| Objective To study the changes in the length of the volar and dorsal radioulnar ligaments during supination of the forearm from 0° to 180° and its relationship with the distal radioulnar joint(DRUJ)stability by using computed tomography(CT)to image the wrist joint under torque load.Based on the published reports,this paper analyzed and compared whether the biomechanical motion of the radioulnar joint under torque load would be changed.Methods The wrist joint of the right(dominant side)hand of 6 healthy volunteers was studied,and a special torque load apparatus was used to apply a certain range of forces(1-1.5kg)to the wrist joint during supination,and the elasticity of the elastic potential energy gradually increased.Subject performs supination movements on forearm from 0° to 180° in 45° increments under anti-torque load.In the process of forearm movement,5 wrist joint locations at specific angles were selected for imaging under CT,and then 3D bone model was reconstructed in mimics medical analysis software according to CT data,and the starting and ending points of 4 radioulnar ligaments of DRUJ were determined according to anatomical knowledge.Namely,palmar superficial radioulnar ligament(PS-RUL),palmar deep radioulnar ligament(DS-RUL),dorsal superficial radioulnar ligament(DD-RUL)and dorsal deep radioulnar ligament(PDRUL).Using Marai’s method,each ligament was virtualized to simulate the path of the ligaments across the bone,and the length of the radioulnar ligaments under different wrist positions was measured separately and analyzed statistically.Results The length of palmar shallow radioulnar ligaments,palmar and dorsal deep radioulnar ligaments increased significantly in the process of resistance from supination position 0° to supination position 180°.Palmar shallow radioulnar ligaments increased the most,especially in the process of forearm supination position 0° to supination position45°,the increase of ligament length was the most obvious,increased by 1.mm.However,the volar and dorsal deep radioulnar ligaments increased slightly during supination and only increased in length by about 1mm.The length of the dorsal superficial radioulnar ligament decreased gradually during the whole process of resistance supination,and the length of the ligament changed the most from the pronation position of the forearm to the pronation position of 90° to 135°,and the decrease reached 1.6mm.The length of volar and dorsal superficial radioulnar ligaments showed a greater trend than that of volar and dorsal deep radioulnar ligaments during resistance supination.Conclusion The results of the 3-dimensional kinematic analysis in normal human body showed that the tension of palmar superficial radioulnar ligaments and palmar and dorsal deep radioulnar ligaments increased and the length of ligaments was elongated in the process of resistance supination of the forearm from 0° to 180°,which was the stable structure in the process of supination of the lower radioulnar joint.However,the palmar and dorsal deep radioulnar ligaments increase in ligament length by about 1 mm during supination,suggesting that the palmar and dorsal deep radioulnar ligaments are critical to maintaining the stability of the lower ulnar radial joint during resistance to supination.Clinical relevance The results of 3-dimensional kinematic analysis showed that the length of the palmar superficial radioulnar ligament 、 the palmar and dorsal deep radioulnar ligaments increased during the resistance supination process。The results suggest that when fighting supination movements that are more resistant than daily activities such as screwing doorknobs and t tighten the screws,the palmar and dorsal deep radioulnar ligaments are likely to tear.The results of this study suggest that supination should be avoided early after TFCC injury or inferior ulnar radial joint reconstruction and protective fixation should be performed with a neutral cast. |
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