Thome 2005.

Methods	Single‐centre RCT Setting: Departments of Neurosurgery, Neurology, and Neuroradiology, University Hospital Mannheim Country: Germany Period: not reported
Participants	Number: 120 patients (40/40/40) Diagnosis: Radiological/neuroimaging evidence of lumbar stenosis Included: symptoms of neurogenic claudication or radiculopathy; radiological/neuroimaging evidence of degenerative lumbar stenosis; absence of associated pathological entities such as disc herniations or instability; no history of surgery for lumbar stenosis or lumbar fusion Excluded: patients who required discectomy Age (years): mean (range) 68 (44‐86) BMI (kg/m²): mean (SD) 28 (4)/29 (6)/29 (4) Lumbar stenosis duration (years): mean (SD) 1.7 (2.5)
Interventions	Group 1: laminectomy Group 2: unilateral laminotomy Group 3: bilateral laminotomy An operating microscope and high‐speed burrs and Kerrison rongeurs were used in all procedures. Special care was taken in all three groups to minimize facet joint resection by using an undercutting technique Follow‐up: 12 months
Outcomes	Pain: 10 cm VAS overall pain Disability: RMDQ Operation time Perioperative blood loss Complications Reoperations
Notes	Surgeon's experience: not reported 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)	Low risk	Quote: "computer‐generated randomization list was used to assign the patient to one of the treatment groups."
Allocation concealment (selection bias)	Unclear risk	Not mentioned.
Blinding of participants (performance bias) All outcomes	Unclear risk	No mention of any attempts to blind the participants.
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	110/120=91.6% of the patients completed the follow‐up. The number of drop‐outs is unlikely to affect the results.
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 the 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 not reported. Financial support was not reported in this study.