Instrumented Posterolateral Fusion Research Articles

Use of Nanocrystalline Hydroxyapatite With Autologous BMA and Local Bone in the Lumbar Spine: A Retrospective CT Analysis of Posterolateral Fusion Results.

Study Design:A retrospective, multicenter, medical record review and independent analysis of computed tomographic scans was performed in 46 patients to determine radiographic arthrodesis rates after 1-segment, 2-segment, or 3-segment instrumented posterolateral fusions (PLF) using autograft, bone marrow aspirate (BMA), and a nanocrystalline hydroxyapatite bone void filler (nHA).Objective:To determine the radiographic arthrodesis rates after instrumented lumbar PLF using local autograft, BMA, and nHA.Summary of Background Data:The use of iliac crest autograft in posterolateral spine fusion carries real and significant risks. Many forms of nanocrystalline hydroxyapatite have been studied in various preclinical models, but no human studies have reviewed its efficacy as a bone graft supplement in PLF.Methods:Posterolateral arthrodesis progression was documented approximately 12 months postoperatively using a computed tomographic scan and evaluated by an independent radiologist for the presence of bridging bone. One-year postoperative clinical outcomes were assessed using the PROLO score.Results:Radiographically, 91% patients treated exhibited bilateral or unilateral posterolateral bridging bone. Ninety-four percent of the segments treated exhibited bilateral or unilateral posterolateral bridging bone, whereas 6% segments exhibited no posterolateral bridging bone on either side. A total of 93% individual sites treated exhibited posterolateral bridging bone. In 1-segment, 2-segment, and 3-segment arthrodesis, 88%, 93%, and 100%, respectively, of individual sites exhibited radiographic bridging bone. One-year postoperative PROLO scores for 77% patients were excellent or good. There were no complications related to the posterolateral graft mass and no symptomatic nonunions.Conclusions:The arthrodesis rates after instrumented lumbar fusion using local autograft mixed with BMA and the nHA is equivalent to the rates reported for iliac crest autograft in these indications, including stringent indications, such as 3-segment procedures. By approximately 12 months postoperatively, there was no significant difference in the rates of bridging bone between the 1-segment, 2-segment, and 3-segment procedures.

Addition of TLIF does not improve outcome over standard posterior instrumented fusion. 5–10 years long-term Follow-up: results from a RCT

The use of inter-body device in lumbar fusions has been difficult to validate, only few long-term RCT are available. Between 2003 and 2005, 100 patients entered a RCT between transforaminal lumbar inter-body fusion (TLIF) or posterolateral instrumented lumbar fusion (PLF). The patients suffered from LBP due to segmental instability, disc degeneration, former disc herniation, spondylolisthesis Meyerding grade<2. Functional outcome parameters as Dallas pain questionnaire (DPQ), SF-36, low back pain questionnaire (LBRS), Oswestry disability index (ODI) were registered prospectively, and after 5-10years. Follow-up reached 93% of available, (94%, 44 in the PLF's and 92%, 44 in the TLIF group p=0.76). Mean follow-up was 8.6years (5-10years). Mean age at follow-up was 59years (34-76years p=0.19). Reoperation rate in a long-term perspective was equal among groups 14%, each p=0.24. Back pain was 3.8 (mean) (Scale 0-10), TLIF (3.65) PLF (3.97) p=0.62, leg pain 2.68 (mean) (Scale 0-10) 2.90 (TLIF) and 2.48 (PLF) p=0.34. No difference in functional outcome between groups p=0.93. Overall, global satisfaction with the primary intervention at 8.6year was 76% (75% TLIF and 77% PLF) p=0.85. In a long-term perspective, patients with TLIF's did not experience better outcome scores.

