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Study Design: A retrospective cohort study., Objective: To present the technique, radiographic, and clinical outcomes of a series of patients who underwent a novel method for revision L5-S1 interbody fusion., Summary of Background Data: Pseudoarthrosis at L5-S1 is a relatively common problem after long fusion to the sacrum. Revision approach to L5-S1 for cage or graft removal by anterior lumbar interbody fusion, posterior lumbar interbody fusion, or transforaminal interbody fusion is challenging and potentially dangerous which makes salvage by a posterior reamed transacral technique appealing., Methods: Consecutive patients with symptomatic pseudoarthrosis at L5-S1, who underwent posterior reamed fluoroscopically guided fusion were identified over a 3-year period. Operative notes, medical records, preoperative and postoperative plain radiographs, computed tomography scans, Visual Analog Scores (VAS) (lower extremity and low back) preoperatively, and at most recent follow-up were studied., Results: Ten patients (age, 53±2.8 y) with prior lumbar spinal operations (mean, 3.5±0.6) met the inclusion criteria. Prior procedures at L5-S1 were anterior lumbar interbody fusion (n=4), posterior lumbar interbody fusion (n=3), and posterolateral fusion (n=3). Mean Meyerding grade was 1.41 (range, 0-4). Reaming was performed between the S1 and S2 (n=9) or S2 and S3 (n=1) nerve roots and allowed fragmentation/removal of polyetheretherketone interbody grafts (n=3) or femoral ring allografts (n=3). Transacral Harms cage (n=8) or autograft (n=1) was passed through the reamed channel or a carbon fiber-reinforced polyetheretherketone directly into the interspace (n=1). VAS scores lower extremity (P=0.003) and low back (P=0.001) were improved at a mean follow-up of 13.5±3.6 months. No neurologic sequelae occurred and solid fusion was achieved in 9/10 (90%)., Conclusions: We report a series of patients who underwent a novel revision technique for symptomatic lumbosacral pseudoarthrosis. Despite the small numbers in this cohort, a salvage technique is presented that permitted fusion as confirmed by computed tomography scan and improved VAS scores in the majority of patients. The data suggest that this technique should be considered as an alternative to the revision anterior or posterior approaches to L5-S1 and merits further investigation.

Study Design: Retrospective analysis of prospective registry data., Objective: To determine the patient characteristics, risk factors, and fracture patterns associated with vertebral artery injury (VAI) in patients with blunt cervical spine injury., Summary of Background Data: VAI associated with cervical spine trauma has the potential for catastrophical clinical sequelae. The patterns of cervical spine injury and patient characteristics associated with VAI remain to be determined., Methods: A retrospective review of prospectively collected data from the American College of Surgeons trauma registries at 3 level-1 trauma centers identified all patients with a cervical spine injury on multidetector computed tomographic scan during a 3-year period (January 1, 2007, to January 1, 2010). Fracture pattern and patient characteristics were recorded. Logistic multivariate regression analysis of independent predictors for VAI and subgroup analysis of neurological events related to VAI was performed., Results: Twenty-one percent of 1204 patients with cervical injuries (n = 253) underwent screening for VAI by multidetector computed tomography angiogram. VAI was diagnosed in 17% (42 of 253), unilateral in 15% (38 of 253), and bilateral in 1.6% (4 of 253) and was associated with a lower Glasgow coma scale (P < 0.001), a higher injury severity score (P < 0.01), and a higher mortality (P < 0.001). VAI was associated with ankylosing spondylitis/diffuse idiopathic skeletal hyperosteosis (crude odds ratio [OR] = 8.04; 95% confidence interval [CI], 1.30-49.68; P = 0.034), and occipitocervical dissociation (P < 0.001) by univariate analysis and fracture displacement into the transverse foramen 1 mm or more (adjusted OR = 3.29; 95% CI, 1.15-9.41; P = 0.026), and basilar skull fracture (adjusted OR = 4.25; 95% CI, 1.25-14.47; P= 0.021), by multivariate regression model. Subgroup analyses of neurological events secondary to VAI occurred in 14% (6 of 42) and the stroke-related mortality rate was 4.8% (2 of 42). Neurological events were associated with male sex (P = 0.024), facet subluxation/dislocation (crude OR = 9.00; 95% CI, 1.51-53.74; P = 0.004) and the diagnosis of ankylosing spondylitis/diffuse idiopathic skeletal hyperosteosis (OR = 40.67; 95% CI, 5.27-313.96; P < 0.001)., Conclusion: VAI associated with blunt cervical spine injury is a marker for more severely injured patients. High-risk patients with basilar skull fractures, occipitocervical dissociation, fracture displacement into the transverse foramen more than 1 mm, ankylosing spondylitis/diffuse idiopathic skeletal hyperosteosis, and facet subluxation/dislocation deserve focused consideration for VAI screening.

