Use of the Geriatric Nutritional Risk Index to Assess Risk for Postoperative Complications Following Posterior Cervical Decompression/Fusion.

BACKGROUND: Posterior cervical decompression with or without fusion (PCD/F) is used to manage degenerative spinal conditions. Malnutrition has been implicated for poor outcomes in spine surgery. The aim of this study was to assess the ability of the Geriatric Nutritional Risk Index (GNRI) as a risk calculator for postoperative complications in patients undergoing PCD/F. METHODS: The 2006 to 2018 American College of Surgeons National Surgery Quality Improvement Program Database was queried for patients undergoing PCD/F. Nutritional status was categorized as normal (GNRI greater than 98), moderately malnourished (GNRI 92-98), or severely malnourished (GNRI less than or equal to 92). Complications within 30 days of surgery were compared among the groups. Preoperative data that were statistically significant (P < 0.05) upon univariate χ2 analysis were included in the univariate then multivariate binary regression model to calculate adjusted ORs. All ORs were assessed at the 95% CI. RESULTS: Of the 7597 PCD/F patients identified, 15.6% were severely malnourished and 19.1% were moderately malnourished. Severe and moderate malnourishment were independent risk factors for mortality (OR = 3.790, 95% CI 2.492-5.763, P < 0.001; OR = 2.150, 95% CI 1.351-3.421, P = 0.011). Severe malnourishment was an independent risk factor for sepsis/septic shock (OR = 3.448, 95% CI 2.402-4.948, P < 0.001). CONCLUSIONS: In elderly patients undergoing PCD/F, severe malnutrition, as defined by the GNRI, was an independent risk factor for mortality and sepsis/septic shock. CLINICAL RELEVANCE: The GNRI may be more useful than other indices for risk stratification in elderly patients because it accounts for confounding variables such as hydration status and paradoxical malnourishment in obese patients.

Efficacy and safety of intrawound antibiotics in patients undergoing posterior spinal fusion for adolescent idiopathic scoliosis: a nationwide database study.

PURPOSE: To assess the efficacy and safety of intrawound antibiotics in posterior fusions for adolescent idiopathic scoliosis (AIS). METHODS: The NSQIP-Pediatric databases 2016-2018 were utilized. Patients 10 years of age or older with AIS who underwent posterior fusion were selected and divided into two cohorts based on the receipt of intrawound antibiotics. Patient characteristics and complications were compared. Multivariate analyses were performed to determine the efficacy and safety of intrawound antibiotics. RESULTS: A total of 4203 patients received intrawound antibiotics while 879 patients did not. The intrawound antibiotic group had longer constructs, higher blood loss, and longer operative times, factors historically associated with higher infection rates. Those that received intrawound antibiotics had SSI rate of 0.69%, while its counterpart had 0.57% (p = 0.689). The reoperation rates were 1.12% and 1.25% (p = 0.735), for those with and without intrawound antibiotics, respectively. In multivariate analyses, intrawound antibiotics use was not found to be a significant predictor for SSI, any complications, reoperation and readmission. CONCLUSION: The current study represents the largest AIS surgery cohort studied to evaluate the efficacy of intrawound antibiotics. Our analysis failed to demonstrate association between the use of intrawound antibiotics and reduction in SSI. While other studies have reported seroma, wound dehiscence and renal failure with the practice, we did not observe an increased rate of such complications. This study highlights the difficulty of understanding the role for individual infection prevention measures in current surgical settings, where the SSI rate for the control group was substantially lower than 1%.

Enhanced Risk Stratification for Short-Term Complications Following Vertebral Augmentation for Osteoporotic Vertebral Compression Fractures.

