Noninstrumented Posterolateral Lumbar Fusion Research Articles

Fusion and Healing Prediction in Posterolateral Spinal Fusion Using 18F-Sodium Fluoride-PET/CT

This study measures the total graft of 18F-sodium fluoride (NaF) uptake in non-instrumented posterolateral lumbar fusion (niPLF) patients one month after surgery and correlates it with the difference in the clinical findings between the baseline and one year after surgery. The walking distance (WLK-D), visual analog scale of back pain (VAS-B), VAS score of leg pain (VAS-L), tandem test (TAN), Oswestry Disability Index questionnaire (ODI), and European Quality of Life-5 Dimensions questionnaire (EQ-5D) were assessed before surgery and one year after. The graft NaF uptake was analyzed quantitatively with a fixed threshold algorithm resulting in the total graft uptake (SUVtotal) and partial volume corrected SUVtotal (cSUVtotal). Only 4 out of 18 patients experienced fusion; they had an insignificantly lower median total graft uptakes, i.e., 1178 SUVtotal vs. 1224 SUVtotal (p = 0.73) and 1282 cSUVtotal vs. 1231 cSUVtotal (p = 0.35), respectively. Similarly, fused patients experienced insignificantly larger pain decreases, i.e., median VAS-B 4.3 vs. 3.8 (p = 0.92) and VAS-L −6.4 vs. −4.4 (p = 0.2). We found an insignificant trend for a lower NaF uptake and less pain in fused patients. The NaF uptake did not correlate with the chronological change in the clinical parameters.

Noninstrumented Lumbar Fusion with Bone Morphogenetic Proteins for Spinal Stenosis with Spondylolisthesis in the Elderly

This study examined the use of noninstrumented posterolateral lumbar fusion with bone morphogenetic protein (BMP) and compared its effectiveness with that of instrumented fusion for the treatment of lumbar spinal stenosis (LSS) with spondylolisthesis in elderly patients. This study was a retrospective review of 93 patients treated in a single-surgeon neurosurgical private practice over a 15-year period. Fifty-nine patients over the age of 65 who underwent noninstrumented posterolateral fusion with rhBMP-2 (Infuse) for LSS with spondylolisthesis were compared with 34 patients who underwent instrumented fusion without rhBMP-2. Outcomes in terms of reoperation rate, pain improvement, Oswestry Disability Index (ODI) score, and number of extra follow-up visits due to persistent problems were characterized by the use of t tests and χ2 tests. The reoperation rate in the noninstrumented rhBMP-2 fusion group was significantly lower than in the instrumented fusion group (17.6% vs. 3.4%, P= 0.048). The mean pain improvement was significantly higher in the noninstrumented rhBMP-2 group at 3 months (8.1 vs. 6.0, P < 0.001, 95% confidence interval [CI] 1.2 to 3.0) and at 1 year (7.25 vs. 5.6, P= 0.030, 95% CI 0.3 to 3.1). The ODI score improvement was significantly higher in the noninstrumented rhBMP-2 group (51 vs. 42.8, P < 0.001, 95% CI 4.7 to 11.6). The mean number of additional follow-up visits per patient was significantly lower in the noninstrumented rhBMP-2 group (0.068 vs. 1.23, P < 0.001, 95% CI 0.59 to 1.75). Noninstrumented posterolateral lumbar fusion with rhBMP-2 in elderly patients with LSS and spondylolisthesis is a viable alternative to instrumented fusion based on clinical outcomes measured in this study.

Outcomes of Instrumented and Noninstrumented Posterolateral Lumbar Fusion.