Laminectomy plus Fusion versus Laminectomy Alone for Lumbar Spondylolisthesis

BackgroundThe comparative effectiveness of performing instrumented (rigid pedicle screws affixed to titanium alloy rods) lumbar spinal fusion in addition to decompressive laminectomy in patients with symptomatic lumbar grade I degenerative spondylolisthesis with spinal stenosis is unknown.MethodsIn this randomized, controlled trial, we assigned patients, 50 to 80 years of age, who had stable degenerative spondylolisthesis (degree of spondylolisthesis, 3 to 14 mm) and symptomatic lumbar spinal stenosis to undergo either decompressive laminectomy alone (decompression-alone group) or laminectomy with posterolateral instrumented fusion (fusion group). The primary outcome measure was the change in the physical-component summary score of the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36; range, 0 to 100, with higher scores indicating better quality of life) 2 years after surgery. The secondary outcome measure was the score on the Oswestry Disability Index (range, 0 to 100, with higher scores indicating more disability related to back pain). Patients were followed for 4 years.ResultsA total of 66 patients (mean age, 67 years; 80% women) underwent randomization. The rate of follow-up was 89% at 1 year, 86% at 2 years, and 68% at 4 years. The fusion group had a greater increase in SF-36 physical-component summary scores at 2 years after surgery than did the decompression-alone group (15.2 vs. 9.5, for a difference of 5.7; 95% confidence interval, 0.1 to 11.3; P=0.046). The increases in the SF-36 physical-component summary scores in the fusion group remained greater than those in the decompression-alone group at 3 years and at 4 years (P=0.02 for both years). With respect to reductions in disability related to back pain, the changes in the Oswestry Disability Index scores at 2 years after surgery did not differ significantly between the study groups (−17.9 in the decompression-alone group and −26.3 in the fusion group, P=0.06). More blood loss and longer hospital stays occurred in the fusion group than in the decompression-alone group (P<0.001 for both comparisons). The cumulative rate of reoperation was 14% in the fusion group and 34% in the decompression-alone group (P=0.05).ConclusionsAmong patients with degenerative grade I spondylolisthesis, the addition of lumbar spinal fusion to laminectomy was associated with slightly greater but clinically meaningful improvement in overall physical health–related quality of life than laminectomy alone. (Funded by the Jean and David Wallace Foundation and others; SLIP ClinicalTrials.gov number, NCT00109213.)

OP-1 Compared with Iliac Crest Autograft in Instrumented Posterolateral Fusion: A Randomized, Multicenter Non-Inferiority Trial.

Spinal fusion with the use of autograft is a commonly performed procedure. However, harvesting of bone from the iliac crest is associated with complications. Bone morphogenetic proteins (BMPs) are extensively used as alternatives, often without sufficient evidence of safety and efficacy. The purpose of this study was to investigate non-inferiority of osteogenic protein-1 (OP-1, also known as BMP-7) in comparison with iliac crest bone graft in posterolateral fusions. This study was a randomized, controlled multicenter trial. Patients who underwent a single-level instrumented posterolateral fusion of the lumbar spine for degenerative or isthmic spondylolisthesis with symptoms of neurological compression were randomized to receive OP-1 combined with local bone (OP-1 group) or autologous bone graft from the iliac crest combined with local bone (autograft group). The primary outcome was overall success, defined as a combination of clinical success and evidence of fusion on computed tomography (CT) scans, at one year postoperatively. One hundred and nineteen patients were included in the study, and analysis of the overall outcome was performed for 113. Non-inferiority of OP-1 compared with iliac crest autograft was not found at one year, with a success rate of 40% in the OP-1 group versus 54% in the autograft group (risk difference = -13.3%, 90% confidence interval [CI] = -28.6% to +2.10%). This was due to the lower rate of fusion (the primary aim of OP-1 application) seen on the CT scans in the OP-1 group (54% versus 74% in the autograft group, p = 0.03). There were no adverse events that could be directly related to the use of OP-1. OP-1 with a collagen carrier was not as effective as autologous iliac crest bone for achieving fusion and cannot be recommended in instrumented posterolateral lumbar fusion procedures. Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Cost-Utility Analysis of Instrumented Fusion Versus Decompression Alone for Grade I L4-L5 Spondylolisthesis at 1-Year Follow-up: A Pilot Study.