BACKGROUND: For patients with back pain from osteoporotic vertebral compression fractures (VCFs), vertebral augmentation remains the most utilized surgical intervention. Previous studies report 30-day readmission and mortality rates of up to 10% and 2%, respectively. These studies, however, have included patients with pathologic fractures and combined patients in different admission settings. We undertook the current study to address such shortcomings, which make risk stratification and appropriate counseling difficult. METHODS: Four consecutive years of the National Surgical Quality Improvement Program database were queried. Patients who underwent vertebral augmentation for osteoporotic VCFs were divided into 3 groups: (1) outpatient group (defined as patients with same-day discharge), (2) inpatient group (defined as those who were admitted postoperatively), and (3) preprocedure hospitalized group (defined as those who were already inpatient or were at acute/intermediate care facilities and transferred). Postoperative 30-day complications and readmission rates were compared between different groups and examined using multivariate analyses. RESULTS: A total of 1023 patients underwent outpatient surgery; 503 were admitted on the day of surgery; and 149 patients were already in-hospital or were transferred from other facility. Mortality rates were 0.68%, 0.60%, and 2.68%, and readmission rates were 6.26%, 6.76%, and 12.8%, for outpatient, inpatient, and preprocedure hospitalization cohorts, respectively. Multivariate analyses identified preprocedure hospitalization as an independent risk factor for urinary tract infection (UTI; OR = 3.98, 95% CI = 1.41-11.20, P = 0.028), pneumonia (OR = 19.69, 95% CI = 3.81-101.65, P < 0.001), readmission (OR = 1.86, 95% CI = 1.06-3.26, P = 0.032), and mortality (OR = 4.49, 95% CI = 1.22-16.53, P = 0.024). CONCLUSION: Our findings suggest that published rates of complications and mortality are substantially impacted by the cohort of patients who are already hospitalized or transferred from other facilities. Such patients are at a higher risk of UTI, pneumonia, readmission, and mortality. Conversely, we show that a relatively healthy patient being offered outpatient same-day augmentation has a readmission risk 40% lower and a mortality risk 3 times lower than previously reported.

Micromonas micros: A rare anaerobic cause of late implant failure following spinal surgery.

Context: Delayed, postoperative, spine infections are rare, most commonly occurring secondary to fastidious, less virulent pathogens. The etiology may involve a distant infectious focus, not related to the index operation. Patients may present months, or even years postoperatively with pain related to mechanical implant failure, often without additional signs of systemic infection.Findings: We present the case of a 59-year-old male who developed rapid disk degeneration and implant failure seven months following instrumented lumbar fusion surgery. The causal organism was found to be Micromonas micros, an anaerobic bacterium typically located in the oral cavity and associated with periodontal disease. The patient was found to have extensive oral caries, which were presumed to have occurred secondary to poor oral hygiene and his use of fentanyl lozenges for chronic back pain. The patient was treated with revision staged spinal surgery and long-term intravenous antibiotics.Conclusion/clinical relevance: This case highlights an unusual etiology of delayed postoperative spinal implant failure and provides evidence for periodontal disease as a source of hematogenous seeding in postoperative spinal infections. The orthopaedist should also be aware of the potential relationship between poor oral hygiene and the use of high sugar content fentanyl lozenges in treating chronic back pain in these patients.

