Table 1

Time of data collection

	Baseline	Operation	Follow-up
Measures	Perioperation	Duration	3 days	1 month	3 months	6 months	12 months	24 months
Screening for inclusion/exclusion criteria	√
Informed consent	√
Assignment to two groups	√
Baseline demographics	√
Operative time		√
Blood loss		√
Complications		√	√	√	√	√	√	√
FR						√	X or √
FJV			√			√	√	√
SLR				√	√	√	√	√
VAS of back pain	√		√	√	√	√	√	√
VAS of leg pain	√		√	√	√	√	√	√
ODI	√		√	√	√	√	√	√
JOA	√		√	√	√	√	√	√
X-ray	√		√	√	√	√	√	√

FJV, adjacent cranial facet joint violation; FR, fusion rate; JOA, Japanese Orthopaedic Association; ODI, Oswestry Disability Index; SLR, screw loosening rate; VAS of back pain: Visual Analogue Scale of back pain; VAS of leg pain, Visual Analogue Scale of leg pain.