Anatomy clinical correlates Quiz: Ace Your Exams

A 56-year-old man presents to his primary care physician with right ring finger pain. The patient recalls that the right ring finger has been “catching and locking” for weeks. The symptoms seem to improve throughout the day, with gradual “unlocking” as the day progresses. Past medical history is notable for type II diabetes mellitus and hypertension, for which he takes metformin and hydrochlorothiazide. Vital signs are within normal limits. Physical examination demonstrates the fourth digit of the right hand to be in a flexed position, as shown below. Passive extension of the digit is met with some resistance. There are no palpable nodules or tenderness along the flexor tendon sheath. Nonetheless, he can fully extend the digit with minimal pain. Which of the following is the most likely diagnosis?  


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