Presentation
Left third MCP region pain. The dorsal side swelling with tendon snapping.
Patient Data
Intact extensor tendon of the middle finger. Short-axis image with MCP extension shows ulnar side subluxation of the 3rd finger extensor tendon. The tendon dislocates with MCP flexion. The radial side sagittal band is not seen.
The first two short-axis cine-loops run from the proximal to the distal direction. During MCP flexion to extension movement, the third cine-loop shows tendon snapping/ tendon relocating.
4th finger extensor tendon and sagittal bands are normal without tendon subluxation/ dislocation.
Case Discussion
The patient tried to get up supporting the left hand on the ground. It resulted in the sudden onset of pain involving the middle finger MCP region. It was followed by dorsal side swelling and snapping with finger extension.
The ultrasound findings favor radial side sagittal band injury with ulnar side tendon subluxation/ dislocation. The tendon relocation with finger extension results in snapping.