Diabetic foot

A pt aged 69 years came with the c/o delayed healing and rotten smell from his thumb finger of the foot. pt gave medical h/o DM since 25 yrs and was on medication was the same.

1 month back he had a local injury to his foor due to which his thumb nail got injured and turned greenish eventually.

o/e: the thumb appears to be rotten and a holoowing is seen. It smells rotten and shows occasional bleeding and oozing

Kindly suggest a suitable treatment plan