Table 1.

Means (standard deviations) of range-of-motion (ROM), neutral zone (NZ), and elastic zone (EZ) of upper (T1/T4), middle (T4/T8), and lower (T8/T12) thoracic segments for all modes of bending for intact rib cage and no rib cage conditions of human thoracic spines with 400 N follower loads under ±5 N·m dynamic moments (*p<0.05, †p<0.1).

		Lateral Bending			Flexion/Extension			Axial Rotation			Flexion	Extension
Segment	Condition	ROM(°)	NZ(°)	EZ(°)	ROM(°)	NZ(°)	EZ(°)	ROM(°)	NZ(°)	EZ(°)	ROM(°)	ROM(°)
Upper (T1/T4)	Intact Ribs	1.43	0.34	0.57	9.07	2.01	3.40	6.69	0.94	2.76	6.13	2.67
		(1.21)	(0.23)	(0.49)	(5.35)	(1.49)	(1.75)	(3.42)	(0.69)	(1.60)	(3.52)	(1.32)
	No Ribs	2.58*	0.44	1.07†	10.37†	1.71	4.38†	12.98*	1.56*	5.66*	6.95	3.42*
		(1.39)	(0.38)	(0.62)	(6.25)	(0.76)	(2.80)	(5.46)	(0.72)	(2.50)	(4.76)	(1.54)
Middle (T4/T8)	Intact Ribs	0.71	0.59	0.22	4.64	1.13	1.70	7.72	0.95	3.48	2.90	1.63
		(0.53)	(0.21)	(0.13)	(3.50)	(1.18)	(1.20)	(5.05)	(1.03)	(1.98)	(2.28)	(1.17)
	No Ribs	1.71†	0.83	0.44	9.47*	1.78*	3.83*	14.99*	1.30*	6.76*	6.15*	3.32*
		(1.64)	(0.69)	(0.60)	(6.01)	(0.75)	(2.67)	(3.26)	(0.63)	(1.63)	(4.15)	(1.93)
Lower (T8/T12)	Intact Ribs	5.14	3.84	0.65	7.33	3.09	2.05	12.16	1.73	5.45	4.40	2.79
		(2.95)	(2.27)	(0.42)	(4.49)	(2.34)	(1.07)	(3.79)	(1.38)	(1.48)	(3.12)	(1.32)
	No Ribs	7.50	5.56	0.97	14.46*	4.26†	4.90*	14.22†	1.51	6.44*	7.24*	7.22*
		(3.27)	(2.87)	(0.29)	(7.29)	(3.58)	(1.96)	(4.53)	(0.68)	(2.18)	(3.89)	(3.45)