Cervical spine reposition errors after cervical flexion and extension

Table 1 Experimental procedures

	Flexion 1	Return of flexion 1	Flexion 2	Return of flexion 2	Setup adjustment	Extension 1	Return of extension 1	Extension 2	Return of extension 2
Time interval	16	4	16	4	280	16	4	16	4
Time line	16	20	36	40	320	336	340	356	360
Fluoroscopy video	X		X			X		X
Reposition Data	0–2		0–2			0–2		0–2
‘Flexion’	→		←
‘Extension’						→		←
‘Setup adaptation’			→			←
‘Complete Session’	→							←

Experiment stages illustrated by rows 1) time interval of the stage, 2) experiment timeline, 3) recording of video (X), 4) the time interval of the stage from where the experiment data was extracted and 5–8) illustration of time periods and experiments stages (→ ←) of the four reposition errors (‘Flexion’, ‘Extension’, ‘Setup adaptation’, ‘Complete Sessions’). ‘Flexion’ and ‘extension’ includes cervical flexion and extension motions with 20 s intervals. ‘Setup adaptation’ includes experimental set up change of 300 s. ‘Complete sessions’ reposition errors between flexion and extension was timed to 340 s. The experimental setup change between flexion and extension motions was timed to approximately 280 s

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