Considering the rising tendency in the application of lumbar spine devices, a rigorous selection of candidates for lumbar spinal fusion must follow the benefit of the patient in terms of a better outcome than classical techniques or conservatory treatment. We pulled essential information from scientific sources regarding the clinical results of patients who underwent fusion surgery to sift patients who do better from fusion. We found out that imagistic proof of instability such as spondylolisthesis associated with lumbar spinal stenosis and refractory pain takes the most from spinal fusion procedures. Oswestry disability index improvement along with restoring the function and reduction of pain remained the postoperative desires of a successful fusion. Clinical amelioration with bracing test prior to intervention was a predictor of better results after fusion. Exclusion criteria like psychiatric disorders and prior lumbar spine surgery were highlighted since studies demonstrated that they are bad predictors of outcome in spinal fusion surgery. Laminectomy was nowhere implemented in the literature as to be urgently fused since only about 20% of patients manifest instability after this classical procedure. Iatrogenic segmental instability after laminectomy, radiologically proven should be a candidate for spinal fusion. These procedures have high costs and high rates of complications putting the patient’s functional status and quality of life at uncertainty since there is still a lot of debate in this area of spinal neurosurgery.