Introduction: In the attempt to improve fusion rates in spondylodesis surgery, focus has been applied on numerous factors, including surgical strategies, instrumentation-devices and –material, technical preparation of the fusion bed, stringency of radiological outcome criteria, patient-related factors such as age, sex, tobacco consumption, and severity of underlying pathology. In recent years the development of new techniques for exploring mechanisms in cellular and molecular biology have further directed focus toward more advanced biological techniques and considerations. To the authors’ knowledge, little or no attention has been focused on one of the basic and important factors in the attempt to achieve fusion, ie the impact of bone graft quantity placed at the fusion bed.

The aim of this study was to investigate the influence of autologous bone graft quantity in posterolateral instrumented spinal fusion (PLF) in respect to fusion rates.

Methods and results: A prospective clinical study in 76 patients, in which CD-instrumented posterolateral lumbar or lumbosacral spine fusion surgery was performed. The quantity of autologous bone graft applied at the fusion bed was recorded peroperatively. Spinal fusion rates were assessed by AP/lateral radiographs at one-year follow-up by two independent observers, according to our strict classification system. The impact of bone graft quantity, tobacco consumption, age and sex of the patients were analysed in respect to fusion-rates by logistic regression.

According to our classification “fusion” was seen in 76% of the patients, “non-union” in 12.7% and “doubtful”fusion in 11.3%. In “fusion” segments, the median amount of bone used was 24.4 (13–53) g and 14.7 (12.5–23.4) g in “non-union” segments. The “non-union” rate was 7.1% for non-smokers in contrast to 21.4% for patients who smoked during the first six post-operative months. The impact on fusion rates by graft quantity and cigarette smoking were significant, p< 0.006 respectively 0.035. Age and gender did not influence fusion rates. Thirty-three percent of patients with “non-union” had a corresponding failure of the implant.

Conclusions: The quantity of graft used at the fusion bed is critical for successful fusion. Based on the results presented here, we recommend a minimum of 24 g of autogenous bone graft at each intervention segment in auto-grafted posterolateral spinal spondylodesis surgery. In addition, this study underlines the importance of tobacco arrest, in at least the first six post-operative months. The data presented here strongly support the importance of quantifying or optimally standardising the amount of graft placed at each intervention segment.

Introduction: Lumbar spine fusion is now an evidence based treatment principle of low back pain. However, much controversy still exists on the choice of surgical technique. Since the source of pain may be located in the intervertebral disc, a disc removal seems logical. Instrumented and non-instrumented fusion as well as PLIF have failed to restore lumbar lordosis.

Aim: The aim of the present study was to study fusion rates, functional outcome, lumbar lordosis and complications in a RCT design using radiolucent cages and titanium instrumentation.

Materials and methods: 148 patients were bloc randomised to either PLF (72) or ALIF + PLF (76) from April 1996 to February 2000. Inclusion criteria were disc degeneration or spondylolisthesis groups 1 and 2; Age> 20 years and < 65 years. Life quality was assessed pre-operatively, one and two years post-operatively by Dallas Pain Questionnaires and by Back and Leg Pain rating scales from 0 to 10.

Results and discussion: A preliminary follow-up at one year post-op of 56 patients in each group showed no difference in admission or blood loss (921/1008 ml) and peroperative morbidity, although the operation time was significantly longer in the ALIF+ group (mean 219/344 minutes). Sagittal lordosis was restored and maintained in the ALIF+ group (p< 0.01), in contrast to the PLF group. There was no difference in functional outcome. Average back pain lasting 14 days scored 4.5 in each group, and leg pain 3.2 in the ALIF+ group versus 4 in the PLF group (NS). The re-operation rate was significantly higher in PLF after both one and two years with 9% refusion versus no refusion in the ALIF+ group. Global patient satisfaction was equal in both groups: 78% versus 76% at one year and at two years 75% versus 80% in PLF and ALIF+ groups.

Conclusion: ALIF+ fusion demands higher operative resources compared to PLF, however ALIF+ restores lordosis and provides the highest union rate and significantly fewer reoperations. A cost/effectiveness analysis after long-term follow-up may also favour the ALIF+ treatment due to improved lordosis and perhaps less degeneration of adjacent motion segments.