Rate Of Instrumentation Failure Research Articles

Logistic analysis of delayed reporting of emergency blood potassium and comparison of improved outcomes

Potassium testing is an essential test in emergency medicine. Turnaround time (TAT) is the time between specimen receipt by the laboratory and the release of the test report. A brief in-laboratory TAT increases emergency department effectiveness. Optimizing processes to shorten TAT using other tools requires extensive time, resources, training, and support. Therefore, we aimed to find a convenient way to shorten TAT, identify risk factors affecting the timeliness of emergency potassium test reporting, and verify the intervention’s effects. The dependent variable was emergency potassium reporting time > 30 or < 30 min. Logistic analysis was performed on monitorable factors, such as sex, age, potassium results, number of items, specimen processing time (including centrifugation and time before specimen loading), critical value ratio, instrument status, shift where the report was issued, specimen status, and work experience, as independent variables. In the multivariate analysis, work experience, instrument failure rate, and specimen processing time were risk factors for emergency blood potassium reporting exceeding 30 min. Improvement measures were implemented, significantly decreasing the timeout rate for acute potassium reporting. Our study confirms the usefulness of logistics in reducing the time required to report potassium levels in the emergency department, providing a new perspective on quality management.

Supplementary posterior fusion in patients operated on employing TLIF may decrease the instrumentation failure rate.

It is supposed that additional posterior fusion may provide additional stability of the pedicle screw; however, the clinical impact of additional posterior fusion in patients treated with TLIF remains uncertain. The objective of this study is to assess the clinical efficacy of circumferential fusion in patients treated with TLIF. This is a single-center retrospective evaluation of consecutive 179 patients with degenerative lumbar stenosis and instability of spinal segments. Patients with axial pain and neurogenic claudication or radiculopathy associated with spinal stenosis were enrolled during the period from 2012 to 2018. Transforaminal lumbar interbody fusion (TLIF) with a single cage was used to treat patients. In 118 cases a supplementary posterior fusion was made. The duration of follow-up accounted for 24 months, logistic regression analysis was used to assess factors that influence the complication rate. The rate of pedicle screw loosening was growing with radiodensity getting decreased and was more frequent in patients with two level fusion. An increase in pedicle screw loosening rate correlated with anterior nonunion Tan 2 and 3 grade while both posterior complete and incomplete fusion resulted in a decline in the complication rate. Lumbosacral fusion, bilateral facet joints` resection and laminectomy turned out to be insignificant factors. The overall goodness of fit of the estimated general multivariate model was χ2 = 87.2230; P < 0.0001. To confirm clinical relevance of those findings, a univariate logistic regression was performed to assess the association between clinically significant pedicle screw instability and posterior fusion in patients operated on employing TLIF. The results of logistic regression analysis demonstrate that additional posterior fusion may decrease the rate of instrumentation failure that requires revision surgery in patients treated with TLIF [B0 = 1.314321; B1 = -3.218279; p = 0.0023; OR = 24.98507; 95% CI (3.209265; 194.5162), the overall goodness of fit of the estimated regression was χ2 = 22.29538, p = <0.0001]. Circumferential fusion in patients operated on employing TLIF is associated with a decline in the rate of pedicle screw loosening detected by CT imaging and clinically significant instrumentation failure.

Osteoporosis as a Risk Factor for Intraoperative Complications and Long-term Instrumentation Failure in Patients With Scoliotic Spinal Deformity.

A retrospective review study. This study aims to determine the effect of osteoporosis on spine instrumentation. Osteoporosis is a common skeletal pathology that affects systemic cortical bone maintenance and remodeling. This disease accelerates the degeneration of the spine, often necessitating spinal surgery for progressive vertebral deformity, pathologic fracture, bony canal stenosis, and/or neural element decompression. There is a paucity of literature describing the role of osteoporosis as it relates to both perioperative complications and outcomes after spine fusion surgery. A retrospective review was conducted of a prospectively maintained database for patients undergoing spine surgery between January 1, 2006 and October 3, 2017. Inclusion criteria included age 18 years and above and surgery performed for the correction of thoracolumbar scoliosis. Data collected included various demographic, clinical, and operative variables. A total of 532 patients met inclusion criteria, including 144 (27%) patients with a diagnosis of osteoporosis. Osteoporosis was significantly associated with increased blood volume loss (P=0.003). Postoperatively, osteoporosis was associated with increased rates of instrumentation failure (19% vs. 10%; P=0.008) and the need for revision surgery (33% vs. 16%; P<0.001). Multivariate analysis confirmed osteoporosis to be an independent risk factor for increased mean number of spinal segments fused (P<0.05), mean blood volume loss (P<0.05), rate of postoperative deep venous thrombosis/pulmonary embolism (P<0.05), rate of instrumentation failure (P<0.05), and need for revision surgery (P<0.05). Osteoporosis is a significant risk factor for instrumentation failure and need for revision surgery following arthrodesis for scoliosis correction. Furthermore, patients with osteoporosis have a significantly higher risk of intraoperative blood volume loss and postoperative thromboembolic events.

Comparing and Contrasting the Clinical Utility of Sagittal Spine Alignment Classification Frameworks: Roussouly Versus SRS-Schwab.

