Publications by authors named "Evalina L Burger"

43 Publications

Postoperative pelvic incidence (PI) change may impact sagittal spinopelvic alignment (SSA) after instrumented surgical correction of adult spine deformity (ASD).

Spine Deform 2021 Jul 19;9(4):1093-1104. Epub 2021 Apr 19.

Department of Orthopedics, University of Colorado Anschutz Medical Campus, 12631 E. 17th Ave., Mail Stop B202, Aurora, CO, 80045, USA.

Objectives: To study factors causing postoperative change of PI after surgical correction of ASD and to assess the effect of this variability on postoperative PI-LL mismatch.

Background: PI is used as an individual constant to define lumbar lordosis (LL) correction goal (PI-LL < 10). Postoperative changes of PI were shown but with opposite vectors. The impact of the PI variability on the postoperative PI-LL has not been studied.

Methods: The medical and radiographic data analyzed for patients who underwent long posterior instrumented spinal fusion. Inclusion criteria are age, ≥ 20 years old; ASD due to degenerative disk disease (DDD) or scoliosis (DS); ≥ 3 levels fused; and 2-year follow-up or revision. Studied parameters are LL (L1-S1), PI, sacral slope (SS), pelvic tilt (PT), and PI-LL. Measurement error and postoperative changes were defined. Statistical analysis includes ANOVA, correlation, regression, and risk assessment by odds ratio; P ≤ 0.05 considered statistically significant.

Results: Eighty patients were included: mean age, 62.4 years-old (SD, 11.1); female, 63.7%; mean body mass index (BMI), 27.1 (SD, 5.6). Distribution of patients by follow-ups includes preoperative 100%; postoperative (1-3 weeks), 100%; 11-13 months. 90%; 22-26 months, 58%; and revision: 24%. Pre- versus postoperative PI (∆PI) changed both positively and negatively and the absolute value of change|∆PI| exceeded measurement error (P ≤ 0.05) reaching as high as 31°, and progressed with time; R dropped from 0.73 to 0.45 (P < 0.001); ∆PI depended on disproportional changes of SS and PT, preoperative PI, and change of LL. Obesity, DS, and absence of sacroiliac fixation increased |∆PI|. The risk of LL insufficient correction (PI-LL > 10°) associated with a |∆PI|> 6°, P = 0.05. Sacroiliac fixation diminished PI variability only during the first postoperative year.

Conclusion: Preoperative variability and postoperative instability of PI diminish the applicability of the PI-LL < 10° goal to plan correction of LL. An alternative method is offered.

Level Of Evidence: IV.
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http://dx.doi.org/10.1007/s43390-020-00283-2DOI Listing
July 2021

The Prevalence of the Use of MIS Techniques in the Treatment of Adult Spinal Deformity (ASD) Amongst Members of the Scoliosis Research Society (SRS) in 2016.

Spine Deform 2019 03;7(2):319-324

Department of Orthopaedics, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.

Study Design: Electronic survey administered to Scoliosis Research Society members.

Objective: To determine the prevalence of minimally invasive surgery (MIS) techniques for the treatment of adult spinal deformity.

Summary Of Background Data: There is a paucity of data available on the practice pattern, prevalence of minimally invasive spine surgery, and the preferred minimally invasive techniques in the treatment of adult spine deformity.

Methods: An electronic nine-question survey regarding individual usage pattern of minimally invasive spine surgery techniques was administered in 2016 to the members of the Scoliosis Research Society. Determinants included complexity in condition of patient population, prevalence of use of minimally invasive techniques in the surgeon's practice, prevalence of use of a particular MIS technique, strategy elected during surgery, adoption of staging of procedures and timing between staging of procedures.

Results: A total of 357 surgeons responded (61.3% response rate), and 154 (43.1%) of the respondents said that they use MIS as a part of their surgical treatment of adult spinal deformity. However, of these 154 respondents, 67 (43.5%) said that their MIS usage in deformity practice was between 1% and 20%. Only 11 (7.2%) said that they used MIS 81% to 100% of the time. The top MIS approaches that surgeons chose were MIS lateral lumbar interbody fusion 109 (70.59%) and MIS percutaneous screws 91 (58.8%).

Conclusions: The low rate of adoption of these techniques among the SRS members may be due to the false perception that there is not enough data to support that MIS techniques are better. This and the fact that a practitioner needs to be facile at different MIS techniques may be the true impediment to the adoption of MIS techniques in the treatment of ASD.

Level Of Evidence: Level IV.
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http://dx.doi.org/10.1016/j.jspd.2018.08.014DOI Listing
March 2019

Surgical Intervention for Cauda Equina Syndrome in the Second and Third Trimesters of Pregnancy: A Report of Three Cases.

JBJS Case Connect 2018 Jul-Sep;8(3):e68

Department of Orthopaedics, Anschutz Medical Campus, University of Colorado, Aurora, Colorado.

Case: Low back pain affects >50% of pregnant women. However, cauda equina syndrome (CES) during pregnancy is rare. Because a delay in treatment increases the risk of irreversible neurologic damage, acute onset is regarded as a surgical emergency. We describe 3 cases of CES in pregnant women at 24, 27, and 30 weeks' gestation, respectively.

Conclusion: All 3 of the patients underwent surgical decompression in the prone position under general anesthesia with continuous external monitoring of the fetal heart rate. Intraoperative findings were noteworthy for epidural venous plexus engorgement in 2 of the patients. There were no complications for the patients or the fetuses, and all 3 of the patients had postoperative resolution of the neurologic symptoms.
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http://dx.doi.org/10.2106/JBJS.CC.17.00289DOI Listing
November 2019

Stand-alone Anterior Lumbar Interbody, Transforaminal Lumbar Interbody, and Anterior/Posterior Fusion: Analysis of Fusion Outcomes and Costs.

Orthopedics 2018 Sep 16;41(5):e655-e662. Epub 2018 Jul 16.

