Medtronic (NYSE:MDT) just learned the hard way: Even -- or maybe especially -- when you're in a recession-resistant industry, you still have to perform, or investors will punish you. Medtronic traded down as much as 14% Tuesday despite reporting that it grew revenue by 14% year over year in its second quarter.

It wasn't one major problem that led Medtronic to fall short of expectations, but a series of smaller gaffes. Sales of InFuse, which promotes bone growth, were hurt by a Department of Justice investigation into off-label marketing for spinal surgeries, which it's not approved for. Off-label use can create problems, as both Medtronic and Stryker (NYSE:SYK) found out earlier this year.

Further, Boston Scientific's (NYSE:BSX) launch of its implantable cardioverter defibrillator (ICD) cut into Medtronic's market share during the quarter. And the spinal business grew 26%, but most of that was from Medtronic's acquisition of Kyphon, which didn't even contribute as much as the company would have hoped.

On the bottom line, Medtronic had to take a couple of charges, one bad and one that's not as big a problem. Medtronic lost its case in a lawsuit with Johnson & Johnson (NYSE:JNJ), resulting in a $229 million charge. It also had to write off $40 million worth of cardiovascular inventory because it won in a lawsuit against Abbott Labs (NYSE:ABT) and can now launch its products with upgraded rapid-exchange technology. It's bad news about the inventory, but good news that its products will be in higher demand with the more popular delivery system.

Besides the charge for the product write-off and a charge for the acquisition of CryoCath Technologies, Medtronic didn't lower its earnings forecast for its fiscal year. Normally that would be a good sign, but the company didn't perform up to its high standards in the most recent quarter, so investors have to wonder whether that's more hope than guidance. In either case, at least the sagging economy should affect Medtronic's performance in the second half.