Table 2.

L3 lower endplate CSA, fat-free muscle CSA (mean of left and right side), intramuscular fat area (mean of left and right side), and mean normalized fat free muscle CSA of the psoas (PS), lumbar erector spinae (LES) and multifidus (MF) in lumbar discectomy patients with and without pain

	Section		Muscle	Discectomy, no pain	Discectomy with pain
Bony CSA	L3 lower endplate	cm2		15,98 ± 2.70	15.30 ± 2.65
Fat-free muscle CSA	L3 lower endplate	Cm2	PS	21.37 ± 6.65	18.71 ± 5.56
			LES	34.57 ± 8.36	28.62 ± 6.31
			MF	13.25 ± 3.38	10.95 ± 3.44
	L4 lower endplate		PS	±	±
			LES	25.69 ± 7.16	21.79 ± 5.06
			MF	17.22 ± 3.59	14.38 ± 3.97
	L5 lower endplate		PS	±	±
			LES	14.17 ± 6.31	10,78 ± 5.03
			MF	19.49 ± 3.79	15.56 ± 3.32
Normalized fat-free	L3 lower endplate		PS	1.33 ± 0.29	1.21 ± 0.24
muscle CSA			LES	2.21 ± 0.44	1.87 ± 0.34
			MF	0.83 ± 0.17	0.71 ± 0.16
	L4 lower endplate		PS	±	±
			LES	1.64 ± 0.39	1.44 ± 0.32
			MF	1.08 ± 0.18	0.94 ± 0.20
	L5 lower endplate		PS	±	±
			LES	0.90 ± 0.43	0.72 ± 0.30
			MF	1.23 ± 0.21	1.02 ± 0.15
Fat area	L3 lower endplate	cm2	PS	0.73 ± 0.45	0.91 ± 0.53
			LES	3.26 ± 1.28	4.34 ± 2.13
			MF	2.52 ± 1.16	3.52 ± 1.84
	L4 lower endplate		PS	±	±
			LES	1.21 ± 0.80	1.54 ± 0.87
			MF	3.65 ± 1.61	5.08 ± 2.46
	L5 lower endplate		PS	±	±
			LES	3.56 ± 1.43	5.22 ± 3.05
			MF	5.41 ± 1.87	7.19 ± 3.00
Normalized fat CSA	L3 lower endplate		PS	0.05 ± 0.03	0.06 ± 0.03
			LES	0.22 ± 0.09	0.29 ± 0.17
			MF	0.16 ± 0.09	0.24 ± 0.16
	L4 lower endplate		PS	±	±
			LES	0.27 ± 0.18	0.33 ± 0.19
			MF	0.24 ± 0.12	0.35 ± 0.21
	L5 lower endplate		PS	±	±
			LES	0.22 ± 0.09	0.37 ± 0.26
			MF	0.35 ± 0.14	0.49 ± 0.25