TABLE 4.

Types and characteristics of fracture reduction robots in RAFR systems.

Types of reduction robot	Human–robot interaction modes	Typical features	Indications	References
Robots based on external fixators	Telemanipulated	RX 130; a force/torque sensor	Femur fracture	Füchtmeier et al. (2004)
	Telemanipulated	RX90; a joystick with force feedback; a force/torque sensor	Femur shaft fracture	Westphal et al. (2006); Westphal et al. (2008); Westphal et al. (2009a); Westphal et al. (2009b)
	Hands-on	HA006; two force/torque sensors	Long bone fracture and femur fracture	Kim et al. (2016); Kim and Ko, (2019)
	Telemanipulated	A force/torque sensor; two master–slave modes	Pelvic fracture	Wu et al. (2020)
	Autonomous	UR16e; traction device	Pelvic fracture	Shi et al. (2021), Zhao et al. (2022a), Ge et al. (2022)
Robots for distraction and reduction	Autonomous	Unilateral external fixator; accurate execution	Femur fracture	Kim and Lee, (2004); Kim and Lee, (2006)
	Autonomous	Hexapod robot external fixator; load measurement capabilities	Femur fracture	Seide et al. (2004a)
	Autonomous	Stewart platform; acts as an external fixator after the reduction	Long-bone fracture	Majidifakhr et al. (2009), Tang et al. (2012)
	Autonomous/hands-on	Traction boot; a force/torque sensor	Femur fracture/femoral head fracture	Warisawa et al. (2004), Mitsuishi et al. (2005), Maeda et al. (2005); Maeda et al. (2008)
	Autonomous	Two mechanical failsafe units; a force/torque sensor	Hip fracture	Joung et al. (2008); Joung et al. (2010)
	Telemanipulated	Cuff-type reduction unit	Femur shaft fracture	Sun et al. (2015), Zhu et al. (2017)
	Telemanipulated/semi-autonomous/autonomous	Emulate the approach of traditional clinical treatment; a force/torque sensor	Femur fracture/tibia fracture	Fu et al. (2004), Kong et al. (2006); Wang et al. (2006); Zhi-jiang et al. (2006)
	Telemanipulated/autonomous	An active force/position controller	Long bone fracture	Mukherjee et al. (2005), Graham et al. (2006); Graham et al. (2008b)
	Telemanipulated	Disk platform and a two-thirds circular ring	Femoral shaft fracture	Wang et al. (2013)
	Telemanipulated/autonomous	Linear movements; A force/torque sensor	Femur fracture	Ye and Chen, (2009b); Ye et al. (2012), Wang et al. (2009); Song et al. (2010)
	Autonomous	Removable series-parallel mechanism	Long bone fracture	Wang et al. (2014)
	Autonomous	Reduction and positioning units;hydraulic drive; a force/torque sensor	Diaphyseal fracture	Li et al. (2014), Du et al. (2015b), Li et al. (2015b)
	Telemanipulated	Master–slave	Diaphyseal fracture	Li et al. (2016)
	Autonomous	Three automated spatial parallel manipulators	Intra-articular joint fracture	Raabe et al. (2012)
	Autonomous	Open-loop and closed-loop position controllers; a force/torque sensor	Joint fracture	Dagnino et al. (2016b); Dagnino et al. (2016c)
	Autonomous	Four motorized actuators	Intra-articular fracture	Dagnino et al. (2016a)
	Autonomous	Two robotic fracture manipulators and two carrier platforms	Joint fracture	Dagnino et al. (2017b); Dagnino et al. (2017c)
	Telemanipulated	Hexpod robot and two series manipulators	Pelvic fracture	Bignardi et al. (2018)