Fusion outcomes and costs of stand-alone anterior lumbar interbody fusion (ALIF), transforaminal lumbar interbody fusion (TLIF) in association with posterior fusion, and anterior/posterior (A/P) fusion were compared using clinical, radiographic, and billing data. Adult patients with symptomatic 1- or 2-level degenerative disk disease in isolation or in association with a grade 1 or 2 degenerative or lytic spondylolisthesis and canal and/or foraminal stenosis who underwent elective stand-alone ALIF, TLIF, or A/P fusion were compared. The analysis focused primarily on fusion rates and costs and secondarily on radiographic and clinical parameters. One hundred six patients at least 2 years beyond surgery (ALIF, 53; TLIF, 17; A/P fusion, 36) were reviewed. Demographics were similar except for age, with the ALIF group being younger (mean, 37.8 years) than the other groups (TLIF, 53.1 years; A/P fusion, 48.2 years). There were no differences between the groups in fusion rates or outcomes as assessed by the Numeric Rating Scale. Compared with the other 2 groups, the ALIF group had a significantly shorter operative time, less blood loss, and a shorter stay (P<.0001). Evaluation of radiographic parameters revealed significant differences regarding disk angle (P<.001), disk height (P<.0001), and pelvic tilt (P=.001) favoring ALIF and A/P fusion over TLIF. Stand-alone ALIF should be considered in the management of patients with 1- or 2-level lumbar degenerative disk disease for which the pathology can be addressed adequately via this approach. [Orthopedics. 2018; 41(5):e655-e662.].
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http://dx.doi.org/10.3928/01477447-20180711-06DOI Listing
September 2018

Development of Bilateral Facet Cysts Causing Recurrent Symptoms After Decompression and the Placement of an Intralaminar Implant: A Case Report.

JBJS Case Connect 2018 Jan-Mar;8(1):e11

Department of Orthopedics, University of Colorado Anschutz Medical Campus, Aurora, Colorado.

Case: We report the development of bilateral symptomatic facet joint cysts in a 78-year-old man who had been treated with decompression and placement of a coflex device (Paradigm Spine) at L3-L4 and L4-L5. Preoperative imaging clearly demonstrated fluid in the facet joints without cysts. He underwent standard surgical treatment, but developed symptomatic facet joint cysts at 4 months postoperatively. The patient was treated with a revision decompression and replacement of the devices; there were no issues at the 32-month follow-up.

Conclusion: While the coflex device has possible long-term biomechanical advantages, vigilance with adherence to appropriate decompression surgical technique is necessary.
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http://dx.doi.org/10.2106/JBJS.CC.17.00009DOI Listing
November 2019

One-step Minimally Invasive Pedicle Screw Instrumentation Using O-Arm and Stealth Navigation.

Clin Spine Surg 2018 06;31(5):197-202

Department of Orthopedics, University of Colorado Anschutz Medical Campus, Aurora, CO.

Study Design: Description of a navigated, single-step, minimally invasive technique for the placement of pedicle screws.

Objective: To describe a new technique for minimally invasive placement of pedicle screws in the lumbar spine using O-arm and StealthStation navigation in combination.

Summary Of Background Data: Minimally invasive surgical techniques are described in the literature as safe and effective methods for pedicle screw instrumentation. These techniques increase radiation exposure and prompt multiple instrument passes through the pedicle.

Materials And Methods: In total, 35 adult patients (187 screws) underwent lumbar surgery with pedicle screw placement using the 1- (8 patients/48 screws) or 2-step (27 patients/139 screws) technique. Complications associated with instrumentation were noted. Pedicle screw position was evaluated.

Results: Of 187 screws placed, 181 (96.8%) were found to be fully contained within the pedicle (grade 1) and 4 (2.1%) had a breach of <2 mm. In the 1-step technique, no screws were malpositioned. One screw at S1 with inadequate fixation was replaced with a screw 1 mm larger in diameter. In the 2-step technique, 2 screws (1.06% overall) were revised due to inferior breach of the pedicle. No neurological sequelae were noted. Also, 1 screw was deemed too long at S1 and was replaced with a shorter screw. None of the revised pedicle screws caused neuromonitoring changes and the breaches were found intraoperatively on 3D imaging.

Conclusions: Using O-arm and StealthStation navigation with minimally invasive surgical technology for placement of posterior spinal instrumentation is safe, effective, and limits radiation exposure.
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http://dx.doi.org/10.1097/BSD.0000000000000616DOI Listing
June 2018

Spinopelvic Parameters in Asymptomatic Subjects Without Spine Disease and Deformity: A Systematic Review With Meta-Analysis.

Clin Spine Surg 2017 Nov;30(9):392-403

*Department of Orthopaedics †Health Sciences Library, University of Colorado Anschutz Medical Campus, Aurora, CO.

Study Design: A systematic review with meta-analysis.

Objective: To combine published data, focusing on the development of optimal spinopelvic parameters in adult asymptomatic subjects without spine deformity while taking into consideration the impact of potential confounders.

Summary Of Background Data: A well-grounded approach to define the optimal spinopelvic parameters is necessary for planning surgical correction of spine deformity.

Materials: Selection criteria: (1) randomized and nonrandomized prospective, cross-sectional, and retrospective studies; (2) participants: asymptomatic subjects without spine deformity aged above 18 years; (3) studied parameters: lumbar lordosis (LL), pelvic incidence, sacral slope, and pelvic tilt; (4) potential confounders: method of measurement, sex, age, ethnicity, weight, height, and body mass index. Search method: Ovid MEDLINE (1946-current) and EMBASE (1980-current), all years through October 2015 were included. Data were collected: number of enrolled subjects, means of the studied characteristics, SD, SE of the means, 95% confidence intervals. A meta-analysis was performed to evaluate the pooled means and range of optimal values (pooled mean±pooled SD) taking into consideration the impact of confounders. The GRADE approach was applied to evaluate the level of evidence.

Results: Seventeen of 1018 studies were included (2926 subjects from 9 countries). The pooled means and the optimal ranges were: LL (L1-S1), 54.6 (42-67) degrees; LL (L1-L5), 37.0 (22-53) degrees; pelvic incidence, 50.6 (39-62) degrees; sacral slope, 37.7 (28-48) degrees; pelvic tilt, 12.6 (3-22) degrees. The pooled results were statistically significant (P<0.001), but heterogeneous. Impact of the following confounders was revealed: method of measurement, ethnicity, age, and body mass index. A methodology was created to define an individualized optimal value and range of each studied parameter taking into consideration the influence of confounders.

Conclusions: The pooled results and developed methodology can be used as diagnostic criteria for evaluation of the spinopelvic parameters, planning of surgical interventions and evaluation of the treatment effect.
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http://dx.doi.org/10.1097/BSD.0000000000000533DOI Listing
November 2017

Strain in Posterior Instrumentation Resulted by Different Combinations of Posterior and Anterior Devices for Long Spine Fusion Constructs.

