Finger Burn

My younger brother, has got a burn since he was a baby on his index finger left had in  the middle. The doctors wrapped it up (no skin graft) and as he got older every time he stretched it out it, would hurt him. So he left it, and it grew along with the attachment of the skin. Now his index finger is bent, but works fine. But however he plays instruments and he's not able to  put his finger out straight.

Would a skin graft have to be done? Will doctors cut the skin and replace it with another piece?