Table 2. Navigation registration guidelines.

Operative region	Optimal imaging modality	Intra-op imaging				Pre-Op CT-based				Novel
		CT	Newer 3D Fluro	Older 3D Fluro		CT-Intra-op 3D Merge	Machine Vision	Region Matching		SpineMask + 3D or CT
Manufacturer		Airo BodyTom	Ziehm RFD Siemens CIOS O-arm I/II	Siemens Orbic Ziehm		Stryker, Stealth, BrainLab	7D Surgical	BrainLab		Stryker
Posterior cervical fusion (open)
C1–C2	Intra-op CT	+++	++	+		++	+++	+++		–
Lateral mass	3D Fluro	++	+++	+		+	++	+		–
Cervicothoracic	Intra-op CT	+++	+	+		+	+++	++		–
Thoraco-lumbar fusion (open)
Thoracic stabilisation	3D Fluro	++	+++	+		+	+++	+		–
Thoraco-lumbar fusion	3D Fluro	++	+++	+		+	+++	+		–
1 level lumbar fusion	3D Fluro	+	+++	++		+	+++	+++		–
≤3 level lumbar fusion	3D Fluro	++	+++	+		+	+++	++		–
Lumbar fusion (high BMI)	Intra-op CT	+++	+	+		+++	+++	++		–
Lumbo-sacral fusion	Intra-op CT	+++	+++	++		+++	+++	++		–
Pelvic fixation	Intra-op CT	+++	+	+		+++	+++	++		–
Thoraco-lumbar fusion (percutaneous)
Thoracic stabilisation	3D Fluro	++	+++	+		+	–	–		+++
Thoraco-lumbar fusion	3D Fluro	++	+++	+		++	–	–		+++
1 level lumbar fusion	3D Fluro	+	+++	++		+	–	–		+++
≤3 level lumbar fusion	3D Fluro	++	+++	++		+	–	–		+++
Lumbar fusion (high BMI)	Intra-op CT	+++	+	+		+++	–	–		+++
Lumbo-sacral fusion	Intra-op CT	+++	++	+		++	–	–		++
Fusion + pelvic fixation	Intra-op CT	+++	+	+		+++	–	–		–
Other
>4 level thoraco-lumbar	Intra-op CT	+++	++	+		++	+++	+		–
Revision with existing hardware	Intra-op CT	++	++	+		+++	++	++		–
Complex deformity	Intra-op CT	+++	+	–		++	+++	++		–

Level of recommendation: + = low; ++ = medium; +++ = strong.