Retrospective cohort study of a prospectively collected database. To compare clinical utility of two common classification systems for adult spinal deformity (ASD) and determine whether both should be considered in surgical planning to improve patient outcomes. Surgical restoration of appropriate Roussouly classification shape or SRS-Schwab ASD classification may improve outcomes. ASD patients with pre- and 2-year postop (2Y) radiographic/health-related quality of life (HRQL) data were grouped by "theoretical" and "current" Roussouly type. Univariate analyses assessed outcomes of patients who mismatched Roussouly types at both pre- and 2Y intervals (Mismatched) and those of preoperative mismatched patients who matched at 2-years (Matched). Subanalysis assessed outcomes of patients who improved in Schwab modifiers, and patients who both improved in both Schwab modifiers and matched Roussouly type by 2Y. Included: 515 ASD patients (59 ± 14 yrs, 80% F). Preoperative breakdown of "current" Roussouly types: Type 1 (10%), 2 (54%), 3 (24%), and 4 (12%). Matched and Mismatched groups did not differ in rates of reaching MCID for any HRQL metrics by 2Y (all P > 0.10). Reoperation, PJK, and complications did not differ between Matched and Mismatched (all P > 0.10), but Roussouly Matched patients had toward lower rates of instrumentation failure (17.2% vs. 24.8%, P = 0.038). By 2Y, 28% of patients improved in PT Schwab modifier, 37% in SVA, and 46% in PI-LL. Patients who both Matched Roussouly at 2Y and improved in all Schwab modifiers met MCID for Oswestry Disability Index (ODI) and Scoliosis Research Society (SRS) activity at higher rates than patients who did not. Isolated restoration per the Roussouly system was not associated with superior outcomes. Patients who both matched Roussouly type and improved in Schwab modifiers had superior patient-reported outcomes at 2-years. Concurrent consideration of both systems may offer utility in establishing optimal realignment goals.Level of Evidence: 3.

Iliac Screw Fixation Revisited: Improved Clinical and Radiologic Outcomes Using a Modified Iliac Screw Fixation Technique.

A retrospective study. To describe the modified iliac screw (mILS) technique and compare it to other spinopelvic fixation techniques in terms of wound healing complications, hardware prominence, and failure. The traditional entry point of an iliac screw often causes postoperative gluteal pain from the prominent screw head. The use of an offset connector also adds a point of weakness to the construct. By choosing a different screw entry point offset connectors can be avoided, and the screw head itself is less prominent, thereby reducing postoperative discomfort. A retrospective analysis was performed of adult patients undergoing lumbopelvic fixation (LPF) between January 2014 and June 2019. Patients were grouped into 1 of 3 groups based on the technique of pelvic fixation: S2 alar-iliac (S2AI) screw, traditional iliac screw (tILS), and mILS. The primary outcome parameter was the minimal distance from screw head to skin. Secondary outcome parameters were instrumentation loosening/failure, adjacent level fractures, pseudoarthrosis, and medial or lateral iliac screw perforation. A total of 190 patients undergoing LPF were included in the following 3 groups: mILS group (n=113), tILS group (n=40), and S2AI group (n=37). The mean minimal distance from screw head to skin in the mILS group was 31.3 mm compared with 23.7 mm in the tILS group (P<0.00199). No statistically significant differences were found when comparing the 3 groups with respect to complications. The mILS group did not show any cases of prominent instrumentation and had the lowest rate of instrumentation failure. The mILS technique is an acceptable alternative for LPF, offering the benefits of iliac screw fixation while avoiding offset connectors and screw prominence complications associated with tILS. Level III.

The Safety and Efficacy of Cervical Laminectomy and Fusion versus Cervical Laminoplasty Surgery in Degenerative Cervical Myelopathy: A Prospective Randomized Trial

BACKGROUND: There is a lack of evidence of whether degenerative cervical myelopathy (DCM) is best treated through cervical laminoplasty (CLP) or cervical laminectomy with lateral mass fusion due to the lack of prospective randomized studies that are well designed. We conducted the largest prospective randomized trial to date to determine the comparative effectiveness and safety of both approaches.&#x0D; METHODS: In this prospective, randomized trial, we randomly assigned patients who had symptoms or signs of DCM to undergo either cervical laminectomy and lateral mass fixation (CLF) or CLP. The primary outcome measures were the change in the Visual Analog Scale (VAS), neck disability index, modified Japanese Orthopedic Association (mJOA) score, and Nurick’s myelopathy grading 1 year after surgery. The secondary outcome measures were the intraoperative, post-operative complications, hospital stay, C2-7 Cobb’s angle, and Odom’s criteria. The follow-up period was at least 1 year.&#x0D; RESULTS: A total of 30 patients (mean age, 54.5 ± 5.5 years, 70% of men) underwent prospective randomization. There was a significantly greater improvement in neck pain (VAS) in the CLF group at 1 year (p &lt; 0.05). The improvement in the mJOA and Nurick’s myelopathy grading showed insignificant improvement between both groups. Furthermore, there was no significant difference in the patient’s post-operative satisfaction (Odom’s criteria). The mean operative time was significantly longer in the CLF group (p &lt; 0.001), with no significant difference in the post-operative complications, however, there was a higher rate of C5 palsy, dural tear and infection in the CLF, and a higher rate of instrumentation failure in the CLP. The mean hospital stay was significantly longer in the posterior group (p &lt; 0.05). Finally, there was a significant better improvement in the C2-7 Cobb’s angle at 1 year in the CLF group (p &lt; 0.05).&#x0D; CONCLUSION: Among patients with multilevel DCM, the CLF approach was significantly better regarding the post-operative pain and Cobb’s angle while the CLP was significantly better in terms of shorter hospital stay and operative time.

