Indication for Spinal Fusion and the Risk of Adjacent Segment Pathology: Does Reason for Fusion Affect Risk? A Systematic Review
ABSTRACT STUDY DESIGN.: A systematic review. OBJECTIVE.: To determine whether different indications or reasons for spinal fusion are associated with different risks of subsequent adjacent segment pathology (ASP) in the lumbar and cervical spine. SUMMARY OF BACKGROUND DATA.: Pre-existing degeneration at levels adjacent to an arthrodesis may play a role in the development of symptomatic adjacent segment pathology. Although most spinal arthrodeses occur in patients with degenerative spinal disease, spinal fusion occurs in the pediatric and trauma population, and also congenitally. Evaluating the risk of ASP in these populations may shed light on its etiology. METHODS.: A systematic search was conducted in PubMed and the Cochrane Library for articles published between January 1, 1990, and December 31, 2011. We included all articles that described the risk of radiographical adjacent segment pathology (RASP) following surgical fusion for degenerative disease, for trauma, or for conditions requiring fusion in pediatrics in the lumbar or cervical spine. In addition, we included studies recording ASP in patients with congenital fusion. RESULTS.: Nineteen studies met our inclusion criteria. In patients who underwent fusion in the lumbar spine for degenerative reasons, the RASP rate averaged 12.4% during an average of 5.6-year follow-up. For patients who underwent fusion in the cervical spine for degenerative reasons, the average RASP rate was 25.3% during a 2.3-year follow-up. For patients with Klippel-Feil syndrome and congenital fusion, the RASP rate averaged 49.7% during an average of 23.5-years of follow-up. In patients who were fused for scoliosis, the average RASP rate was 20.3% of 3.9-year follow-up. However there is significant variation between studies in patient population, follow-up, and definition of RASP. CONCLUSION.: In the cervical spine, the rate of RASP in patients with fusion for degenerative reasons indications is greater than the rate of RASP in patients with congenital fusion suggesting that the pre-existing health and status of the adjacent level at the time of fusion may play a contributory role in the development of ASP. There is insufficient evidence in the literature to determine whether the indication/reason for fusion affects the risk of RASP in the lumbar spine CONSENSUS STATEMENT: In the cervical spine, the rate of RASP in patients with fusion for degenerative reasons indications is greater than the rate of RASP in patients with congenital fusion suggesting that the pre-existing health and status of the adjacent level at the time of fusion may play a contributory role in the development of ASP.Strength of Statement: Weak.
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ABSTRACT: The aim of this study was to analyse the clinical and radiological outcomes of unilateral versus bilateral instrumented TLIF in two-level degenerative lumbar disorders. A prospective randomised clinical study was performed from January 2008 to May 2011. Sixty-eight consecutive patients with severe low back pain and radicular pain were divided randomly into the unilateral (n = 33) or bilateral (n = 35) pedicle screw fixation group based on a random number list. Operative time, blood loss, duration of hospital stay, fusion rate, complication rate and implant costs were recorded and analysed statistically. Visual analog scale (VAS) scores, Oswestry Disability Index (ODI), and SF-36 were used to assess the preoperative and postoperative clinical results in the two groups. No differences were observed between the two groups with respect to demographic data. The patients of the two groups had significant improvement in functional outcome compared to preoperatively. There was no significant difference comparing fusion rate, complication rate and duration of hospital stay between the two groups at postoperative follow-up (P > 0.05). However, compared with the bilateral pedicle screw group, a significant decrease occurred in operative time, blood loss and implant costs in the unilateral group. Two-level unilateral instrumented TLIF is an effective and safe method with reduced operative time and blood loss for multiple-level lumbar diseases. But it is imperative that the larger cage should be appropriately positioned to support the contralateral part of the anterior column by crossing the midline of the vertebral body.International Orthopaedics 08/2013; 38(1). DOI:10.1007/s00264-013-2026-y · 2.02 Impact Factor
