Table 1.

Summary of the Trials Included

The numbers (1, 2, 3) indicate the corresponding groups in each study. Group 1 data in the Fritzell⁵⁾ and Hallett⁶⁾ studies were not included in the present analysis. CLBP: chronic low back pain, MRI: magnetic resonance imaging, FBS: failed back surgery, SS: spinal stenosis, SL: spondylolisthesis, NS: not specified, ALIF: anterior lumbar interbody fusion, PLF: posterolateral fusion, PLIF: posterior lumbar interbody fusion, TLIF: transforaminal interbody fusion, TSRH: Texas Scottish Rite Hospital, VSP: variable screw placement, CDI: Cotrel-Dubousset instrumentation, FRA: femoral ring allograft, ICBG: iliac crest bone graft, RR: relative risk.