Retrospective 1-year cost-utility analysis. To determine the cost-effectiveness of decompression with and without instrumented fusion for patients with grade I degenerative L4-L5 spondylolisthesis at 1-year follow-up. Despite its benefits to health outcomes, lumbar fusion is associated with substantial costs. This study analyzed the cost-effectiveness of instrumented fusion for grade I L4-L5 spondylolisthesis at 1-year follow-up. Four cohorts of 25 patients with grade I L4-L5 degenerative spondylolisthesis were analyzed: cohort 1 (decompression), cohort 2 (decompression with instrumented posterolateral fusion (PLF), cohort 3 (decompression with instrumented posterior lumbar interbody fusion/transforaminal lumbar interbody fusion), and cohort 4 (decompression with instrumented PLF and posterior lumbar interbody fusion/transforaminal lumbar interbody fusion). One-year postoperative health outcomes were assessed based on Visual Analogue Scale, Pain Disability Questionnaire, and EuroQol 5 Dimensions questionnaires. Direct medical costs were estimated using Medicare national payment amounts and indirect costs were based on patient missed work days. Postoperative 1-year cost/utility ratios and incremental cost-effectiveness ratios (ICERs) were calculated. Cost-effectiveness was assessed using a threshold of $100,000/QALY gained. Compared with preoperative health states, EuroQol 5 Dimensions QALY scores improved for all cohorts (P<0.01). The 1-year cost-utility ratio for cohort 1 was significantly lower ($56,610/QALY gained; P<0.01) than that for cohorts 2 ($116,991/QALY gained), 3 ($109,740/QALY gained), and 4 ($107,546/QALY gained). The 1-year ICERs relative to cohort 1 were: cohort 2 (dominated), cohort 3 ($1,060,549/QALY gained), and cohort 4 ($830,047/QALY gained). Decompression without fusion is cost-effective for patients with grade I L4-L5 spondylolisthesis. Decompression with fusion is not cost effective in a 1-year timeframe for these patients based on the threshold. Accordingly, although fusion is beneficial for improving health outcomes in patients with spondylolisthesis, it is not cost-effective when analyzing a 1-year timeframe based on the threshold. The durability of these results must be analyzed with longer term cost-utility analysis studies.

Case Study: Use of Electrodiagnostic Evaluation to Assess Lumbar Radiculopathy

Abstract The electrodiagnostic examination is an important diagnostic tool that defines the location, pathophysiology, severity, and chronicity of a wide array of neuromuscular disorders. The test comprises two parts, a nerve conduction study (NCS) and needle electromyography (EMG), and is an extension of the neuromuscular portion of the physical examination. Together, NCS and EMG provide complementary information about the integrity of the peripheral nervous system. The article presents a case example that is evaluated using the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Sixth Edition. The case describes a 52-year-old woman who had a back injury that was managed conservatively for fifteen months and then underwent a three-level lumbosacral instrumented posterolateral fusion (the rationale is unclear from the records). Her pain persisted and treatment has included chronic narcotics; she reported multiple physical and psychological complaints and difficulties, and illness behavior and unreliable self-reports failed to corroborate her reports. Needle EMG must be performed on the patient's paraspinal muscles for proper evaluation of radiculopathy, and in this case there was no evidence of involvement of any ventral ramus and thus no evidence was documented of nerve root abnormality involving two or more limb muscles that receive innervation from the same nerve root. For this individual, the changes seen in paraspinal EMGs were unlikely to be due to a true lumbar radiculopathy, which was not convincingly established.

Impact of Lumbar Fusion on Health Care Resource Utilization.

A longitudinal cohort. The aim of this study was to determine the extent of health care resource utilization decrease 2 years after lumbar spinal fusion. Despite the assumption that surgery will minimize the need for ongoing nonsurgical treatment, the impact of lumbar fusion on subsequent health care resource utilization has not been effectively studied. Patients who had continuous coverage by a major insurer during the year before decompression and posterolateral instrumented spinal fusion, and the 2 and a half years following were identified. All charges processed during this time-period were collected. Charges associated with the index surgery, the 90-day postoperative period, and those unrelated to spinal care were excluded. Associations with Oswestry Disability Index (ODI) score improvement at 2 years after surgery and health care resource utilization were determined. Sixty-six patients were included in the analysis. The mean age was 59 years and 39% were males. There was a decrease in health care utilization costs 1 year after surgery ($3267.59) compared with pre-op ($4246.32), but this was not statistically significant (P = 0.197). There was a statistically significant decrease in costs during the second year after surgery ($1420.97) compared with either pre-op (P = 0.000) or 1-year costs (P = 0.001). No statistically significant correlations could be found between change in ODI scores and costs incurred at either year post-op. Health care utilization decreased at 1 year and significantly at 2 years after lumbar fusion. However, there was no correlation between use of nonsurgical resources and clinical outcome based on ODI scores. This raises the question as to whether these resources were used in a rational manner. This cooperative study between a major insurer and a tertiary spine center provides improved insight into the cost profile of lumbar fusion surgery. Further study is needed to determine whether ongoing post-op treatment is necessary or simply established practice. 2.

Within Patient Radiological Comparative Analysis of the Performance of Two Bone Graft Extenders Utilized in Posterolateral Lumbar Fusion: A Retrospective Case Series.

