Ligament Reconstruction For Distal Radioulnar Joint Instability With The Biomechanical Analysis

Background:In clinical practice,instability of the distal radioulnar joint（DRUJ）is a common problem,but there is little understanding of its pathogenesis and etiology.Injuries to the wrist joint are often the cause of DRUJ instability,and fractures of the ulnar styloid process are an important cause of this condition.Acute DRUJ instability can occur after recent traumatic injuries to the wrist,while patients with chronic DRUJ instability often have a history of traumatic events to the wrist.If not treated properly,DRUJ instability can cause pain on the ulnar side of the wrist,and in severe cases,can cause weakness and limited rotation of the forearm,among other problems.The triangular fibrocartilage complex（TFCC）is a key component on the ulnar side of the wrist,playing an important role in maintaining the stability of the DRUJ.TFCC injury is a common cause of discomfort,limited movement,weakened grip,and DRUJ instability on the ulnar side of the wrist.If not diagnosed and treated in a timely manner,TFCC injury can seriously affect patients’work and daily lives^[1,2].Although there are many emerging surgical techniques for treating DRUJ,the prognosis for some of these procedures is controversial.Understanding the complex anatomy,biomechanics,and stable structure of the distal radioulnar joint is crucial for evaluating and treating both acute and chronic instability.Objective:The purpose of this study is to evaluate the clinical efficacy,feasibility,and prognosis of arthroscopic TFCC repair and ligament reconstruction for chronic DRUJ instability,and to analyze the biomechanical characteristics of the rehabilitation process through finite element modeling.Methods:A patient with chronic DRUJ instability underwent Adams Berger surgery to reconstruct the distal radioulnar ligament.Piano key sign and forearm rotation tests were used to evaluate DRUJ function.Grip strength,range of motion,and visual analog scale（VAS）scores were recorded at the final follow-up.Joint function was evaluated using the Disability of the Arm,Shoulder,and Hand（DASH）score.The geometric model,meshing,and stress distribution of the repaired ligament during forearm rotation were analyzed using finite element modeling.Results:The patient had no complications after surgery and achieved stability during the6-month follow-up period.The stress and forearm rotation tests were negative.At the final follow-up,compared with before surgery,there were significant improvements in grip strength,DASH score,VAS score,and wrist range of motion（P<0.05）.This study suggests that the rotation angle of the wrist joint should be limited to within 75°in the short term after surgery to avoid tendon graft rupture due to excessive force.Arthroscopic TFCC repair and reconstruction can effectively treat chronic DRUJ and improve wrist function.This study established a three-dimensional finite element model of the entire DRUJ,which provided a digital visual platform for simulating the biomechanical features of TFCC,DRUJ,and other structures in different states.It also provided an intuitive simulation tool for the design of TFCC repairment and evaluation of curative effects.