Clinical and radiographic differences between two displacement patterns of the scaphoid nonunion

Scaphoid fracture patterns can be divided into volar and dorsal types using three-dimensional computed tomography. We retrospectively studied the differences in clinical features and radiographic findings between 61 volar type and 38 dorsal type displacements in 99 scaphoid nonunions. Ninety-two patients were male and seven were female, with an average age of 25. Regarding the causes of their injuries, the most evident difference between the two types was that all nine fractures resulting from punching motion were of the volar type, while all eight fractures sustained in falls from heights represented the dorsal type. We suspect that the direction of external forces affected the direction of displacement. The interval between injury and initial examination was longer in the dorsal type than in the volar type nonunions. Clinical symptoms such as wrist pain, range of motion and grip strength did not differ between two displacement types. Radiographic measurements showed that no differences were evident between the two types with respect to prevalence of dorsal intercalated segment instability deformity. The prevalence of scaphoid nonunion advanced collapse (SNAC) was greater in the dorsal type than in the volar type nonunions. More cases of the dorsal type than the volar type nonunion were treated by radial styloidectomy as a salvage operation or by conservative management, and this was influenced by the prevalence of SNAC wrist in these cases. (author)