A 72 years male( golfer), controlled diabetic, had callosity on latral aspect of dital phalynx of left index finger fo the last about 8 months. Skin on it got sloughed out about 6 weeks back.

That ulcer granulated and almost healed with anticeptic dressings but a sinus persisted through which milky fluid discharges off and on , on pressing, and mild tenderness. What is the diagnosis of this condition?