Usb to firewire converter?

I'm using protools 9 on a macbook pro. There are 2 usb 2.0 ports, 1 firewire, and one thunderbolt port. One usb is used for my audio interface, the other is used for my iLok (authorizes pt9). But i have an akai mpd18 MIDI pad controller that requires a usb port. Since i'm already using using both of my usb ports, is there a way to buy some kind of usb to firewire/thunderbolt converter to use my MIDI controller?