Spine Deform 2017 Jan;5(1):27-36

Department of Orthopedics, University of Colorado, Anschutz Medical Campus, 13001 E 17th Pl, Aurora, CO 80045, USA.

Study Design: Clinically related experimental study.

Objective: Evaluation of strain in posterior low lumbar and spinopelvic instrumentation for multilevel fusion resulting from the impact of such mechanical factors as physiologic motion, different combinations of posterior and anterior instrumentation, and different techniques of interbody device implantation.

Summary Of Background Data: Currently different combinations of posterior and anterior instrumentation as well as surgical techniques are used for multilevel lumbar fusion. Their impact on risk of device failure has not been well studied. Strain is a well-known predictor of metal fatigue and breakage measurable in experimental conditions.

Methods: Twelve human lumbar spine cadaveric specimens were tested. Following surgical methods of lumbar pedicle screw fixation (L2-S1) with and without spinopelvic fixation by iliac bolt (SFIB) were experimentally modeled: posterior (PLF); transforaminal (TLIF); and a combination of posterior and anterior interbody instrumentation (ALIF+PLF) with and without anterior supplemental fixation by anterior plate or diverging screws through an integrated plate. Strain was defined at the S1 screws, L5-S1 segment of posterior rods, and iliac bolt connectors; measurement was performed during flexion, extension, and axial rotation in physiological range of motion and applied force.

Results: The highest strain was observed in the S1 screws and iliac bolt connectors specifically during rotation. The S1 screw strain was lower in ALIF+PLF during sagittal motion but not rotation. Supplemental anterior fixation in ALIF+PLF diminished the S1 strain during extension. Strain in the posterior rods was higher after TLIF and PLF and was increased by SFIB; this strain was lowest after ALIF+PLF, as supplemental anterior fixation diminished the strain during extension, in particular, cages with anterior screws more than anterior plate. Strain in the iliac bolt connectors was mainly determined by direction of motion.

Conclusions: Different devices modify strain in low posterior instrumentation, which is higher after transforaminal and posterior techniques, specifically with spinopelvic fixation.

Level Of Evidence: N/A.
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http://dx.doi.org/10.1016/j.jspd.2016.09.045DOI Listing
January 2017

An analysis of spine fusion outcomes in sheep pre-clinical models.

Eur Spine J 2017 01 10;26(1):228-239. Epub 2016 May 10.

Department of Orthopedics, University of Colorado, Anschutz Medical Campus, 13001 E. 17th Place, Mail Stop F432, Aurora, CO, 80045, USA.

Purpose: The ovine model is often used to evaluate new spine fusion technologies prior to clinical testing. An important aspect of designing sheep surgery protocols is to select the appropriate postoperative time period for comparing fusion outcomes. Unfortunately, determining the ideal study endpoint is complicated by the fact that prior published studies have not used consistent timeframes. Thus, the primary aim of this study was to provide a reference for investigators as to the expected fusion outcomes of control groups at varying timepoints in sheep spine surgery models.

Methods: We identified published sheep fusion studies using autograft, interbody cages, and/or instrumentation. Fusion data were extracted, converted to a common scale, and analyzed across studied timepoints.

Results: Overall, 29 studies of 360 fusion levels were identified: 11 ALIF (158 levels), 3 PLIF/TLIF (28 levels), 8 PLF (90 levels), and 7 ACDF (84 levels). Studied timepoints ranged from 4 to 48 weeks postoperative. In general, fusion rates varied across techniques and instrumentation. The time to reach solid fusion differed by as many as 20 weeks between control groups.

Conclusions: Recommended timeframes for future studies designed to show either superiority over controls or equivalent outcomes with controls were developed based on aggregate results. Designating ideal study endpoints for sheep fusion models has both ethical implications associated with responsible use of animals in research, and economic implications given the cost of animal research. The current results can guide the development of future research methods and help investigators choose appropriate study timelines for various control groups.
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http://dx.doi.org/10.1007/s00586-016-4544-yDOI Listing
January 2017

Patient-Specific Templating of Lumbar Total Disk Replacement to Restore Normal Anatomy and Function.

Orthopedics 2016 Mar-Apr;39(2):97-102

The purpose of this study was to develop a tool to determine optimal placement and size for total disk replacements (TDRs) to improve patient outcomes of pain and function. The authors developed a statistical shape model to determine the anatomical variables that influence the placement, function, and outcome of lumbar TDR. A patient-specific finite element analysis model has been developed that is now used prospectively to identify patients suitable for TDR and to create a surgical template to facilitate implant placement to optimize range of motion and clinical outcomes. Patient factors and surgical techniques that determine success regarding function and pain are discussed in this article.
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http://dx.doi.org/10.3928/01477447-20160304-06DOI Listing
December 2016

Sacroiliac Joint Treatment Personalized to Individual Patient Anatomy Using 3-Dimensional Navigation.

Orthopedics 2016 Mar-Apr;39(2):89-94

During the past 10 years, the sacroiliac (SI) joint has evolved from being barely recognized as a source of pain, to being a joint treated only nonsurgically or with great surgical morbidity, to currently being a joint treated with minimally invasive techniques that are personalized to the individual patient. The complex 3-dimensional anatomy of the SI joint and lack of parallel to traditional imaging planes requires a thorough understanding of the structures within and around the SI joint that may be at risk of injury. Thus, the SI joint is ideally suited for intraoperative 3-dimensional imaging and surgical navigation when being treated minimally invasively.
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http://dx.doi.org/10.3928/01477447-20160304-05DOI Listing
December 2016

A new 3-dimensional method for measuring precision in surgical navigation and methods to optimize navigation accuracy.

Eur Spine J 2016 06 22;25(6):1764-74. Epub 2015 Sep 22.

Department of Orthopedics, University of Colorado Anschutz Medical Campus, 12631 E. 17th Ave, Mail Stop B202, Aurora, CO, 80045, USA.

Purpose: Description of a novel method for evaluation of pedicle screws in 3 dimensions utilizing O-arm(®) and StealthStation(®) navigation; identifying sources of error, and pearls for more precise screw placement.

Methods: O-arm and StealthStation navigation were utilized to place pedicle screws. Initial and final O-arm scans were performed, and the projected pedicle probe track, projected pedicle screw track, and final screw position were saved for evaluation. They were compared to evaluate the precision of the system as well as overall accuracy of final screw placement.

