The Influence Of The Changes Of The Proximal Humerus Angles On The Treatment Of Proximal Humerus Fractures With The Locking Plate

【Objective】 The proximal humerus angles of the proximal humerus fracture patients who were treated by locking plate were measured by the method of CT reconstruction. Then some humerus fracture models were developed on the artificial bones to research the reason why the changes of the proximal humerus angles can influence on the treatment of proximal humerus fractures locking plate.【Methods】 In the first part of the experiment, CT reconstruction measure technology together with the signal denoising and fake shadow removing were firstly applied on proximal humerus fracture who were treated with locking plate. 52 patients of proximal humeral fracture were treated with the locking plate(AO PHILOS) between September 20012 to October 2014. 38 patients received a follow-up more than 12 months. During the follow-up, the Constant Score of the affected shoulders, visual analogue scale(VAS) and related complications were evaluated. 3D reconstruction methods were applied for measuring the humerus retroversion angle(HRA) and neck-shaft angle(NSA). The patients were divided into NSA increasing group and NSA reducing group as well as HRA increasing group and HRA reducing group by comparing the angles of the affected shoulders with the healthy shoulders. In the second part of the experiment, several two-part proximal humeral fracture were established by osteotomy around the surgical neck. Five groups were established, each group contains 10 simples, the groups were marked as20° retroversion group,10°retroversion group, normal group, 10° anteversion group and 20°anteversion group. Then the models were fixed by AO PHILOS under the different angles. At last, the extreme length of humerus head screws were measured to explore if the change of the humeral retroversion angle can influence on the extreme length of humerus head screws【Results】 There were no statistically significant difference of HRA between the affected shoulders with the contralateral. However, the NSA of the affected shoulder were significant larger than the contralateral. There was no difference of fracture type between the groups. We have not found any statistically significant difference between the groups of HRA. While NSA reducing group possessed the lower incidence of postoperative complications and the higher Constant Score than the other group. The extreme length of humerus head screws of 20° retroversion group and the 20°anteversion group were significantly less than the other three groups, especially the screws which locked towards the anterior inferior part of the humerus head.【Conclusion】There are many factors influence the prognosis of proximal humeral fractures treated with locking plate, among that the increasing retroversion angle constitute the risk factors. If the humeral retroversion angle was changed beyond 20°, the extreme length of humerus head screws will be significantly reduced.