Revision surgery for instrumentation failure after total en bloc spondylectomy: a retrospective case series

BackgroundThere have been several reports of instrumentation failure after three-column resections such as total en bloc spondylectomy (TES) for spinal tumors; however, clinical outcomes of revision surgery for instrumentation failure after TES are seldom reported. Therefore, this study assessed the clinical outcomes of revision surgery for instrumentation failure after TES.MethodsThis study employed a retrospective case series in a single center and included 61 patients with spinal tumors who underwent TES between 2010 and 2015 and were followed up for > 2 years. Instrumentation failure rate, back pain, neurological deterioration, ambulatory status, operation time, blood loss, complications, bone fusion after revision surgery, and re-instrumentation failure were assessed. Data were collected on back pain, neurological deterioration, ambulatory status, and management for patients with instrumentation failure, and we documented radiological bone fusion and re-instrumentation failure in cases followed up for > 2 years after revision surgery.ResultsOf the 61 patients, 26 (42.6%) experienced instrumentation failure at an average of 32 (range, 11–92) months after TES. Of these, 23 underwent revision surgery. The average operation time and intraoperative blood loss were 204 min and 97 ml, respectively. Including the six patients who were unable to walk after instrumentation failure, all patients were able to walk after revision surgery. Perioperative complications of reoperation were surgical site infection (n = 2) and delayed wound healing (n = 1). At the final follow-up, bone fusion was observed in all patients. No re-instrumentation failure was recorded.ConclusionBone fusion was achieved by revision surgery using the posterior approach alone.

154. The use of autologous free vascularized fibula grafts in reconstruction of the mobile spine following tumor resection: illustrated surgical technique and outcomes

BACKGROUND CONTEXT Reconstruction of the mobile spine following total en bloc spondylectomy (TES) of one or multiple vertebral bodies in patients suffering from malignant spinal tumors is a challenging procedure with high failure rates. One of the most common reasons for reconstructive failure is nonunion, which is an even greater problem in the setting of local radiation. Radiation is an integral part of the management of primary malignant bone tumors in the spine at our institution. Vascularized grafts may help prevent nonunion in the setting of radiation therapy. We have routinely utilized free vascularized fibular grafts (FVFG) for the reconstruction of the mobile spine following TES. PURPOSE The purpose of this study is to describe the surgical technique utilized for vascularized reconstruction of defects following TES. In addition, we report the outcomes of a consecutive series of patients treated with this technique. STUDY DESIGN/SETTING Retrospective review of electronic health records at one tertiary care center and an illustrated explanation of the surgical technique. PATIENT SAMPLE Adult patients, 18 years or older, undergoing total en bloc resection of primary malignant tumors of the mobile spine followed by reconstruction using a free vascularized fibula graft. OUTCOME MEASURES The primary outcome was reconstruction failure of the construct. METHODS Thirty-nine patients treated at our tertiary care institution between 2010 and 2018 for a diagnosis of malignant tumor in the mobile spine with the use of FVFG following TES were reviewed. Postoperative union, complications, neurological outcome, reoperations, and survival were reported. The median time of follow-up was 50 months (range, 14 – 109 months). RESULTS The cohort consisted of 26 males and 13 females, with a median age of 58 years. Chordoma was the tumor that occurred most often (67%) and tumors occurred most often in the lumbar spine (46%). Complete union was seen in 26 patients (76%), the overall complication rate was 56%, and instrumentation failure was the most common complication with 26% of patients affected. In total 12 patients (31%) suffered from – instrumentation loosening or breakage, nonunion, graft fracture, or a combination of these – for which ten patients (26%) required revision surgery. The fixation was revised a total of 15 times (42% of reoperations). In 18 patients (46%) one or more reoperations were needed. The overall 1-, 3-, and 5-year survival rate was 95%, 92%, and 87%, respectively. CONCLUSIONS The FVFG is an adequate reconstruction technique of the mobile spine following TES for malignant tumors. Although we see higher union rates and comparable complication rates compared to other techniques, the rate of instrumentation failure was high. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

The complication trends of pediatric spinal deformity surgery in Japan – The Japanese Scoliosis Society Morbidity and Mortality survey from 2012 to 2017

