulnar sides in males;On the sagittal plane(P＜0.05),there was a correlation between the safe placement distance of the ulnar coronoid process in women's proximal and distal ends(P＜0.05).Conclusion Studying the safe screw placement distance of the ulnar coronoid process is beneficial to guide the clinical placement of screws for coronoid process fractures,the design of new steel plates,and the correction of deformity.