Identification of Risk Factors for Readmission in Patients Undergoing Anterior Cervical Discectomy Fusion: A Predictive Risk Scale.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: The objective of this study was to analyze readmission rates among patients undergoing anterior cervical discectomy and fusion (ACDF), determine which factors were associated with higher readmission rates, and develop a scale for utilization during surgical planning. SUMMARY OF BACKGROUND DATA: ACDF is the most common surgical treatment for many cervical disk pathologies. With the Centers for Medicare and Medicaid Services selecting readmissions as a measure of health care quality, there has been an increased focus on reducing readmissions. MATERIALS AND METHODS: There were 114,174 recorded ACDF surgeries in the derivation cohort, the State Inpatient Database (SID) of New York and California between 2006 and 2014. There were 115,829 ACDF surgeries recorded in the validation cohort, the SID from Florida and Washington over the same time period. After identification of risk factors using univariate and multivariate analysis of the derivation cohort, a predictive scale was generated and tested utilizing the validation cohort. RESULTS: Overall, readmission rates within 30 days of discharge were 5.87% and 5.52% in the derivation and validation cohorts, respectively. On multivariate analysis of the derivation cohort, age older than 80 years [odds ratio (OR), 1.67] male sex (OR, 1.16), Medicaid insurance (OR, 1.90), Medicare insurance (OR, 1.64), revision ACDF (OR, 1.43), anemia (OR, 1.45), chronic lung disease (OR, 1.23), coagulopathy (OR, 1.42), congestive heart failure (OR, 1.31), diabetes (OR, 1.23), fluid and electrolyte disorder (OR, 1.56), liver disease (OR, 1.37), renal failure (OR, 1.59), and myelopathy (OR, 1.19) were found to be statistically significant predictors for readmission. These factors were incorporated into a numeric scale that, that when tested on the validation cohort, could explain 97.1% of the variability in readmission rate. CONCLUSIONS: Overall, 30-day readmission following ACDF surgery was 5%-6%. A novel risk scale based on factors associated with increased readmission rates may be helpful in identifying patients who require additional optimization to reduce perioperative morbidity. LEVEL OF EVIDENCE: Level III-prognostic.

Chylous Leak During Posterior Approach to Juvenile Scoliosis Surgery: A Case Report.

CASE: We report the first documented case of chylous leak recognized intraoperatively during posterior spinal instrumentation and fusion for juvenile scoliosis in a female patient with a history of thoracotomy and decortication for an empyema. CONCLUSIONS: Thoracic duct injury can lead to severe morbidity and mortality because of chylothorax formation. Although chylous leaks are a well-documented complication of the anterior approach to spine surgery, leaks during the posterior approach are rarely reported. When these chylous leaks are recognized intraoperatively, the likelihood of serious complications may be minimized by drain placement before closure.

The use of inferior vena cava filters in spine trauma: A nationwide study using the National Trauma Data Bank.

OBJECTIVE: To determine the prevalence and variation of inferior vena cava filter (IVCF) use in the spine trauma population and evaluate patient and facility level factors associated with their use. STUDY DESIGN: Retrospective cohort. Participants/Outcome Measures: Patients with spinal injuries were identified by ICD-9 codes from the National Trauma Data Bank (NTDB), the best validated national trauma database. Patients whose spine injuries were operatively treated and those who received IVCF were identified from procedure description fields. Additional information compiled included patient demographics, injury severity score (ISS), time until surgery, concomitant fractures, and facility level information. Multivariate logistic regression analyses were conducted to examine the relationship of associated factors for IVCF use. RESULTS: Of the 120,920 patients identified with spinal injuries, 2.4% received prophylactic IVCF. Of the 13,273 patients with operatively treated spinal injuries, 8.2% received prophylactic IVCF. Of the 7,770 patients with spinal cord injury (SCI), 10.8% received prophylactic IVCF. The interquartile ranges of placement rates among centers demonstrated greater than 10 fold variation. Based on multivariate logistic regression, ISS score >12 demonstrated the strongest association with prophylactic IVCF (adjusted OR = 4.908). Concomitant pelvic and lower extremity fractures (adj OR 2.573 and 2.522) were also associated with their use. CONCLUSIONS: Currently the only data regarding existing IVCF use in the spine trauma population amounts to surveys. The present study provides the most detailed and objective information regarding their use in this setting. Even in the operatively treated and SCI subgroups, prophylactic filters were used in only a small percentage of cases but placement rates varied widely among centers. More severely injured patients (ISS >12) had highest odds of receiving prophylactic IVCF. Further study is needed to clarify their role in this vulnerable population.

Do postoperative drain volumes correlate with intraoperative blood loss and postoperative transfusion requirements in posterior spinal fusion for adolescent idiopathic scoliosis?

