TABLE 3.

Types and characteristics of intraoperative navigation and registration technologies in RAFR systems.

Types of navigation	Using preoperative CT	Intraoperative data	Registration techniques	Typical features	Indications	References
2D fluoroscopy-based navigation	NO	2D fluoroscopic images	No preoperative images registration	Last X-ray image is overlaid with the moving bone axis	Femur shaft fracture	Westphal et al. (2006)
3D fluoroscopy-based navigation	NO	Iso C 3D		Surgical planning is conducted and implemented in the operation room	Femur fracture/femoral head fracture/femoral shaft fractures/intra-articular joint fractures	Warisawa et al. (2004), Mitsuishi et al. (2005), Westphal et al. (2008); Westphal et al. (2009a); Westphal et al. (2009b); Westphal et al. (2009b); Oszwald et al. (2009), Raabe et al. (2012)
CT-based navigation	NO	CT images		Special design of orthopedic pins	Intra-articular lower-limb fracture	Dagnino et al. (2017b), Dagnino et al. (2017c)
	YES	2D fluoroscopic images	2D/3D image-based registration	Conventional	Long bone fracture	Kim et al. (2016)
	YES	2D fluoroscopic images		CT-scan is conducted before inserting the orthopedic pins; a custom-made fiducial marker	Joint fracture	Dagnino et al. (2017b), Dagnino et al. (2017c)
	YES	Locations of fiducial markers	3D/3D feature-based registration	Paired–point matching; fiducial markers	Femur fracture	Lee et al. (2013), Kim and Ko, (2019)
	YES	Locations of fiducial markers		Micron tracker	Diaphyseal fracture	Li et al. (2015b), Li et al. (2016)
	YES	Digitized anatomical points		Match landmarks on the preoperative CT and the spatial coordinates	Pelvic fracture	Wu et al. (2020)
	YES	Iso C 3D	Image fusion-based registration	Non-rigid ICP algorithm; high-precision registration	Pelvic fracture	Zhao et al. (2022b), Ge et al. (2022), Shi et al. (2021)