Agree- something has been wrapped tightly round that foot. Wire likely, could be fence, snare etc..
The healing pattern looks like granulation tissue plus (and can't be sure from the pic) possibly exposed bone? Whilst likely older/more chronic, to my mind that wound is potentially still trying to heal. I'd be cautious about whether there's any ongoing infection- check the popliteal lymph node in particular (the one behind the knee, nestled between the end of the hamstrings).