Table 3.

The differences in the CSA and FI % of the paraspinal muscles between LDD and asymptomatic groups in different age strata and gender

		18–39			40–59			≥ 60
		LDD (n = 64)	Asymptomatic (n = 130)	p value	LDD (n = 102)	Asymptomatic (n = 107)	P value	LDD (n = 204)	Asymptomatic (n = 90)	p value
Men	Multifidus CSA (cm2)	21.33 ± 3.55	20.31 ± 2.91	0.126	21.13 ± 3.08	20.22 ± 2.77	0.119	19.64 ± 3.75	18.73 ± 3.34	0.189
	Erector spinae CSA (cm2)	37.23 (33.66 ~ 40.59)	34.06 (29.76 ~ 37.28)	0.051	35.88 ± 7.96	33.77 ± 6.89	0.156	30.11 (25.70 ~ 35.02)	28.59 (25.77 ~ 35.92)	0.760
	Psoas CSA (cm2)	35.55 (32.49 ~ 40.10)	33.39 (30.34 ~ 3940)	0.083	31.57 ± 5.48	30.93 ± 6.04	0.577	25.46 ± 5.62	25.99 ± 5.42	0.618
	Multifidus FI%	19.21 ± 5.40	14.54 ± 3.41	< 0.001*	22.49 ± 7.83	17.42 ± 4.82	< 0.001*	31.74 (27.39 ~ 36.19)	26.68 (23.78 ~ 33.83)	0.008*
	Erector spinae FI%	13.69 (11.57 ~ 16.10)	10.10 (7.57 ~ 12.66)	< 0.001*	16.69 (12.05 ~ 22.75)	12.58 (10.81 ~ 15.88)	< 0.001*	23.09 (18.27 ~ 28.95)	19.96 (16.43 ~ 23.61)	0.009*
Women	Multifidus CSA (cm2)	17.53 ± 3.20	16.78 ± 2.76	0.247	17.05 ± 2.91	16.93 ± 2.92	0.836	15.98 ± 2.76	16.77 ± 2.80	0.098
	Erector spinae CSA (cm2)	24.74 (23.15 ~ 29.87)	23.77 (20.90 ~ 28.04)	0.147	27.00 (22.36 ~ 31.55)	24.60 (22.89 ~ 27.65)	0.097	25.97 ± 5.21	25.43 ± 5.68	0.549
	Psoas CSA (cm2)	20.16 (17.32 ~ 22.85)	19.88 (17.46 ~ 22.79)	0.864	19.98 (16.85 ~ 21.69)	18.35 (16.49 ~ 20.57)	0.239	16.53 (14.04 ~ 18.65)	16.04 (13.81 ~ 19.11)	0.772
	Multifidus FI%	25.35 (23.10 ~ 29.76)	18.07 (16.09 ~ 20.97)	< 0.001*	28.65 ± 6.91	23.28 ± 5.00	< 0.001*	36.66 (32.02 ~ 41.66)	31.59 (29.01 ~ 35.55)	< 0.001*
	Erector spinae FI%	15.80 (12.44 ~ 19.27)	11.80 (9.62 ~ 14.02)	< 0.001*	21.25 (16.94 ~ 26.66)	15.46 (13.27 ~ 19.14)	< 0.001*	28.66 ± 7.16	24.23 ± 5.80	< 0.001*

LDD Lumbar degenerative diseases, CSA Cross sectional area, FI% Fatty infiltration rate

*Statistical significance at the level of 0.05