Most studies have excluded postoperative drain volumes in analyzing blood loss associated with scoliosis surgery. We sought to analyze patient and surgical factors that influenced postoperative drain outputs. A retrospective review was conducted on 50 consecutive patients who had undergone posterior spinal fusion with pedicle screw instrumentation and subfascial drain placement over a 6-year period at a single institution for adolescent idiopathic scoliosis. Postoperative drain volumes were correlated to patient factors, surgical variables, and change in postoperative hemoglobin values. The association between drain output volumes and the need for allogeneic blood transfusion was also analyzed using univariate and multivariate analysis. Total postoperative drain volume positively correlated with Cell Saver volume (r=0.28, P=0.049), units of packed red blood cells transfused intraoperatively (r=0.31, P=0.03), and a number of Ponte osteotomies (r=0.43, P=0.002). On the basis of multiple linear regression analysis, only the number of osteotomies performed was associated with increasing total drain volume (R=0.25, P=0.003). Total drain output did not correlate with postoperative change in hemoglobin (P=0.85), the need for postoperative blood transfusion (P=0.22), or the total volume of blood transfused perioperatively (P=0.06). Patients with large intraoperative blood loss or multiple osteotomies are more likely to have higher postoperative drain volumes. Drain volume alone, however, should not be used as a trigger for recommending a postoperative blood transfusion.

Lumbar Spine Injuries in Sports: Review of the Literature and Current Treatment Recommendations.

Low back pain is one of the most prevalent complaints of athletes at all levels of competition. The purpose of this literature review is to provide an overview of sport-specific injuries and treatment outcomes that can be used by healthcare providers to better recognize injury patterns and treatment options for different groups of athletes. To our knowledge, no prior comprehensive review of lumbar spine injuries in sports is currently available in the literature, and it is essential that healthcare providers understand the sport-specific injury patterns and treatment guidelines for athletes presenting with low back pain following an athletic injury. Injury mechanisms were found to vary significantly by sport, although some broad recommendations can be made with regards to optimal treatment for these injuries and return to play. Additionally, it was found that certain treatments were more beneficial and resulted in higher rates of return to play depending on the specific sport of the injured athlete. Healthcare providers need to be aware of the different injury patterns seen in specific sports in order to properly evaluate and treat these injuries. Furthermore, an individualized treatment plan needs to be selected in a sport-specific context in order to meet the needs of the athlete in the short and long term.

Use of stand-up magnetic resonance imaging for evaluation of a cervicothoracic injury in a patient with ankylosing spondylitis.

BACKGROUND CONTEXT: Injuries at the cervicothoracic junction are common in patients with ankylosing spondylitis. These injuries present challenges for both initial and follow-up imagings. PURPOSE: To describe a case of a patient with ankylosing spondylitis who was treated with laminectomy and a cervicothoracic orthosis for a spinal epidural hematoma after a nondisplaced fracture at the cervicothoracic junction and to discuss the merits of stand-up magnetic resonance imaging (MRI) for follow-up evaluation of this type of injury. STUDY DESIGN/SETTING: Case report. METHODS: Clinical data of a patient with ankylosing spondylitis who sustained a nondisplaced C7 fracture are presented, followed by a detailed review of the literature concerning imaging techniques available for the evaluation of cervical spine trauma in this patient population. RESULTS: The patient was treated with emergent laminectomy and evacuation of the epidural hematoma, followed by definitive management in a cervicothoracic orthosis secondary to medical comorbidities. The patient was then successfully followed postoperatively with stand-up MRI because conventional imaging techniques could not adequately image the injury level in an upright position. CONCLUSIONS: Cervicothoracic injuries are common in patients with ankylosing spondylitis and may be difficult to follow with conventional imaging techniques. Stand-up MRI is a relatively new modality that may offer significant advantages over conventional imaging because of the ability to evaluate the cervicothoracic junction in a more functional position and the lack of a confining space such as that found in standard MRI units.

Postoperative spinal wound infections and postprocedural diskitis.