BackgroundThe Japanese Scoliosis Society Morbidity & Mortality Committee performed a longitudinal nationwide complication survey of spinal deformity surgery from 2012 to 2017. The present study aimed to analyze the survey results and report the complication trends of pediatric spinal deformity surgery in Japan. MethodsAll Japanese Scoliosis Society members were invited to participate in the survey. Diagnoses were grouped into idiopathic scoliosis, congenital scoliosis, neuromuscular scoliosis, other types of scoliosis, and pediatric kyphosis. Complications were grouped into death, blindness, neurological deficits (motor/sensory), infection, massive bleeding, hematoma, pneumonia, cardiac failure, deep vein thrombosis/pulmonary embolism, gastrointestinal perforation, and instrumentation failure. ResultsThe surveys were performed in 2012, 2014, and 2017. The overall complication rate decreased from 10.7% in 2012 to 8.1% in 2017. In particular, the complication rate in patients with idiopathic scoliosis decreased from 8.8% in 2012 to 4.0% in 2017. The complication rate of patients with neuromuscular scoliosis and kyphosis remained high. The rate of neurological deficits, especially in motor deficits, significantly decreased from 2.0% in 2012 to 0.7% in 2017, and tended to be highest in patients with kyphosis. The rate of massive bleeding was significantly decreased from 3.3% in 2012 to 0.8% in 2017, especially in patients with neuromuscular scoliosis (12.2–4.4%). However, patients with neuromuscular scoliosis had a high rate of postoperative pneumonia (3.7%, 2.6%, and 5.1%, respectively). The rate of instrumentation failure was also high (2.1%, 1.5%, and 2.2%, respectively), especially in patients with early onset idiopathic, congenital and other types of scoliosis. ConclusionsThe overall surgical complication rates in pediatric patients decreased due to decreased rates of neurological deficits and massive bleeding, especially in patients with idiopathic scoliosis. However, the complication rates remain high in patients with neuromuscular scoliosis and kyphosis.

Osteoporosis increases the likelihood of revision surgery following a long spinal fusion for adult spinal deformity

BACKGROUNDAdult spinal deformity (ASD) can be a debilitating condition that requires surgical intervention. ASD patients often present with osteoporosis, predisposing them to increased rates of instrumentation failure and postoperative fractures, frequent reasons for revision surgery. We hypothesized that the rate and timing of revision surgery are different in osteoporotic and nonosteoporotic patients undergoing long fusions for ASD. To our knowledge, the timing of revision surgeries, in particular, have not previously been explored. PURPOSETo determine the rate and timing of revision surgery in osteoporotic and nonosteoporotic patients following a long fusion for ASD. STUDY DESIGNRetrospective comparative study. PATIENT SAMPLEASD patients who underwent a long spinal fusion surgery at two large academic medical centers from 2010 to 2019. OUTCOME MEASURESOccurrence of revision surgery. METHODSInclusion criteria were patient age of least 40 years and spinal fusion spanning at least seven levels for ASD. Patient records were reviewed for a diagnosis of osteoporosis as per ICD codes and revision surgery within 2 years of the index procedure. Revision surgery was defined as an unplanned procedure related to the index surgery for the treatment of a spine-related complication. Chi-squared tests comparing demographic data, revision rates, and multiple revisions were conducted. The incidence and prevalence of revision surgeries as a function of time and osteoporotic status were evaluated for significant differences via the Mann-Whitney U and Mantel-Haenszel log rank tests. Finally, a logistic regression analysis was utilized to determine the predictive value of osteoporosis, age, and gender on the likelihood for complications. RESULTSThree hundred ninety-nine patients matched the study criteria. In the osteoporotic group, 40.5% of patients underwent a revision surgery compared to 28.0% in the nonosteoporotic group (p=.01). The occurrence of multiple revision surgeries following the index procedure was similar in both groups: 8.4% in osteoporotic patients and 8.6% in nonosteoporotic patients. Age and gender were not statistically correlated with the incidence of revision surgery. CONCLUSIONSASD patients with osteoporosis have an increased risk of undergoing revision for a surgery-related complication within 2 years of the index procedure. These complications included failure of hardware, pseudoarthrosis, proximal junction failure, and infection, among other issues that required surgical intervention. As others have also highlighted the importance of poor bone density on construct failure, our data further underscore the importance of preoperative osteoporosis surveillance. Though intuitive, further study is needed to demonstrate that improving patients’ bone density can decrease the incidence of related complications and the need or revision surgery.

The complication trends of adult spinal deformity surgery in Japan – The Japanese Scoliosis Society Morbidity and Mortality survey from 2012 to 2017

BackgroundThe Japanese Scoliosis Society Morbidity & Mortality Committee performed a longitudinal nationwide complication survey of spinal deformity surgery from 2012 to 2017. The present study aimed to analyze the survey results and report the complication trends of adult spinal deformity surgery in Japan. MethodsAll Japanese Scoliosis Society members were invited to participate in the survey. Adult spinal deformity was categorized into three groups by age: 20–39 years, 40–64 years and ≥65 years. Complications were grouped into death, blindness, neurological deficits (motor/sensory), infection, massive bleeding, hematoma, pneumonia, cardiac failure, deep vein thrombosis/pulmonary embolism, gastrointestinal perforation, and instrumentation failure. ResultsThe surveys were performed in 2012, 2014, and 2017. The overall complication rates were 21.6%, 26.0%, and 25.4%, respectively. The complication rates differed significantly by age group in all years such that older patients had a higher complication rate than younger patients. The rate of neurological deficits, particularly motor deficits, significantly increased in 2014 (3.1%–5.5%), and decreased in 2017 (4.3%). Massive bleeding and postoperative hematoma decreased significantly year by year (8.0%, 4.8%, 2.5% and 1.3%, 0.5%, 0.3%, respectively). The complication rate of instrumentation failure remained high, increasing without significant difference (5.2%, 5.8%, 6.5%, respectively), and was more common in the middle-aged and older patients. ConclusionsSurgical complication rates in patients with adult spinal deformity remain high, especially neurological deficits and instrumentation failure in patients aged over 40 years. However, the complication rates of massive bleeding and postoperative hematoma decreased over this period.

