A 55-year-old man with diabetes presents with a 4-month history of progressive inability to extend his ring finger at the MCP joint while all other fingers extend normally. Passive extension is full. The correct diagnosis is:

• A Rupture of the extensor digitorum communis tendon to the ring finger (closed tendon rupture) ✓
• B Posterior interosseous nerve palsy causing selective ring finger drop
• C Trigger finger (stenosing tenosynovitis) of the ring finger flexor
• D Sagittal band rupture of the ring finger extensor hood

Explanation

Closed spontaneous rupture of the extensor digitorum communis tendon to the ring finger (Vaughan-Jackson syndrome variant in rheumatoid, but also in diabetes with tenosynovitis) presents as isolated inability to actively extend the ring finger at MCP with preserved passive extension — this distinguishes tendon rupture from joint disease. Posterior interosseous nerve palsy affects multiple fingers and wrist extension partially. Trigger finger causes clicking or locking in flexion, not extension loss. Sagittal band rupture causes ulnar subluxation of the extensor tendon but typically presents after trauma with snapping rather than pure extension loss. Tendon rupture requires surgical repair or tendon transfer.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.