Subcutaneous extensor tendon rupture caused by Kienböck disease complicated by carpal tunnel syndrome: A case report

Dorsal lunate bone fragments associated with advanced Kienböck disease can cause extensor tendon rupture. When ultrasonography confirms that the volar fragment of the lunate bone does not impinge upon the median nerve or flexor tendons, surgical intervention on the volar fragment may be unnecessary. Computed tomography, magnetic resonance imaging, and ultrasonography are valuable for accurate assessment and preoperative planning.