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Study Design: Retrospective cohort study., Objective: This study aimed to evaluate the association between nerve lengthening after adult deformity correction and motor deficits dervied from the upper lumbar plexus or femoral nerve., Summary of Background Data: Adult spinal deformity (ASD) surgery is associated with high rates of neurological deficits. Certain postoperative deficits may be related to lengthening of the upper lumbar plexus (ULP) and/or femoral nerve (FN) after correction of lumbar deformity., Methods: Patients with ASD who underwent posterior-only corrective surgery from the sacrum to L3 or above were included. The length of each lumbar nerve root was calculated geometrically using the distance from the foramen to the midpoint between the anterosuperior iliac crest and pubic symphysis on AP and lateral radiographs. The mean lengths of the L1 to 3 and L2 to 4 nerve roots were used to define the lengths of the ULP and FN, respectively. Preoperative to postoperative changes in nerve length were calculated. Neurological examination was performed at discharge. Proximal weakness (PW) was defined as the presence of weakness compared with baseline in either hip flexors or knee extensors. Multiple linear regression analysis was used for estimating the postoperative lengthening according to the magnitude of preoperative curvature and postoperative correction angles., Results: A total of 202 sides were analyzed in 101 patients, and PW was present on 15 (7.4%) sides in 10 patients. Excluding the 10 cases with three-column osteotomies, those with PW had a significantly higher rate of pure sagittal deformity ( P <.001) and greater nerve lengthening than those without PW (ULP 24 vs. 15 mm, P =0.02; FN 18 vs. 11 mm, P =0.05). No patient had advanced imaging showing neural compression, and complete recovery of PW occurred in eight patients at one-year follow-up., Conclusions: After ASD surgery, lengthening of the ULP was associated with PW. In preoperative planning, surgeons must consider how the type of correction may influence the risk for nerve lengthening, which may contribute to postoperative neurological deficit., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background/Objectives : While the economic cost of adult spinal deformity (ASD) surgery has been studied extensively, its environmental impact is unknown. The aim of this study is to determine the carbon footprint (CF) associated with ASD surgery. Methods : ASD patients who underwent > four levels of corrective surgery between 2017 and 2021 were included. The open group included a posterior-only, single-stage technique, while the minimally invasive surgery (MIS) group was defined as the use of lateral interbody fusion and percutaneous posterior screw fixation. The two groups were propensity-score matched to adjust for baseline demographic, surgical, and radiographic characteristics. Data on all disposables and reusable instruments, anesthetic gas, and non-gas medications used during surgery were collected from medical records. The CF of transporting, using, and disposing of each product and the footprint of energy use in operating rooms were calculated. The CF produced was evaluated using the carbon dioxide equivalent (CO 2 e), which is relative to the amount of CO 2 with an equivalent global warming potential. Results : Of the 175 eligible patients, 15 pairs (65 ± 9 years, 47% female) were properly matched and analyzed for all variables. The average CF generated per case was 147.7 ± 37.3 kg-CO 2 e, of which 54% was attributable to energy used to sterilize reusable instruments, followed by anesthetic gas released into the environment (17%) and operating room air conditioning (15%). Conclusions : The CF generated during ASD surgery should be reduced using a multidisciplinary approach, taking into account that different surgical procedures have different impacts on carbon emission sources.

Background/Objectives : There exists limited data guiding open-door laminoplasty. The objective of this study is to determine if open-door laminoplasty affects radiographic decompression or arm pain outcomes. Methods : Adult patients who underwent unilateral open-door laminoplasty cervical myelopathy were included. The side opened was dependent on surgeon discretion. We recorded preoperative side of symptoms, side of radiographic compression, arm pain scores, and canal diameter. Patients with open-side ipsilateral or contralateral to dominant symptoms or compression were compared to determine any effect on arm pain outcomes or spinal canal diameter. If the symptoms were equal bilaterally, patients were neutral. Results : A total of 167 patients were included, with an average age of 64 ± 11 years and average follow-up time of 64.5 ± 72 weeks. The average preoperative arm pain visual analog score (VAS) was 2.13 ± 2.86, and the average arm VAS after 6 months was 1.52 ± 2.68. For dominant symptoms, the ipsilateral, contralateral, and neutral groups had a significant improvement in arm VAS at >6 months postoperatively. For dominant compression, the ipsilateral and contralateral groups had a significant improvement in both arm VASs and canal diameter at >6 months postoperatively. No differences were seen between groups for either. We observed a significant correlation between size of plate and change in canal diameter; however, no differences were noted for arm pain. Conclusions : Laminoplasty may be effective in addressing radicular arm pain by increasing the spinal canal's diameter and space available for the cord. The laterality of open-door laminoplasty did not affect arm pain improvement or canal expansion.