Two bone graft extenders differing in chemical composition were implanted contralaterally in 27 consecutive patients undergoing instrumented posterolateral lumbar fusion as standard-of-care. Bone marrow aspirate and autogenous bone graft were equally combined either with β-tricalcium phosphate (β-TCP) or a hybrid biomaterial [containing hyaluronic acid (HyA) but lacking a calcium salt] and implanted between the transverse processes. Fusion status on each side of the vertebrae was retrospectively graded (1–5 scale) on AP planar X-ray at multiple visits as available, through approximately 12 months. Additionally, consolidation or resorption since prior visit for each treatment was recorded. Sides receiving β-TCP extender showed marked resorption prior to bone consolidation during the first 6 months. By contrast, sides receiving the hybrid biomaterial containing integrated HyA showed rapid bone consolidation by week 6–8, with maintenance of initial bone volume through 12 months. Fusion grade was superior for the hybrid biomaterial, differing significantly from β-TCP at day 109 and beyond. Fusion success at >12 months was 92.9 vs. 67.9% for the hybrid biomaterial and β-TCP-treated sides, respectively. The hybrid biomaterial extender demonstrated a shortened time-to-fusion compared to the calcium-based graft. Mode of action has been demonstrated in the literature to differ between these compositions. Therefore, choice of synthetic biomaterial composition may significantly influence the mode of action of cellular events regulating appositional bone growth.

The effect of increased microporosity on bone formation within silicate-substituted scaffolds in an ovine posterolateral spinal fusion model.

This study compared the bone forming capacity of the same formulation of silicate-substituted bone graft substitute materials with different microporosity in an instrumented posterolateral spinal fusion ovine model. Materials with a strut porosity of (i) 22.5% (SiCaP) or (ii) 36.0% (SiCaP(+)) were packed along either side of the spine. Bone apposition rates, % new bone formation, % bone-implant contact, and % graft resorption were quantified at 8, 12, and 24 weeks post surgery. Computed Tomography (CT) was used to grade the formation of fusion bridges between vertebrae. Results showed no significant difference in bone apposition rates, % new bone formation, and % bone-implant contact when the two materials were compared. However, at 8 weeks, a significantly higher CT score was obtained in the SiCaP(+) group (0.83 ± 0.17) when compared with the SiCaP group (0.17 ± 0.17; p = 0.027). Significantly less scaffold remained in the SiCaP(+) group at 12 weeks (p = 0.018). Both SiCaP and SiCaP(+) formulations augmented bone formation. Increasing the strut porosity did not significantly increase bone formation however, at 8 weeks it promoted the formation of more highly mineralized bone resulting in a significantly higher CT score, suggesting the bone tissue formed was more mature. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 805-814, 2017.

The fusion rate of demineralized bone matrix compared with autogenous iliac bone graft for long multi-segment posterolateral spinal fusion

BackgroundAlthough autogenous iliac bone graft (AIBG) remains the gold standard for spine fusion, harvesting morbidity has prompted the search for alternatives especially for multi-segment fusion. This study aimed to evaluate the efficacy of using demineralized bone matrix (DBM) as a substitute of AIBG for long instrumented posterolateral fusion (≧ three-level fusion).MethodsA total of 47 consecutive patients underwent laminectomy decompression, and multi-level instrumented posterolateral fusions were reviewed. Group 1 comprised 26 patients having DBM with autologous laminectomy bone (ALB). Group 2 consisted of 21 patients having AIBG with ALB. The fusion success evaluation was based on findings using the 12-month anteroposterior and dynamic plain radiographs.ResultsGender, age, and the number of fusion levels were similar for both groups. 21 of 26 (80.8 %) patients in group 1 and 18 of 21 (85.7 %) patients in group 2 were observed to achieve solid bony fusion. There was no statistical difference in the fusion success (p = 0.72). Blood loss was significantly more in group 2 (p = 0.02). The duration of the hospital stays and operative times being longer for group 2, but the difference was not significant.ConclusionsDBM combined with ALB and osteoconductive materials is as effective as an autologous iliac bone graft with respect to long multi-segment posterolateral fusion success. DBM can be used as an effective bone graft substitute and may decrease morbidities associated with iliac bone graft harvest.