Surgical Treatment of Ossifications of the Cervical Anterior Longitudinal Ligament: A Retrospective Cohort Study.

Study Design:Retrospective cohort studyObjectives:The study aims to evaluate anterior cervical discectomy and fusion (ACDF) in the treatment of patients with ossification of the anterior longitudinal ligament (OALL).Methods:We retrospectively reviewed cases performed at our institution between January 2015 and December 2018; adult (age ≥18 years) patients who underwent anterior cervical decompression and fusion in the presence of dysphagia and OALL. Ten patients (9 male, 1 female, mean age 64.4 years) with OALL who underwent ACDF were included. Charts were reviewed for demographics and comorbidities. Primary outcomes assessed were intra- and postoperative complications. Secondary outcomes were fusion rates, instrumentation failure, postsurgical instability/deformity, and readmission rates.Results:The average duration of symptoms prior to surgery was 12.3 months. All patients presented with dysphagia (mean Bazaz score 2.0). The average number of levels with OALL was 4.7 (±1.67). All patients underwent ACDF and 3 patients underwent additional posterior cervical fusion for kyphotic deformity correction or when extensive laminectomy was required. We did not encounter any intraoperative complications. Eight patients (72%) had solid fusion demonstrated on the lateral x-rays and no evidence of progressive kyphotic deformity. We did not encounter any instrumentation failure or loosening. Two patients developed recurrence of dysphagia (Bazaz scores 2 and 3 respectively).Conclusion:ACDF for OALL with dysphagia and concomitant myelopathy in our small series of 10 patients demonstrate good fusion and clinical outcomes. Larger studies will be necessary to determine the optimal treatment for patients with dysphagia due to OALL.

Staged instrumentation with magnetically controlled growing rods in early-onset scoliosis: indications and preliminary outcomes.

Severe scoliosis, kyphosis, stiffer curves, short trunk height, and poor bone density are known risk factors for instrumentation failure with traditional growing rods or magnetically controlled growing rods (MCGR). To minimize the risk of instrumentation failure in managing complex early-onset scoliosis (EOS) with MCGR, we propose a strategy for staged MCGR insertion. We performed a single-center retrospective review of all consecutive MCGR cases with 24months' minimum follow-up. Inclusion criteria included diagnosis of EOS of any etiology with severe and stiff curves in the coronal or sagittal planes, poor bone density, short trunk height (T1-T12 smaller than 150mm) or previous instrumentation failure managed with staged MCGR. During the first stage, anchor points and halo-gravity were applied, followed by halo-gravity traction. At a second stage, halo-gravity was removed and MCGR were inserted. Outcome measures included pre- and postoperative radiographic measurements and complications. Seventeen patients with a median age of 7 (range 6-9) years were managed in two stages. Indications for two-stage surgery were short trunk height (T1-T12 height less than 150mm) in six patients, five poor bone quality, three dislodgement of proximal anchor points in previous instrumentation, and three rigid curves. The rate of unplanned revision surgeries was 11.8%. No infections or traction-related complications were found. According to our results, the staged MCGR insertion strategy combined with halo-gravity traction to manage complex EOS yielded a relatively low instrumentation failure rate as compared with the rates previously reported in the current literature. To our knowledge, this is the first study reporting the staged strategy for instrumentation with MCGR. IV.

P92. Preventing rod failure in pedicle subtraction osteotomy revision surgeries for sagittal deformity with a satellite rod technique

BACKGROUND CONTEXT Pedicle subtraction osteotomy (PSO) is used to treat rigid sagittal deformities. The traditional 2-rod PSO technique has resulted in high instrumentation failure rates. We investigated the use of a multiple rod satellite configuration for PSO. PURPOSE Demonstrate that a multiple rod satellite configuration for PSO will result in substantial improvement in sagittal parameters and global alignment and proportion (GAP) score with a low instrumentation failure rate. STUDY DESIGN/SETTING Case series. PATIENT SAMPLE Patients who underwent PSO with a multiple rod satellite rod technique during revision surgery for sagittal plane deformity by a single surgeon. OUTCOME MEASURES Instrumentation failure and sagittal parameters including PSO angle, proximal junctional kyphosis, sagittal vertical axis (SVA), pelvic incidence – lumbar lordosis (PI-LL) mismatch and GAP score. METHODS Independent observers collected demographics, surgical variables, and radiographic measurements from 40 patients who underwent revision surgery for sagittal deformity with a PSO. Procedures were performed by a single surgeon at two different centers. Student's t test compared groups. RESULTS A total of 40 patients underwent PSO with satellite rod technique. Eight were smokers and 7 were diabetic. The most common level was L3 (91%), with 9% at L4. Low dose BMP (1-2 large kits) was distributed over all segments and supplemental allograft was used in all patients. No intradiscal fusion was performed with PSOs, but all patients were previously fused. Mean PSO angle was 28.7±7.6°. Two out of 40 patients had rod fracture necessitating revision surgery at 32 and 34 months. One patient developed an infection requiring replacement of instrumentation. Three patients developed proximal junctional kyphosis, none required revision. Mean preoperative SVA was 13.5±7.3 cm, which significantly decreased to 4.8±7.3 cm (p = 0.002). Mean preoperative PI-LL mismatch was 35.9±16.6, which significantly improved to 11.8±14.6 post-op (p CONCLUSIONS Despite a high rate of comorbid conditions and severely disproportioned postoperative GAP scores, rod failure rate after PSO with the multiple rod satellite configuration was very low (5%) compared to previous reports. SVA and PI-LL mismatch were significantly improved. GAP score was also significantly improved, but still considered severely disproportioned, most likely due to the high rate of PSO's at L3 in previously fused spines, which did not correct low lumbar lordosis. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

