ABSTRACT
BACKGROUND: Through clinical research, we found that in the treatment of distal radius fracture combined with ulnar styloid process fracture, the proportion of complications of ulnar column after manual reduction and splint fixation was smaller than that of patients who only received open reduction and internal fixation of distal radius. We deemed that the wrist joint was treated as a whole in the treatment cycle, the splint as elastic fixation could provide the relative stability of the ulnar column and reconstruct the stability of the three columns of the wrist. OBJECTIVE: To explore the biomechanical mechanism of splint intervention on the ulnar column after type Frykman VIII fracture of the distal radius by finite element analysis. METHODS: A three-dimensional finite element model of normal wrist joint was established based on the forearm and wrist CT images of a healthy volunteer. Two kinds of finite element models of type Frykman VIII fracture of the distal radius with ulnar styloid type I and type II fractures were established by using finite element software to divide the mesh, cut and mold. On this basis, four wrist joint finite element models with splint fixation and steel plate fixation for type Frykman VIII fracture of the distal radius were established. Under axial compression, lateral extension, pronation and supination working conditions, stress distribution and relative displacement of the distal radioulnar joint, displacement and direction of the ulnar styloid fracture broken end were analyzed. RESULTS AND CONCLUSION: (1) The stress values of the ulnolunate ligament, ulnotriquetral ligament, and the palmar dorsal radioulnar ligament in the model of type Frykman VIII fracture of the distal radius with ulnar styloid type I fracture after splint intervention were lower than those in the model after plate intervention in the lateral tension, pronation and supination conditions. (2) In the pronation and supination conditions, the relative displacement values of the distal radioulnar joints in type Frykman VIII fracture of the distal radius models with ulnar styloid type I and type II fractures after splint intervention were smaller than those in the models after plate intervention. (3) In the lateral tension, pronation and supination conditions, the relative displacement values of the ulnar styloid fracture broken end in type Frykman VIII fracture of the distal radius models with ulnar styloid type I and type II fractures after splint intervention were smaller than those in the models after plate intervention. (4) The finite element study shows that distal radioulnar joint stability becomes worse after type Frykman VIII fracture of the distal radius, which is more obvious in the model with ulnar styloid type II fracture. In the treatment of this kind of fracture, compared with the simple internal fixation of distal radius fracture, the splint as elastic fixation takes the wrist joint as a whole in the treatment cycle and provides the relative stability of the ulnar column, thus further revealing the advantages of the splint elastic fixation.