BACKGROUND/OBJECTIVE: Postprocedural infections are a significant cause of morbidity after spinal interventions. METHODS: Literature review. An extensive literature review was conducted on postprocedural spinal infections. Relevant articles were reviewed in detail and additional case images were included. RESULTS: Clinical findings, laboratory markers, and imaging modalities play important roles in the detection of postprocedural spinal infections. Treatment may range from biopsy and antibiotics to multiple operations with complex strategies for soft tissue management. CONCLUSIONS: Early detection and aggressive treatment are paramount in managing postprocedural spinal infections and limiting their long-term sequelae.

Kinematics of the Cervical Spine After Unilateral Facet Fracture: An In Vitro Cadaver Study.

STUDY DESIGN: Biomechanical study utilizing human cadaveric cervical spines. OBJECTIVE: To quantitatively assess the effects on intervertebral motion of isolated unilateral cervical facet fracture, and after disruption of the intervertebral disc at the same level. SUMMARY OF BACKGROUND DATA: Clinical evidence has indirectly suggested that cervical facet fractures involving 40% of the height of the lateral mass can cause instability of the involved segment. No study to date has demonstrated the kinematic effects of such an injury in a cadaveric model of the cervical spine. METHODS: Nine six-segment cervical spines were defrosted and fixated to a spine motion simulator capable to apply unconstrained bending moments in the three anatomical planes. The spines were subjected to a maximum torque of 2 N ·â€Šm in flexion, extension, left and right lateral bending, and of 4 N ·â€Šm in left and right axial rotation. Each spine was tested in the intact configuration (INTACT), and following two increasing degrees of injury at C4-C5: fracture of the facet (CF1), and CF1 with disruption of the intervertebral disc at the same level (CF2). Intervertebral kinematics was tracked via clusters of active markers fixated on each vertebra. Differences in kinematics between INTACT and the two injured configurations were assessed via one-way Analysis of Variance (P < 0.05). RESULTS: No significant differences were detected between INTACT and CF1 across all kinematic parameters (P > 0.05) at C4-C5. CF2, however, resulted in significant increase of flexion, left axial rotation, and left lateral bending with respect to INTACT (flexion at C4-C5: INTACT = 8.7°â€Š±â€Š3.5°; CF2 = 14.3 ±â€Š5.7; P < 0.05). CONCLUSION: Our findings suggest that superior articular facet fractures alone involving 40% of the lateral mass may not necessarily result in intervertebral instability under physiologic loading conditions. The addition of partial injury to the intervertebral disc, however, resulted in statistically significant increase in angular displacement. LEVEL OF EVIDENCE: N /A.

The paraspinal muscles and their role in the maintenance of global spinal alignment. Another wrinkle in an already complex problem.

COMMENTARY ON: Yagi M, Hosogane N, Watanabe K, Asazuma T, Matsumoto M, Keio Spine Research Group. The paravertebral muscle and psoas for the maintenance of global spinal alignment in patient with degenerative lumbar scoliosis. Spine J 2016:16:451-8 (in this issue).

Zinc has insulin-mimetic properties which enhance spinal fusion in a rat model.