210. Comparing and contrasting the clinical utility of sagittal spine alignment classification frameworks: Roussouly vs SRS-Schwab

BACKGROUND CONTEXT For surgical adult spinal deformity (ASD) patients, incorporating restoration of appropriate Roussouly Classificaion shape into surgical planning may improve outcomes. With the introduction and use of the SRS-Schwab ASD classification system, it is important to compare the utility of both classification frameworks as they relate to surgical outcomes. PURPOSE Compare outcomes of surgical ASD patients classified by both Roussouly and Schwab systems. STUDY DESIGN/SETTING Retrospective review of prospective ASD database. PATIENT SAMPLE A total of 515 ASD patients. OUTCOME MEASURES Complications; Health-related quality of life (HRQL): ODI, SF-36 PCS, SRS-22r. METHODS ASD patients with pre- and 2-year postop (2Y) radiographic/HRQL data were grouped by “theoretical” Roussouly type (Type 1: PI 60°) and “current” Roussouly type (1: SS 45°), as published. Means comparison tests assessed outcomes of those that mismatched “theoretical” and “current” types at both pre- and 2Y intervals (mismatched) to those of preoperative mismatched patients that matched at 2-years (matched). Subanalysis assessed outcomes of patients that improved in Schwab modifiers, and patients that both improved in both Schwab modifiers and matched Roussouly type by 2Y. RESULTS Included 515 ASD patients (59±14yrs, 80%F). The overall cohort showed moderate preoperative global and lumbo-pelvic deformity: SVA(64mm±73), PT(25°±11), PI-LL(16°±21). Preoperative breakdown of “current” Roussouly types: Type 1 (10%), Type 2 (54%), Type 3 (24%), Type 4 (12%). Preoperative mismatch between “current” and “theoretical” types was 60%. By 2Y, 16% of patients matched Roussouly types. Matched and Mismatched groups did not differ in rates of reaching MCID for any HRQL metrics by 2Y(all p>0.1). Reop, PJK and complications did not differ between matched and mismatched(all p>0.1), though mismatched patients showed a trend of increased instrumentation failure(17% vs 26%, p=0.080). By 2Y, 28% of patients improved in PT Schwab modifier, 37% in SVA, and 46% in PI-LL. Patients that improved in PT modifier had lower instrumentation failure rates (16% vs 24%) and higher rates of reaching 2Y MCID for ODI (58% vs 48%) and SRS Activity (75% vs 64%) than patients that did not improve. Patients that both Matched Roussouly at 2Y and improved in all Schwab modifiers met MCID for ODI and SRS Activity at higher rates than patients that did not. Roussouly Match patients that improved in Schwab PT met SRS Activity MCID at a higher rate, and had less renal, infection, and neurologic complications than patients that did not. Roussouly Match patients that improved in Schwab SVA also had superior SF-36 scores and fewer cardiopulmonary complications(all p CONCLUSIONS For surgical ASD patients, isolated restoration of sagittal spinal shape per the Roussouly system was not associated with superior clinical outcomes or complications by 2 years. In contrast, improvement in PT, per the SRS-Schwab system, was associated with substantial improvement in low-back disability by 2 years. Collectively, patients that both matched Roussouly sagittal type and improved in Schwab modifiers had superior complication and patient-reported outcomes by 2 years. These results suggest that concurrent consideration of both existing systems may offer utility in establishing optimal realignment targets. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Comparison of radiographic parameters after anterior cervical discectomy and fusion with semiconstrained translational versus rotational plate systems

ObjectiveA plate is commonly applied after anterior cervical discectomy and fusion (ACDF); particularly in cases of multilevel fusion. Recent comparative studies have focused on constrained versus semiconstrained plates, however little data is available to assess differences between semiconstrained plates. Patients and MethodsA retrospective review of 60 consecutive adult patients undergoing a 1, 2 or 3 level ACDF with a lordotic allograft for treatment of symptomatic cervical spondylosis was conducted at a single center. The cohort was separated into two groups depending on the cervical plating system used. Patients in the first group had a semiconstrained translational plate and those in the second group had a semiconstrained rotational plate. Plain neutral radiographs were assessed preoperatively, immediately after surgery and at most recent follow-up. The measured radiographic parameters focused on sagittal alignment, adjacent segment pathology, fusion rate and implant failure. ResultsThere were 30 patients in each group. There were no significant differences in demographic characteristics or distribution of levels fused between groups. All patients had at least 6 months of follow-up and mean follow-up was 14.8 ± 6.2 months in the translational plate group and 13.1 ± 4.8 months in the rotational plate group (p = 0.227). Significant improvement in sagittal segmental alignment was noted in both groups following surgery. The translational plate group improved from 1.0 ± 7.5 degrees to 4.8 ± 7.6 degrees (p = 0.03) and the rotational group improved from 2.7 ± 9.1 degrees to 8.4 ± 7.8 degrees (p = 0.001). This significant sagittal correction was maintained through follow-up for those in the rotational plate group; 5.5 ± 9.1 degrees (p = 0.002). However, a partial loss of segmental lordosis was observed in the translational plate group leading to a failure to maintain significance of the lordotic correction; 1.7 ± 8.3 degrees (p = 0.280) over the follow-up period. Segmental fusion rates were not significantly different between groups. However, there was a higher rate of screw breakage within the rotational plate group (4 instances versus 0 instances in the translational plate group). ConclusionThis comparative cohort series suggests that performing an ACDF with a lordotic allograft using either semiconstrained translational or rotational plate system allows for correction and maintenance of cervical alignment, however the rotational plate appears more effective at maintaining segmental lordotic correction. Further prospective controlled study will be needed to determine if this may come at the expense of greater rates of instrumentation failure in the rotational plate group.

