Table 6. Effects of pelvic tilt, pelvic incidence and sacral slope on disc composition measured by linear regression with mixed effects controlled by age.

	Nucleus pulposus (NP)					Posterior annulus fibrosus (PAF)					Anterior annulus fibrosus (AAF)
	Effect (β)	P	95% CI			Effect (β)	P	95% CI			Effect (β)	P	95% CI
PT
L1L2	0.09	0.74	−0.45	0.64		−0.46	0.24	−1.23	0.31		0.92	0.08	−0.10	1.94
L2L3	0.76	<0.01*	0.22	1.30		−0.22	0.58	−0.99	0.55		0.57	0.28	−0.45	1.58
L3L4	1.24	<0.01*	0.70	1.78		0.05	0.90	−0.72	0.82		0.51	0.33	−0.51	1.53
L4L5	0.30	0.28	−0.25	0.84		0.02	0.96	−0.75	0.79		0.20	0.70	−0.82	1.22
L5S1	−0.26	0.34	−0.81	0.28		0.49	0.21	−0.28	1.26		−1.25	0.02*	−2.27	−0.23
Mean	0.42	0.07	−0.03	0.88		−0.02	0.94	−0.69	0.64		0.19	0.68	−0.70	1.08
PI
L1L2	0.22	0.21	−0.13	0.57		0.13	0.62	−0.38	0.65		0.58	0.10	−0.10	1.27
L2L3	0.47	<0.01*	0.12	0.82		0.22	0.39	−0.29	0.74		0.48	0.17	−0.21	1.16
L3L4	0.62	<0.01*	0.27	0.97		0.31	0.24	−0.20	0.83		0.48	0.17	−0.20	1.17
L4L5	0.38	0.03*	0.03	0.73		0.34	0.19	−0.17	0.86		0.34	0.33	−0.35	1.03
L5S1	0.21	0.23	−0.14	0.56		0.50	0.06	−0.02	1.01		−0.07	0.84	−0.76	0.62
Mean	0.38	0.03*	0.04	0.72		0.30	0.24	−0.20	0.81		0.36	0.29	−0.31	1.04
SS
L1L2	0.14	0.61	−0.38	0.66		0.74	0.05	0.00	1.47		1.19	0.02*	0.19	2.18
L2L3	0.46	0.08	−0.06	0.98		0.86	0.02	0.13	1.60		1.05	0.04*	0.05	2.04
L3L4	0.66	0.01*	0.14	1.18		0.97	0.01	0.24	1.71		1.06	0.04*	0.07	2.06
L4L5	0.36	0.18	−0.16	0.88		1.02	0.01	0.29	1.76		0.86	0.09	−0.14	1.86
L5S1	0.15	0.56	−0.37	0.67		1.22	0.00	0.49	1.95		0.35	0.49	−0.64	1.35
Mean	0.35	0.18	−0.16	0.86		0.96	0.01	0.24	1.69		0.90	0.07	−0.08	1.89

PT, pelvic tilt; PI, pelvic incidence; SS, sacral slope. *P<0.05.