BACKGROUND CONTEXT: Previous studies have found that insulin or insulin-like growth factor treatment can stimulate fracture healing in diabetic and normal animal models, and increase fusion rates in a rat spinal fusion model. Insulin-mimetic agents, such as zinc, have demonstrated antidiabetic effects in animal and human studies, and these agents that mimic the effects of insulin could produce the same beneficial effects on bone regeneration and spinal fusion. PURPOSE: The purpose of this study was to analyze the effects of locally applied zinc on spinal fusion in a rat model. STUDY DESIGN/SETTING: Institutional Animal Care and Use Committee-approved animal study using Sprague-Dawley rats was used as the study design. METHODS: Thirty Sprague-Dawley rats (450-500 g) underwent L4-L5 posterolateral lumbar fusion (PLF). After decortication and application of approximately 0.3 g of autograft per side, one of three pellets were added to each site: high-dose zinc calcium sulfate (ZnCaSO4), low-dose ZnCaSO4 (half of the high dose), or a control palmitic acid pellet (no Zn dose). Systemic blood glucose levels were measured 24 hours postoperatively. Rats were sacrificed after 8weeks and the PLFs analyzed qualitatively by manual palpation and radiograph review, and quantitatively by micro-computed tomography (CT) analysis of bone volume and trabecular thickness. Statistical analyses with p-values set at .05 were accomplished with analysis of variance, followed by posthoc tests for quantitative data, or Mann-Whitney rank tests for qualitative assessments. RESULTS: Compared with controls, the low-dose zinc group demonstrated a significantly higher manual palpation grade (p=.011), radiographic score (p=.045), and bone formation on micro-CT (172.9 mm(3) vs. 126.7 mm(3) for controls) (p<.01). The high-dose zinc also demonstrated a significantly higher radiographic score (p=.017) and bone formation on micro-CT (172.7 mm(3) vs. 126.7 mm(3)) (p<.01) versus controls, and was trending toward higher manual palpation scores (p=.058). CONCLUSIONS: This study demonstrates the potential benefit of a locally applied insulin-mimetic agent, such as zinc, in a rat lumbar fusion model. Previous studies have demonstrated the benefits of local insulin application in the same model, and it appears that zinc has similar effects.

Timing of surgery following spinal cord injury.

BACKGROUND: The optimal timing for surgical intervention after traumatic spinal injuries with spinal cord injury remains unclear. DESIGN: Literature review. FINDINGS: Multiple laboratory investigations (in animal models) and many clinical studies suggest better neurological outcomes with early surgical intervention. Conclusive evidence (well-designed randomized, controlled studies), however, is lacking, partly due to the logistics involved in executing such an investigation. Early surgery also appears to decrease the incidence of complications, reduces hospital stay, and helps reduce costs associated with acute management. CONCLUSION: Early surgical treatment is beneficial in terms of reducing complications, length of stay, and hospital costs. Further studies are needed to clearly demonstrate the impact of operative timing on neurological outcome.

Traumatic atlantoaxial dislocation with Hangman fracture.

BACKGROUND CONTEXT: Traumatic bilateral-atlantoaxial dislocations are rare injuries. Hangman fractures, conversely, represent 4% to 7% of all cervical fractures and frequently involve a combination C1-C2 fracture pattern. Presently, there is no report in the English literature of a traumatic C2-spondylolisthesis associated with a C1-C2 rotatory dislocation. This injury complex cannot be cataloged using current classification schemes and no established treatment recommendations exist. PURPOSE: To report a unique case of a Hangman fracture associated with bilateral C1-C2 rotatory-dislocation, which does not fit into existing classification systems, and discuss our treatment approach. STUDY DESIGN: A clinical case report and review of the literature. METHODS: Chart review and analysis of relevant literature. There were no study-specific conflicts of interest. RESULTS: A 26-year-old man sustained a traumatic C2-spondylolisthesis along with C1-C2 rotatory subluxation in an automobile collision. The patient was originally placed in a halo crown and vest and then taken for an open reduction and stabilization through a posterior approach for persistent C1-C2 subluxation. The patient is currently 16 months postoperative and back to work as a plumber. CONCLUSIONS: The injury complex encountered cannot be described using the available classification systems. Our treatment included initial stabilization with halo placement, followed by a posterior C1, C2, and C3 segmental reduction and fixation resulting in radiographic fusion and a good clinical outcome.

Evaluation of recurring meniscal tears with gadolinium-enhanced magnetic resonance imaging: a randomized, prospective study.