The Japanese Scoliosis Society Morbidity and Mortality Survey in 2014: The Complication Trends of Spinal Deformity Surgery from 2012 to 2014.

Introduction The Japanese Scoliosis Society (JSS) created a longitudinal complication survey of spinal deformity surgery and established the Morbidity and Mortality (M&M) Committee in 2012. The purpose of this study was to analyze the results of the complication survey in 2014 and to report the differences in the complication rates between the years 2012 and 2014. Methods A request to participate in this survey was mailed to all JSS members. The questionnaires were sent through e-mail to the members who took part in this survey, and the responses were returned through the same. Diagnosis was grouped into idiopathic scoliosis, congenital scoliosis, neuromuscular scoliosis, spondylolisthesis, pediatric kyphosis and adult spinal deformity. Complication was grouped into death, blindness, neurological deficit (motor or sensory deficit), infection, massive bleeding, hematoma, pneumonia, cardiac failure, DVT/PE, gastrointestinal perforation and instrumentation failure. Results A total of 2,012 patients were reported from 71 institutes. Overall, complications were observed in 326 patients, and the complication rate increased from 10.4% in 2012 to 15.3% in 2014. The complication rate decreased from 8.8% to 3.7% in idiopathic scoliosis, 21.9% to 15.8% in neuromuscular scoliosis and 26.8% to 0% in kyphosis. The complication rate increased from 6.6% to 14.4% in congenital scoliosis, 9.3% to 12.0% in other types of scoliosis, 3.5% to 14.3% in spondylolisthesis and 21.6% to 26.0% in adult spinal deformity. The rate of neurological deficit, especially in motor deficit, increased from 3.2% to 7.7% in older patients with adult spinal deformity. Instrumentation failure was also more common in patients with adult spinal deformity (5.2% to 5.8%), especially in patients aged 40-65 years (4.4% to 9.1%). Conclusions The major complication trends were an increasing rate of neurological deficit and instrumentation failure, especially in adult spinal deformity.

The Effect and Safety of Polymethylmethacrylate-Augmented Sacral Pedicle Screws Applied in Osteoporotic Spine with Lumbosacral Degenerative Disease: A 2-Year Follow-up of 25 Patients

A high rate of instrumentation failure is frequently seen in osteoporotic spines, especially at the sacral segment because of the great shear stress. Several techniques of sacral pedicle screw placement, such as bicortical and tricortical fixation, have been developed; however, the problems of loosening and pulling out of the screws are still a concern. Recently, the polymethylmethacrylate (PMMA)-augmented pedicle screws have been shown to strengthen the purchase in osteoporotic spine, but there are few reports on the effect of S1 pedicle screw with PMMA augmentation. Seventy-five patients receiving cement-augmented pedicle screws at lumbosacral vertebra were enrolled and divided into 3 groups by different patterns of S1 pedicle screw placement: S1 pedicle screw with PMMA augmentation (group A, 25 patients), S1 bicortical pedicle screw fixation (group B, 25 patients), and S1 tricortical pedicle screw fixation (group C, 25 patients). The Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) scores were assessed preoperatively and at the last follow-up. Besides, the complications, loosening rate, and fusion rate were recorded. The VAS and ODI scores at the last follow-up were significantly improved in the 3 groups compared with preoperative results. Better pain relief and functional improvement at the last follow-up was seen in group A compared with the other 2 groups; however, no significant difference was detected between groups B and C. Although the lowest screws loosening rates and the highest fusion rate were found in group A, no significant difference among these 3 groups. Furthermore, longer fusion segments and larger postoperative pelvic incidence-lumbar lordosis (PL-LL) were found as risks related to S1 screw loosening without cement augmentation. The S1 pedicle screws with PMMA augmentation achieved better stability with less screw loosening in the osteoporotic spine with lumbosacral degenerative diseases compared with bicortical/tricortical fixation at S1. This procedure is especially recommended for patients with long segment fixation and large postoperative PI-LL, but there is also a risk of bone cement leakage and a learning curve.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P98. Does additional bone grafting of atlantoaxial joint increase the bone fusion rate of iliac crest autograft in posterior occipitocervical fusion? A retrospective, controlled study with a two-year follow-up

