MAKO Surgical (MAKO), a medical device company that markets the RIO Robotic Arm Interactive Orthopedic system and orthopedic implants, is falling after Blue Belt Technologies received clearance from the FDA to market its NavioPFS orthopedic surgical system for partial knee replacement. MAKOplasty, as MAKO calls its knee and hip surgery process, uses the company's RIO robotic system and its RESTORIS implant to improve surgical outcomes by offering "a new level of precision and accuracy in aligning and placing implants," according to the company's website. Meanwhile, Blue Belt says its NavioPFS system uses patented technology to "provide precision to surgeons via smart instrumentation with robotic control," in its press release announcing its FDA approval. In a note to investors this afternoon, research firm Piper Jaffray acknowledged that the Blue Belt system, which has a lower price than MAKO's solution, is a new competitive threat in the U.S., but Piper thinks it will take time for NavioPFS to build momentum and acceptance with surgeons. Also, Piper believes MAKO's system still has some advantages in terms of implant availability, ease of use and broader applications in hips. Piper reiterated its Overweight rating and $28 target on MAKO shares, which were down 51c, or 3.86%, to $12.71 in early afternoon trading.