Study Design: Retrospective cohort., Objective: Determine effects of bracing on proximal junctional kyphosis (PJK) after adult deformity correction., Methods: Patients were identified from a single-surgeon dataset of posterior-only fusions for ASD (pelvis to UIV of T9-12) with a minimum of 1-year follow up. Starting in 2021, all lower thoracic fusions were braced using a hyperextension brace. Patients wore the brace at all times (unless in bed) for the first 6 weeks after surgery. A 1:1 propensity-match was performed based on age, number of levels, 3 column osteotomies, and magnitude of correction to identify a comparative non-braced cohort., Results: 141 patients (113 non-brace, 28 brace) were evaluated. After matching, 56 patients were identified to form similar cohorts. Non-matched and matched groups had no statistically significant differences in demographics, comorbid conditions, surgical characteristics (except shorter operative time and lower EBL in the braced group), and preoperative radiographic parameters. For the overall cohort, the change in proximal junctional angle at 1-year was higher in the non-braced group (7.6° vs 8.1°, P = .047), and non-braced patients had a higher incidence of PJK at 1-year in both the overall cohort (36% vs 14%, P = .045) and matched cohort (43% vs 14%, P = .038). There was no difference in proximal junctional failure between groups., Conclusion: This pilot study shows that our protocol for extension bracing may reduce rates of PJK. These findings can form the basis for future multi-center trials examining the effect of extension bracing on junctional complications., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Cross-sectional survey and retrospective review of prospectively collected data., Objective: To explore how patients perceive their decision to pursue spine surgery for degenerative conditions and evaluate factors correlated with decisional regret., Summary of Background Data: Prior research shows that one-in-five older adults regret their decision to undergo spinal deformity surgery. However, no studies have investigated decisional regret in patients with degenerative conditions., Methods: Patients who underwent cervical or lumbar spine surgery for degenerative conditions (decompression, fusion, or disk replacement) between April 2017 and December 2020 were included. The Ottawa Decisional Regret Questionnaire was implemented to assess prevalence of decisional regret. Questionnaire scores were used to categorize patients into low (<40) or medium/high (≥40) decisional regret cohorts. Patient-reported outcome measures (PROMs) included the Oswestry Disability Index, Patient-reported Outcomes Measurement Information System, Visual Analog Scale (VAS) Back/Leg/Arm, and Neck Disability Index at preoperative, early postoperative (<6 mo), and late postoperative (≥6 mo) timepoints. Differences in demographics, operative variables, and PROMs between low and medium/high decisional regret groups were evaluated., Results: A total of 295 patients were included (mean follow-up: 18.2 mo). Overall, 92% of patients agreed that having surgery was the right decision, and 90% would make the same decision again. In contrast, 6% of patients regretted the decision to undergo surgery, and 7% noted that surgery caused them harm. In-hospital complications (P=0.02) and revision fusion (P=0.026) were significantly associated with higher regret. The medium/high decisional regret group also exhibited significantly worse PROMs at long-term follow-up for all metrics except VAS-Arm, and worse achievement of minimum clinically important difference for Oswestry Disability Index (P=0.007), Patient-Reported Outcomes Measurement Information System (P<0.0001), and VAS-Leg (P<0.0001)., Conclusions: Higher decisional regret was encountered in the setting of need for revision fusion, increased in-hospital complications, and worse PROMs. However, 90% of patients overall were satisfied with their decision to undergo spine surgery for degenerative conditions. Current tools for assessing patient improvement postoperatively may not adequately capture the psychosocial values and patient expectations implicated in decisional regret., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective review of prospectively collected multisurgeon data., Objective: Examine the rate, clinical impact, and predictors of subsidence after expandable minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) cage., Summary of Background Data: Expandable cage technology has been adopted in MI-TLIF to reduce the risks and optimize outcomes. Although subsidence is of particular concern when using expandable technology as the force required to expand the cage can weaken the endplates, its rates, predictors, and outcomes lack evidence., Materials and Methods: Patients who underwent 1 or 2-level MI-TLIF using expandable cages for degenerative lumbar conditions and had a follow-up of >1 year were included. Preoperative and immediate, early, and late postoperative radiographs were reviewed. Subsidence was determined if the average anterior/posterior disc height decreased by >25% compared with the immediate postoperative value. Patient-reported outcomes were collected and analyzed for differences at the early (<6 mo) and late (>6 mo) time points. Fusion was assessed by 1-year postoperative computed tomography., Results: One hundred forty-eight patients were included (mean age, 61 yr, 86% 1-level, 14% 2-level). Twenty-two (14.9%) demonstrated subsidence. Although statistically not significant, patients with subsidence were older, had lower bone mineral density, and had higher body mass index and comorbidity burden. Operative time was significantly higher ( P = 0.02) and implant width was lower ( P < 0.01) for subsided patients. Visual analog scale-leg was significantly lower for subsided patients compared with nonsubsided patients at a >6 months time point. Long-term (>6 mo) patient-acceptable symptom state achievement rate was lower for subsided patients (53% vs . 77%), although statistically not significant ( P = 0.065). No differences existed in complication, reoperation, or fusion rates., Conclusions: Of the patients, 14.9% experienced subsidence predicted by narrower implants. Although subsidence did not have a significant impact on most patient-reported outcome measures and complication, reoperation, or fusion rates, patients had lower visual analog scale-leg and patient-acceptable symptom state achievement rates at the >6-month time point., Level of Evidence: Level 4., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective chart review., Objective: This study aimed to examine postoperative radiculitis after isolated L5-S1 anterior lumbar interbody fusion (ALIF), determine which factors contribute to its development, and investigate the comparative outcomes of patients with versus without postoperative radiculitis., Summary of Background Data: Both standalone and traditionalALIF are common and safe lumbar spine fusion techniques. Although optimal safety and effectiveness are achieved through appropriate patient selection, postoperative radiculitis after L5-S1 ALIF is a potential complication that seems to be the least predictable in the absence of iatrogenic injury., Patients and Methods: All adult patients (18-80 yr) with preoperative radiculopathies who underwent L5-S1 ALIF by 9 board-certified spine surgeons at a single academic institution from January 2016 to December 2021 with a minimum of 3 months follow-up were included. Patient records were assessed for data on clinical characteristics and patient-reported outcome scores (patient-reported outcome measures). All patient records were evaluated to determine whether postoperative radiculitis developed. Radiographic measurements using x-rays were completed using all available pre and postoperative imaging. Multivariable logistic regressions were performed utilizing radiculitis as the dependent variable and various independent predictor variables., Results: One hundred forty patients were included, 48 (34%) patients developed postoperative radiculitis, with symptom onset and resolution occurring at 14.5 and 83 days, respectively. The two groups had no differences in preoperative or postoperative radiographic parameters. Multivariable regression showed 3 independent predictors of postoperative radiculitis: methylprednisolone use [OR: 6.032; (95% CI: 1.670-25.568)], increased implant height [OR: 1.509; (95% CI: 1.189-1.960)], and no posterior fixation [OR: 2.973; (95% CI: 1.353-0.806)]., Conclusions: Of the 34% of patients who developed postoperative radiculitis after L5-S1 ALIF, it resolved on average within 3 months of surgery. These findings may help reduce the risk of undue short-term morbidity after isolated L5-S1 ALIF by informing preoperative counseling and intraoperative decision-making., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Adult cervical spine deformity is associated with decreased health-related quality of life, disability, and myelopathy. A number of radiographic parameters help to characterize cervical deformity and aid in the diagnosis and treatment. There are several etiologies for cervical spine deformity, the most common being iatrogenic. Additionally, spine surgery can accelerate adjacent segment degeneration which may lead to deformity. It is therefore important for all spine surgeons to be aware of the potential to cause iatrogenic cervical deformity. The aim of this review is to highlight concepts and techniques to prevent cervical deformity after spine surgery.

Case: Two patients (ages 5 and 14 years) with Larsen syndrome and severe cervical kyphosis (patient 1) and spondyloptosis (patient 2), as well as complete anterior-posterior dissociation of the cervical spine, presented with severe, progressive myelopathy. Both patients underwent preoperative halo-gravity traction to slowly reduce the deformity followed by staged anterior-posterior decompression and fusion. Both patients demonstrated complete return of neurologic function., Conclusion: Patients with Larsen syndrome should be screened for cervical deformity at the time of diagnosis. Proper screening will facilitate early detection and treatment of significant deformities to prevent neurologic deterioration, which can be catastrophic in these patients., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/B588)., (Copyright © 2021 by The Journal of Bone and Joint Surgery, Incorporated.)

