Table 3.

Implant bending moment and axial force derived experimentally from TFAS (n = 6) and UCR (n = 6) implants and theoretically from FE-TFAS model

Loading mode	Implant side	Implant bending moments (Nm)			Implant axial force (N)
		TFAS	UCR	FE-TFAS	TFAS	UCR	FE-TFAS
Flexion	Left
	Mean	2.40*	0.72	0.21	99.8	72.3	25.1
	SD	1.46	0.25	–	66.1	35.8	–
	Right
	Mean	1.42*	0.45*	0.38	59.2	57.3	50.8
	SD	0.59	0.24	–	40.6	39.8	–
Extension	Left
	Mean	1.32*	2.70*	0.85	−24.1*	−145.0*	11.6
	SD	1.05	0.69	–	−23.4	−71.8	–
	Right
	Mean	0.87*	2.58*	0.79	−38.6	−168.3	3.2
	SD	0.53	0.61	–	−33.78	−61.1	–
Left axial rotation	Left
	Mean	1.48	1.12	0.22	23.9*	−24.8*	−22.5
	SD	0.99	0.81	–	49.0	−55.6	–
	Right
	Mean	0.80	0.90	1.44	47.56*	−42.3*	157.9
	SD	0.51	0.64	–	56.3	−57.7	–
Right axial rotation	Left
	Mean	1.80	1.52	2.04	73.1*	−67.1*	187.4
	SD	1.15	0.51	–	44.4	−36.7	–
	Right
	Mean	0.85	1.13	0.40	−8.9	−37.1	−45.2
	SD	0.59	0.50	–	−37.7	−53.7	–
Left lateral bending	Left
	Mean	1.43*	2.88*	0.50	9.5*	−141.6*	16.8
	SD	1.07	0.94	–	41.8	−66.4	–
	Right
	Mean	1.00	0.72	1.15	42.6	36.7	76.6
	SD	0.45	0.49	–	39.3	56.9	–
Right lateral bending	Left
	Mean	1.87	0.78	1.01	75.3	68.0	82.1
	SD	1.34	0.6	–	68.2	59.2	–
	Right
	Mean	0.67*	2.20*	0.28	−6.3*	−108.7*	−3.2
	SD	0.43	0.48	–	−33.4	−44.3	–

TFAS Total Facet Arthroplasty System, UCR posterior fusion system, FE finite element, SD standard deviation

* Significant difference between TFAS and UCR