Fact-sheet: Disruption of the sagittal bands of the extensor hood - Boxer knuckle
Updated on 02/14/2024 at 9:56 AM
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Definition
Rupture of a sagittal band of the extensor mechanism, most often occurring after direct trauma from a closed fist (punch). More rarely, the rupture may be spontaneous in a setting of inflammatory rheumatism (RA)
Clinical features
Dislocation of the extensor tendon over the dorsal aspect of the metacarpophalangeal joint
Rupture of the radial sagittal band is more common than rupture of the ulnar sagittal band
Ultrasound
Radial or ulnar dislocation of the extensor tendon at the level of the MCP joint during finger flexion
Rupture of the sagittal band opposite the side of the dislocation
MRI
Rupture of the radial (or ulnar) sagittal band of the extensor mechanism with surrounding edematous infiltration, hyperintense on T2 FatSat