Results: Thoracolumbar deformity patients were analyzed, with 153 of 158 screws in adequate position. Only 5 screws were malpositioned, requiring replacement or removal. All 5 were breached laterally and no neurologic or other complications were noted in any of these patients. This resulted in 97 % accuracy using the navigation system, and no neurological injuries or deficits. The average distance of the screw tip and angle of separation for the predicted path versus the final pedicle screw position were analyzed for precision. The mean screw tip distance from the projected tip was 6.43 mm, with a standard deviation of 3.49 mm when utilizing a navigated probe alone and 5.92 mm with a standard deviation of 3.50 mm using a navigated probe and navigated screwdriver (p = 0.23). Mean angle differences were 4.02° and 3.09° respectively (p < 0.01), with standard deviations of 2.63° and 2.12°.

Conclusions: This new technique evaluating precision of screw placement in 3 dimensions improves the ability to define screw placement. Pedicle screw position at final imaging showed the use of StealthStation navigation to be accurate and safe. As this is a preliminary evaluation, we have identified several factors affecting the precision of pedicle screw final position relative to that predicted with navigation.
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http://dx.doi.org/10.1007/s00586-015-4235-0DOI Listing
June 2016

Patient-Controlled Transdermal Fentanyl Versus Intravenous Morphine Pump After Spine Surgery.

Orthopedics 2015 Sep;38(9):e819-24

Patient-controlled analgesia (PCA) is regularly used to manage pain following major surgery. The fentanyl hydrochloride iontophoretic transdermal system (ITS) was developed to overcome some of the limitations of intravenous (IV) PCA. The small, self-adhesive, needle-free disposable system is applied to the skin on the upper arm or chest and is controlled by patients clicking a button on the device. The authors identified patients who were underwent spinal surgery from 2 prior multicenter, randomized studies and analyzed their data. Of the 1296 patients in the original trials, 170 underwent spine surgery procedures: 90 were randomized to the fentanyl ITS (40 mcg/activation) and 80 to IV PCA morphine (1 mg/dose). More patients treated with the fentanyl ITS rated their method of pain control as "excellent" across all time points, but differences did not reach statistical significance. However, investigators' ratings of "excellent" satisfaction with study treatment were significantly higher for the fentanyl ITS. Discontinuation rates and overall adverse event rates were similar between groups. The only significant difference was that patients treated with the fentanyl ITS had a higher rate of application site reactions than infusion site reactions in the IV PCA morphine group; the reactions were typically mild-to-moderate erythema that resolved shortly after removal of the fentanyl ITS device and did not require further treatment. Ratings of satisfaction with pain control method were consistently higher for the fentanyl ITS than the IV PCA morphine. The 2 groups had a similar safety profile. These results suggest that the fentanyl ITS appears to be a safe, efficacious alternative to IV PCA in spine surgery patients.
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http://dx.doi.org/10.3928/01477447-20150902-61DOI Listing
September 2015

Predictors of spine deformity progression in adolescent idiopathic scoliosis: A systematic review with meta-analysis.

World J Orthop 2015 Aug 18;6(7):537-58. Epub 2015 Aug 18.

Andriy Noshchenko, Emily M Lindley, Evalina L Burger, Christopher MJ Cain, Vikas V Patel, Department of Orthopaedics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, United States.

Aim: To evaluate published data on the predictors of progressive adolescent idiopathic scoliosis (AIS) in order to evaluate their efficacy and level of evidence.

Methods:

Selection Criteria: (1) study design: randomized controlled clinical trials, prospective cohort studies and case series, retrospective comparative and none comparative studies; (2) participants: adolescents with AIS aged from 10 to 20 years; and (3) treatment: observation, bracing, and other.

Search Method: Ovid MEDLINE, Embase, the Cochrane Library, PubMed and patent data bases. All years through August 2014 were included. Data were collected that showed an association between the studied characteristics and the progression of AIS or the severity of the spine deformity. Odds ratio (OR), sensitivity, specificity, positive and negative predictive values were also collected. A meta-analysis was performed to evaluate the pooled OR and predictive values, if more than 1 study presented a result. The GRADE approach was applied to evaluate the level of evidence.

Results: The review included 25 studies. All studies showed statistically significant or borderline association between severity or progression of AIS with the following characteristics: (1) An increase of the Cobb angle or axial rotation during brace treatment; (2) decrease of the rib-vertebral angle at the apical level of the convex side during brace treatment; (3) initial Cobb angle severity (> 25(o)); (4) osteopenia; (5) patient age < 13 years at diagnosis; (6) premenarche status; (7) skeletal immaturity; (8) thoracic deformity; (9) brain stem vestibular dysfunction; and (10) multiple indices combining radiographic, demographic, and physiologic characteristics. Single nucleotide polymorphisms of the following genes: (1) calmodulin 1; (2) estrogen receptor 1; (3) tryptophan hydroxylase 1; (3) insulin-like growth factor 1; (5) neurotrophin 3; (6) interleukin-17 receptor C; (7) melatonin receptor 1B, and (8) ScoliScore test. Other predictors included: (1) impairment of melatonin signaling in osteoblasts and peripheral blood mononuclear cells (PBMC); (2) G-protein signaling dysfunction in PBMC; and (3) the level of platelet calmodulin. However, predictive values of all these findings were limited, and the levels of evidence were low. The pooled result of brace treatment outcomes demonstrated that around 27% of patents with AIS experienced exacerbation of the spine deformity during or after brace treatment, and 15% required surgical correction. However, the level of evidence is also low due to the limitations of the included studies.

Conclusion: This review did not reveal any methods for the prediction of progression in AIS that could be recommended for clinical use as diagnostic criteria.
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http://dx.doi.org/10.5312/wjo.v6.i7.537DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4539477PMC
August 2015

What Is the Clinical Relevance of Radiographic Nonunion After Single-Level Lumbar Interbody Arthrodesis in Degenerative Disc Disease?: A Meta-Analysis of the YODA Project Database.

Spine (Phila Pa 1976) 2016 Jan;41(1):9-17

Department of Orthopedics, University of Colorado Anschutz Medical Campus, Aurora, CO.

Study Design: Meta-analysis of 4 randomized controlled clinical trials (RCTs).

Objective: The aim of the study was to determine if patients with degenerative disc disease who achieve radiographic fusion after single-level lumbar interbody arthrodesis have better clinical outcomes than patients with radiographic pseudarthrosis at 12 and 24 months postoperative.

Summary Of Background Data: The clinical relevance of successful fusion after lumbar arthrodesis with recombinant human bone morphogenetic protein-2 or iliac crest bone autograft has recently been questioned in the literature.

