Relationship between ulnar styloid fracture and DRUJ instability

Changes in the distal radioulnar joint (DRUJ) stiffness after simulating four types of ulnar styloid fracture were examined. After the tip, middle, base horizontal, and base oblique type of styloid fracture was made sequentially, changes in dorsopalmar DRUJ stiffness were measured in intact wrist, each fracture at 60degrees pronation, neutral and 60degrees supination. Additional cutting of the radioulnar ligament (RUL) was also simulated with the base horizontal fracture. The tip and middle type fractures did not demonstrate significant loss of stiffness compared with the intact. The base horizontal and base oblique fractures demonstrate significant loss of dorsopalmar stiffness of the DRUJ. Additional section of the RUL induced significant loss of stiffness of the DRUJ with the intact.