Purpose of Review: To discuss the automated risk calculators that have been developed and evaluated in orthopedic surgery., Recent Findings: Identifying predictors of adverse outcomes following orthopedic surgery is vital in the decision-making process for surgeons and patients. Recently, automated risk calculators have been developed to quantify patient-specific preoperative risk associated with certain orthopedic procedures. Automated risk calculators may provide the orthopedic surgeon with a valuable tool for clinical decision-making, informed consent, and the shared decision-making process with the patient. Understanding how an automated risk calculator was developed is arguably as important as the performance of the calculator. Additionally, conveying and interpreting the results of these risk calculators with the patient and its influence on surgical decision-making are paramount. The most abundant research on automated risk calculators has been conducted in the spine, total hip and knee arthroplasty, and trauma literature. Currently, many risk calculators show promise, but much research is still needed to improve them. We recommend they be used only as adjuncts to clinical decision-making. Understanding how a calculator was developed, and accurate communication of results to the patient, is paramount.

Study Design: Retrospective cohort., Objective: To describe our technique for and evaluate the time demand, radiation exposure and outcomes of skin-anchored intraoperative three-dimensional navigation (ION) in minimally invasive (MIS) lumbar surgery, and to compare these parameters to 2D fluoroscopy for MI-TLIF., Summary of Background Data: Limited visualization of anatomic landmarks and narrow access corridor in MIS procedures result in greater reliance on image guidance. Although two-dimensional fluoroscopy has historically been used, ION is gaining traction., Methods: Patients who underwent MIS lumbar microdiscectomy, laminectomy, or MI-TLIF using skin-anchored ION and MI-TLIF by the same surgeon using 2D fluoroscopy were selected. Operative variables, radiation exposure, and short-term outcomes of all procedures were summarized. Time-demand and radiation exposure of fluoroscopy and ION for MI-TLIF were compared., Results: Of the 326 patients included, 232 were in the ION cohort (92 microdiscectomies, 65 laminectomies, and 75 MI-TLIFs) and 94 in the MI-TLIF using 2D fluoroscopy cohort. Time for ION setup and image acquisition was a median of 22 to 24 minutes. Total fluoroscopy time was a median of 10 seconds for microdiscectomy, 9 for laminectomy, and 26 for MI-TLIF. Radiation dose was a median of 15.2 mGy for microdiscectomy, 16.6 for laminectomy, and 44.6 for MI-TLIF, of this, 93%, 95%, and 37% for microdiscectomy, laminectomy, and MI-TLIF, respectively were for ION image acquisition, with the rest attributable to the procedure. There were no wrong-level surgeries. Compared with fluoroscopy, ION for MI-TLIF resulted in lower operative times (92 vs. 108 min, P < 0.0001), fluoroscopy time (26 vs. 144 s, P < 0.0001), and radiation dose (44.6 vs. 63.1 mGy, P = 0.002), with equivalent time-demand and length of stay. ION lowered the radiation dose by 29% for patients and 55% for operating room personnel., Conclusion: Skin-anchored ION does not increase time-demand compared with fluoroscopy, is feasible, safe and accurate, and results in low radiation exposure., Level of Evidence: 3.

Introduction: Open reduction with internal fixation (ORIF) and intramedullary nailing (IMN) have similar union rates for treating humerus shaft fractures, but IMN leads to increased incidence of shoulder impingement and reoperation. The difference in 30-day readmission rate and length of stay (LOS) between these procedures is unknown. The objective of the study was to compare 30-day unplanned readmissions and length of stay between humeral shaft fractures fixed with either ORIF or IMN., Methods: The nationwide readmissions database (NRD) was queried for patients with humeral shaft fractures treated with ORIF or IMN between 2015-2016. IMN cases were propensity matched to ORIF cases based on demographic and co-morbid variables. Multivariable logistic regression determined if treatment modality was an independent risk factor for 30-day readmission or length of stay >3 days., Results: There were 406 patients treated with IMN matched to 406 patients treated with ORIF. The 30-day readmission rate was 6.4% for IMN and 4.9% for ORIF (p = 0.45), and the median LOS was 3 days for each group (p = 0.45). Congestive heart failure (CHF)(OR=2.7, p = 0.04), depression (OR=3.3, p = 0.0008), and electrolyte abnormality (OR=3.6, p = 0.0003) were independent risk factors for readmission. Older age (OR=1.02, p = 0.03), CHF (OR=2.4, p = 0.03), electrolyte abnormality (OR=2.6, p = 0.0001), obesity (OR=2.8, p<0.0001), Medicaid (OR=2.1, p = 0.04), discharge to a facility (OR = 5.2, p<0.0001), discharge with home health services (OR=2.4, p = 0.0003), and open fracture (OR=2.3, p = 0.01) were independent risk factors for LOS >3 days. Procedure (ORIF vs. IMN) was not a predictor of 30-day readmission or LOS >3 days., Conclusion: Comorbid conditions are risk factors for 30-day readmission and increased LOS. Comorbidity, discharge disposition, and open fractures are risk factors for increased LOS. Treating humeral shaft fractures with either ORIF or IMN did not affect readmission or length of stay., Competing Interests: Declaration of Competing Interest The authors have no relevant conflicts of interest. The senior author, Emmanuel M. Illical, was a paid consultant for Biocomposits Inc. (Wilmington, NC, USA). This does not pose a conflict of interest relevant to the submitted work., (Copyright © 2020. Published by Elsevier Ltd.)

We present a case of lumbar radiculopathy due to a vascular malformation in the lumbar spine and discuss various causes of atypical lumbar radiculopathy. Lumbar radiculopathy is a condition of neurologic deficits and painful symptoms of the lower extremities due to nerve root compression, most commonly at the L5 and S1 levels. Several factors contribute to lumbar radiculopathy, including intervertebral disc herniation, foraminal stenosis, and spinal instability. There are also a number of atypical causes, including medication side effects or metabolic disorders, which produce symptoms of radiculopathy but do not involve compression of the nerve root. Anatomic variations in the nerve roots or vascular supply surrounding the nerve root may also increase the risk of developing radiculopathy and serve as an obstacle to interpreting imaging during a preoperative workup. A 38-year-old woman presented with sudden onset radicular symptoms in her right lower extremity. Lumbar magnetic resonance imaging demonstrated a right-sided L5-S1 extruded nucleus pulposus. Her symptoms failed to improve after conservative management so she underwent surgical decompression of L4-S1. Intraoperatively, we discovered an extensive, extradural vascular malformation present at the L5-S1 level and believed this to be the true cause of her radiculopathy. This case represents an atypical cause of lumbar radiculopathy and demonstrates the importance of considering atypical causes during diagnostic workup and preoperative planning., Competing Interests: Disclosures and COI: The authors received no funding for this study and report no conflicts of interest., (©International Society for the Advancement of Spine Surgery 2020.)