Study Design: Prospective in vivo radiation exposure study., Objective: To assess surgeon exposure to ionizing radiation in the setting of lateral lumbar interbody fusion (LLIF)., Summary of Background Data: Minimally invasive spine surgery relies heavily on image guidance. Rapid popularization of minimally invasive spine surgery procedures, such as LLIF, is appropriately accompanied by concern regarding occupational radiation exposure related to intraoperative fluoroscopy., Methods: Optically stimulated luminescence technology dosimeters were used to record radiation exposure prospectively at 5 anatomic locations during 18 LLIF procedures: (1) eye, (2) thyroid, (3) chest, (4) axilla, and (5) gluteal region. Additionally, a ring dosimeter was worn during 13 of the LLIF cases., Results: Average fluoroscopy time was 88.7 ± 36.8 seconds and skin dose to the patient was 25.2 ± 21.1 mGy. The chest dosimeter protected by lead recorded the lowest readings per procedure (0.44 ± 0.49 mrem). The gluteal dosimeter recorded an average exposure of 2.31 ± 4.50 mrem and the dosimeter at the axilla recorded an average of 4.20 ± 7.76 mrem per procedure. Exposure to the thyroid and eye were 2.19 ± 2.07 mrem and 2.64 ± 2.76 mrem, respectively. With the exception of the gluteal region, dosimeter readings from all unprotected areas were significantly higher than those from the chest dosimeter (P < 0.0125). In the course of 13 procedures, 190 mrem of exposure to the hand was recorded by the ring dosimeters. More than 2700 LLIF procedures may be performed annually before occupational limits are exceeded., Conclusion: Prolonged exposure to "low-level" radiation as an occupational risk remains a concern for medical personnel. Radiation exposures to unprotected, radiosensitive locations, such as the axilla or eye, are worrisome. However, following radiation safety guidelines, 2700 LLIF procedures can be performed per year before exceeding occupational dose limits. Adherence to radiation safety guidelines is necessary to avoid sequelae related to an invisible but potentially deadly risk of minimally invasive spine surgery procedures.

The advent of recombinant DNA technology has substantially increased the intra-operative utilization of biologic augmentation in spine surgery over the past several years after the Food and Drug Administration approval of the bone morphogenetic protein (BMP) class of molecules for indications in the lumbar spine. Much less is known about the potential benefits and risks of the "off-label" use of BMP in the cervical spine. The history and relevant literature pertaining to the use of the "off-label" implantation of the BMP class of molecules in the anterior or posterior cervical spine are reviewed and discussed. Early prospective studies of BMP-2 implantation in anterior cervical spine constructs showed encouraging results. Later retrospective studies reported potentially "life threatening complications" resulting in a 2007 public health advisory by the FDA. Limited data regarding BMP-7 in anterior cervical surgery was available with one group reporting a 2.4% early (< 30 d) complication rate (brachialgia and dysphagia). BMP use in the decompressed posterior cervical spine may result in neurologic or wound compromise according to several retrospective reports, however, controlled use has been reported to increase fusion rates in select complex and pediatric patients. There were no cases of de novo neoplasia related to BMP implantation in the cervical spine. BMP-2 use in anterior cervical spine surgery has been associated with a high early complication rate. Definitive recommendations for BMP-7 use in anterior cervical spine surgery cannot be made with current clinical data. According to limited reports, select complex patients who are considered "high risk" for pseudoarthrosis undergoing posterior cervical or occipitocervical arthrodesis or children with congenital or traumatic conditions may be candidates for "off-label" use of BMP in the context of appropriate informed decision making. At the present time, there are no high-level clinical studies on the outcomes and complication rates of BMP implantation in the cervical spine.

