Opening MAY be co-surgery
Arlene, I respectfully disagree. It all depends on what was done.
Our general surgeons will typically open (and close) for the Ortho surgeons performing an anterior spinal fusion.
For illustration purposes let's say it's a thoracic arthrodesis - CPT 22556. BOTH the general surgeon and the Orthopaedic surgeon will bill out CPT 22556 [M62]. ONLY the orthopaedic surgeon will code for insertion of instrumentation ... e.g. CPT 22845.
(And as for "only opened" ... I did have one case where Gen'l surgeon A opened, but Gen'l surgeon B closed ... they're in the same practice, so we still only coded ONE co-surgery, and per our office protocol it was submitted under the name of G.S. A)
evecox .... you need to be clear in your post. You ask about co-surgery, but you keep using the term "assist." There is a big difference, as Arlene correctly pointed out.
Hope that helps.
F Tessa Bartels, CPC, CEMC