Posterolateral instrumented fusion with and without transforaminal lumbar interbody fusion for the treatment of adult isthmic spondylolisthesis: A randomized clinical trial with 2-year follow-up

Background:Spondylolisthesis is a common cause of surgery in patients with lower back pain. Although posterolateral fusion and pedicle screw fixation are a relatively common treatment method for the treatment of spondylolisthesis, controversy exists about the necessity of adding interbody fusion to posterolateral fusion. The aim of our study was to assess the functional disability, pain, and complications in patients with spondylolisthesis treated by posterolateral instrumented fusion (PLF) with and without transforaminal lumbar interbody fusion (TLIF) in a randomized clinical trial.Materials and Methods:From February 2007 to February 2011, 50 adult patients with spondylolisthesis were randomly assigned to be treated with PLF or PLF+TLIF techniques (25 patients in each group) by a single surgeon. Back pain, leg pain, and disability were assessed before treatment and until 2 years after surgical treatment using visual analog scale (VAS) and oswestry disability index (ODI). Patients were also evaluated for postoperative complications such as infection, neurological complications, and instrument failure.Results:All patients completed the 24 months of follow-up. Twenty patients were females and 30 were males. Average age of the patients was 53 ± 11 years for the PLF group and 51 ± 13 for the PLF + TLIF group. Back pain, leg pain, and disability score were significantly improved postoperatively compared to preoperative scores (P < 0.001). At 3 months of follow-up, there was no statistically significant difference in VAS score for back pain and leg pain in both groups; however, after 6 months and 1 year and 2 years follow-up, the reported scores for back pain and leg pain were significantly lower in the PLF+TLIF group (P < 0.05). The ODI score was also significantly lower in the PLF+TLIF group at 1 year and 2 years of follow-up (P < 0.05). One screw breakage and one superficial infection occurred in the PLF+TLIF group, which had no statistical significance (P = 0.373).Conclusion:It seems that accompanying TLIF with PLF might lead to better functional improvement and pain reduction in patients with spondylolisthesis.

Commentary on: Laminectomy plus fusion versus laminectomy alone for lumbar spondylolisthesis by Ghogawala Z, Dziura J, Butler WE, Dai F, Terrin N, Magge SN, et al. NEJM 2016;374 (15):1424-34.

Background:How does an article involving only 66 patients randomized into two spinal surgical groups get into the New England Journal of Medicine? Nevertheless, this one did. The article by Ghogawala et al. entitled Laminectomy plus fusion versus laminectomy alone for lumbar spondylolisthesis, compared the efficacy/outcomes of pedicle/screw/rod instrumented posterolateral lumbar fusions vs. decompressions alone for treating lumbar stenosis with grade I degenerative spondylolisthesis (DS).Methods:They designed a randomized controlled study involving only 66 patients between the ages of 50–80 (average age: 67) with lumbar stenosis and stable DS (3–14 mm). Outcomes were measured utilizing the physical measures from the Short Form 36 (SF-36) up to 4 postoperative years, and the Oswestry Disability Index (ODI) upt to 2 postoperative years. Data were available for 86% of patients at 2, but only for 68% of the patients at 4 postoperative years.Results:At 2 postoperative years, SF-36 scores were higher for the instrumented patients (28 patients) vs. decompressed (29 patients) patients. However, the scores were comparable for both groups using the ODI at 4 years. SF-36 scores, however, remained higher for the 19 remaining instrumented patients. Additionally, reoperation rates were 14% for fusions and a staggering 34% for decompressions alone.Conclusions:The authors concluded; laminectomy with fusion offered a “slightly greater but clinically meaningful improvement in overall physical health-related quality of life vs. laminectomy alone.” Rather, it should have read there were no statistically significant differences between the two groups and an insufficient number of patients were included in the study at all stages.

Bone Union Rate Following Instrumented Posterolateral Lumbar Fusion: Comparison between Demineralized Bone Matrix versus Hydroxyapatite.

Study DesignRetrospective study.PurposeTo compare the union rate of posterolateral lumbar fusion (PLF) using demineralized bone matrix (DBM) versus hydroxyapatite (HA) as bone graft extender.Overview of LiteratureTo our knowledge, there has been no clinical trial to compare the outcomes of DBM versus HA as a graft material for PLF.MethodsWe analyzed prospectively collected data from consecutive 79 patients who underwent instrumented PLF. Patients who received DBM were assigned to group B (n=38), and patients who received HA were assigned into group C (n=41). The primary study outcome was fusion rate assessed with radiographs. The secondary outcomes included pain intensity using a visual analogue scale, functional outcome using Oswestry disability index score, laboratory tests of inflammatory profiles and infection rate.ResultsOne year postoperatively, bone fusion was achieved in 73% in group B and 58% in group C without significant difference between the groups (p=0.15). There were no differences between the groups with respect to secondary outcomes.ConclusionsDBM would provide noninferior outcomes compared to the HA as a fusion material for PLF, and could be a notable alternative.