The purpose of this study was to evaluate the long-term clinical and radiographic outcomes of posterolateral lumbar fusion for lumbar stenosis cases requiring bilateral facetectomy in conjunction with a laminectomy. The authors evaluated 34 consecutive patients who had undergone a lumbar laminectomy, bilateral partial facetectomy, and posterolateral fusion at a single institution between 1981 and 1996. They included 25 men and 9 women with a mean age of 42 years (range, 27-57 years). Twenty-three cases were instrumented and 11 were noninstrumented. Mean follow-up was 21 years (range, 15-29 years). Outcomes evaluated included reoperation rate, clinical outcomes evaluated by the Oswestry Disability Index (ODI) score, radiographic evaluations of adjacent segmental degeneration (ASD) and lumbar lordosis, and contributing demographic factors to disease progression. At final follow-up, 17 of the 34 patients had undergone reoperation (43% of the instrumented group and 64% of the noninstrumented group). There were no differences in the reoperation rate or ODI improvement between the instrumented and noninstrumented groups (P>.05). Female patients required more revisions, had less ODI improvement, had greater postoperative ASD, and had less maintenance of their postoperative lumbar lordosis. There was no difference in maintenance of postoperative lumbar lordosis or ASD between the instrumented and noninstrumented groups. Instrumentation did not improve revision rates, clinical outcomes, or radiographic outcomes in laminectomies requiring contemporaneous facetectomies.

Biomechanical evaluation and comparison of polyetheretherketone rod system to traditional titanium rod fixation on adjacent levels

PurposeAdjacent segment degeneration or fracture of the vertebral body was commonly reported in rigid fusion. Use of semirigid instruments such as PEEK rod system could be an alternative treatment. However, the biomechanical implications of using PEEK rod systems are not well understood. Purpose of this study was to compare a PEEK rod fixation system to traditional titanium rod fixation via a finite element analysis. MethodsA lumbar spine model from L2–L5 vertebral bodies was constructed. A fusion model, created by modifying the intact lumbar model, was used to simulate anterior interbody and posterolateral lumbar fusion. Loading was applied through flexion, extension, lateral bending, torsion. ResultsThe greatest increase in stress was estimated at the upper disc adjacent to the titanium rod with interbody fusion. The lower increase in stress on adjacent segments occurred with PEEK rod fixation without fusion and noninstrumented posterolateral lumbar fusion models. With the same fusion or nonfusion procedures, the stress on discs and facet joints of adjacent segments in the PEEK rod group decreased by 5–25% of that in the titanium rod group for all loading conditions. ConclusionIn comparison with rigid fixation, some potential advantages of using PEEK rod systems include a reduced stress on adjacent segment disc and facet joint, and the elastic ability of PEEK rod fixation allows for a greater range of motion, which may reduce the incidence of clinical complications seen with rigid fusion devices.

The Efficacies of 2 Ceramic Bone Graft Extenders for Promoting Spinal Fusion in a Rabbit Bone Paucity Model

Prospective, randomized, controlled animal study. To determine the efficacies of 2 ceramic composite bone graft extenders for promoting spinal fusion. Although autogenous bone is still considered the "gold standard" graft material for fusion procedures, its use is associated with a number of limitations. Synthetic ceramic composites represent a class of osteoconductive materials that may be employed as supplements or even alternatives to autograft. In this study, we compared the fusion rates generated by 2 ceramic composite bone graft extenders (MasterGraft and Mozaik Strips) with that obtained with autograft in a rabbit bone paucity model. Thirty-two New Zealand white rabbits undergoing noninstrumented posterolateral lumbar fusion were randomized to 1 of the following 4 groups: 100% autograft, 50% autograft, 50% autograft with Mozaik Strip, and 50% autograft with MasterGraft Strip. The rabbits were followed postoperatively for 8 weeks at which time the spinal segments were explanted and assessed for the presence of a solid fusion. The arthrodesis rates by manual palpation of the 100% and 50% autograft controls were 75% (6 of 8 animals) and 12.5% (1 of 8), respectively (P < 0.01). In the 50% autograft/Mozaik and 50% autograft/MasterGraft groups, 3/8 and 1/8 of the rabbits were determined to have fused successfully, respectively (P = 0.569). However, there were no significant differences between the fusion rate of the 50% autograft cohort and those exhibited by the Mozaik or MasterGraft animals (P = 0.569 and 1.00, respectively). This study provides further evidence that the quantity of autograft may influence the process of spinal fusion such that the arthrodesis rate was significantly lower when less bone was implanted. Neither of the ceramic composite scaffolds seemed to enhance the fusion response compared to an equivalent amount of autograft alone, suggesting that these substances may need to be combined with other osteogenic materials to optimize bone production.

