Stitches Not Dissolved Two Months After Angiography. What Can Be Done?

Hello Doctor, My mother is 49 years old and she underwent Angigraphy bypass surgery in september 2012. the operation was successful and she is fine. She had stitches on her both the legs and on her last visit to the doctor, she was told that her stitches will dissolve by themselves but still its been almost 2 months , her stitches are not cured. could you please suggest what could be done for this ??? Also can you please suggest a routine Diet for my mother and what to be avoided? is there anything else needs to be done? Many Thanks Manav