Background: Surgical fixation of acetabular fractures is technically challenging, and quality of reduction directly correlates to patient outcomes. Considering the difficulty of open reduction and internal fixation (ORIF), increased case volumes may improve patient outcomes. No studies have investigated case volume as a risk factor for readmission after acetabular fracture ORIF. The present study sought to answer the question of whether annual case volume is a risk factor for 30-day unplanned readmission after acetabular fracture ORIF, if there is an identifiable threshold number of cases most predictive of a readmission, and if differences exist between reasons for readmission between high and low-volume centers., Hypothesis: Institutions with a lower annual case volume will have a higher incidence of 30-day unplanned readmissions., Materials and Methods: The national readmissions database (NRD) was queried for acetabular fractures that underwent ORIF during 2016. Comorbid conditions were summed, and annual hospital case volume was identified. A receiver operating characteristic (ROC) curve was generated and the Youden index identified threshold case volume most predictive of a 30-day readmission. A multivariable logistic regression was performed with 30-day readmission as the dependent variable and case volume below the threshold an independent variable., Results: A total of 3,407 cases were included with a median age of 43. The 30-day readmission for this cohort was 6.5% (220/3407). ROC curve analysis identified 22 annual cases as the threshold value most predictive of 30-day readmission. Multivariable logistic regression identified age (Odds Ratio (OR)=1.01, p=0.005), number of comorbidities (OR=1.35, p<0.0001), and ≤22 cases (OR=1.50, p=0.006) as statistically significant risk factors for 30-day readmission. The most common reason for readmission at both high and low-volume centers was surgical site infection., Discussion: Annual case volume is a statistically significant predictor of 30-day readmission after acetabular fracture ORIF. Performing ≤22 acetabular ORIFs places patients at greater risk for a readmission. Patients at low-volume centers may be predisposed to readmission, and it is paramount to optimize patients prior to discharge, and have appropriate surgeon and hospital resources to treat these complex injuries., Level of Evidence: III, Cross-sectional study., (Published by Elsevier Masson SAS.)

Background: End-stage ankle arthritis is a debilitating condition that negatively impacts patient quality of life. Tibiotalar fusion and total ankle replacement are treatment options for managing ankle arthritis. Few studies have examined short term readmission rates of these two procedures. The objective of this study was compare all-cause 30-day readmission rates between patients undergoing tibiotalar fusion vs. total ankle replacement., Methods: This study queried the Nationwide Readmission Database (NRD) from 2013-2014 and used international classification of disease, 9th revision (ICD-9) procedure codes to identify all patients who underwent a tibiotalar fusion or a total ankle replacement. Comorbidities, insurance status, hospital characteristics, and readmission rates were statistically compared between the two cohorts. Risk factors were then identified for 30-day readmission., Results: A total of 5660 patients were analyzed with 2667 in the tibiotalar fusion cohort and 2993 in the total ankle replacement cohort. Univariate analysis revealed that the readmission rate after tibiotalar fusion (4.4%) was statistically greater than after total ankle replacement (1.4%). Multivariable regression analysis indicated that deficiency anemia (OR 2.18), coagulopathy (OR 3.51), renal failure (OR 2.83), other insurance relative to private (OR 3.40), and tibiotalar fusion (OR 2.51) were all statistically significant independent risk factors for having a readmission within 30-days., Conclusions: These findings suggest that during the short-term period following discharge from the hospital, patients who received a tibiotalar fusion are more likely to experience a 30-day readmission. These findings are important for decision making when a surgeon encounters a patient with end stage ankle arthritis., Level of Evidence: Level III, cohort study., (Published by Elsevier Ltd.)

Ankle fractures are common orthopedic injuries with favorable outcomes when managed with open reduction and internal fixation (ORIF). Several patient-related risk factors may contribute to poor short-term outcomes, and machine learning may be a valuable tool for predicting outcomes. The objective of this study was to evaluate machine-learning algorithms for accurately predicting short-term outcomes after ORIF for ankle fractures. The Nationwide Inpatient Sample and Nationwide Readmissions Database were queried for adult patients ≥18 years old who underwent ORIF of an ankle fracture during 2013 or 2014. Morbidity and mortality, length of stay >3 days, and 30-day all-cause readmission were the outcomes of interest. Two machine-learning models were created to identify patient and hospital characteristics associated with the 3 outcomes. The machine learning models were evaluated using confusion matrices and receiver operating characteristic area under the curve values. A total of 16,501 cases were drawn from the Nationwide Inpatient Sample and used to assess morbidity and mortality and length of stay >3 days, and 33,504 cases were drawn from the Nationwide Readmissions Database to assess 30-day readmission. Older age, Medicaid, Medicare, deficiency anemia, congestive heart failure, chronic lung disease, diabetes, hypertension, and renal failure were the variables associated with a statistically significant increased risk of developing all 3 adverse events. Logistic regression and gradient boosting had similar area under the curve values for each outcome, but gradient boosting was more accurate and more specific for predicting each outcome. Our results suggest that several comorbidities may be associated with adverse short-term outcomes after ORIF of ankle fractures, and that machine learning can accurately predict these outcomes., (Copyright © 2018 the American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.)

Background: Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) has comparable fusion rates and outcomes to the open approach, though many surgeons avoid the technique due to an initial learning curve. No current studies have examined the learning curve of MI-TLIF with respect to fluoroscopy time and exposure. Our objective with this retrospective review was to therefore use a repeatable mathematical model to evaluate the learning curve of MI-TLIF with a focus on fluoroscopy time and exposure., Methods: We conducted a retrospective review of single level, primary fusions performed by a single surgeon during his initial experience with minimally invasive spine surgery. Chronologic case number was plotted against variables of interest, and learning was identified as the point at which the instantaneous rate of change of a curve fit to the data set equaled the average rate of change of the data set., Results: One hundred nine cases were reviewed. Proficiency in operative time was achieved at 38 cases with the first 38 requiring a median of 137 minutes compared to 104 minutes for the latter 71 cases ( P < .0001). Mastery of fluoroscopy use occurred at case 51. The median fluoroscopy time for the first 51 cases was 2.8 minutes, which dropped to 2.1 minutes for cases 52 to 109 ( P < .0001). The complication rate plateaued after 43 cases, with 3 of 11 total complications occurring in the latter 76 cases., Conclusions: Our results demonstrate the most gradual learning occurred with respect to fluoroscopy time and exposure, and operative time improved the quickest., Level of Evidence: IV., Clinical Relevance: These findings may guide spine surgeon education and training in minimally invasive techniques, and help determine safe case loads for radiation exposure during the initial learning phase of the technique. The model used to identify the learning curve can also be applied to several fields and surgical techniques., Competing Interests: Disclosures and COI: The Institutional Review Board approved this study. No funding was received to conduct this study. Sheeraz Qureshi is currently receiving grant/research support from the Cervical Spine Research Society; receives consulting fees from Zimmer-Biomet, Stryker Spine, Globus Medical, Inc.; holds shareholder interest in Avaz Surgical; and receives royalties from RTI, Zimmer-Biomet, Stryker Spine.

