Table 1.

Characteristics of included studies

Author (years)	Country	Study type	Number of samples	Gender (male)	Average age	Follow-up (months)	Technique of fusion	Outcomes
			CS/PS	CS/PS	CS/PS	CS/PS	CS/PS
Hoffman et al. (2019) [15]	USA	Cohort	23/35	16/16	48.5/53.4	52.5/52.5	MIDLF/TLIF	1, 2, 3, 4, 5, 6, 8, 9
Marengo et al. (2018) [16]	Italy	Cohort	20/20	12/9	45.75/54	12/12	PLIF/PLIF	1, 2, 3, 4, 6, 8, 9, 10
Lee and Ahn (2017) [17]	Korea	RCT	35/37	31/33	51.2/51.7	24/24	PLIF/PLIF	4, 5, 6, 9, 10
Takenaka et al. (2017) [18]	Japan	Cohort	42/77	18/31	65.8/66.0	17/35.4	PLIF/PLIF	1, 2, 4, 5, 8, 9, 10
Sakaura et al. (2017) [19]	Japan	Cohort	22/20	4/6	70.7/68.3	39/35	PLIF/PLIF	1, 2, 7, 8, 9, 10
Peng et al. (2017) [20]	China	Cohort	51/46	23/21	62.8/61.9	12/12	PLIF/PLIF	1, 2, 3, 6, 8, 9, 10
Sakaura et al. (2016) [21]	Japan	Cohort	95/82	46/36	68.7/67.0	39/35	PLIF/PLIF	1, 2, 7, 8, 9, 10
Orita et al. (2016) [22]	Japan	Cohort	20/20	11/12	63.5/63.7	12/12	TLIF/TLIF	1, 2
Hung et al. (2016) [14]	China	Cohort	16/16	6/5	60.37/63.12	18/18	PLIF/PLIF	1, 2, 3, 4, 5, 6, 7
Ninomiya et al. (2016) [23]	Japan	Cohort	11/10	7/5	62.2/61.4	12/12	PLIF/PLIF	9
Chin et al. (2016) [24]	USA	Cohort	30/30	18/15	48/62	24/24	NM/NM	1, 2, 4, 5, 6
Lee et al. (2015) [13]	Korea	RCT	38/39	33/34	51.3/51.9	12/12	PLIF/PLIF	1, 2, 3, 4, 5, 6, 9, 10

Outcomes: 1. Blood loss, 2. Operating time, 3. Length of stay, 4. Visual analog score (back pain), 5. Visual analog score(leg pain), 6. Oswestry Disability Index, 7. Japanese Orthopaedic Association, 8. Intraoperative complications, 9. Postoperative complications, 10. Fusion rate. CS: cortical screw PS: pedicle screw RCT: Randomized controlled trial MIDLF: midline lumbar fusion TLIF: transforaminal lumbar interbody fusion PLIF: posterior lumbar interbody fusion NM: not mentioned