Hallett 2007.

Methods	Single‐centre RCT Setting: Spinal Unit, Royal Infirmary of Edinburgh, Edinburgh Country: Scotland, UK Period: January 1998 to August 2001
Participants	Number: 44 patients (14/15/15) Diagnosis: plain radiographs and magnetic resonance images Included: foraminal stenosis; single‐level degenerative disc disease; uni or bilateral leg pain, with or without positive root tension sign, muscle weakness and/or sensory loss; minimum 3 months of conservative care Excluded: spondylolisthesis Grade II or greater; vertebral translocation > 1 cm (instability); disc space narrowing of greater than 50%; serious disease Age (years): mean (range) 57 (34–75)
Interventions	Group 1: decompression (single or bilateral foraminotomy) Group 2: decompression plus instrumented pedicular postero‐lateral fusion Group 3: decompression plus fusion with pedicular screw instrumentation with titanium interbody cages filled with autologous bone. Minimal microdiscectomy was performed if necessary Follow‐up: 60 months
Outcomes	Pain: 10 cm VAS from the Low Back Outcome Score Disability: RMDQ Costs Operation time Perioperative blood loss Reoperations
Notes	Surgeon's experience: All surgery was performed by the same surgeon in a laminar ventilated theatre. Funding: "supported by a grant from DePuy Ltd., U.K. Corporate/Industry funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "type of treatment was randomly allocated immediately before surgery."
Allocation concealment (selection bias)	Low risk	Quote: "shuffled, closed, opaque envelopes, that were numbered 1 to 150 and opened in sequence."
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	High risk	Quote: "the 3 observers were not blinded and any dispute was resolved by discussion."
Incomplete outcome data (attrition bias) All outcomes	Low risk	93.1% of the patients completed the follow‐up. The number of drop‐outs is unlikely to affect the results.
Intention‐to‐treat analysis (attrition bias)	Low risk	Quote: "analysis of the results was by intention to treat."
Selective reporting (reporting bias)	Low risk	All expected outcomes were reported.
Group similarity at baseline (selection bias)	Unclear risk	No information about patient characteristics at baseline.
Co‐interventions (performance bias)	Low risk	Only the surgical technique differed between treatment groups. Similar percentage of concomitant discectomy.
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	Quote: "supported by a grant from DePuy Ltd., U.K. Corporate/ Industry funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript."