Hand Orthopedics Scaphoid Fracture Criteria Calculator

About scaphoid fractures

Of the carpal bones, the scaphoid breaks most often, usually when someone falls onto an outstretched hand with the wrist bent back. What makes it matter clinically is how it gets its blood. Perfusion runs backwards here, from the distal pole up toward the proximal pole, so a fracture can cut off that supply. Break the proximal pole or the waist and you have a genuine risk of avascular necrosis (AVN) and non-union, especially if the injury is missed or undertreated. Proximal-third fractures sit at the top of the AVN scale at around 30%. Waist fractures happen most often and the risk there is moderate.

Clinical criteria and how it is assessed

You diagnose it through both exam and imaging. Here are the findings this calculator draws on:

• Tenderness in the anatomical snuffbox, which is very sensitive (~90%) but not very specific (~40%).
• Tenderness over the scaphoid tubercle on the volar wrist, plus pain when you load the thumb axially.
• Where the tenderness is focused points to where the break is: the distal pole at the volar prominence, the waist at the snuffbox, the proximal pole just below Lister's tubercle.
• Early radiographs can look normal. When a fracture is clinically suspected, the wrist is splinted and re-imaged about 2 weeks later, or worked up with MRI or a bone scan.
• The Herbert classification sorts fractures into stable (A), unstable (B), delayed union (C) and established non-union (D).

Who uses this

Orthopedic and hand surgeons reach for these criteria, as do emergency physicians, residents and physiotherapists. They use them to keep an occult fracture from slipping through, to choose between immobilization and fixation, and to talk patients through their union and AVN risk.

FAQ

Why splint a normal X-ray? Plenty of scaphoid fractures just don't show up on early films, and missing one opens the door to non-union and AVN.

Why is the proximal pole high risk? With blood flowing in retrograde, the proximal fragment loses its perfusion, which pushes up the odds of avascular necrosis.

This tool is educational only and does not replace a medical evaluation. A suspected scaphoid injury needs assessment, imaging and follow-up from a qualified clinician.