Table 4.

Fat infiltration percentage of the multifidus and erector spinae before and 24 months after surgery

	OLIF (n = 32)	OLIF+PPSF (n = 41)	P a
Multifidus (%)
Pre-op	15.91 ± 5.30	16.13 ± 7.01	0.885
Post-op 2 years	14.38 ± 3.21	49.38 ± 20.54	< 0.001
P b	0.721	< 0.001
Erector spinae (%)
Pre-op	11.63 ± 3.05	11.93 ± 3.22	0.686
Post-op 2 years	11.22 ± 3.12	22.60 ± 4.99	< 0.001
P b	0.578	< 0.001

OLIF Oblique lateral interbody fusion, PPSF Percutaneous pedicle screw fixation

^a Comparison between two groups

^b Comparison between pre- and post-operation