Robotic surgery company MAKO Surgical (UNKNOWN:UNKNOWN) released earnings after the market closed today, and shares are rising slightly in after-market activity. Here's what you need to know.

While MAKO is only now reporting fourth quarter financial results, the company didn't leave much for the imagination after providing a great glimpse into it's vital signs before an investor conference in early January. Because of that, investors aren't paying too much attention to metrics like systems sales and procedure numbers from last quarter.

What they were looking forward to is guidance, especially given that we're about two-thirds of the way through the first quarter. While there wasn't any explicit financial guidance, investors did receive a full-year outlook for RIO system sales, 45 to 48, along with procedure guidance for the full year of 13,500 to 14,500.

I'll need more time to listen to the conference call in its entirety and run through the financials, but it's clear that management has learned it's lesson from 2012 by going into 2013 with relatively flat expectations on systems sales. Last year management's reputation took a major hit after leading with aggressive guidance in January, only to make major revisions throughout the year.

It seems unlikely that the March quarter will offer any shock to investors given how late we are in the year, so my guess is that we'll have to wait until mid-year to get a true feel for how 2013 will shape up for the company.

Without question, MAKO is no longer the growth story it once was. However, patient shareholders could stand to benefit if the company can continue to expand its installed base, even at a measured pace, while also improving utilization with existing customers.

Brenton Flynn has no position in any stocks mentioned. The Motley Fool recommends MAKO Surgical . Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.