Methods: Individual patient-level data of 4 RCTs were obtained from the Yale University Open Data Access Project project and analyzed. Clinical outcomes (Oswestry Disability Index [ODI]; Numeric Rating Scales [NRSs] for back and leg pain) were compared between patients with radiographically confirmed fusion and those with radiographic nonunion 1 and 2 years postoperative. The results of each study were first analyzed separately, and then were pooled by meta-analysis. The GRADE approach was applied to evaluate the level of evidence.

Results: A total of 496 patients with clinical and radiographic data at 1- and 2-year follow-ups were identified. Of these, 5.5% (95% confidence interval: 3.7; 8.3) had radiographic nonunion which did not require reoperation. Patients with fusion had better improvements in ODI (P < 0.001) and NRS back pain scores (P < 0.001). The overall percentage of fused patients with ODI and NRS back pain scores that exceeded the criteria for minimal clinically important differences was also significantly higher than that of patients with nonunion (ODI, odds ratio [OR] = 2.7, P = 0.019; NRS back pain, OR = 3.5, P = 0.033). The predictive values of fusion for clinical outcomes, however, were poor, with low specificity and low negative predictive values.

Conclusion: The presence of radiographic fusion is clinically significant, as patients with fusion had better clinical outcomes at 1 and 2 years postoperative than those with nonunion; however, patient-centered clinical outcomes should also be taken into consideration as independent, complimentary variables when assessing treatment success.
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http://dx.doi.org/10.1097/BRS.0000000000001113DOI Listing
January 2016

Discography with epidural contrast extravasation along an exiting nerve root.

Spine J 2015 Apr 25;15(4):782. Epub 2014 Nov 25.

Department of Orthopedic Surgery, University of Colorado, Anschutz Medical Campus, 13001 E 17th Place, Aurora, CO 80045, USA.

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http://dx.doi.org/10.1016/j.spinee.2014.10.030DOI Listing
April 2015

ScoliScore: Is It Enough?

Spine Deform 2014 Jul 2;2(4):239-240. Epub 2014 Jul 2.

Department of Orthopedics, Spine Division, University of Colorado, Anschutz Medical Campus, 12631 E 17th Avenue, Room 4603, Aurora, CO 80045, USA.

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http://dx.doi.org/10.1016/j.jspd.2014.04.007DOI Listing
July 2014

Perioperative and long-term clinical outcomes for bone morphogenetic protein versus iliac crest bone graft for lumbar fusion in degenerative disk disease: systematic review with meta-analysis.

J Spinal Disord Tech 2014 May;27(3):117-35

*Department of Orthopedics †Health Sciences Library, University of Colorado Anschutz Medical Campus, Aurora, CO.

Study Design: Systematic review with meta-analysis.

Objectives: To compare the perioperative and long-term postoperative effectiveness of bone morphogenetic protein (BMP) for lumbar arthrodesis in skeletally mature adults with degenerative disk disease (DDD) to that of the current golden standard treatment, iliac crest autologous bone graft (ICBG).

Summary Of Background Data: The treatment efficacy of lumbar arthrodesis in DDD is a complex clinical and economic issue for patients and health care providers.

Methods: Comprehensive electronic literature search was performed using following databases: Ovid MEDLINE; Embase; Cochrane Library; Central Register of Controlled Trials (CENTRAL); Database of Abstracts of Reviews of Effects; Methodology Register; Technology Assessment Database; and Economic Evaluation Database. The full year ranges of each database until May of 2012 were included.

Results: Eight randomized controlled clinical trials of 383 citations were selected. The included studies involved 1138 participants. The pooled 2-year postoperative clinical outcomes were equivalent in BMP and ICBG groups, and exceeded minimum clinically important differences for Oswestry Disability Index, SF-36 (physical scale), and numeric rating scale (back pain). ICBG was associated with increased pain and complications at the donor site (P<0.01). The pooled average operative time was 21 minutes less in BMP versus ICBG (P<0.001). The pooled rate of additional surgical treatment was 2 times less in the BMP than in the ICBG groups (P=0.006). The pooled risk of nonunion at 24-month follow-up was 2 times less in the BMP than in the ICBG groups (P=0.037), however, this effect was likely biased.

Conclusions: BMP, in particular rhBMP-2, is a good alternative to autogenous bone graft, especially in cases when harvesting of autologous bone is contraindicated or undesirable, operation time is limited, and there are no contraindications for BMP use.However, the current study did not reveal evidence robust enough to develop strong medical recommendations concerning BMP use for lumbar arthrodesis in degenerative disk disease.
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http://dx.doi.org/10.1097/01.bsd.0000446752.34233.caDOI Listing
May 2014

Long-term Treatment Effects of Lumbar Arthrodeses in Degenerative Disk Disease: A Systematic Review With Meta-Analysis.

J Spinal Disord Tech 2015 Nov;28(9):E493-521

*Department of Orthopaedics †Health Sciences Library, University of Colorado, Anschutz Medical Campus, Aurora, CO.

Study Design: Systematic review with meta-analysis.

Objective: To (1) evaluate long-term patient-centered clinical outcomes after lumbar arthrodesis with or without decompression for lumbar spondylosis (LS); and (2) compare these outcomes with those of alternative treatments, including nonsurgical and surgical which maintain mobility of the lumbar spine.

Summary Of Background Data: The effective treatment of LS is a complex clinical and economic concern for patients and health care providers.

Methods:

Selection Criteria: (1) randomized controlled clinical trials (RCTs) comparing treatment effects of lumbar arthrodesis with other interventions; (2) participants: skeletally mature adults with lumbar degenerative disk disease.

Search Methods: Ovid MEDLINE, Embase, the Cochrane Library, and others. All years through February of 2013 were included. Patient-centered clinical outcomes before treatment, at 12, 24, or >24 months of follow-up, and rate of complications and additional surgical treatment were collected. A meta-analysis was performed to evaluate pooled treatment effects. The GRADE approach was applied to evaluate the level of evidence.

Results: The review included 38 studies of 5738 participants. All studies showed strong or at least moderate treatment effects of lumbar arthrodesis at 12, 24, and 48-72 months of follow-up. The level of evidence was moderate at 12 and 24 months, and low at 48-72 months. The pooled long-term treatment effect of lumbar arthrodesis exceeded those of: nonsurgical treatment (P<0.0001) with a moderate level of evidence, and decompression without fusion (P=0.005) with a low level of evidence. The treatment effect of lumbar arthrodesis showed a small inferiority versus arthroplasty at 12 and 24 months of follow-up (P<0.001), but not after 24 months postoperative.

