Iliotibial band syndrome

Our surgeon performed a diagnostic arthroscopy and an open IT band procedure.

He wants to bill 27305 as the primary and 29870-59 as his secondary code.

He feels since 29870 was an unrelated/distinct procedure from the primary procedure code 27305 it should be able to be billed using modifier 59.

I am not sure this is correct coding per CCI.

Please advise.

Thanks!

Peggy