BACKGROUND CONTEXT Occipitocervical fusion can be utilized to correct joint instability caused by trauma, rheumatological conditions, infection, neoplasm, or congenital conditions. Bone-graft-related complication was relatively frequent during occipitocervical fusion surgery. In previous studies, the reported fusion rates were ranged from 83.6% to 100%; and the rate of instrumentation failure after nonunion was as high as 7% during occipitocervical fusion. PURPOSE To explore whether additional bone grafting of atlantoaxial joint increase the bone fusion rate of iliac crest autograft in posterior occipitocervical fusion surgery. STUDY DESIGN/SETTING A retrospective, controlled study with a 2-year follow-up. PATIENT SAMPLE Between January 2014 and January 2016, a total of 48 consecutive patients underwent posterior occipitocervical fusion with a screw-rod fixation system in a tertiary spine center. OUTCOME MEASURES In the postoperatively follow up, patients underwent computed tomography (CT) scan at every interval until bone fusion was confirmed. The related complications were also recorded. METHODS In the control group, we only placed a piece of autogenous iliac corticocancellous bone between the occipital and C2 vertebral laminae for fusion. In the hybrid fusion group, besides posterior occipitocervical autograft, we additionally pack some granular bone harvested from the iliac crest into bilateral atlantoaxial joint. RESULTS Only a piece of autogenous iliac corticocancellous bone was placed between the occipital and C2 in 24 patients to perform posterior occipitocervical fusion. In the other 24 cases, besides posterior occipitocervical autograft, we additionally pack some granular bone harvested from the iliac crest into bilateral atlantoaxial joint. All patients were followed for at least 24 months. Only 21 (87.5%) patients in the control group had confirmed posterior bony fusion on CT imaging while 24 (100%) patients in the hybrid fusion group had confirmed posterior bony fusion. There were postoperative implant-related complications in 2 patients; screw loosening was visible in one case, pullout and breakage of internal fixation was observed in another case. All two cases were belong to the control group (8.3%). Mean duration to posterior occipitocervical fusion was 5.5 months in the hybrid fusion group versus 6.1 months in the control group (P=.037). Of note, in the hybrid fusion group, the process of atlantoaxial joint fusion was faster than that of posterior occipitocervical fusion (5.1 months vs. 5.5 months, p=.103). CONCLUSIONS Additional bone grafting of atlantoaxial joint could increase the bone fusion rate of iliac crest autograft and promote the process of bone fusion in posterior occipitocervical fusion.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P11. The regional effects of lumbosacral anterior column support on rod and screw strain in a pedicle subtraction osteotomy model: an in silica investigation

BACKGROUND CONTEXT Pedicle subtraction osteotomy (PSO) for the treatment of adult spinal deformity is associated with a 20%–30% revision rate, often as the result of rod fracture at the PSO level or lumbosacral junction. Recent clinical literature reports decreased rates of instrumentation failure when multirod reconstruction or an anterior lumbar interbody fusion (ALIF) device is used at the L5–S1 disc space. While multirod techniques are shown to reduce rod strain at the PSO, it is presently unclear whether anterior column support (ACS) prevents disc collapse or reduces rod strain as a flexion blocker. Such information is necessary for determining appropriate reconstruction following PSO. PURPOSE The present study investigated whether ACS reduces rod strain, thus explaining the reduced rates of rod fracture seen clinically following PSO. STUDY DESIGN/SETTING Finite element analysis. METHODS A lumbosacral finite element model (T12-S1) was developed and validated with cadaveric range of motion data. Vertebral segments were modeled as three-dimensional solid elements. Intervertebral discs (nucleus and annulus fibrosis) were structured as hyperelastic materials. The intact model underwent PSO at L3, and titanium pedicle screws and rods from T12-S1. Simulations assessed (1) the addition of a short accessory rod affixed to the left primary rod at the PSO level (three-rod) or bilaterally (four-rod), and (2) ACS at L5-S1. A pure 10 Nm moment was applied at T12 to simulate flexion-extension. ACS was simulated by changing intervertebral disc properties to match cancellous bone. Strain was normalized to the two-rod construct (100%), averaged between the left and right primary rods, and evaluated along the primary rods at the PSO, L5-S1, and S1 screws. RESULTS Both the three- and four-rod constructs reduced primary rod strain at the PSO and L5-S1 relative to two-rod, irrespective of ACS. At the PSO, three- and four-rod constructs reduced primary rod strain to 65% and 49%, respectively; the addition of ACS had a negligible effect (three-rod, 66%; four-rod, 50%). At the lumbosacral junction, three- and four-rod constructs reduced primary rod strain to 82% and 85%, respectively; the addition of ACS dramatically reduced rod strain to 31% and 36%. Lastly, three- and four-rod constructs observed sacral screw strain of 102% and 94%, respectively; the addition of ACS reduced rod strain considerably to 34% and 34%. CONCLUSIONS While both multirod reconstruction techniques reduced motion-induced strain across the primary rods at the PSO, the four-rod construct reduced strain an additional 16% in comparison to the three-rod configuration. Lumbosacral ACS dramatically reduced L5-S1 rod strain between an additional 49% and 52% in comparison to multirod constructs without ALIF; sacral screw strain was reduced an additional 60%–68%. Nevertheless, reduction of mechanical demand of the rods and screws appears to be limited to the lumbosacral junction, with minimum influence of motion-induced rod strain at the PSO. These results suggest that the mechanical benefit of ACS may be limited to the localized level of insertion, and that reduction of rod fractures at the PSO observed clinically may be due to maintenance of disc height and subsequent sagittal balance.