Shares of Mako Surgical (NSDQ:MAKO) are down 6.6 percent since the robotic surgery firm reported wider third-quarter losses, despite a nearly 67 percent increase in sales.

Mako reported losses of $9.7 million, or 24 cents per share, on sales of $20.0 million during the three months ended Sept. 30.

The wider losses – which missed Wall Street analysts’ expectations of 22 cents by two pennies – sent MAKO shares down 6.6 percent, to $33.50, as of about 10:10 this morning. The stock lost 7.0 percent yesterday, falling to a $33.34 close.

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"We are pleased with our strong operating results in the third quarter of 2011, including the commercial introduction of MAKOplasty Total Hip Arthroplasty," president & CEO Dr. Maurice Ferre said in prepared remarks. "We believe that the expansion of our product offering through the launch of the hip application will allow us to continue to drive the adoption of MAKOplasty to help enable surgeons to deliver consistent, reproducible precision to orthopedic procedures."

CFO Fritz LaPorte told analysts on a conference call that the company reaffirmed its prediction that it will sell between 44 and 48 of its Rio systems this year.

"We also expect that by year end at least one-third of our installed base will include the hip application, either through upgrades or new sales," LaPorte added. "As for MAKOplasty procedures, we are narrowing our range of guidance and now expect that our customers will perform 6,600 to 6,900 procedures in 2011."