Scaphoid Fracture Nonunion Due to Interposition of a Radial Styloid Fracture Fragment

Radial styloid fractures (RSFs) and scaphoid fractures often occur together and are considered part of Mayfield stage 1 perilunate fracture dislocation. Proper management is crucial to maintain wrist stability. Interposition of an RSF within a scaphoid fracture is less common and can lead to nonunion.

We report a case of a 35-year-old patient with nonunion of a scaphoid fracture following failed conservative management 2 months' postinjury. Imaging revealed increased flexion of the proximal pole due to the interposition of the RSF, which prevented proper approximation and healing of the fracture. Surgical intervention involved a dorsal approach to the scaphoid, removal of the scarred styloid fragment, and fixation with a screw, along with bone grafting. The fracture healed within 2 months, as confirmed by computed tomography (CT) scan. The wrist recovered normally, achieving a Mayo Wrist Score of 90 at the 6-month follow-up.

Nonunion of a scaphoid fracture due to the interposition of an RSF is a rare occurrence that, to our knowledge, has not been reported in the past.

We propose that this situation may represent an incomplete injury pattern similar to transstyloid transscaphoid perilunate fracture dislocation. Mechanisms such as wrist ulnar deviation and extension followed by radial deviation may contribute to this complication. CT scans are valuable in assessing fragment interposition that causes extreme flexion of the proximal pole. This case highlights the importance of thorough evaluation in similar injuries to optimize outcomes.