Background: Several fusion adjuncts exist to enhance fusion rates during minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). The objective of this study was to compare fusion rates in patients undergoing MI-TLIF with either rhBMP-2 or cellularized bone matrix (CBM)., Methods: We conducted a single surgeon retrospective cohort study of patients who underwent MI-TLIF with either rhBMP-2 or CBM placed in an interbody cage. Single and multilevel procedures were included. Fusion was assessed on computed tomography scans at 12-month follow-up by an independent, blinded, board-certified neuroradiologist. Fusion rates and rate of revision surgery were compared with a Fisher exact test between the 2 groups. A multivariate regression analysis was performed to identify patient factors that were predictive of radiographic nonunion after MI-TLIF., Results: A total of 93 fusion levels in 78 patients were reviewed. Thirty-nine patients received CBM, and 39 patients received rhBMP-2. The patients receiving rhBMP-2 were older on average (61.4 vs 55.6, P = .03). The overall fusion rate was 68% in the CBM group (32/47 levels) and 78% in the rhBMP-2 group (36/46) ( P = .35). Only preoperative hypertension was predictive of radiographic nonunion (odds ratio = 3.5, P = .05). There were 3 smokers in the CBM group and 4 smokers in the BMP group, and 1 in each group experienced radiographic pseudarthrosis. A total of 4 patients, 3 in the CBM group and 1 in the BMP group ( P = .61), required revision for symptomatic pseudarthrosis. All of these patients had a single-level index procedure., Conclusions: There were no differences in radiographic fusion and rate of revision surgery in patients who underwent MI-TLIF with either rhBMP-2 or CBM as fusion adjuncts., Level of Evidence: 3., Clinical Relevance: Both rhBMP-2 and CBMs can be used as effective fusion adjuncts without any clear advantage of one over the other., Competing Interests: Disclosures and COI: An institutional review board approved this study. No funding was received to conduct this study. Sheeraz Qureshi is currently receiving grant/research support from the Cervical Spine Research Society; consulting fees from Zimmer-Biomet, Stryker Spine, Globus Medical, Inc.; and shareholder interest in Avaz Surgical and royalties from RTI, Zimmer-Biomet, Stryker Spine.

Study Design: Meta-analysis., Objective: Proximal junctional kyphosis (PJK) is a complication of surgical management for adult spinal deformity with a multifactorial etiology. Many risk factors are controversial and their relative importance are not fully understood. We aimed to identify the surgical, radiographic, and patient-related risk factors associated with PJK and proximal junctional failure (PJF)., Methods: A systematic literature search was performed using PubMed, Cochrane Database of Systematic Reviews, and EMBASE. The inclusion criteria included prospective randomized control trials and prospective/retrospective cohort studies of adult patients with radiographic evidence of PJK, which was defined as a proximal junctional sagittal Cobb angle ≥10° and at least 10° greater than the preoperative measurement. Studies required a minimum of 10 patients and 12 months of follow-up., Results: A total of 14 unique studies, including 1908 patients were included. The pooled analysis showed significant differences between the PJK and non-PJK groups in age (weighted mean difference [WMD] -3.80; P = .03), prevalence of osteopenia/osteoporosis (odds ratio [OR] 1.99; P = .0004), preoperative sagittal vertical axis (SVA) (WMD -17.52; P = .02), preoperative lumbar lordosis (LL) (WMD -1.22; P = .002), pedicle screw instrumentation at the upper instrumented vertebra (UIV) (OR 1.67; P = .02), change in SVA (WMD -11.87; P = .01), fusion to sacrum/pelvis/ilium (OR 2.14; P < .00 001), change in LL (WMD -5.61; P = .01), and postoperative SVA (WMD -7.79; P = .008)., Conclusions: Our meta-analysis suggests that age, osteopenia/osteoporosis, high preoperative SVA, high postoperative SVA, low preoperative LL, use of pedicle screws at the UIV, SVA change/correction, LL change/correction, and fusion to sacrum/pelvis/iliac region are risk factors for PJK., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Rigid flatfoot deformity is a debilitating condition that can be managed by triple arthrodesis surgery. Triple arthrodesis has the potential to restore health-related quality of life, but it is also associated with several complications. Few studies have examined the 30-day readmission rates after triple arthrodesis. The objective of this study was to investigate risk factors for 30-day all-cause readmissions after triple arthrodesis. The nationwide readmission database was queried from 2013. By using International Classification of Disease, Ninth Revision, procedure codes, all triple arthrodesis procedures were identified. Demographic factors, comorbidities, insurance status, and hospital characteristics were statistically compared between patients who experienced a 30-day readmission and those who did not. Multivariable logistic regression was used to identify independent risk factors for 30-day readmission. Overall, 1916 triple arthrodesis cases were identified. The overall 30-day readmission rate after triple arthrodesis was 4.6%. Univariate analysis revealed a statistically higher proportion of patients with electrolyte abnormalities (13.8% vs 4.6%; p < .01) in the patients who were readmitted within 30 days compared with those who were not. Multivariable analysis demonstrated Medicaid insurance, relative to private insurance, as the only statistically significant predictor of 30-day readmission with an odds ratio of 4.43 (p < .05). These results suggest that patients of lower socioeconomic status may be at a greater risk for development of a short-term readmission after triple arthrodesis surgery. These findings are important for surgeon and patient communication, counseling, and postoperative care when choosing to pursue triple arthrodesis surgery., (Copyright © 2018. Published by Elsevier Inc.)

Study Design: A cross-sectional database study., Objective: The aim of this study was to train and validate machine learning models to identify risk factors for complications following posterior lumbar spine fusion., Summary of Background Data: Machine learning models such as artificial neural networks (ANNs) are valuable tools for analyzing and interpreting large and complex datasets. ANNs have yet to be used for risk factor analysis in orthopedic surgery., Methods: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was queried for patients who underwent posterior lumbar spine fusion. This query returned 22,629 patients, 70% of whom were used to train our models, and 30% were used to evaluate the models. The predictive variables used included sex, age, ethnicity, diabetes, smoking, steroid use, coagulopathy, functional status, American Society for Anesthesiology (ASA) class ≥3, body mass index (BMI), pulmonary comorbidities, and cardiac comorbidities. The models were used to predict cardiac complications, wound complications, venous thromboembolism (VTE), and mortality. Using ASA class as a benchmark for prediction, area under receiver operating curves (AUC) was used to determine the accuracy of our machine learning models., Results: On the basis of AUC values, ANN and LR both outperformed ASA class for predicting all four types of complications. ANN was the most accurate for predicting cardiac complications, and LR was most accurate for predicting wound complications, VTE, and mortality, though ANN and LR had comparable AUC values for predicting all types of complications. ANN had greater sensitivity than LR for detecting wound complications and mortality., Conclusion: Machine learning in the form of logistic regression and ANNs were more accurate than benchmark ASA scores for identifying risk factors of developing complications following posterior lumbar spine fusion, suggesting they are potentially great tools for risk factor analysis in spine surgery., Level of Evidence: 3.

