Os Styloideum

Description

a Sagittal view showing a separate carpal bone fragment along the dorsal area of the 3rd metacarpal base (arrows). b Axial view showing an accessory bone, the os styloideum (arrow) between the capitate (c) and the trapezoid (Tz). This image rules out third metacarpal base fracture as a differential diagnosis

Name

• Os Styloideum
• Carpal Boss

General

• Accessory ossicle of the wrist
• Ossicle is located between the trapezoid and capitate
• At the base of the second and third metacarpal

Radiographic Appearance

• Seen at the base of the 2nd/3rd metacarpal base
• May be mistaken for a metacarpal fracture

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Clinical Significance

• Carpal Boss Syndrome

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See Also

• Hand And Wrist Anatomy
• Physical Exam Hand
• Wrist Pain Main

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