Help. My finger keeps cracking.

[anon10]

When I am playing gradually over the course of a match my index finger is causing me pain. Particularly off forehands, the finger bends and cracks sideways on both the knuckle joint and the joint on the line or crease above the knuckle. I don't know whether this is grip, technique or a bit of both.

I am concerned because I think the finger bending and cracking in such an unnatural manner will be doing damage. What do you think? Should I get my grip and technique seen to by a coach?

 

[anon10]

Just to add. The finger has healed over night. But it is still slightly painful.