Not all sagittal band tears come with extensor instability: a case report with radiological and operative correlation.

The sagittal bands are a component of the extensor hood. They serve an important role in stabilizing the extensor tendon by forming a "check-rein" to radial-ulnar translation of the tendon over the metacarpal head, and extending the metacarpophalangeal (MCP) joint by virtue of attaching the extensor tendon to the palmar plate. Injury to the sagittal band is thought to cause extensor instability and subluxation to the contralateral side by disruption of this "check-rein" function, although recent evidence from cadaver studies suggests that ulnar sagittal band tear may be spared of extensor instability. As a case in point, we encountered a patient with surgically proven ulnar sagittal band tear, who did not have any extensor tendon subluxation or any limitation in motion. Intraoperative findings demonstrated a chronic-appearing ulnar sagittal band tear, indicating that chronic injury with fibrosis may stabilize the central band. Therefore, in patients with metacarpophalangeal pain without central tendon subluxation or limitation of motion, it remains important to raise the concern of sagittal band tear for appropriate treatment. We present the clinical course of this case, with radiological and operative findings, followed by a review of the relevant literature.