Background Context: The lateral transpsoas approach to interbody fusion of the lumbar spine (lateral lumbar interbody fusion [LLIF]) with recombinant human bone morphogenetic protein-2 (BMP-2) augmentation has been increasingly performed in recent years. Potential side effects and adverse sequelae of BMP-2 in the acute setting remain to be fully elucidated., Purpose: To review the literature for reports of complications related to BMP-2 implantation in lumbar spinal surgery and present a case of a contralateral psoas muscle seroma after LLIF with BMP-2 implantation., Study Design: Case report and literature review., Methods: The PubMed database was searched for articles related to adverse events to BMP-2 in lumbar spinal surgery. We report the case of a 57-year-old woman who underwent routine right-sided transpsoas approach for LLIF with the use of BMP-2 at our institution and developed a left-sided psoas muscle fluid accumulation 2 weeks postoperatively., Results: No reports of complications contralateral to an LLIF approach attributable to an inflammatory response to BMP-2 were identified in the English literature. In the presented patient, a large (4.2×6.5×2.7 cm) left-sided sterile intramuscular psoas fluid collection was seen on a magnetic resonance imaging study obtained on postoperative day 14. At a 6-month follow-up, left-sided L5 radiculopathy resulting in 4/5 foot drop was confirmed by electromyography. The patient reported here represents the only case of a contralateral psoas seroma with suspected association to BMP-2 utilization in LLIF encountered at our institution., Conclusions: A serous psoas muscle fluid accumulation after BMP-2 implantation may rarely occur contralateral to the surgical approach for LLIF. Further characterization of complications related to BMP-2 implantation after lumbar spinal surgery will help guide preoperative informed decision making and the management of this unusual postoperative adverse event., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Low back pain as a result of degenerative disc disease imparts a large socioeconomic impact on the health care system. Traditional concepts for treatment of lumbar disc degeneration have aimed at symptomatic relief by limiting motion in the lumbar spine, but novel treatment strategies involving stem cells, growth factors, and gene therapy have the theoretical potential to prevent, slow, or even reverse disc degeneration. Understanding the pathophysiological basis of disc degeneration is essential for the development of treatment strategies that target the underlying mechanisms of disc degeneration rather than the downstream symptom of pain. Such strategies ideally aim to induce disc regeneration or to replace the degenerated disc. However, at present, treatment options for degenerative disc disease remain suboptimal, and development and outcomes of novel treatment options currently have to be considered unpredictable.

Background Context: Increased fusion rates have been reported with the addition of an anterior cervical plate (ACP) to anterior cervical discectomy and fusion (ACDF). Bioabsorbable implants have become increasingly used in orthopedic and spine surgical procedures. There are limited data regarding the outcomes of bioabsorbable ACP (bACP) with ACDF., Purpose: To compare the clinical and radiographic outcomes of patients undergoing ACDF for single-level degenerative disorders with a bACP versus a conventional metal ACP (mACP)., Study Design: Retrospective comparative cohort study., Patient Sample: Thirty-one patients undergoing ACDF for a single-level degenerative disorder (ie, disc herniation or spondylotic neural compression)., Outcome Measures: Incidence of early (within 2 weeks) complications, postoperative sagittal alignment, Odom's criteria, and pseudarthrosis rate., Methods: The authors retrospectively reviewed the results of a consecutive series of patients undergoing ACDF for symptomatic single-level disc herniation or spondylotic neural compression with either a bACP or an mACP over a 3-year period. Operative notes, clinical charts, and radiographs were analyzed. Radiographic outcomes were assessed for intersegmental alignment, graft subsidence, fusion rate, prevertebral soft-tissue shadow, and graft containment. Clinical outcome was evaluated by Odom's criteria., Results: Fourteen patients underwent ACDF with a bACP and 15 with an mACP. Radiographic outcomes at the most recent follow-up demonstrated pseudarthrosis in 4 of 14 patients (29%) in the bACP group and 0 of 15 patients in the mACP group. Graft extrusion and anterior displacement was present in three of four pseudarthroses (75%). Comparing preoperative and final radiographs, cervical lordosis was maintained at the operative segment in only 3 of 14 bACP patients (21%) compared with 8 of 15 patients (53%) in the mACP group. The mean Cobb angle was 2.4°±1.9° lordosis in the mACP group and -2.7°±2.5° kyphosis in the bACP group (p=.12). In the mACP group, 14 of 15 patients had good or excellent results. In the bACP group, only 7 of 14 patients had good or excellent results., Conclusions: Bioabsorbable ACP fixation was associated with a high rate of graft extrusion and early loss of intersegmental cervical alignment. Inferior clinical outcomes were observed in patients in the bACP group compared with the mACP group. Based on these findings, continued use of the bACP used in this study cannot be recommended., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Age-related changes in the spinal column result in a degenerative cascade known as spondylosis. Genetic, environmental, and occupational influences may play a role. These spondylotic changes may result in direct compressive and ischemic dysfunction of the spinal cord known as cervical spondylotic myelopathy (CSM). Both static and dynamic factors contribute to the pathogenesis. CSM may present as subclinical stenosis or may follow a more pernicious and progressive course. Most reports of the natural history of CSM involve periods of quiescent disease with intermittent episodes of neurologic decline. If conservative treatment is chosen for mild CSM, close clinical and radiographic follow-up should be undertaken in addition to precautions for trauma-related neurologic sequelae. Operative treatment remains the standard of care for moderate to severe CSM and is most effective in preventing the progression of disease. Anterior surgery is often beneficial in patients with stenotic disease limited to a few segments or in cases in which correction of a kyphotic deformity is desired. Posterior procedures allow decompression of multiple segments simultaneously provided that adequate posterior drift of the cord is attainable from areas of anterior compression. Distinct risks exist with both anterior and posterior surgery and should be considered in clinical decision-making.