Conclusions: This review indicates that surgical stabilization of the lumbar spine is an effective treatment for LS; in particular, for patients with severe chronic low back pain that has been resistant to ≥3 months of conservative therapy.
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http://dx.doi.org/10.1097/BSD.0000000000000124DOI Listing
November 2015

Mineralization and collagen orientation throughout aging at the vertebral endplate in the human lumbar spine.

J Struct Biol 2013 Nov 30;184(2):310-20. Epub 2013 Aug 30.

Department of Mechanical Engineering, University of Colorado at Boulder, United States.

The human vertebral body and intervertebral disc interface forms the region where the cartilaginous endplate, annulus fibrosis and bone of the vertebral body are connected through an intermediate calcified cartilage layer. While properties of both the vertebral body and components of the disc have been extensively studied, limited quantitative data exists describing the microstructure of the vertebral body-intervertebral disc interface in the spine throughout development and degeneration. Quantitative backscattered scanning electron and second harmonic generation confocal imaging were used to collect quantitative data describing the mineral content and collagen fiber orientation across the interface, respectively. Specimens spanned ages 56 days to 84 years and measurements were taken across the vertebral endplate at the outer annulus, inner annulus and nucleus pulposis. In mature and healthy endplates, collagen fibers span the calcified cartilage layer in all regions, including the endplate adjacent to the central nucleus pulposis. We also observed an abrupt transition from high mineral volume fractions (35-50%) to 0% over short distances measuring 3-15 microns in width across the transition from calcified cartilage to unmineralized cartilage. The alignment of collagen fibers at the outer annulus and thickness of the CC layer indicated that collagen fiber mineralization adjacent to the bone may serve to anchor the soft tissue without a gradual change in material properties. Combining backscattered scanning electron microscopy and second harmonic generation imaging on the same sections thus enable a novel assessment of morphology and properties in both mineralized and soft tissues at the vertebral body-intervertebral disc throughout development and aging.
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http://dx.doi.org/10.1016/j.jsb.2013.08.011DOI Listing
November 2013

C1-C2 fusion: postoperative C2 nerve impingement-is it a problem?

Evid Based Spine Care J 2012 Feb;3(1):53-6

The Spine Center, Department of Orthopaedics, University of Colorado, Denver, CO, USA.

Objective:  The purpose of this comparison case study is to show a potential complication associated with atlantoaxial fusion, and the preoperative evaluation that could help to avoid it.

Background Data:  The use of lateral mass screw fixation in atlantoaxial fusion has provided surgeons the ability to create rigid fixation, with a high success rate of fusion. While the use of screws for fixation is relatively easy to adopt, the risk of causing neurological damage to the patient is ever present. Many major structures, such as the vertebral artery, carotid artery, and spinal cord, must all be considered during surgery.

Methods:  A comparison of two patients who underwent the same procedure was reviewed-the first had no complications from surgery and the second underwent revision surgery because of the C1 screw impinging on the C1 nerve exiting the foramen.

Results:  After removal of the C1 screw and converting to a cable technique, the patient made a full recovery and neurological function was restored.

Conclusions:  When considering C1-C2 lateral mass screw fixation for atlantoaxial fusion, the size of the foramen should be considered. If the foramen is significantly narrowed, alternate fixation should be selected.
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http://dx.doi.org/10.1055/s-0031-1298601DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3503508PMC
February 2012

Retrograde ejaculation after anterior lumbar spine surgery.

Spine (Phila Pa 1976) 2012 Sep;37(20):1785-9

Department of Orthopaedics, The Spine Center, University of Colorado Denver, Anschutz Medical Campus, Denver, CO, USA.

Study Design: A retrospective cohort study.

Objective: To compare the incidence of retrograde ejaculation (RE) after anterior lumbar spine surgery with disc replacement versus fusion with the use of recombinant human bone morphogenetic protein-2 (BMP).

Summary Of Background Data: Anterior lumbar interbody fusion (ALIF) has become a popular choice for treating a number of pathologies, largely because it preserves the posterior paravertebral muscles and ligaments. Despite these advantages, the anterior approach is also associated with various complications, one of which is RE. A recent study has questioned whether the risk of RE is increased by the use of BMP in ALIF procedures rather than by the approach alone.

Methods: We conducted a retrospective review of all male patients who received ALIF using BMP or artificial disc replacement (ADR) on at least the L5-S1 level between 2004 and 2011. Medical records were evaluated for the occurrence of RE, and patients were contacted via the phone to obtain current information. The incidence of RE was then compared between the 2 anterior lumbar surgery procedures.

Results: Of the 95 cases of anterior surgery including L5-S1, 54 patients underwent ALIF with BMP (56.8%) and 41 patients were treated with ADR (43.2%). Postoperative RE occurred in 4 of the 54 ALIF patients (7.4%) and in 4 of the 41 ADR patients (9.8%). The incidence of RE was not significantly different between groups (P = 0.7226). At latest follow-up, 1 ALIF and 1 ADR patient reported resolution of the RE.

Conclusion: This study found that RE occurred at a similar rate in patients treated with ADR and ALIF with BMP. The overall rate of RE after retroperitoneal anterior lumbar surgery was higher than expected, which underscores the importance of counseling patients about this risk and specifically questioning patients about the symptoms of RE at postoperative visits.
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http://dx.doi.org/10.1097/BRS.0b013e31825752bcDOI Listing
September 2012

L5 hemivertebra resection and T12-S1 fusion in a 14-year-old female with a 36-year follow-up.

Spine (Phila Pa 1976) 2012 Apr;37(7):E445-50

Twin Cities Spine Center, Minneapolis, MN, USA.

Study Design: Case report.

Objective: To demonstrate a 36-year follow-up of a rare operation.

Summary Of Background Data: There have been no reports of follow-up of pediatric hemivertebra excision and fusion into midadult life.

Methods: A chart and radiological review at 36 years after surgery.

Results: The patient is alive and well and leading a normal life. Her Oswestry Disability Index is 0. Mild degenerative radiological signs are evident at the adjacent level above (T10-T12) and below (sacroiliac joints).

