Carpal Fractures -Scaphoid and Other Carpal Fractures-Screw Fixation of Scaphoid Fractures: A Biomechanical Assessment of Screw Length and Screw Augmentation

Screw Fixation of Scaphoid Fractures: A Biomechanical Assessment of Screw Length and Screw Augmentation

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A study conducted by the Department of Orthopaedics and Rehabilitation at Yale University School of Medicine assessed the biomechanical stability of scaphoid fractures using screw fixation. The study aimed to determine the impact of screw length and K-wire augmentation on fracture stability. The experiment involved applying flexion and extension loading through wrist tendons on cadaveric wrists with scaphoid fractures. The wrists were divided into three groups: short screw, long screw, and long screw augmented with a K-wire. Interfragmentary displacements were measured to evaluate fracture fragment motion. The results showed that longer screws provided significantly greater stability than short screws in four of the six displacement axes. The flexion/extension rotations for the short, long, and augmented long-screw groups were 8.2°, 3.9°, and 1.8°, respectively. K-wire augmentation reduced displacement but did not significantly decrease interfragmentary motion compared to the long-screw group. The study concluded that the optimal screw for scaphoid fracture fixation stability is a long screw positioned centrally and deep into subchondral bone. The authors also suggested that screw manufacturers should provide more options for screw length to optimize stability without risking screw prominence.

Keywords

scaphoid fractures

biomechanical stability

screw fixation

screw length

K-wire augmentation

fracture stability

flexion and extension loading

cadaveric wrists

interfragmentary displacements

fracture fragment motion