Welcome to the forum :)
I'm not sure if you can even see ringbone from the outside, to me it just looks like a hoof with her coronet band up top.
Your best bet would be to consult your vet if you are worried, a friend of mine had her huge wb gelding for several years and he kept going lame with no apparent cause, but when the vet did x-rays etc on him not long ago it was confirmed that he has ringbone, nobody could tell from the outside.
What makes you wonder if your horse has ringbone?
R.I.P ~ Bubbles - 25yo tb mare - 13.04.2011 ~ 8:30am ~ passed away naturally and peacefully in my arms