Study On The Change Of The Contact Area And The Distribution Of The Centroid Of The Radiocarpal Joint During Dart Throwing With Four-Dimensional CT

Objective The biomechanics of the wrist joint is still a hot topic in hand surgery research,and its degeneration is related to chronic wrist pain.This experiment applies a specific imaging technique: four-dimensional CT(4DCT),which is a dynamic threedimensional scan,combined with the recognized physiological movement of the wrist joint: dart-throwing motion.The aim of this paper is to study the changes in the contact area of the radiocarpal joint and the distribution of the contact centroid during dartthrowing motion in daily life,in order to provide a reasonable explanation for chronic pain caused by wrist joint degeneration,and evaluate the feasibility of applying fourdimensional CT in calculating the contact area of the wrist joint simultaneously.Methods Recruit sixteen volunteers and conduct movement training,then use a specific mold to run the dart throwing motion with an motion plane of 45° from the sagittal plane,the direction of which is from a radially deviated-extended position(radial extension)to an ulnarly deviated-flexed position,and use four-dimensional CT to continuously photograph the wrist joint in 30 seconds,and each volunteer will get the wrist joint CT images of 30 positions.Finally,the imaging data of 7 volunteers met the criteria and were included in the study.The images were imported into Mimics,Geomagic Wrap and Magics software to reconstruct and modify the radius,scaphoid and lunate bones,extract and calculate the contact area,and mark the centroid of the two contact areas.The change trend of the contact area of the radioscaphoid joint and the radiolunate joint and the distribution of the centroid of the contact surface of the radiocarpal joint were studied when the normal people doing the dart throwing motion.Results The contact area of the radioscaphoid joint and the radiolunate joint of the seven volunteers showed a decreasing trend during the dart throwing motion from radially radial extension position to ulnarly deviated-flexed position,and there are individual differences in the decreasing trend and no special rule of the distribution of the centroid was found.The reliability of calculating the contact area of the wrist joint using fourdimensional CT was high.Conclusions In the process of dart throwing from radially radial extension position to ulnarly deviated-flexed position with an motion plane of 45° from the sagittal plane,the contact area of the radial scaphoid and radial lunate joint shows a decreasing trend,this trend and the distribution of the centroid of the two contact areas varies from person to person.As a dynamic imaging evaluation method,we believe that four-dimensional CT is a feasible way to evaluate the contact area of the wrist joint,but we need to improve the success rate of inclusion.