Hypothesis: Traumatic thoracic aortic injury (TAI) is traditionally treated with immediate surgery. Previously published studies have established the safety and efficacy of treating TAI with endovascular stents. Our hypothesis was that stents are supplanting operative repair as the primary therapy for TAI., Design: Retrospective cohort., Setting: University level I trauma center., Patients and Methods: Blunt trauma patients admitted to a level I trauma center diagnosed with TAI between September 1997 and November 2003 were identified from an institutional trauma registry (N = 25). Data were abstracted from medical records and analyzed. Three groups were defined: surgical repair (cardiopulmonary bypass or clamp and sew) (n = 10); medical management (n = 8); and endovascular stent (n = 7)., Results: Prior to 2002, 9 (75%) of 12 patients were treated by surgical repair, 2 (17%) by medical management, and 1 (8%) by endovascular stent. Since 2002, 1 patient (8%) was treated by surgical repair, 6 (46%) by medical management, and 6 (46%) by endovascular stent. Injury Severity Scores were comparable between the surgical cohort (mean +/- SEM score, 34.9 +/- 3.4), stent placement (35.1 +/- 3.7), and medical management (29.9 +/- 2.8) (P = .48). Overall survival was 80% with no differences in morbidity or mortality. The stented group had shorter hospital lengths of stay compared with surgical management (28 vs 46 days) (P<.05). The 1 operative case since 2002 was a combined arch/innominate injury that anatomically precluded stent placement., Conclusion: Initial reports suggested thoracic aortic stents as an alternative for injured patients with prohibitive operative risks. Our data suggest stent placement is quickly evolving into the primary therapy for TAI across all Injury Severity Score profiles.

Objective: A major limitation of stem cell transfer is early donor-cell death. Here, we seek to enhance myocardial repair following injury through transplantation of cardiomyocyte-enriched human embryonic stem cells (hESC) and recipient treatment with cytoprotective (allopurinol+uricase) and anti-inflammatory (ibuprofen) agents., Methods: We injected 10(6) (15% hESC-derived cardiomyocytes) green fluorescent protein (GFP+) hESC in the infarcted area following left anterior descending artery (LAD)-ligation in SCID-beige mice. In Group I, 1.6 mg allopurinol and 0.2 mg of uricase were injected i.p. for 3 days prior to cell transplantation. In Group II, 0.35 mg/ml of ibuprofen were added to the drinking water before and after cell implantation. In Group III, the LAD was ligated and allopurinol/uricase was administered without cell treatment. In Group IV, ibuprofen was added to the drinking water and the LAD was ligated without additional cell treatment. In Group V, only cells were transplanted. Group VI involved infarcted controls and Group VII involved sham-operated mice (all groups: n=5). We evaluated heart function (ejection fraction (EF)) by MRI (4.7 T) 3 weeks later. The hearts were harvested for histology., Results: Differentiated hESC formed clusters and expressed alpha-sarcomeric actin and Connexin 43. Cell treatment improved heart function, which was best in the ibuprofen- and allopurinol-treated groups (+cell transfer), compared to the infarcted controls [EF: Group I: 76.6+/-8.6%, Group II: 78.6+/-7.3%, Group III: 58.1+/-5.7%, Group IV: 53.9+/-5.2%, Group V: 57.7+/-7.5%, Group VI: 43.5+/-4.3%, and Group VII: 66.3+/-7.8%]. We did not observe tumors in any group., Conclusions: Allopurinol/uricase and ibuprofen enhance differentiated hESC-engraftment and myocardial restoration following transplantation into the injured heart.

