My Dr. is doing a right thumb interpositional arthroplasty w/graft, trapezoid resection, and a scaphoid-trapezoid fusion.

I know 25447 is the arthroplasty which also includes the resection. I'm having trouble w/the fusion. I was looking at 25820 but that doesn't seem quite right, as it includes the capitate and lunate as well as the scaphoid.

Any ideas out there?