Finite Element Analysis And Clinical Study Of 3D Printing Personalized Customized Plate For The Treatment Of Bony Bankart Injury Through Axillary Approach

Background:The shoulder joint is one of the most flexible joints in the human body,and it is also the most vulnerable joint.Shoulder dislocation accounts for about 50% of all joint dislocations in the body,among which anterior shoulder dislocation is the most common.When the shoulder is dislocated anteriorly,an avulsion injury to the attachment of the glenohumeral ligament complex anterior and inferior to the labrum is called a Bankart injury.Violence continues through the humeral head and the inferior glenohumeral ligament complex to the anterior glenoid rim,resulting in a fracture of the anterior glenoid rim known as a Bankart fracture.Anterior glenoid compression fractures or bone defects and Bankart fractures resulting from chronic anterior shoulder dislocation are collectively referred to as bony Bankart injuries.Untreated bony Bankart injuries are prone to malunion and nonunion leading to complications such as persistent pain,osteoarthritis,and chronic shoulder instability.At present,the surgical therapy of osseous Bankart injury is mainly divided into open surgery represented by Bristow-Latarjet surgery,and arthroscopic surgery.Previous open surgery for bony Bankart injury used a deltoid muscle pectoralis major space approach to expose the bone injury area,but this approach required coracoid osteotomy and subscapularis tendon cutting,which greatly damaged the original anatomical structure of the shoulder joint.Arthroscopic surgery is favoured by many physicians because of its minimally invasive features,but it is not ideal for the treatment of large Bankart bone defects.Moreover,arthroscopic surgery mainly uses suture anchors and screws to fix Bankart fractures,and it is still doubtful whether suture anchors or screws alone are reliable enough.Therefore,the research on the treatment of osseous Bankart injury has always been the focus of clinical research.Objective:This article presents a new method for the treatment of bony Bankart injuries with a 3D-printed personalized custom plate through the axillary approach.First,the Bankart fracture model was constructed,and the fractures were fixed with customized plates and screws only respectively.And use computer finite element analysis technology to analyze the advantages of the personalized customized steel plate and screw only fixation in stress distribution and fracture displacement,and explore the reliability of steel plate fixation for Bankart fractures;Then,the clinical case study was conducted to further verify the advantages of the axillary approach combined with the customized plate in the treatment of osseous Bankart injury.We hope that this new surgical approach and personalized treatment concept can provide new options for the treatment of bony Bankart injuries.Methods:The CT data of the shoulder joint of healthy volunteers was obtained,and then the CT data was used to construct a scapula model through Mimics,Geomagic,and other software.The scapula model was reprocessed by Solidworks software to construct the Bankart fracture model.According to the detailed parameters of the steel plate and screws obtained from the internal fixation manufacturer,a personalized customized steel plate fixation model and a screw-only fixation model were respectively constructed by Solidworks software.The finite element analysis of the fracture fixation model was carried out by ANSYS software.The obtained stress distribution data and fracture displacement data were statistically analyzed by SPSS software,and the biomechanical characteristics of the two fixation modes were compared.A total of 27 patients with Bankart fractures treated by open surgery,between September 2017 and June 2021 at the Department of Orthopaedic Trauma,China-Japan Union Hospital of Jilin University,were retrospectively analyzed.Among them,a total of 13 patients treated with 3D printing personalized customized steel plates through the axillary approach were selected as the observation group,and a total of 14 patients treated with the pectoralis major deltoid space approach were set as the control group.SPSS software was used to compare and analyze the differences in operation time,intraoperative bleeding,postoperative axial CT residual fracture displacement distance,and postoperative functional score between the two groups.P<0.05 was considered statistically significant.Results:The data obtained by computer finite element analysis showed that when resisting vertical pressure load and shear load,the maximum stress of the internal fixation device,the maximum stress of the fracture fragment,and the maximum displacement of the fracture section of the group a were all lower than those of group b（P < 0.05）.The maximum stress of the internal fixation device,the maximum stress of fracture fragment and the maximum displacement of the fracture section in group A were lower than those in group B（P < 0.05）.The results of clinical case analysis showed that the operation time,intraoperative blood loss and postoperative CT residual fracture displacement distance of the observation group were smaller than those of the control group（P < 0.05）.Moreover,patients in the control group obtained higher postoperative functional scores（P < 0.05）.Conclusion:The use of 3D models helps physicians to understand the injury characteristics of patients more intuitively,facilitates communication between physicians and between physicians and patients,and preoperative simulation of reset and planning helps improve the accuracy and efficiency of surgery.The axillary approach exposes the fracture through muscle,nerve,and vascular spaces,avoiding damage to the original shoulder anatomy.It solves the drawbacks of the traditional deltoid pectoralis major space approach requiring coracoid osteotomy and subscapularis tendon incision and exposes the lower part of the glenoid more fully.The 3D printing personalized customized plate can provide stable fixation for the repaired bony Bankart injury,and has more mechanical advantages than simple screw fixation.It avoids the disadvantages of steel plate metal fatigue and screw hole failure caused by repeated bending and shaping during the operation,and also reduces the number of screw measurements and intraoperative fluoroscopy,shortens the operation time,and reduces intraoperative bleeding.In conclusion,we believe that this new surgical approach and individualized therapy concept can provide a research basis for the optimization of the therapy of bony Bankart injuries.