Scaphoid Fracture Imaging Signs: Occult Wrist Fracture and AVN Risk

Up to 20% of scaphoid fractures are occult on initial radiographs because non-displaced waist fractures produce only a faint lucency obscured by overlapping carpal bones. MRI achieves near 100% sensitivity by detecting bone marrow edema as decreased T1 and increased T2 signal even when the fracture line itself is invisible on X-ray. Our AI evaluates both modalities to maximize detection and guides whether immediate MRI is warranted based on clinical and radiographic findings.

The scaphoid receives its blood supply in a retrograde fashion primarily through the dorsal ridge vessels entering at the waist. Proximal pole fractures disrupt this supply, leaving the proximal fragment at high risk for avascular necrosis and nonunion if immobilization is delayed. Distal pole fractures have an independent blood supply and heal reliably with casting. Our AI identifies the fracture zone, measures displacement and angulation, and flags proximal pole involvement requiring urgent orthopaedic evaluation.

Nonunion is characterized by sclerotic fracture margins, cyst formation, and a humpback deformity indicating dorsal intercalated segment instability (DISI) with a scapholunate angle exceeding 60 degrees. Avascular necrosis of the proximal pole appears as diffuse low T1 signal without gadolinium enhancement, reflecting absent perfusion. CT quantifies the gap and deformity for surgical planning. Our AI reports on each of these parameters to guide management decisions between bone grafting procedures and salvage surgery.