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ABSTRACT: Experimental study. To compare the effects of fusionless instrumentation (FI) and instrumented fusion (IF) on the adjacent segment in an immature pig model. Observations reveal proximal junctional kyphosis after FI. Possible reasons are stress concentration, repeated distractive forces, and/or soft tissue damage done in the index surgery. It was speculated that FI can decrease stressors to the junctional area by preserving the spinal mobility in some manner; however, this has not been proven to date. Thirteen piglets of 10- to 14-week age were used. FI and IF were performed on 7 and 3 piglets, respectively, and 3 piglets formed the control group. Control piglets did not undergo any surgical procedures. T11-L4 instrumentation, decortication, and grafting were applied to IF piglets. In FI groups, however, L1-L2 was left uninstrumented and unfused using T11-T12 and L3-L4 levels as anchors to the growing construct. A total of 4 lengthening procedures were performed: 1 in the index operation and 3 more, once in each lengthening procedure monthly, for 3 months. Four months after the index operations, all piglets were killed and the adjacent segment motion capabilities, disc, and facets were evaluated with radiographical, magnetic resonance imaging, biomechanical, and histological analyses. Comparison of proximal junctional Cobb angles of the postindex (mean: 21, range: 17-27) and presacrification (mean: 21, range: 11-31) radiographs in the FI group revealed no difference (P> 0.05). In magnetic resonance imaging, both surgical group proximal adjacent discs showed degeneration to some degree that was statistically indifferent (P = 0.903). Biomechanical evaluation revealed restriction of adjacent segment motion in all directions for both groups; however, this negative effect was significantly less in FI group (P < 0.01). Degeneration observed in histological evaluation in adjacent discs and facets of FI group was significantly lower (P = 0.00). In this quadruped straight spine model, in comparison with IF applications, FI is closer to normal physiology even after several lengthening procedures regarding the adjacent segment discs, facet joints, and motion, when interpreting the radiological, biomechanical, and histological results altogether.Spine 12/2013; 38(25):2156-2164. DOI:10.1097/BRS.0000000000000026 · 2.45 Impact Factor
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ABSTRACT: Object The aim of this study was to study the long-term outcomes of patients undergoing instrumented posterior fusion of the lumbar spine. Methods The authors present 511 patients who underwent instrumented arthrodesis for lumbar degenerative disease over a 23-year period at a single institution. Patients underwent follow-up for an average of 39.73 ± 46.52 months (± SD) after the index lumbar arthrodesis procedure. Results The average patient age was 59.45 ± 13.48 years. Of the 511 patients, 502 (98.24%) presented with back pain, 379 (74.17%) with radiculopathy, 76 (14.87%) with motor weakness, and 32 (6.26%) with preoperative bowel/bladder dysfunction. An average of 2.04 ± 1.03 spinal levels were fused. Postoperatively, patients experienced a significant improvement in back pain (p < 0.0001) and radiculopathy (p < 0.0001). Patients with fusions excluding the sacrum (floating fusions) were statistically more likely to develop adjacent-segment disease (ASD) than those with fusion constructs ending at S-1 distally (p = 0.030) but were less likely to develop postoperative radiculopathy (p = 0.030). In the floating fusion cohort, 31 (12.11%) of 256 patients had cephalad ASD, whereas 39 (15.29%) of 255 patients in the lumbosacral cohort had cephalad ASD development; this was not statistically different (p = 0.295). This suggests that caudad ASD development in the floating fusion cohort is due to the added risk of an unfused L5-S1 vertebral level. Because of the elevated risk of symptomatic radiculopathy but lower risk of ASD, patients in the lumbosacral fusion cohort had a reoperation rate similar to those undergoing floating fusions (p = 0.769). Conclusions In this paper, the authors present one of the largest cohorts in the Western literature of patients undergoing instrumented fusion for degenerative lumbar spine disease. Patients who had floating lumbar fusions were statistically more likely to develop ASD over time than those who had lumbosacral fusions incorporating the S-1 spinal segment, but were less likely to experience postoperative radicular symptoms. Additional prospective studies may more clearly delineate the long-term risks of instrumented posterolateral fusions of the lumbar spine.Journal of neurosurgery. Spine 01/2014; 20(4). DOI:10.3171/2013.12.SPINE13789 · 2.36 Impact Factor