# Robotic Systems and Navigation Techniques in Orthopedics: A Historical Review
## 2 Robotic Systems (RSs)
### Hands-On RS
#### 2.2.4 NavioPFS/NAVIO  
NavioPFS (precision freehand sculpting) (Blue Belt Technologies, Plymouth, MN, USA) system is a computer-aided orthopedic navigation and surgical burring system, and is also a semi-autonomous, hand-held, and image-free system. It was approved by the FDA (NavioPFS FDA 2012 file (accessed on 28 June 2023): [[https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K121936](https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K121936)]([https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K121936](https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K121936))) in 2012 for unicondyl knee arthroplasty (uKA) [2].  
The NavioPFS is a hand piece that has a cutting tool (a motorized burr) installed at the robot end effector, and the burr can extend and retract. A related safety strategy is that by modulating the retraction (exposure control) and speed of the burr (speed control) [27], inadvertent bone removal can be avoided, although there is no haptic feedback in this system. Another big advantage of this system is its imageless feature, meaning that preoperative CT imaging is not needed, and all the registration, planning, and navigation will be performed during the surgery. Note that the imageless feature is equivalent to the image-free feature in this paper. NavioPFS employs an optical-based navigation system via a passive infrared (IR) tracking camera and trackers. Intraoperative data from the trackers are collected and displayed in a graphical format, and together with anatomic landmarks and surface painting techniques, a 3D model of the patient's femur and tibia can be created; thus, a surgical plan can be made by the surgeon intraoperatively [2;9].  
The NavioPFS system has been proven to have reduced implant position errors [43], satisfied mechanical axis alignment accuracy, decreased bone cutting time, and improved Oxford Knee Scores [2]. The learning curve for operating the NavioPFS has been shown to be fairly rapid [44;45].  
Blue Belt Technologies Inc., a Carnegie Mellon University spin-off company that was founded in 2003, was acquired by Smith & Nephew plc (London, UK) in 2016 [10]. In 2019, Smith & Nephew acquired the orthopedic unit of Brainlab, after which Smith & Nephew's NAVIO surgical system upgraded its software to Navio 7.0. The softwareupgrade resulted in a significant reduction in the required data point collection and in the workflow stages, faster surface modeling, and improved usability [9]. The current Smith & Nephew's NAVIO surgical system (NAVIO Surgical System website (accessed on 28 June 2023): [[https://www.smithnephewlivesurgery.com/navio-surgical-system](https://www.smithnephewlivesurgery.com/navio-surgical-system)]([https://www.smithnephewlivesurgery.com/navio-surgical-system](https://www.smithnephewlivesurgery.com/navio-surgical-system))) expanded the applications to TKA and UKA, and together with its PFJ software, it can assist the surgeon in making implant plans and help them to prepare the bone for implantation [24].