Conclusion: Early excision of the L5 hemivertebra would have been preferable, but the long-term results are good.
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http://dx.doi.org/10.1097/BRS.0b013e31824a4b26DOI Listing
April 2012

Pedicle screw placement with O-arm and stealth navigation.

Orthopedics 2012 Jan 16;35(1):e61-5. Epub 2012 Jan 16.

The Spine Center, Department of Orthopaedics, University of Colorado, Mail Stop B202, 12631 E 17th Ave, Aurora, CO 80045, USA.

Various navigation systems are available to aid pedicle screw placement. The O-arm replaces the need for fluoroscopy and generates a 3-dimensional volumetric dataset that can be viewed as transverse, coronal, and sagittal images of the spine, similar to computed tomography (CT) scanning. The dataset can be downloaded to the Stealth system (Medtronic Navigation, Louisville, Colorado) for real-time intraoperative navigation.The main objectives of the current study were to assess (1) accuracy of pedicle screw placement using the O-arm/Stealth system, and (2) time for draping, positioning of the O-arm, and screw placement. Of 188 screws (25 patients), 116 had adequate images for analysis. The average time for O-arm draping was 3.5 minutes. Initial O-arm positioning was 6.1 minutes, and final positioning was 4.9 minutes. Mean time for screw placement, including O-arm draping and positioning and array attachment, was 8.1 minutes per screw. Mean time for screw placement alone was 5.9 minutes per screw. Screw placements on final O-arm images were on average 3.14 mm deeper than on the snapshot navigation images. Three screws (2.6%) breached the medial cortex, and 3 screws (2.6%) were misaligned and did not follow the pilot hole trajectory.The use of the O-arm/Stealth system was associated with a low rate of pedicle screw misalignment. The time to place screws was less than previously reported with CT navigation, but longer than conventional techniques. It is important to be aware of the potential discrepancy between snapshot navigation images and actual screw placement on final O-arm images. Our findings suggest that final screw positions may be deeper than awl positions appear on navigation images.
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http://dx.doi.org/10.3928/01477447-20111122-15DOI Listing
January 2012

Lumbar artificial disc replacement in Ehlers-Danlos syndrome: A case report and discussion of clinical management.

Int J Spine Surg 2012 1;6:124-9. Epub 2012 Dec 1.

Department of Orthopaedics, University of Colorado Denver, Anschutz Medical Campus, Denver, CO.

Background: Ehlers-Danlos syndrome (EDS) is a heterogeneous collection of connective tissue disorders characterized by varying degrees of skin hyperextensibility, joint hypermobility, and tissue fragility. Surgical treatment of EDS patients is complicated by the extreme fragility of their vessels and tissues. The purpose of this case report is to present the management of an EDS patient with debilitating low-back pain.

Methods: A 52-year-old woman with a clinical diagnosis of EDS presented with degenerative disc disease at L4-5 that had not been alleviated by previous microdiscectomies. The clinical course, decision-making process, and treatment are discussed in this case report.

Results: The patient was referred for genetic evaluation, which classified her with type III EDS, or hypermobility type. We presented the patient with the risks and benefits of fusion versus artificial disc replacement (ADR), particularly with regard to her EDS diagnosis of the hypermobility subtype. Given the patient's lack of extreme spinal hypermobility on examination and the absence of clear contraindications regarding ADR in type III EDS, the decision was made to proceed with ADR. There were no surgical complications, and the patient's low-back pain and radicular symptoms resolved with no evidence of implant migration or hypermobility at 1 year postoperatively.

Conclusions: In this case report, the referral to a geneticist and consultation with a vascular surgeon were integral steps in the decision to proceed with surgery. Although the clarified diagnosis of type III EDS did not eliminate the potential risk for vascular compromise during surgery, it placed the patient at lower risk than patients with other subtypes of EDS. Similarly, her lack of extreme hypermobility made us more comfortable with pursuing ADR. Although we emphasize extreme caution when considering surgical treatment, this case report suggests that some patients with less severe forms of EDS may be able to successfully undergo anterior spine surgery, including ADR.
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http://dx.doi.org/10.1016/j.ijsp.2012.02.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4300890PMC
February 2015

Unusual spine anatomy contributing to wrong level spine surgery: a case report and recommendations for decreasing the risk of preventable 'never events'.

Patient Saf Surg 2011 Dec 14;5(1):33. Epub 2011 Dec 14.

Department of Orthopaedics, University of Colorado Denver, Denver CO, USA.

Background: Wrong site surgery is one of five surgical "Never Events," which include performing surgery on the incorrect side or incorrect site, performing the wrong procedure, performing surgery on the wrong patient, unintended retention of a foreign object in a patient, and intraoperative/immediate postoperative death in an ASA Class I patient. In the spine, wrong site surgery occurs when a procedure is performed on an unintended vertebral level. Despite the efforts of national safety protocols, literature suggests that the risk for wrong level spine surgery remains problematic.

Case Presentation: A 34-year-old male was referred to us to evaluate his persistent thoracic pain following right-sided microdiscectomy at T7-8 at an outside institution. Postoperative imaging showed the continued presence of a herniated disc at T7-8 and evidence of a microdiscectomy at the level immediately above. The possibility that wrong level surgery had occurred was discussed with the patient and revision surgery was planned. During surgery, the site of the previous laminectomy was clearly visualized; however, we also experienced confusion when verifying the level of the previous surgery. We ultimately used the previous laminectomy site as a landmark for identifying and treating the correct pathologic level. Postoperative consultation with Musculoskeletal Radiology revealed the patient had two abnormalities in his spinal anatomy that made intraoperative counting of levels inaccurate, including a pair of cervical ribs at C7 and the absence of a pair of thoracic ribs.

Conclusion: This case highlights the importance of strict adherence to a preoperative method of vertebral labeling that focuses on the landmarks used to label a pathologic disc space, rather than simply relying on the reference to a particular level. That is, by designating the pathological level as the disc space associated with the fourth rib up from the last rib-bearing vertebrae, rather than calling it "T7-8", then the correct level can be found intraoperatively even in the case of abnormal segmentation. We recommend working closely with radiology during preoperative planning to identify unusual anatomy that may have been overlooked. We also recommend that radiology colleagues use the same system of identifying pathological levels when dictating their reports. Together, these strategies can reduce the risk of wrong level surgery and increase patient safety.
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http://dx.doi.org/10.1186/1754-9493-5-33DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3259034PMC
December 2011

A biomechanical study on the effects of rib head release on thoracic spinal motion.

