Gurelik 2012.

Methods	Single‐centre RCT Setting: Department of Neurosurgery, Van Training and Research Hospital, Van Country: Turkey Period: January 2006 to February 2009
Participants	Number: 52 patients (26/26) Diagnosis: MRI of degenerative lumbar spinal stenosis with symptoms of neurogenic claudication or radiculopathy Included: symptoms of neurogenic claudication or radiculopathy; radiological evidence of degenerative lumbar stenosis; absence of associated pathological entities such as instability and significant disc herniation; absence of previous surgery for lumbar spine disorder; non‐respondents to conservative care Excluded: not reported Age (years): mean (SD) 57.5 (8.5)/60.7 (10.0)
Interventions	Group 1: laminectomy Group 2: unilateral laminotomy. Unilateral laminotomy was performed followed by ipsilateral medial facetectomy and foraminotomy, and the ligamentum flavum were resected partially. For both procedures, the medial aspects of the contralateral facet joints were resected partially. Follow‐up: 6 months
Outcomes	Disability: ODI, walking distance
Notes	Surgeon's experience: "all operations were performed by one author" Funding: Conflict of interest and financial support were not reported in this study.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "patients were randomly assigned to one of the following groups"
Allocation concealment (selection bias)	Unclear risk	Not mentioned.
Blinding of participants (performance bias) All outcomes	High risk	Quote: "patients were made aware of the method" and "told which operative procedure they were going to have"
Bliding of personnel/ care providers (performance bias)	High risk	The surgeon could not have been blinded to the intervention.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No mention of any attempts to blind the assessors.
Incomplete outcome data (attrition bias) All outcomes	Low risk	100% of the patients completed the follow‐up.
Intention‐to‐treat analysis (attrition bias)	Unclear risk	No information about intention‐to‐treat analysis.
Selective reporting (reporting bias)	Low risk	All expected outcomes were reported.
Group similarity at baseline (selection bias)	Low risk	Patients did not differ in their baseline characteristics, based on Table 1.
Co‐interventions (performance bias)	Low risk	Only the surgical technique differed between treatment groups.
Compliance (performance bias)	Low risk	Compliance in both treatment groups: 100% (surgery).
Timing of outcome assessment (detection bias)	Low risk	All important outcome assessments for both groups were measured at the same time.
Other bias	Unclear risk	Conflict of interest and financial support were not reported in this study.