My experience are that as long as it's just the glass that are fractured and the cells are still connected; trying to pry the glass fragments off will only ruin the whole panel (whats left of it, that is...)
The cells are usually encased in a form of silicone, and as soon one try to 'dig them out' through the broken glass, they're getting exposed to the enviroment, and in the process, the cells often break...
my 2 cents...
Edit;
As long as that silicone layer between the broken glass and the cells are not broken, the cells are ok. That 85W panel i have that only gives 20W have one point where someting really sharp hit and some of one of the cells are exposed; thus the low output. The other panel have an uniform fracture overall, and has much better performance...