There are different types of robotic knee arthroplasty. Certain types actively do all steps of tibial and femoral bone resections, known as “fully active. Other types enable the surgeons to do the surgery while giving feedback intraoperatively to assist in control resection of the tibia and femur to the pre-operative surgical plan, and this group is known as “semi-active.” The surgeon makes the approach, puts the retractors to protect the soft tissues.

New robotic systems such as the Navio PFS (Blue Belt Technologies, Plymouth, MN, USA), Mako (Mako Stryker, Fort Lauderdale, FL, USA), Rosa (Zimmer-Biomet, Warsaw, Indiana, USA) and iBlock (OMNIlife Science, East Taunton, MA, USA) were developed that are being used more and more. (12) Various classification systems have been proposed to characterize the different designs of robotic technology used in medicine. The most well-known is the one proposed by Schneider and Troccaz in 2001 [13].

It places robotic systems in four categories: passive, active, interactive, and tele-operated passive systems consist of an articulated arm that holds an instrument moved manually by the surgeon, with the instrument's position being recognized by the navigation system. They do not directly participate in carrying out the procedure, which remains completely under the surgeon's control. The OMNI® robot fits in this group. Conventional navigation systems used for TKA are often integrated into this type of system.

active systems are robots that use preoperative and intraoperative planning data to perform multiplanar surgical manipulations autonomously (without the surgeon's participation). The Robodoc® fits into this group. interactive systems are robots that require an interaction between the robot and the surgeon who constrains the robot. There are two types of strategies in this group: semi-active and synergistic systems.

In semi-active systems, this mechanical constraint can be summarized as a movement without feedback to the surgeon. Conversely, for synergistic systems, the mechanical constraints are programmable: these newer systems are based on the principle of haptic models (i.e. information feedback) with the robot generating forces where the amplitude and frequency reproduce true sensations (touch, vision). Lastly, teleoperated systems correspond to robots that are controlled remotely by a surgeon. The most well-known example is the DaVINCI® robot.

Developed in 1986, Robodoc (Curexo Technology, Sacramento, CA, USA) was the first system with ORTHODOC (robotic arm and software) to be used for joint replacement surgery [15], [16] (Fig. 2). It is currently sold under the name TSolution-One (Think Surgical Inc, Fremont, CA, USA; previously Curexo Technology). This is an autonomous active system (without surgeon interaction) based on preoperative CT scan images with an open platform (i.e. suitable for all implants) [14], [17]. The iBlock robotic cutting guide (OMNIlife Science, Raynham, MA, USA), which was previously called Praxiteles, was approved by the Food and Drug Administration (FDA) in 2010 to assist with TKA implantation [14].