Lumbar Fusion With and Without Pedicle Screw Fixation

In Brief Study Design. In this Journal Club review, the study design, conduct, and analysis of Zdeblick's prospective, randomized trial comparing instrumented and noninstrumented posterolateral lumbar fusion, “A Prospective, Randomized Study of Lumbar Fusion: Preliminary Results,” are examined. Objective. The objective of this paper is to review one of the most frequently cited papers published in Spine, to evaluate and discuss its methods and conclusions, and to understand its significance in light of subsequent research. Summary of Background Data. At the time of publication (1993), there were no published studies comparing the fusion rates and clinical outcomes of noninstrumented and instrumented posterolateral lumbar fusion. Methods. The study protocol and methods were critically examined. The results as originally reported and as verified or modified by the reanalysis are discussed in their original context and based on ensuing studies. Results. The original paper reported a benefit with rigid pedicle screw fixation in both the proportion of patients achieving fusion and clinical outcome in patients with degenerative lumbar disease. The reanalysis demonstrated that the difference between the rigid fixation and noninstrumented groups persisted even after accounting for the postrandomization reassignment of patients. Although the difference in clinical outcome between the rigidly instrumented and noninstrumented groups was statistically significant, a nonvalidated, physician-based measure was used. Subgroup analyses of fusion did not reach statistical significance. Conclusions. This prospective, randomized trial demonstrated that, compared with noninstrumented posterolateral lumbar fusion, rigid pedicle screw fixation results in an increase in the proportion of patients achieving arthrodesis from 64% to 88%. It is not possible to generalize these results to other patient populations. Subsequent research by other investigators has generally confirmed the beneficial effect of rigid segmental fixation on achieving fusion, but a positive relationship between rigid fixation and clinical outcome has yet to be definitively demonstrated. A Journal Club review reexamines Zdeblick's randomized, controlled trial of instrumented versus noninstrumented posterolateral lumbar fusion for degenerative disease. The methods and results are critically analyzed and discussed in the context of the original study and subsequent research.

Efficacy of Mesenchymal Stem Cell Enriched Grafts in an Ovine Posterolateral Lumbar Spine Model

Four groups of 6 animals underwent single-level noninstrumented posterolateral lumbar fusion (PLF) with one of the following grafts: 1) autograft, 2) cell-enriched beta-tricalcium phosphate (TCP), 3) TCP with whole bone marrow, and 4) TCP alone. Plain radiographs were taken after surgery and at death, 6 months after surgery. Explanted spine segments were analyzed by manual palpation, micro-CT, and histology. A sheep spine fusion study was undertaken to evaluate the healing performance of a TCP graft enriched with osteoprogenitor cells using Selective Cell Retention technology (SCR), compared with autograft, TCP with whole bone marrow, and TCP alone. Improved bone healing with previously demonstrated using grafts enriched in osteoprogenitor cells. Cell-enriched grafts were obtained by processing 30 mL of bone marrow through 10 mL of TCP. TCP was also used either saturated with bone marrow or alone. At 6 months, 33% of the SCR-enriched TCP and 25% of the autograft sites were fused, compared with 8% of the TCP plus whole bone marrow and 0% of the TCP alone. Histology of fused samples showed denser bone formation in the SCR-enriched TCP grafts than in the autograft sites. The use of SCR-enriched TCP and autograft resulted in similar fusion rates in an ovine posterolateral noninstrumented lumbar spine fusion model.