BACKGROUND: Magnetic resonance imaging has been shown to be of questionable accuracy in detecting recurrent meniscal tears after previous resection or repair. PURPOSE: To compare the accuracy of nonenhanced magnetic resonance imaging with that of intraarticular contrast-enhanced direct magnetic resonance arthrography and intravenous contrast-enhanced indirect magnetic resonance arthrography for detection of recurrent meniscal tears. STUDY DESIGN: Prospective cohort study. METHODS: Forty-one patients who had previous meniscal tears treated by resection or repair but who were experiencing recurrent knee symptoms were prospectively randomized into one of three groups: conventional magnetic resonance imaging, indirect arthrography, and direct arthrography. The interpretations of two musculoskeletal radiologists were compared with the findings of an arthroscopic procedure performed 2 to 14 weeks later. RESULTS: Conventional imaging had a sensitivity of 57.9%, specificity of 80%, and overall accuracy of 62.5%. Intravenous contrast improved the sensitivity to 90.9%, specificity to 100%, and overall accuracy to 93.8%; intraarticular contrast had a sensitivity of 91.7%, specificity of 100%, and an overall accuracy of 92.9%. CONCLUSIONS: We demonstrated an increased accuracy of intravenous or intraarticular contrast-enhanced magnetic resonance arthrography in detecting recurrent meniscal tears. Both contrast routes demonstrated similar accuracy, a finding not previously reported.

The halo vest: principles of application and management of complications.

BACKGROUND: The halo skeletal device commonly is used both as primary treatment and as an adjunct to internal fixation in patients with cervical spinal injuries. For optimal outcome, the multidisciplinary team should have a basic understanding of the indications, design rationale, and complications associated with the halo skeletal fixator. DESIGN: Literature review. FINDINGS: The halo device provides the most rigid form of external cervical immobilization. Adherence to established application guidelines is critical to minimize morbidity. Safe zones for pin placement have been delineated. Protocols for management of pin-site infections have been established to appropriately manage these unfortunate complications. CONCLUSION: Although the halo is an effective form of cervical immobilization, complications with its use are encountered periodically. Familiarity with the design rationale, proper method of application, and potential complications can help to minimize the morbidity of this commonly used device.

Blood loss during posterior spinal fusion for adolescent idiopathic scoliosis.

STUDY DESIGN: Retrospective uncontrolled case series. OBJECTIVE: The purpose of this study was to determine the association, if any, between intraoperative blood loss and need for transfusion with the use of periapical (Ponte) osteotomies, as well as other patient and surgical variables among patients with adolescent idiopathic scoliosis (AIS) undergoing posterior spinal instrumentation and fusion. SUMMARY OF BACKGROUND DATA: Blood loss during posterior spinal fusion for AIS can be substantial. Numerous techniques are used to minimize intraoperative blood loss and the need for allogeneic transfusion. However, it is unclear which patient and surgeon variables affect blood loss most significantly. METHODS: A review was conducted on consecutive patients with AIS who had undergone posterior spinal fusion from July 1997 to February 2013 by a single primary surgeon at 1 institution. The relationship of estimated blood loss, normalized blood loss (normalized blood loss = estimated blood loss/number of levels fused/patient's weight in kilograms), autologous blood retrieved, and allogeneic transfusion received with various patient- and procedure-related variables were analyzed. RESULTS: Estimated blood loss, normalized blood loss, and autologous blood retrieved were higher in patients who underwent periapical Ponte osteotomies (n = 38) (P < 0.0001, P < 0.001, P < 0.01, respectively). The mean major curve correction was 64% in patients without osteotomies, and 65% in patients with osteotomies (P = 0.81). All patients who underwent osteotomies (38/38) received allogeneic transfusion versus 26% (19/73) of those without osteotomies (P < 0.001). The likelihood of transfusion correlated with increasing number of osteotomies and a lower preoperative hemoglobin level (odds ratio, 3.34; P = 0.003; and odds ratio, 0.51; P = 0.02, respectively). CONCLUSION: In patients with AIS undergoing posterior spinal fusion with instrumentation, performing periapical osteotomies increased all measures of intraoperative blood loss and need for transfusion without substantially improving major curve correction. As expected, a lower preoperative hemoglobin level was observed in patients who received a blood transfusion after posterior instrumentation and fusion. LEVEL OF EVIDENCE: 4.

