Existing studies on micro-endoscopic lumbar discectomy report similar outcomes to those of open and microdiscectomy and conflicting results on complications. We designed a randomised controlled trial to investigate the hypothesis of different outcomes and complications obtainable with the three techniques. 240 patients aged 18-65 years affected by posterior lumbar disc herniation and symptoms lasting over 6 weeks of conservative management were randomised to micro-endoscopic (group 1), micro (group 2) or open (group 3) discectomy. Exclusion criteria were less than 6 weeks of pain duration, cauda equina compromise, foraminal or extra-foraminal herniations, spinal stenosis, malignancy, previous spinal surgery, spinal deformity, concurrent infection and rheumatic disease. Surgery and follow-up were made at a single Institution. A biomedical researcher independently collected and reviewed the data. ODI, back and leg VAS and SF-36 were the outcome measures used preoperatively, postoperatively and at 6-, 12-and 24-month follow-up. 212/240 (91%) patients completed the 24-month follow-up period. VAS back and leg, ODI and SF36 scores showed clinically and statistically significant improvements within groups without significant difference among groups throughout follow-up. Dural tears, root injuries and recurrent herniations were significantly more common in group 1. Wound infections were similar in group 2 and 3, but did not affect patients in group 1. Overall costs were significantly higher in group 1 and lower in group 3. In conclusion, outcome measures are equivalent 2 years following lumbar discectomy with micro-endoscopy, microscopy or open technique, but severe complications are more likely and costs higher with micro-endoscopy.

Direct repair of spondylolisthesis can save a functional segment in young patients with slight slipping. Since 1968 many surgeons have proposed different technical solutions to obtain the isthmic repair. Their results changed according to the technique used, the extent of listhesis and the age of the patient. The aim of our study was to perform a retrospective review on the long-term results of the direct repair of spondylolisthesis, according to the different techniques used. We operated 62 patients for isthmic repair, with three different techniques, from 1994 to 2007. We analysed the clinical and radiographic results of 52 cases, with an average follow-up of 9 ± 3 years (range 2-15). Ten patients were lost to the follow-up. The results were different depending on the technique used. Good or excellent clinical outcome by Odom's criteria were observed in the 83.3% of patients operated with the modified Scott technique. These results are better than those obtained in the group of patients operated with the Scott (62.5%) and the Buck technique (28.5%). Patients with clinical and radiological failure, who then underwent spinal fusion, were 57% with the Buck technique, 12.5% with the Scott technique and 2.7% with the Scott modified technique. The reasons for a new operation were symptomatic pseudarthrosis and progression of slipping. In conclusion, the pars defect repair is a helpful technique in lumbar spondylolisthesis, especially in young patient with slight slipping and painful symptoms resistant to conservative treatment. In our experience, the modified Scott technique seems to provide a better outcome than the Scott and Buck techniques.

Grob et al. (Eur Spine J 5:281-285, 1996) illustrated a new fixation technique in inveterate cases of grade 2-3 spondylolisthesis (degenerative or spondylolytic): a fusion without reduction of the spondylolisthesis. Fixation of the segment was achieved by two cancellous bone screws inserted bilaterally through the pedicles of the lower vertebra into the body of the upper slipped vertebra. Since 1998 we have been using this technique according to the authors' indications: symptomatic spondylolisthesis with at least 25% anterior slippage and advanced disc degeneration. Afterwards this technique was used also in spondylolisthesis with low reduction of the disc height and slippage less than 25%. In every case we performed postero-lateral fusion and fixation with two AO 6.5 Ø thread 16 mm cancellous screws. From 1998 to 2002 we performed 62 fusions for spondylolisthesis with this technique: 28 males (45.16%) and 34 females (54.84%), mean age 45 years (14-72 years). The slipped vertebra was L5 in 57 cases (92%), L4 in 2 cases (3.2%), L3 in 1 case (1.6%), combined L4 and L5 in 2 cases (3.2%). In all cases there was an ontogenetic spondylolisthesis with lysis. Lumbar pain was present in 22 patients and lumbar-radicular pain was present in 40 patients. The mean preoperative VAS was 6.2 (range 5-8) for lumbar pain, and 5.5 (range 4-7) for leg pain. The fusion area was L5-S1 in 53 cases (85.5%), L3-L4 in 1 case (1.6%), L4-S1 in 8 cases (12.9%). A decompression of the spinal canal by laminectomy was performed in 33 procedures (53%). When possible a bone graft was done from the removed neural arc, and from the posterior iliac crest in the other cases. The mean blood loss was about 254 ml (100-1,000). The mean operative time was 75 min (range 60-90). The results obtained by computerized analysis at follow-up at least 5 years after surgery showed a significant improvement in preoperative symptoms. The patients were asymptomatic in 52 cases (83.9%); strained-back pain was present in 8 cases (12.9%), and there was persistent lumbar-radicular pain in 2 cases (3.2%). The mean ODI score was 2.6%, the mean VAS back pain was 1.3, the mean VAS leg pain 0.7. Some complications were observed: a nerve root compression by a screw invasion of intervertebral foramen, resolved by screw removal; an iliac artery compression by a lateral exit screw from pediculo, resolved by screw removal; a deep iliac vein phlebitis with thrombosis caused by external compression due to a wrong intraoperative position, treated by medicine. Two cases of synthesis mobilization and two cases of broken screws was detected. No cases of pseudoarthrosis and immediate or late superficial or deep infection were observed. The analysis of the long-term results of the spondylolisthesis surgical treatment with direct pediculo-body screw fixation and postero-lateral fusion gave a very satisfactory response. The technique is reliable in allowing an optimal primary stability, creating the best biomechanical conditions to obtain a solid fusion.

Minimally invasive lateral lumbar interbody fusion is an effective technique in improving sagittal parameters. When combined with posterior open approach and/or application of ACR procedure greater corrections are possible.

As shown by the obtained clinical and radiographic results, the anterior interbody fusion with stand-alone peek cage containing β-tricalcium phosphate could be considered an effective and reliable procedure.