Lumbar Muscle Fat Content Has More Correlations with Living Quality than Sagittal Vertical Axis in Elderly Patients with Degenerative Lumbar Disorders

Figures & data

Figure 1 (A) The fascial boundary of lumbar paravertebral muscles (white circle). (B) The boundary of vertebral body (white circle). Muscle–disc ratio was (muscle area)/(disc area): 19.53/16.30=1.20. (C) Bright pixels of fat tissue in the MR images were colored in red (darker color in the black and white version) using pseudocoloring technique (threshold technique). The percentage of the red pixel area in the white circle was calculated (14.21%).

Table 1 Comparisons of Demographic Data Between Group D and Group ND

Characteristics	Group D (n=75)	Group ND (n=104)	P
Mean age (years)	72.2±7.4	69.7±8.1	0.217
Gender (M/F)	30/45	48/56	0.413^†
Body mass index (kg/m^2)	25.7±1.3	26.4±1.5	0.712
Bone mineral density (g/cm^2)	1.012±0.139	1.095±0.115	0.508
Degenerative lumbar disorders
Disc herniation	1 level: 17 2 levels: 20 3 levels: 9 4 levels: 0	1 level: 25 2 levels: 28 3 levels: 13 4 levels: 1	0.736^†
Spondylolisthesis	1 level: 12 2 levels: 0	1 level: 30 2 levels: 2	0.265^†
Scoliosis	18	33	0.635^†
Hyperkyphosis	14	7	0.014^†

Notes: Group D indicates the group including patients with ODI score≥40 points; Group ND, the group including patients with ODI score<40 points. ^†Calculated by Chi-square analysis.

Table 2 Comparisons of Radiographic Assessments Between Group D and Group ND

Characteristics	Group D (n=75)	Group ND (n=104)	P
Spinopelvic parameters
Thoracic kyphosis (°)	29.9±9.3	27.7±8.0	0.612
Thoracolumbar kyphosis (°)	28.0±10.1	14.4±11.2	0.017
Lumbar lordosis (°)	30.6±14.2	42.3±8.8	0.014
Pelvic incidence (°)	46.4±9.1	49.0±9.8	0.206
Pelvic tilt (°)	18.7±8.6	14.3±.7	0.107
Sacral slope (°)	28.5±14.9	34.6±12.9	0.081
Pelvic incidence minus lumbar lordosis (°)	16.3±4.4	7.5±3.6	<0.001
Sagittal vertical axis (mm)	116.3±26.8	86.5±16.5	0.008
T1 pelvic angle (°)	22.3±12.3	17.5±8.8	0.030
Disk degeneration	3.45±1.02	3.61±0.99	0.311
Facet degeneration	2.48±0.55	2.39±0.62	0.441
Paravertebral muscle degeneration
Muscle–disc ratio	1.15±0.32	1.42±0.35	0.022
Percentage of fat infiltrated (%)	40.4±5.0	25.8±4.3	<0.001

Notes: Group D indicates the group including patients with ODI score≥40 points; Group ND, the group including patients with ODI score<40 points.

Table 3 The Correlations Between the Selected Radiologic Parameters and ODI Score in the Whole Cohort

		TLK	LL	PI-LL	SVA	TPA	MDR	FI
ODI score	r	0.133	−0.160	0.195	0.408	0.201	0.191	0.768
	P	0.327	0.212	0.102	<0.001	0.088	0.116	<0.001

Abbreviations: TLK, thoracolumbar kyphosis; LL, lumbar lordosis; PI-LL, pelvic incidence minus LL; SVA, sagittal vertical axis; TPA, T1 pelvic angle; MDR, muscle-disc ratio; FI, percentage of fat infiltrated.

Table 4 Linear Regression Analysis for ODI with Percentage of Fat Infiltrated and SVA

Groups	Variables	R^2	Unstandardized Coefficients	Standardized Coefficients	P
Whole cohort	Percentage of fat infiltrated	0.594	0.770	0.732	<0.001
	Sagittal vertical axis		0.047	0.076	0.164

Figure 2 Scatterplots for the relationships of ODI with percentage of fat infiltrated and SVA. In the whole cohort of patients with degenerative lumbar disorders, ODI was strongly correlated with the percentage of fat infiltrated (A) and SVA (B). The association between SVA and quality-of-life depends on the quality of paravertebral muscle. ODI was moderately correlated with SVA in patients with major fat infiltration (>33%) of lumbar muscle (C), while not correlated with SVA in patients with moderate or minor fat infiltration (≤33%) of lumbar muscle (D).

Figure 3 A 68-year-old male with an SVA of 88.5mm (A) and a mean percentage of lumbar muscle fat infiltration of 16.3% (B). His ODI score was 24%. Another 66-year-old male with an SVA of 75.7 mm (C) and a mean percentage of lumbar muscle fat infiltration of 48.4% (D). His ODI score was 46%.