What is the acceptable displacement for a scaphoid (carpal navicular) fracture?

From the Guidelines

For a scaphoid fracture, minimal to no displacement is generally acceptable for non-operative management, with a displacement of less than 1 mm typically considered acceptable for conservative treatment with cast immobilization. This is based on the principle that the scaphoid has a tenuous blood supply, particularly to its proximal pole, which increases the risk of avascular necrosis and non-union with displaced fractures 1. The goal of treatment is to restore the anatomy of the scaphoid and prevent long-term complications such as osteoarthritis.

Key Considerations

• Displacement greater than 1 mm, gap or step-off deformities, or any significant angulation (typically greater than 15-20 degrees) usually require surgical fixation.
• The scaphoid's critical role in wrist biomechanics means that even small amounts of displacement can lead to altered carpal mechanics and subsequent degenerative arthritis.
• When evaluating displacement, multiple radiographic views or advanced imaging such as CT scans may be necessary for accurate assessment, as conventional X-rays can sometimes underestimate the true extent of displacement in scaphoid fractures.

Treatment Thresholds

• A study published in the Journal of the American College of Radiology in 2019 notes that successful treatment of fractures requires restoration of anatomy and realignment of fracture fragments, with operative fixation resulting in <2 mm of residual articular surface step-off usually considered necessary to avoid long-term complications 1.
• However, for scaphoid fractures, a more stringent threshold of <1 mm displacement is typically applied due to the unique anatomy and blood supply of the scaphoid.

Clinical Implications

• Clinicians should prioritize accurate assessment of displacement and angulation in scaphoid fractures to determine the appropriate treatment approach.
• Non-operative management with cast immobilization may be suitable for minimally displaced fractures, while surgical fixation is often necessary for more significantly displaced or angulated fractures.

From the Research

Displacement Acceptable for a Scaphoid Fracture

• The acceptable displacement for a scaphoid fracture is generally considered to be less than 1-1.5 mm 2, 3, 4, 5.
• Fractures with a displacement of 1 mm or more are associated with a higher risk of nonunion and avascular necrosis 4, 5.
• A displacement of 1.5 mm or more is often considered an indication for surgical treatment 3.
• The treatment of displaced scaphoid fractures depends on the degree of displacement, the location of the fracture, and the presence of any instability or other complications 2, 3, 4, 5.

Treatment Options

• Nonsurgical treatment with cast immobilization is recommended for stable, nondisplaced or minimally displaced fractures 2, 3.
• Percutaneous screw fixation or open reduction and internal fixation are recommended for displaced or unstable fractures 2, 3, 4, 5.
• The choice of treatment depends on the individual patient and the specific characteristics of the fracture 2, 3, 4, 5.

Complications of Displaced Scaphoid Fractures

• Displaced scaphoid fractures are associated with a higher risk of nonunion, avascular necrosis, and late carpal osteoarthritis 4, 5.
• The risk of nonunion is higher for fractures with a displacement of 1 mm or more 5.
• Early diagnosis and treatment are important to minimize the risk of complications and improve outcomes 2, 3, 4, 5.