Abstract
Smith's fractures generally occur when falling on a flexed wrist; however, orthopedic trauma surgeons often encounter distal radius fractures with volar displacement in patients who have allegedly fallen on the palm of their hands. This study aimed to reveal both the basic and clinical pathogenesis of Smith's fracture through a step-by-step investigation. We enrolled 17 patients with Smith's fractures, of which 71% fell on the palm and only 6% on the dorsum of the hand. First, we interviewed the outpatients to determine the mechanics of the injury and the position of their arm during injury. Second, we created a three-dimensional (3D) finite element model to predict the arm's position when the Smith's fracture occurred, which finite element analysis revealed as a 30° angle between the long axis of the forearm and the ground in the sagittal plane. Third, using this predicted position, we conducted experiments on 10 fresh frozen cadavers to prove the possibility of causing a Smith's fracture by falling on the palm of the hand. The results showed Smith-type fractures in seven of 10 wrists, whereas Colles-type fractures did not occur. Finally, we analyzed stress distribution in the distal radius when a Smith's fracture occurs using the 3D finite element model. In conclusion, this study demonstrates that Smith's fractures can also occur by falling on the palm of the hand.