Background: The optimal cell-matrix combination for robust and sustained myocardial restoration has not been identified. The present study utilizes embryonic stem cells as the substrate of bioartificial myocardial tissue and evaluates engraftment in, and functional recovery of, the recipient heart., Methods: Collagen type I was populated with undifferentiated green fluorescent protein (GFP)-positive mouse embryonic stem cells. An intramural left ventricular pouch was fashioned after ligation of the left anterior descending artery in an athymic nude rat heterotopic heart transplant model. The bioartificial mixture (0.125 ml) was implanted in the infarcted area within the pouch. Echocardiography was performed to assess fractional shortening in: Group I, infarcted rats that received cell-matrix implants; Group II, rats given matrix implant without cells; Group III, rats given no matrix or cells; and Group IV, rats receiving transplanted hearts without ligation (n = 5/group). Hearts were stained for GFP, cardiac markers (connexin-43, alpha-sarcomeric actin), hematoxylin-eosin (H&E) and trichrome., Results: Embryonic stem cells formed stable intramyocardial grafts that were incorporated into the surrounding area without distorting myocardial geometry, thereby preventing ventricular wall thinning (anterior wall thickness was: Group I, 1.4 +/- 0.1 mm; Group II, 1.0 +/- 0.1 mm, Group III, 0.9 +/- 0.2 mm; and Group IV, 1.3 +/- 0.2 mm). The inoculated cells expressed connexin-43 and alpha-sarcomeric actin in vivo. Fractional shortening was better in embryonic stem cell-treated animals (Group I, 21.5 +/- 3.5%; Group II, 12.4 +/- 2.8%; Group III, 8.2 +/- 2.9%; Group IV, 23.2 +/- 4.2%)., Conclusions: Embryonic stem cells are an efficient alternative substrate for myocardial tissue engineering and can prevent myocardial wall thinning and improve contractility after implantation into injured myocardium in a 3-dimensional matrix.

Objectives: Most tissue-engineering approaches to restore injured heart muscle result in distortion of left ventricular geometry. In the present study we suggest seeding embryonic stem cells in a liquid matrix for myocardial restoration., Methods: Undifferentiated green fluorescent protein-labeled mouse embryonic stem cells (2 x 10 6 ) were seeded in Matrigel (B&D, Bedford, Mass). In a Lewis rat heterotopic heart transplant model an intramural left ventricular pouch was fashioned after ligation of the left anterior descending coronary artery. The liquid mixture (0.125 mL) was injected in the resulting infarcted area within the pouch and solidified within a few minutes after transplantation (37 degrees C). Five recipient groups were formed: transplanted healthy hearts (group I), infarcted control hearts (group II), matrix recipients alone (group III), the study group that received matrix plus cells (group IV), and a group that received embryonic stem cells alone (group V). After echocardiography 2 weeks later, the hearts were harvested and stained for green fluorescent protein and cardiac muscle markers (connexin 43 and alpha-sarcomeric actin)., Results: The graft formed a sustained structure within the injured area and prevented ventricular wall thinning. The inoculated cells remained viable and expressed connexin 43 and alpha-sarcomeric actin. Fractional shortening and regional contractility were better in animals that received bioartificial tissue grafts compared with control animals (infarcted, matrix only, and embryonic stem cells only: group I, 17.0% +/- 3.5%; group II, 6.6% +/- 2.1%; group III, 10.3% +/- 2.2%; group IV, 14.5% +/- 2.5%; and group V, 7.8% +/- 1.8%)., Conclusions: Liquid bioartificial tissue containing embryonic stem cells constitutes a powerful new approach to restoring injured heart muscle without distorting its geometry and structure.

Insulin-like growth factor-1 (IGF-1) promotes myocyte proliferation and can reverse cardiac abnormalities when it is administered in the early fetal stage. Supplementation of a mouse embryonic stem cell (ESC) suspension with IGF-1 might enhance cellular engraftment and host organ-specific differentiation after injection in the area of acute myocardial injury. In the study reported here, we sought to enhance the restorative effect of ESCs in the injured heart by adding IGF-1 to the injected cell population. Green fluorescent protein (GFP)-labeled sv129 ESCs (2.5 x 10(5)) were injected into the ischemic area after left anterior descending (LAD) artery ligation in BalbC mice. Recombinant mouse IGF-1 (25 ng) was added to the cell suspension prior to the injection (n = 5). Echocardiography was performed before organ harvest 2 weeks later. The degree of restoration (ratio of GFP+ to infarct area), expression of cardiac markers by GFP+ cells, inflammatory response, and tumorigenicity were evaluated. Mice with LAD ligation only (n = 5) and ESC transfer without IGF-1 (n = 5) served as controls. ESCs formed viable grafts and improved cardiac function. Left ventricular wall thickness was higher in the IGF-1 group (p = .025). There was a trend toward higher fractional shortening in the IGF-treated group. Histological analysis demonstrated that IGF-1 promoted expression of alpha-sarcomeric actin (p = .015) and major histocompatibility complex class I (p = .01). IGF did not affect the cellular response to the donor cells or tumorigenicity. IGF-1 promotes expression of cardiomyocyte phenotype in ESCs in vivo. It should be considered as an adjuvant to cell transfer for myocardial restoration.