Eur Spine J 2012 Apr 13;21(4):606-12. Epub 2011 Oct 13.

Showa Ika Kohgyo Company, Toyohashi, Japan.

Purpose: Idiopathic scoliosis is generally treated by surgical derotation of the spine. A secondary goal of surgery is minimization of the "rib hump" deformity. Previous studies have evaluated the effects of surgical releases such as diskectomy, costo-vertebral joint release, facetectomy, and costoplasty on spine mobilization and overall contribution to thoracic stability. The present study was designed to evaluate the biomechanical effects of the rib head joints alone on axial rotation, lateral bending, and segmental rotation, without diskectomy or disruption of anterior or posterior elements.

Methods: Four female cadaver thoracic spines with intact sternums and rib cages were mounted in an Instron servo-hydraulic bi-axial MTS. In a 12-step sequence, the costo-vertebral and costo-transverse ligaments were released, first unilaterally from T10-T7, then bilaterally until complete disarticulation between the rib heads and the vertebral bodies. After each release, biomechanical testing, including axial rotation and lateral bending, was performed. Vertebral body displacement was also measured using electromagnetic trackers.

Results: We found that rib displacement during axial rotation was significantly increased by unilateral rib head release, and torque was decreased with each successive cut. We also found increased vertebral displacement with sequential rib head release.

Conclusions: Our results show that sequential costo-vertebral joint releases result in a decrease in the force required for axial rotation and lateral bending, coupled with an increase in the displacement of vertebral bodies. These findings suggest that surgical release of the costo-transverse and costo-vertebral ligaments can facilitate segmental correction in scoliosis by decreasing the torso's natural biomechanical resistance to this correction.
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http://dx.doi.org/10.1007/s00586-011-2031-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3326120PMC
April 2012

Failure of resorbable plates and screws in an ovine model of anterior cervical discectomy and fusion.

Spine J 2011 Sep 20;11(9):876-83. Epub 2011 Jul 20.

Orthopaedic Bioengineering Research Laboratory, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA.

Background Context: Containment plates are often placed anteriorly in anterior cervical discectomy and fusion (ACDF) to provide stability and prevent migration of the interbody device or autograft. The main advantage of a bioresorbable plate over the typical metallic plate is that it will resorb after fusion has occurred, thus mitigating any long-term instrumentation-related complications. Furthermore, the plates are radiolucent, allowing complete visualization of the fusion site and eliminating imaging artifact.

Purpose: To evaluate radiographic fusion, mechanical success rates, and histologic characteristics of a bioresorbable containment plate and screws in a 3-month ovine model of ACDF.

Study Design: An in vivo prospective analysis of resorbable anterior cervical plates and screws for use in ACDF in an ovine model.

Methods: Six sheep underwent C2-C3 and C4-C5 discectomies. Fusions were performed using a polyetheretherketone cage filled with autograft bone. A polymeric plate (70/30 poly-dl-lactic acid), and four screws were placed over an intervertebral disc spacer at each of these two levels. After 3 months, the animals were euthanized and radiographically imaged. Radiographs were analyzed for fusion and instrumentation failures. Functional spinal units were harvested for histologic processing and evaluation.

Results: Radiographic fusion was noted in three of the 12 levels with no evidence of device failure at any of the levels. However, at necropsy, it was observed that six of the 12 specimens had either a broken screw or a cracked plate. These gross observations were confirmed within the histologic sections. Fusion was verified histologically at C2-C3 in three of the six sheep; none of the fusions were successful at C4-C5. Histologic analysis also found that the tissue surrounding the plate and disc spacer consisted of vascularized fibrous tissue with islands of active woven bone. Inflammatory cells were rarely observed.

Conclusions: Although the bioresorbable plates and screws did not elicit an iatrogenic tissue response, a high percentage of them failed mechanically. This phenomenon was difficult to observe radiographically, as the radiolucent markers were not able to convey these instrumentation failures. Additionally, there was only a 25% fusion rate. These findings suggest that resorbable implant materials with the current biomechanical and chemical properties are inadequate for cervical fusion. The results of this study strongly suggest that radiographic outcomes alone may not be adequate and that gross or histologic methods should accompany radiographs in studies of bioresorbable materials in animal models.
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http://dx.doi.org/10.1016/j.spinee.2011.06.016DOI Listing
September 2011

Complications of axial lumbar interbody fusion.

J Neurosurg Spine 2011 Sep 20;15(3):273-9. Epub 2011 May 20.

The Spine Center, Department of Orthopaedics, University of Colorado, Denver, Aurora, Colorado 80045, USA.

Object: Axial lumbar interbody fusion (AxiaLIF) is a novel minimally invasive approach for fusion of L4-5 and L5-S1. This technique uses the presacral space for percutaneous access to the anterior sacrum. The AxiaLIF procedure has the potential to decrease patient recovery time, length of hospital stay, and overall occurrence of surgical complications. It can be used alone or in combination with minimally invasive or traditional open fusion procedures. The purpose of this study was to evaluate complications of the AxiaLIF procedure at the authors' institutions.

Methods: Patients who underwent AxiaLIF surgery between October 2005 and June 2009 at the authors' institutions were identified. The authors retrospectively reviewed these patients' charts, including operative reports and postoperative medical records, to determine what complications were encountered.

Results: A total of 68 patients underwent AxiaLIF surgery, with an average follow-up time of 34 months. Sixteen patients (23.5%) experienced a total of 18 complications (26.5%); this group included 8 men and 8 women (mean age 52.1 years). These complications included pseudarthrosis (8.8%), superficial infection (5.9%), sacral fracture (2.9%), pelvic hematoma (2.9%), failure of wound closure (1.5%), transient nerve root irritation (1.5%), and rectal perforation (2.9%).

Conclusions: The complication rate associated with AxiaLIF in the present study was relatively low (26.5%). The most common complications were superficial infection and pseudarthrosis. There were 2 cases of rectal perforation associated with AxiaLIF; one case was found intraoperatively and the other presented 4 days postoperatively. Both patients underwent emergency repair by a general surgeon and had no long-term sequelae as a result of the rectal injuries. It is important for surgeons to be aware of the potential for these complications. Many of these complications can probably be avoided with proper patient selection and operative planning. Preoperative MR imaging, a detailed patient physical examination and history, full bowel preparation, and the use of live fluoroscopy can all help to prevent complications with AxiaLIF surgery.
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http://dx.doi.org/10.3171/2011.3.SPINE10373DOI Listing
September 2011
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