Study Design: Cost-effectiveness analysis., Objective: To investigate 7-years cost-effectiveness of two-level cervical disc replacement (CDR) and anterior cervical discectomy and fusion (ACDF)., Summary of Background Data: CDR and ACDF are both effective treatment strategies for managing degenerative conditions of the cervical spine. CDR has been shown to be a more-cost effective intervention in the short term, but the long-term cost-effectiveness has not been established., Methods: We analyzed 7-years follow-up data from the two-level Medtronic Prestige LP investigational device exemption study. Short-form 36 (SF-36) data were converted into health utility scores using the SF-6D algorithm. Costs were based on direct costs from the payer perspective, and effectiveness was measured as quality-adjusted life years (QALYs). The willingness-to-pay (WTP) threshold was set to $50,000/QALY. A probabilistic sensitivity analysis was conducted via Monte Carlo simulation., Results: Two-level CDR had a 7-year cost of $176,654.19, generated 4.65 QALYs, and had a cost-effectiveness ratio of $37,993.53/QALY. Two-level ACDF had a 7-year cost of $158,373.48, generated 4.44 QALYs, and had a cost-effectiveness ratio of $35,635.72. CDR was associated with an incremental cost of $18,280.71 and an incremental effectiveness of 0.21 QALYs, resulting in an incremental cost-effectiveness ratio (ICER) of $89,021.04, above the WTP threshold. Our Monte Carlo simulation demonstrated CDR would be chosen 46% of the time based on 10,000 simulations., Conclusion: Two-level CDR and ACDF are both cost-effective procedures at 7-year follow up for treating degenerative conditions of the cervical spine. Based on an ICER of $89,021.04/QALY, we cannot conclude which treatment is the more cost-effective option at 7-years. CDR would be chosen 46% of the time based on 10,000 iterations of our Monte Carlo probabilistic sensitivity analysis., Level of Evidence: 3.

Cervical laminoplasty was initially described for the management of cervical myelopathy resulting from multilevel stenosis secondary to ossification of the posterior longitudinal ligament. The general concepts are preservation of the dorsal elements, preservation of segmental motion, and expansion of the spinal canal via laminar manipulation. No clear evidence suggests that laminoplasty is superior to either posterior laminectomy or anterior cervical diskectomy and fusion. However, laminoplasty has its own advantages, indications, and complications. Surgeons have refined the technique to decrease complication rates and improve efficacy. Recent efforts have highlighted less invasive approaches that are muscle sparing and associated with less postoperative morbidity. Although the long-term outcomes suggest that cervical laminoplasty is safe and effective, continued research on the development of novel modifications that decrease common complications, such as C5 nerve palsy, axial neck pain, and loss of lordosis, is required.

Study Design: Retrospective cohort study., Objective: Elucidate negative sagittal balance following adult spinal deformity surgery., Methods: We conducted a retrospective review of adult spinal deformity patients who underwent long fusion (>5 levels) to the sacrum by a single surgeon at a single institution between 2011 and 2015. Patients were divided into cohorts of postoperative sagittal vertical axis (SVA) <-10 mm, between -10 and +10 mm, or >+10 mm, denoted as groups 1, 2, and 3, respectively. Univariate analysis compared preoperative factors between the groups, and a multivariable logistic regression model was used to determine independent risk factors for developing a negative sagittal balance (SVA<-10 mm) following adult spinal deformity correction., Results: We reviewed 8 patients in group 1, 9 patients in group 2, and 25 patients in group 3. The average postoperative SVA for group 1, group 2, and group 3 were -30.99, +3.67, and +55.56 mm, respectively. There was a trend toward higher upper-instrumented vertebra (UIV) in group 1 (T2) compared with group 2 (T10) and group 3 (T9) ( P = .05). A trend toward lower preoperative SVA in groups 1 and 2 compared with group 3 was also seen (+53.36 vs +71.73 vs +122.80 mm) ( P = .06). Finally, we found a trend toward lower body mass index in group 1 compared with groups 2 and 3 (24.71 vs 25.92 vs 29.33 kg/m 2 ) ( P = .07). Based on multivariable regression, higher UIV was found to be a statistically significant independent predictor for developing a postoperative negative sagittal balance of <-10 mm ( P = .02, odds ratio = 0.67)., Conclusions: Our results demonstrate that a higher UIV may predispose patients undergoing adult spinal deformity correction to have a postoperative negative sagittal balance., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Meta-analysis., Objectives: To assess return to play (RTP) rates in adolescent athletes with lumbar spondylolysis without spondylolisthesis treated conservatively or operatively., Methods: A review of Medline, EMBASE, and Cochrane Reviews was performed. The pooled results were performed by calculating the effect size based on the logit event rate. Studies were weighted by the inverse of the variance. Confidence intervals were reported at 95%. Heterogeneity was assessed using the Q statistic and I 2 value., Results: The initial literature search resulted in 724 articles, of which 29 were deemed relevant on abstract review. Overall, 11 studies provided data for 376 patients with a pars interarticularis defect. Return to athletic competition, based on logit event rate, was found to be statistically favored after both nonoperative and operative treatment (92.2% vs 90.3%). There was no heterogeneity noted among the studies reporting nonoperative treatment ( Q value of 4.99 and I 2 value of 0). There was mild heterogeneity within the operative studies ( Q value of 3.54 and I 2 value of 15.18)., Conclusions: Adolescent athletes RTP 92.2% of the time with nonoperative management, compared with 90.3% when treated operatively, though both treatment groups strongly favor RTP. As this is the first study to pool results of all relevant literature, it provides strong evidence to guide decision making and help manage expectations in this unique patient population., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: A retrospective cohort study., Objective: The aim of this study was to investigate the effect depression has on the improvement of patient-reported outcome measures (PROMs) following lumbar decompression., Summary of Background Data: Decompression without fusion is a viable treatment option for lumbar spine stenosis. Depression reportedly has a negative impact on PROMs after certain types of spine surgery, though verification of this with new, more precise outcome measures is needed., Methods: We included consecutive adult patients who underwent lumbar decompression for lumbar spine stenosis between 2016 and 2017 who had PROM information system (PROMIS) physical function, pain, depression, and Oswestry Disability Index (ODI) questionnaires completed preoperatively and at 6-month follow-up. Patients with a PROMIS depression score >50 or <50 were allocated to the depressed and not depressed groups, respectively. The cohorts were compared using unpaired t tests and repeated-measures two-way analysis of variance (ANOVA) with statistical significance taken at P < 0.05., Results: The analysis included 55 patients without depression and 56 patients with depression. Depressed patients had worse preoperative PROMIS physical function (30.08 vs. 36.66, P = 0.005), PROMIS pain (69.36 vs. 64.69, P < 0.0001), and ODI scores (51.92 vs. 36.35, P < 0.0001). Similarly, the depressed group had worse postoperative PROMIS physical function (36.29 vs. 40.34, P = 0.005), PROMIS pain (60.16 vs. 54.87, P < 0.0001), and ODI scores (37.01 vs. 23.44, P = 0.0003). We observed a statistically significant interaction between depression status and pre to postoperative improvement in outcome for PROMIS physical function (F[1,109] = 102.5, P < 0.0001) and depression scores (F[1,109] = 15.38, P = 0.0002). No interaction was found for pain and ODI scores., Conclusion: Our results suggest that depressed patients experience a greater magnitude of improvement in PROMIS physical function and depression scores than nondepressed patients. Despite this, depressed patients have worse postoperative outcomes for PROMIS physical function, depression, pain, and ODI. These findings are important for risk stratifying and treating depressed patients before lumbar spine decompression., Level of Evidence: 3.

