Paraspinal muscle changes after single-level posterior lumbar fusion: volumetric analyses and literature review

Table 2 Comparative analysis of pre- versus post-operative paraspinal muscle volume on MRI and CT

	MRI (n = 24)		p-value	CT (n = 16)		p-value
	pre	post	p-value	pre	post	p-value
MF (cm³ ± SD)
Right	33.08 ± 3.89	19.66 ± 1.69	0.003^a	34.25 ± 3.65	27.63 ± 3.65	0.005^a
Left	33.83 ± 3.45	20.11 ± 2.08	< 0.001^a	34.67 ± 3.53	26.71 ± 3.28	< 0.001^a
ES (cm³ ± SD)
Right	90.83 ± 6.79	82.90 ± 6.96	0.121	71.47 ± 9.05	49.54 ± 6.88	< 0.001^a
Left	85.24 ± 6.45	78.76 ± 6.19	0.244	66.15 ± 9.70	53.75 ± 8.60	0.019
Psoas (cm³ ± SD)
Right	59.96 ± NA	59.82 ± NA	0.511^b	68.25 ± NA	72.77 ± NA	0.352^b
Left	63.59 ± 5.24	64.41 ± 5.93	0.768	63.79 ± 7.08	67.60 ± 7.44	0.142
Height of vertebrae	5.73 ± 0.48	5.81 ± 0.38	0.177	5.58 ± 0.39	5.63 ± 0.37	0.181

MRI magnetic resonance imaging, CT computed tomography, SD, standard deviation, MF multifidus, ES erector spinae, NA not applicable
^a Statistically significant difference was defined as p < 0.00714 (0.05/7) by Bonferroni correction
^b Wilcoxon signed ranks test was used because the data was not normally distributed

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