Design of a novel anatomical plate for fractures of ulnar coronoid process

Objective To evaluate a self-designed novel anatomical bone plate for fractures of ulnar coronoid process in cadaveric specimens. Methods Our database search in the Imaging Center, Qilu Hospital of Shandong University (Qingdao) yielded CT reconstruction images of 45 normal adult elbows (26 males and 19 females) which met our criteria. On the 3D reformatted CT images, sagittal curvature angle of the ulnar coronal process (△1), tangent angle of the coronal process apex to olecranon fossa (△2), projective length (L) and projective height (H) were measured; the transverse width of the coronal process was also measured at 5 mm and 10 mm from the tip (K1 and K2). The minimum value was used for △2° in order to avoid cutting into the joint while the mean value for other parameters. After the shape of the plate and angles of the screws were designed using computer 3D software, a new anatomic plate for coronal process was produced. Five cadaver specimens were used to test the internal fixation of the coronal process with our novel anatomic bone plate. Attachment of the bone plate to the coronal process and screw penetration into the joint cavity were observed by X-ray and 3D CT scanning. Results △1 was 45.52°±6.07°, △2 65.25°±7.09° (the minimum value 53.2°), L 52.27±7.78 mm, H 21.62±2.63 mm, K1 16.32±2.22 mm and K2 14.58±2.18 mm. Our new anatomic bone plate was designed based on the above data. X-ray and 3D CT scan after plate internal fixation showed that our self-designed bone plate produced fine attachment and no screws penetrated into the joint. Conclusion Our new anatomical bone plate may perfectly fit the anatomy of the adult ulnar coronal process in size and shape so that the coronary process can be fully covered and no screws will penetrate into the joint cavity. Key words: Bone plate; Elbow Joint; Anatomy; Cadaver