The effects of local insulin application to lumbar spinal fusions in a rat model.

BACKGROUND CONTEXT: The rates of pseudoarthrosis after a single-level spinal fusion have been reported up to 35%, and the agents that increase the rate of fusion have an important role in decreasing pseudoarthrosis after spinal fusion. Previous studies have analyzed the effects of local insulin application to an autograft in a rat segmental defect model. Defects treated with a time-released insulin implant had significantly more new bone formation and greater quality of bone compared with controls based on histology and histomorphometry. A time-released insulin implant may have similar effects when applied in a lumbar spinal fusion model. PURPOSE: This study analyzes the effects of a local time-released insulin implant applied to the fusion bed in a rat posterolateral lumbar spinal fusion model. Our hypothesis was twofold: first, a time-released insulin implant applied to the autograft bed in a rat posterolateral lumbar fusion will increase the rate of successful fusion and second, will alter the local environment of the fusion site by increasing the levels of local growth factors. STUDY DESIGN: Animal model (Institutional Animal Care and Use Committee approved) using 40 adult male Sprague-Dawley rats. METHODS: Forty skeletally mature Sprague-Dawley rats weighing approximately 500 g each underwent posterolateral intertransverse lumbar fusions with iliac crest autograft from L4 to L5 using a Wiltse-type approach. After exposure of the transverse processes and high-speed burr decortication, a Linplant (Linshin Canada, Inc., ON, Canada) consisting of 95% microrecrystalized palmitic acid and 5% bovine insulin (experimental group) or a sham implant consisting of only palmitic acid (control group) was implanted on the fusion bed with iliac crest autograft. As per the manufacturer, the Linplant has a release rate of 2 U/day for a minimum of 40 days. The transverse processes and autograft beds of 10 animals from the experimental and 10 from the control group were harvested at Day 4 and analyzed for growth factors. The remaining 20 spines were harvested at 8 weeks and underwent a radiographic examination, manual palpation, and microcomputed tomographic (micro-CT) examination. RESULTS: One of the 8-week control animals died on postoperative Day 1, likely due to anesthesia. In the groups sacrificed at Day 4, there was a significant increase in insulinlike growth factor-I (IGF-I) in the insulin treatment group compared with the controls (0.185 vs. 0.129; p=.001). No significant differences were demonstrated in the levels of transforming growth factor beta-1, platelet-derived growth factor-AB, and vascular endothelial growth factor between the groups (p=.461, .452, and .767 respectively). Based on the radiographs, 1 of 9 controls had a solid bilateral fusion mass, 2 of 9 had unilateral fusion mass, 3 of 9 had small fusion mass bilaterally, and 3 of 9 had graft resorption. The treatment group had solid bilateral fusion mass in 6 of 10 and unilateral fusion mass in 4 of 10, whereas a small bilateral fusion mass and graft resorption were not observed. The difference between the groups was significant (p=.0067). Based on manual palpation, only 1 of 9 controls was considered fused, 4 of 9 were partially fused, and 4 of 9 were not fused. In the treatment group, there were 6 of 10 fusions, 3 of 10 partial fusions, and 1 of 10 were not fused. The difference between the groups was significant (p=.0084). Based on the micro-CT, the mean bone volume of the control group was 126.7 mm(3) and 203.8 mm(3) in the insulin treatment group. The difference between the groups was significant (p=.0007). CONCLUSIONS: This study demonstrates the potential role of a time-released insulin implant as a bone graft enhancer using a rat posterolateral intertransverse lumbar fusion model. The insulin-treatment group had significantly higher fusion rates based on the radiographs and manual palpation and had significantly higher levels of IGF-I and significantly more bone volume on micro-CT.