107. A biomechanical, histological and radiographic comparison of instrumented versus non-instrumented posterolateral lumbar fusion with osteogenic protein-1 in an ovine model

107. A biomechanical, histological and radiographic comparison of instrumented versus non-instrumented posterolateral lumbar fusion with osteogenic protein-1 in an ovine model

Friday, November 1, 2001 3:45–4:28 pm Concurrent Session 3B: Lumbar Fusion Enhancements: 3:45 Randomized radiostereometric study comparing osteogenic protein–1 (bone morphogenic protein–7) and autograft bone in human noninstrumented posterolateral lumbar fusions

Purpose of study: To address the question whether osteogenic protein-1 (OP-1; bone morphogenic protein [BMP-7]) could improve the formation of stabilizing bridging bone in human noninstrumented posterolateral lumbar fusions as compared with autograft bone.Methods used: After ethical committee approval, 20 patients (12 women) aged 23 to 57 (mean, 42) years were randomized to noninstrumented posterolateral lumbar fusion with either OP-1 in the form of OP-1 implant or autograft bone. The inclusion criteria were L5 spondylolysis, maximal vertebral slip of 50% and longstanding intractable lumbosacral pain. The patients were instructed to keep the trunk straight for 5 months postoperatively with the aid of a soft lumbar corset. At surgery 0.8-mm metallic markers were positioned in sacrum and L5 enabling follow-up with radiostereometric analysis (RSA) according to the Selvik method [1] during 1 year. The three-dimensional vertebral movements as measured by RSA induced by positional change from supine to standing and sitting were calculated with an accuracy of 0.5 to 0.7 mm and 0.5 to 2.0 degrees. Conventional radiography was added.of findings: There was no significant difference between the two fusion versions concerning speed and rate of intervertebral stabilization as measured by RSA and signs of bridging bone on conventional radiography. There was a significant correlation between reduced vertebral movements and better bone formation. No adverse effects of the OP-1 implant occurred. Persistent minor pain at the iliac crest after bone harvest was noticed in one patient.Relationship between findings and existing knowledge: Animal studies of osteoinductive proteins in noninstrumented posterolateral lumbar fusions have revealed high fusion rates. No prior conclusive study on humans has been performed. The present study revealed that a posterolateral lumbar fusion using OP-1 can provide fusion healing in humans. No significant difference was noted between the radiostereometric and radiographic results of fusion with OP-1 implant and fusion with autograft bone. Thus, the OP-1 implant did not yield better formation of stabilizing bridging bone than autograft bone in human noninstrumented posterolateral lumbar fusions.Overall significance of findings: The present study revealed that a posterolateral lumbar fusion using OP-1 can provide fusion healing in humans.Disclosures: Device of drug: osteogenic protein 1 (OP-1). Status: investigational.Conflict of interest: No conflicts.

On lumbar spine stabilization

71 consecutive posterolateral lumbar fusions without decompression or internal fixation were evaluated with a mean follow-up time of 3.5 (2-7) years. The diagnoses were spondylolysis-olisthesis in 43 cases, degenerative disc disease and/or facet joint arthrosis in 16 cases and pain post laminectomy/ decompression in 12 cases. 54/70 patients had a solid fusion. In the group with spondylolysis-olisthesis, 29 patients were good and clinical improvement correlated with solid fusion. For both the other diagnostic groups, the clinical outcome was inferior and less correlated to the radiographic result. In 50 patients scheduled for lumbar fusion, spinal immobilization in a lumbar orthosis had some pain relieving effect registered before surgery, but this pain relief could not predict the clinical outcome of subsequent surgery. External pedicular fixation provided an adequate mechanical basis for the prognostic external fixation test in lumbar fusion studied by roentgen stereophotogrammetric analysis (RSA) in 7 patients. Fusion of the olisthetic lumbosacral segment transformed mobility to the juxta-fused level inducing relative hypermobility in this segment in 2 out of 6 patients examined by RSA. The healing rate of noninstrumented posterolateral lumbar fusion was increased by extending the postoperative immobilization period from 3 to 5 months. A lumbar orthosis, soft or rigid, could not stabilize the intervertebral translations studied by RSA without active mobility provocation, consistent with the postoperative regimen when the patient cooperates to minimize gross body motions and keeps the trunk straight. Adding unilateral hip fixation to the orthosis yielded a tendency towards intervertebral stabilization however not shown important for the postoperative situation after fusion. During this period any lumbar support can be used as long as it reminds the patient of the regimen to avoid all active movements of the spine.