Study Design: This is a retrospective cohort study., Objective: To determine whether age, sex, and race have independent effects on sagittal pelvic parameters., Summary of Background Data: Pelvic parameters and sagittal balance correlate with health-related quality of life and are important for patient assessment and surgical planning. Age, sex, and race are 3 unalterable patient factors that may influence pelvic morphology., Methods: We conducted a retrospective review of consecutive adult patients who presented to our radiology practice between 2010 and 2015 and had a standing, lateral lumbosacral radiograph. Any patients without both femoral heads and L1-S1 visible on the radiograph, and any patients presenting with traumatic injury, coronal deformity, prior instrumentation, spondylolisthesis, or neoplasm of the spine were excluded. Univariate analysis determined differences in measurements among African American, white, and Hispanic races, as well as between male and female sexes. Correlation analysis between age and different measurements was also conducted. Multivariable regression was then used to determine the independent effect of age, sex, and race on pelvic parameters., Results: We investigated 1801 adults (older than 18 y) and 1246 had a recorded race. There were 1165 women, 636 men, 525 whites, 404 African Americans, and 317 Hispanics. Multivariable regression demonstrated a statistically significant increase in pelvic tilt (PT), pelvic incidence (PI), and pelvic incidence-lumbar lordosis (PI-LL) with aging, and statistically significant decrease in sacral slope (SS) and LL with aging. Women had a statistically greater LL than men. African Americans had a statistically smaller PT and greater SS and PI-LL relative to whites, while Hispanics had a statistically smaller PT and PI-LL, and a statistically greater SS and LL relative to whites., Conclusions: Pelvic parameters were different between sexes, among races, and changed with age. These findings are important for patient assessment and preoperative planning to obtain optimal sagittal balance., Level of Evidence: Level 3.

Study Design: Cost-effectiveness analysis., Objectives: To determine the 7-year cost-effectiveness of cervical disc replacement (CDR) and anterior cervical discectomy and fusion (ACDF)., Methods: We analyzed 7-year Short Form-36 Health Survey data collected from the Prestige Cervical Disc investigational device exemption study (IDE). The SF-6D algorithm was used to convert this data into health state utilities. Costs were calculated from the payer perspective, and quality adjusted life years (QALYs) were used to represent effectiveness. A Markov transition-state model was used to evaluate the cost-effectiveness of single-level CDR versus ACDF, and a Monte Carlo simulation was performed to assess the probabilistic sensitivity of the model., Results: CDR generated a 7-year cost of $172 989 compared to a 7-year cost of $143 714 for ACDF. CDR generated 4.53 QALYs compared to 3.85 QALYs generated by ACDF. The cost-effectiveness ratio of CDR was $38 247/QALY, while the cost-effectiveness ratio of ACDF was $37 325/QALY. The incremental cost-effectiveness ratio of CDR was $43 522/QALY, under the willingness to pay threshold of $50 000/QALY. Our probabilistic sensitivity analysis demonstrated CDR would be chosen 56% of the time based on 10 000 simulations., Conclusions: Single-level CDR and ACDF were both cost-effective strategies at 7 years for treating degenerative conditions of the cervical spine. Both the Markov simulation and the Monte Carlo simulation demonstrate CDR to be the more cost-effective strategy at 7 years. Continued analysis of IDE data should be performed to validate long-term cost-effectiveness of these treatment strategies., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Retrospective cohort study., Objectives: To determine the incidence of index level fusion following open or minimally invasive lumbar microdiscectomy., Methods: We conducted a retrospective review of 174 patients with a symptomatic single-level lumbar herniated nucleus pulposus who underwent microdiscectomy via a mini-open approach (MIS; 39) or through a minimally invasive dilator tube (135). Outcomes of interest included revision microdiscectomy and the ultimate need for index level fusion. Continuous variables were analyzed with independent sample t test, and χ 2 analysis was used for categorical data. A multivariate regression analysis was performed to identify predictive factors for patients that required index level fusion after lumbar microdiscectomy., Results: There was no difference in patient demographics in the open and MIS groups aside from length of follow-up (60.4 vs 40.03 months, P < .0001) and body mass index (24.72 vs 27.21, P = .03). The rate of revision microdiscectomy was not statistically significant between open and MIS approaches (10.3% vs 10.4%, P = .90). The rate of patients who ultimately required index level fusion approached significance, but was not statistically different between open and MIS approaches (10.3% vs 4.4%, P = .17). Multivariate regression analysis indicated that the need for eventual index level fusion after lumbar microdiscectomy was statistically predicted in smokers and those patients who underwent revision microdiscectomy ( P < .05) in both open and MIS groups., Conclusions: Our results suggest a low likelihood of patients ultimately requiring fusion following microdiscectomy with predictors including smoking status and a history of revision microdiscectomy., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Prospective randomized control trial., Objective: To investigate the role of cervical collars in postoperative care following 1- and 2-level instrumented anterior cervical discectomy and fusion (ACDF)., Methods: The Cervical Spine Research Society Resident Fellow Grant funded this project. Fifty consecutive patients undergoing 1- or 2-level ACDF surgery were randomized into groups receiving either no brace or a cervical brace for 6 weeks postoperatively. Neck Disability Index scores were recorded preoperatively and at regular follow-up visits up to 1 year. Computed tomography scans were read 1 year postoperatively to determine fusion rates, and subsidence was measured as change in middle vertebral distance between initial postoperative and 6-month follow-up lateral cervical radiographs., Results: Twenty-two patients were in the no-brace group, and 22 patients were in the brace group at final follow-up, with an average age of 50 and 55 years, respectively. The no-brace group had a total of 32 operative levels, whereas the brace group had 38 operative levels. There was no statistically significant difference in 1-year postoperative Neck Disability Index scores between the brace (9.30) and no-brace (6.95) groups ( P = .28), in 6-month subsidence of all operative levels between the brace (0.85 mm) and no-brace (0.79 mm) groups ( P = .72), or in the proportion of fused levels between the brace (89%) and no-brace (97%) groups ( P = .37)., Conclusions: Our results suggest no advantage in wearing a cervical brace following 1- or 2-level ACDF surgery with respect to 1-year outcome scores, 1-year fusion rates, and 6-month subsidence., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: SK has received personal fees from Globus Medical and Zimmer. AH has received personal fees from Medtronic, Stryker, and Zimmer. SQ has received personal fees from Globus Medical, Medtronic, Stryker, Zimmer, and Orthofix Inc. These disclosures presented no conflicts of interest relevant to this research study.