Treatment for spondylolysis and spondylolisthesis in children.

To review outcome of 44 children who underwent conservative or surgical treatment for spondylolysis or spondylolisthesis. Records of 25 male and 19 female children aged 5 to 14 (mean, 10.2) years who underwent conservative (n=39) or surgical (n=5) treatment for spondylolysis (n=19) or spondylolisthesis (n=25) were reviewed. Conservative treatment involved application of a thoracolumbosacral orthotic brace for all day except bedtime until symptoms resolved and then physiotherapy including exercises to strengthen the abdominal and back muscles and stretching exercises of the hamstrings and hip flexors. Surgery (instrumented posterolateral fusion [n=4] or Wiltse posterolateral fusion [n=1]) with allografts was indicated in patients with refractory pain (n=2) or nerve root irritation (n=1) and in patients with iatrogenic spondylolisthesis (n=2), followed by application of the brace for 3 months and then physiotherapy. Outcome was assessed using the Seitsalo scoring system. The mean follow-up period was 6.5 (range, 3-10) years. No patient developed any postoperative complication. Outcome was excellent in 35 patients, good in 8, and fair in one. All 5 patients who underwent posterolateral fusion for refractory spondylolisthesis achieved good outcome. In 11 patients with spondylolysis, the pars defect healed. None of the spondylolysis progressed to spondylolisthesis. All displacements remained stable, without any progression. Conservative treatment is effective for most patients with spondylolysis or spondylolisthesis. Instrumented posterolateral fusion is indicated in patients with persistent symptoms and for iatrogenic cases.

A prospective, multi-center clinical and radiographic outcomes evaluation of ChronOS strip for lumbar spine fusion

This prospective clinical study evaluated the use of a composite bone void filler (ChronOS Strip, DePuy Synthes, West Chester, PA, USA), combined with bone marrow aspirate plus local autologous bone, in a series of patients undergoing instrumented posterolateral spinal fusion with interbody support. Seventy-six patients were enrolled and treated per protocol at 13 clinical sites. At 24months, 55/76 patients (72%) were evaluated, with 49/76 (65%) having sufficient data to determine the primary endpoint. The primary endpoint, posterolateral fusion success, was achieved in 48/54 (88.9%) patients at 12months and in 45/49 (91.8%) patients at 24months. At all follow-up time points, statistically significant improvements were observed when compared to baseline in back and leg pain and functional status as measured by visual analog scale, Oswestry Disability Index and 12-Item Short Form health surveys. This prospective multi-center series provides evidence that the composite bone void filler, when applied posterolaterally with instrumentation, bone marrow aspirate and/or local autologous bone and concomitant interbody support, can be used to achieve a successful posterolateral fusion, resulting in improvements in clinical outcomes in patients with degenerative disc disease.

Risk factors for rod fracture after posterior correction of adult spinal deformity with osteotomy: a retrospective case-series.

BackgroundOsteotomies including pedicle subtraction (PSO) and/or Smith-Peterson (SPO) are used to facilitate surgical correction of adult spinal deformity (ASD), but are associated with complications including instrumentation failure and rod fracture (RF). The purpose of this study was to determine incidence and risk factors for RF, including a clinically significant subset (CSRF), after osteotomy for ASD.MethodsA retrospective review of clinical records was conducted on consecutive ASD patients treated with posterolateral instrumented fusion and osteotomy. Seventy-five patients (50 female; average age, 59) met strict inclusion/exclusion criteria and follow-up of ≥1 year. Data was extracted pertaining to the following variables: patient demographics; details of surgical intervention; instrumentation; and postoperative outcomes. Patients were divided into two subgroups: 1) rod fracture (RF) and 2) non-RF. The RF subgroup was further divided into CSRF and non-CSRF. Odds ratios (OR) were calculated to evaluate the association between risk factors and RF. The χ2-test was used to define P-values for categorical variables, and T-test was applied for continuous variables, P-values ≤0.05 were considered significant.ResultsIncidence rates of RF were: for entire population, 9.3 % (95 % Cl: 2.7 %; 15.9 %); for PSO, 16.2 % (95 % Cl: 4.3; 28.1); and for SPO, 2.6 % (95 % Cl: 0 %; 7.7 %); the OR of PSO versus SPO was 7.2 (95 % Cl: 0.8; 62.7, P = 0.1). CSRF incidence was 5.3 % (95 % CI: 0.2 %; 10.4 %). Significant risk of RF was revealed for following factors: fusion construct crossing both thoracolumbar and lumbosacral junctions (OR = 9.1, P = 0.05), sagittal rod contour >60° (OR = 10.0, P = 0.04); the presence of dominos and/or parallel connectors at date of rod fracture (OR = 10.0, P = 0.01); and pseudarthrosis at ≥1 year follow-up (OR = 28.9, P < 0.001). Statistically significant risk of CSRF was revealed for fusion to pelvis (P = 0.05) and pseudarthrosis at ≥1 year follow-up (OR = 50.3, CI: 4.2; 598.8, P < 0.01).ConclusionsThe risk of RF after posterolateral instrumented correction of ASD with osteotomy had statistically significant association with the following factors: pseudarthrosis at ≥1 year follow-up; sagittal rod contour >60°; presence of dominos and/or parallel connectors at date of fracture; and fusion construct crossing both thoracolumbar and lumbosacral junctions. Statistically significant risk for the CSRF subset was fusion to the pelvis and pseudarthrosis at ≥1 year follow-up.

