Fat in the lumbar multifidus muscles - predictive value and change following disc prosthesis surgery and multidisciplinary rehabilitation in patients with chronic low back pain and degenerative disc: 2-year follow-up of a randomized trial

Table 4 Number of levels registered with fat (grade 1 or 2) in the multifidus muscles at pre-treatment in the two analysis- / treatment groups

	Predictor analysis (n = 147)		Analysis of change in fat infiltration (n = 126)
	Rehab (n = 64)	Surgery (n = 83)	Rehab (n = 63)	Surgery (n = 63)
0 levels with fat (n / %)	31 (48.4)	36 (43.4)	30 (47.6)	29 (46.0)
1 level with fat (Grade^a 1 or 2; n / %)	18 (28.1)	24 (28.9)	18 (28.6)	19 (30.2)
2 levels with fat (Grade^a 1 or 2; n / %)	12 (18.8)	18 (21.7)	13 (20.6)	11 (17.5)
3 levels with fat (Grade^a 1 or 2; n / %)	3 (4.7)	5 (6.0)	2 (3.2)	4 (6.3)

^aGrading according to the criteria by Kjaer et al [9] and Solgaard et al [31]: Grade 0: 0 or < 20% of total cross-section (left plus right side) contains fat, Grade 1: 20%–50% of cross-section (left plus right side) contains fat, Grade 2: >50% of cross-section (left plus right side) contains fat

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