Finite Element Analysis Of Dislocation Of Lower Radioulnar Joint And Clinical Application Of Loop Plate In The Treatment Of Dislocation Of Lower Radioulnar Joint

BackgroundDRUJ is an important joint connecting the hand and forearm.Due to the mismatch between ulna and sigmoid notch of radius,it is easy to dislocate after peripheral ligament injury.DRUJ dislocation is not a rare disease.It is usually secondary to distal radius fractures.If it is not found in time and treated as soon as possible,it may evolve into chronic dislocation,aggravating the symptoms and increasing the difficulty of treatment.Conservative treatment is often ineffective.TFC is the main stabilizing device of DRUJ,and the radioulnar ligament is an important component of TFCC in exerting the joint stabilization effect.Usually,fracture or trauma causes damage to the radioulnar ligaments or its attachment point,which leads to DRUJ dislocation.Scholars try to use tendon grafts to simulate the anatomical structure of radioulnar ligament,or use the method of hanging DRUJ to simulate the function of radioulnar ligaments,so as to rebuild the stability of DRUJ.In recent years,the loop steel plate elastic suspension device has been used for the treatment of DRUJ dislocation and obtained certain curative effects.ObjectiveFinite element analysis:The finite element model is used to analyze the displacement of normal DRUJ.and the changes of displacement of DRUJ in radial ulnar ligament injury.Based on the comparison of the analytical results,the importance of the radioulnar ligament in maintaining the stability of the DRUJ was discussed.Clinical research:15 patients with dislocation of DRUJ treated by elastic suspension of DRUJ with loop plate were retrospectively analyzed to determine the clinical effect of suspension of DRUJ with loop plate on DRUJ dislocation.MethodsFinite element analysis:The model object in this study adopted the CT image of the right upper limb of a woman with no injury history as the basic data for establishing the three-dimensional finite element model.They are imported into Mimics 17.0 for image segmentation and other related processing,and the geometric model of ulna and radius are made.The nonlinear spring are used to simulate the ligament,and according to the shape of forearm movement,the appeal element is assembled into a DRUJ model with normal neutral position.The relevant units that simulated the radioulnar ligaments were removed to make a DRUJ model of neutral radioulnar ligament injury.The established models were imported into the finite element analysis software ANSYS 2020R1,and the models were meshed and material assignment was performed.The stress conduction distribution and relative displacement of DRUJ under the normal neutral position(axial compressive force 66.7N along the forearm,transverse tensile force 66.7N,pronation 22N,and supination 22N)are simulated by loading on the normal neutral position DRUJ model and the model of radioulnar ligament injury.Clinical research:A total of 15 patients with DRUJ dislocation were selected from January 2016 to June 2020 in our hospital.All patients were treated with loop plate suspension for DRUJ dislocation and followed up.According to the Gartland-Werley Wrist Score,the postoperative wrist function was scored and graded(excellent:0-2 points,good:3-8 points,fair:9-20 points,and poor:≥21 points).The paired t-test was used to compare the wrist range of motion of the affected side and the healthy side,as well as the Gartland-Werley scores and VAS scores of the affected side before and after the operation,so as to evaluate the clinical efficacy of this surgical method.ResultsFinite element analysis:According to the analysis of finite element model,the relative displacement of ulna and radius radioulnar ligaments injury model is obviously larger than that of the normal model.Clinical research:During the clinical follow-up,the selected patients had no complications such as incision infection,dislocation recurrence,iatrogenic fracture and so on.Postoperative X-ray examination showed that the dislocation of the joint had been reduced and no recurrence.The fractures of the patients combined with the fractures had good healing.At the last follow-up,the wrist function of the affected side was evaluated according to Gartland-Welley score,among which,10 cases were excellent,4 cases were good,and 1 case was fair.After statistical analysis,there was no significant difference in bilateral wrist range of motion among all patients.The preoperative and postoperative Gartland-Werley wrist function scores and VAS scores were compared,and the difference was statistically significant.Conclusion1.Finite element analysis:injury of the radial ulnar ligaments can lead to instability of the DRUJ.2.There is no significant difference in the wrist joint range of motion between the affected side and the healthy side in the treatment of DRUJ dislocation with loop plate suspension.The wrist function score and VAS score of the affected side improved significantly after operation.The wrist function recovered well after operation,and the follow-up results were satisfactory.Loop plate suspension is a safe and effective method to treat DRUJ dislocation.