The effect of preoperative diagnosis on the incidence of adjacent segment disease after lumbar fusion.

The aim of this study was to determine the incidence of adjacent segment disease (ASD) requiring reoperation after lumbar fusion and to compare survivorship of adjacent levels according to preoperative diagnosis. Two hundred and seventy five patients who underwent instrumented posterolateral fusion of the lumbar spine without an interbody device were included. Patients were stratified by preoperative diagnoses (lumbar spinal stenosis, spondylolisthesis, or postlaminectomy revision) and were followed for an average time of 59 months. The incidence of ASD requiring reoperation was calculated via Kaplan-Meier survivorship analysis. A Cox-proportional hazards regression analysis was performed to identify the independent impact of preoperative diagnosis, age, sex, and number of segments fused on ASD development. A total of 59 (21.5%) patients required reoperation for ASD. Following Kaplan-Meier analysis, the predicted ASD-free survival was 79.7% (95% CI, 72.3-85.3) at 5 years and 53.4% (95% CI, 40.0-65.0) at 10 years. Moreover, the incidence was not significantly different between diagnostic subgroups by the log-rank test (P=0.144). Following risk factor analysis, the only significant factor associated with ASD was increasing age (RR 1.02; 95% CI, 1.00-1.05). Male sex, preoperative diagnosis, and the numbers of segments fused were not significantly associated with ASD. Few studies to date have specifically investigated the influence of pre-operative diagnosis on lumbar fusion outcomes. The incidence of ASD requiring reoperation was estimated at 20.3% and 45.7% at 5 and 10 years, respectively. In this study, the incidences of ASD based on preoperative diagnosis were not significantly different between groups; the only significant risk factor was increasing age.

Minimally invasive anterior lumbar interbody fusion for adult degenerative scoliosis with 1 or 2 dislocated levels.

Frequent complications of posterolateral instrumented fusion have been reported after treatment of degenerative scoliosis in elderly patients. Considering that in some cases, most of the symptomatology of adult degenerative scoliosis (ADS) is a consequence of the segmental instability at the dislocated level, the use of minimally invasive anterior lumbar interbody fusion (ALIF) to manage symptoms can be advocated to reduce surgical morbidity. The purpose of this study was to evaluate the midterm outcomes of 1- or 2-level minimally invasive ALIFs in ADS patients with 1- or 2-level dislocations. A total of 47 patients (average age 64 years; range 43-80 years) with 1- or 2-level ALIF performed for ADS (64 levels) in a single institution were included in the study. An independent spine surgeon retrospectively reviewed all the patients' medical records and radiographs to assess operative data and surgery-related complications. Clinical outcome was reported using the Oswestry Disability Index (ODI) and the visual analog scale (VAS) for lumbar and leg pain. Intraoperative data and complications were collected. Fusion and risk for adjacent-level degeneration were assessed. The mean follow-up duration was 3 years (range 1-10 years). ODI, and back and leg pain VAS scores were significantly improved at last follow-up. A majority of patients (74%) had a statistically significant improvement in their ODI score of more than 20 points at latest follow-up and 1 had a worsening of his disability. The mean operating time was 166 minutes (range 70-355 minutes). The mean estimated blood loss was 410 ml (range 50-1700 ml). Six (5 major and 1 minor) surgical complications (12.7% of patients) and 13 (2 major and 11 minor) medical complications (27.7% of patients) occurred without death or wound infection. Fusion was achieved in 46 of 47 patients. Surgery resulted in a slight but significant decrease of the Cobb angle, and improved the pelvic parameters and lumbar lordosis, but had no effect on the global sagittal balance. At latest follow-up, 9 patients (19.1%) developed adjacent-segment disease at a mean of 2 years' delay from the index surgery; 4 were symptomatic but treated medically, and none required iterative surgery. Single- or 2-level minimally invasive fusion through a minimally invasive anterior approach in some selected cases of ADS produced a good functional outcome with a high fusion rate. They were associated with a significantly lower rate of complications in this study than the historical control.

