From page 307 of my Civil Procedure casebook:

"The same year, a decision of the Sixth Circuit expressed concern about mass tort product liability class actions, particularly when they embraced a nationwide class. Anerican Medical Systems, Inc. sought class certification of a nationwide class of people who suffered damages from implants of allegedly defective penile prostheses manufactured by defendant. *** It noted that class members had used at least ten different models of the prosthesis and that legal claims would 'differ depending upon the model and the year it was issued.' It also found that there would be individualized evidence as to such issues as 'surgical error, improper use of the device, anatomical incompatibility, infection, device malfunction, or psychological problems.'"

And you thought law school reading was dry and boring!