Degenerative Spondylolisthesis

Analysis of the Nationwide Inpatient Sample database. To investigate national trends, risks, and benefits of surgical interventions for degenerative spondylolisthesis (DS). The surgical management of DS continues to evolve whereas the most clinically and cost-effective treatment is debated. With an aging US population and growing restraints on a financially burdened health care system, a clear understanding of national trends in the surgical management of DS is needed. The Nationwide Inpatient Sample database was queried for patients with DS undergoing lumbar fusions from 2001 to 2010, using International Classification of Diseases, Ninth Revision (ICD-9) diagnosis and procedure codes. Analyses compared instrumented posterolateral fusion (PLF), posterolateral fusion with anterior lumbar interbody fusion (ALIF + PLF), PLF with posterior interbody fusion (P/TLIF + PLF), anterior instrumented interbody fusion (ALIF), and posterior interbody fusion with posterior instrumentation (P/TLIF). Clinical data were analyzed representing the initial acute phase care after surgery. There were 48,911 DS surgical procedures identified, representing 237,383 procedures. The percentage of patients undergoing PLF, ALIF + PLF, or ALIF increased whereas the percentage of P/TLIF or P/TLIF + PLF decreased over time. Total charges were less (P < 0.001), average length of hospital stay was shorter (P < 0.01), and average age was older (P < 0.01) for patients who underwent PLF compared with any other procedure. Type of procedure varied on the basis of the geographic region of the hospital, teaching versus nonteaching hospital, and size of hospital (P < 0.01). Patients who had P/TLIF + PLF or ALIF had a higher risk of mortality than patients who had PLF (odds ratios: 5.02, 2.22, respectively). Patients were more likely to develop a complication if they had ALIF + PLF, P/TLIF + PLF, ALIF, and P/TLIF than if they had PLF (odds ratios: 1.45, 1.23, 1.49, 1.12, respectively). Variation in the surgical management of DS related to patient demographics, hospital charges, length of hospital stay, insurance type, comorbidities, and complication rates was found within the Nationwide Inpatient Sample database. During the acute phase of care immediately after surgery, PLF procedures were found to reduce length of hospital stay, hospital charges, and postoperative complications. 3.

Impact of Age on Short-term Outcomes After Lumbar Fusion: An Analysis of 1395 Patients Stratified by Decade Cohorts.

The safety and efficacy of spinal fusion in the elderly population remains uncertain with conflicting data. To determine if elderly patients undergoing instrumented lumbar fusion have increased 30-day complication rates compared to younger patients. The American College of Surgeons National Surgical Quality Improvement Program was used to identify all patients undergoing instrumented posterolateral lumbar fusion between 2005 and 2011. Patients were stratified by decade cohorts as follows: <65, 65 to 75, 75 to 85, and ≥85 years old. All 30-day complications were grouped as overall composite morbidity and were compared using multivariate analysis. A total of 1395 patients were identified and the overall 30-day complication rate was 11.47%. The complication rates were 9.04% and 14.05% for patients younger than 65 and older than 65, respectively. When stratified by decade cohorts, the complication rates were 9.04% for the <65 cohort, 13.46% for the 65 to 75 cohort, 16.17% for the >75 to 85 cohort, and 4.00% for the ≥85 cohort. Multivariable regression analysis revealed no statistically significant difference between the <65 and ≥65 age cohorts (odds ratio = 1.26; 95% confidence interval: 0.87-2.19). After stratifying into age cohorts, multivariable analyses revealed no difference in odds of postoperative complication occurrence for any age cohort when compared with the referent group (<65 years of age). Patients older than 65 years of age have significantly higher rates of complications after lumbar fusion when compared to younger patients. However, multivariable analysis revealed that age was not an independent risk factor for complication occurrence after lumbar fusion.