Study Design: Health utility analysis., Objectives: To determine the health state utility (HSU) of 1- and 2-level anterior cervical discectomy and fusion (ACDF) and cervical disc replacement (CDR)., Methods: Data from the Medtronic Prestige Cervical Disc investigational device exemption studies was used. Four groups were defined: 1-level ACDF, 1-level CDR, 2-level ACDF, and 2-level CDR. The 36-item Short Form Health Survey (SF-36) was collected at baseline, 12 months, 24 months, 36 months, and 60 months postoperatively and converted into utility scores for each time point. A repeated-measures 1-way analysis of variance (ANOVA) was used to detect differences among groups. Tukey's method for multiple comparisons was used to determine which means within the groups were statistically different ( P < .05)., Results: We found a statistically significant difference in HSU among groups as determined by repeated-measures 1-way ANOVA ( P = .0008). Post hoc analysis indicated that 1-level ACDF had a statistically lower utility score compared with 1- and 2-level CDR ( P = .04 and P = .02, respectively). Similarly, 2-level ACDF had lower utility values compared with 2-level CDR ( P = .010). One-level ACDF utility values were not different from 2-level ACDF values ( P = .55). Similarly, 1-level CDR and 2-level CDR did not have different utility values ( P = .67)., Conclusions: Overall, CDR had higher health state utility scores for 1- and 2-level procedures at every time point. This study indicates that CDR results in a higher postoperative health utility state than ACDF, and may therefore be an effective alternative to ACDF for treating degenerative conditions of the cervical spine., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background Context: Anterior cervical discectomy and fusion (ACDF) and cervical disc replacement (CDR) are both acceptable surgical options for the treatment of cervical myelopathy and radiculopathy. To date, there are limited economic analyses assessing the relative cost-effectiveness of two-level ACDF versus CDR., Purpose: The purpose of this study was to determine the 5-year cost-effectiveness of two-level ACDF versus CDR., Study Design: The study design is a secondary analysis of prospectively collected data., Patient Sample: Patients in the Prestige cervical disc investigational device exemption (IDE) study who underwent either a two-level CDR or a two-level ACDF were included in the study., Outcome Measures: The outcome measures were cost and quality-adjusted life years (QALYs)., Materials and Methods: A Markov state-transition model was used to evaluate data from the two-level Prestige cervical disc IDE study. Data from the 36-item Short Form Health Survey were converted into utilities using the short form (SF)-6D algorithm. Costs were calculated from the payer perspective. QALYs were used to represent effectiveness. A probabilistic sensitivity analysis (PSA) was performed using a Monte Carlo simulation., Results: The base-case analysis, assuming a 40-year-old person who failed appropriate conservative care, generated a 5-year cost of $130,417 for CDR and $116,717 for ACDF. Cervical disc replacement and ACDF generated 3.45 and 3.23 QALYs, respectively. The incremental cost-effectiveness ratio (ICER) was calculated to be $62,337/QALY for CDR. The Monte Carlo simulation validated the base-case scenario. Cervical disc replacement had an average cost of $130,445 (confidence interval [CI]: $108,395-$152,761) with an average effectiveness of 3.46 (CI: 3.05-3.83). Anterior cervical discectomy and fusion had an average cost of $116,595 (CI: $95,439-$137,937) and an average effectiveness of 3.23 (CI: 2.84-3.59). The ICER was calculated at $62,133/QALY with respect to CDR. Using a $100,000/QALY willingness to pay (WTP), CDR is the more cost-effective strategy and would be selected 61.5% of the time by the simulation., Conclusions: Two-level CDR and ACDF are both cost-effective strategies at 5 years. Neither strategy was found to be more cost-effective with an ICER greater than the $50,000/QALY WTP threshold. The assumptions used in the analysis were strongly validated with the results of the PSA., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Study Design: Cadaver study., Objective: To investigate the safety of the extraforaminal lumbar interbody fusion approach., Summary of Background Data: Over the last decade the number of techniques available for lumbar interbody fusion has increased. Recent interest has developed in an extraforaminal approach to the intervertebral disc to reduce the morbidity associated with facetectomy. The safety of this extraforaminal corridor with regards to the exiting nerve root and lumbar plexus has yet to be assessed., Methods: With the cadaver prone, the C-arm was positioned over the disc of interest and aligned perpendicular to the superior endplate of the inferior vertebral body, with the superior articular process bisecting the available disc space. Three needles were passed into the disc and labeled medial, middle, and lateral. After needle placement, each nerve root and the lumbar plexus were dissected. The distance of each needle to these structures was measured and discectomy was performed to assess potential graft length from a transforaminal and extraforaminal approach., Results: We performed the method on levels L1-L5 bilaterally on 2 cadavers, totaling 16 attempts for each needle position. The average distance to nerve of the medial approach (3.2±1.1 mm) was statistically greater than both the middle (1.1±1.4 mm) and lateral (-0.2±2.9 mm) approaches (P<0.0001 for both). The distance to plexus of the medial approach (14.3±6.2 mm) was greater than the middle (9.2±6.1 mm) approach and statistically greater than the lateral (5.2±5.6 mm) approach (P=0.001). There was a greater graft length available by the extraforaminal lumbar interbody fusion approach (36.1±2.7 mm) than the transforaminal lumbar interbody fusion approach (29.3±3.5 mm, P<0.0001)., Conclusions: The safest trajectory was the medial, passing adjacent to the superior articular process. The close proximity, however, means that neuromonitoring and tubular dilators would be necessary to use this technique in a clinical setting., Level: Level V.

Background: Tandem spinal stenosis refers to spinal canal diameter narrowing in at least 2 distinct regions of the spine, most commonly the lumbar and cervical regions. This entity can be an asymptomatic radiographic finding, or it can present with severe myelopathy and lower-extremity symptoms. Tandem spinal stenosis may impact surgeon decision-making when planning either cervical or lumbar spine surgery, and there is currently no consensus in the literature regarding the treatment algorithm for operative intervention., Methods: A MEDLINE literature search was performed using PubMed, the Cochrane Database of Systematic Reviews, and Embase from January 1980 to February 2015 using Medical Subject Heading queries for the terms "tandem spinal stenosis," "cervical stenosis AND lumbar stenosis," and "concomitant spinal stenosis." We included studies involving adult patients, tandem spinal stenosis of the cervical and lumbar regions, and a minimum of 5 patients. Articles that did not discuss spinal disorders or only explored disorders at a single spinal region were excluded., Results: The initial database review resulted in 234 articles. After abstracts were reviewed, only 17 articles that met inclusion criteria were identified: 2 cadaveric studies, 5 clinical studies of patients with radiographic tandem spinal stenosis, and 10 clinical studies of patients with symptomatic tandem spinal stenosis., Conclusions: Tandem spinal stenosis is a common condition present in up to 60% of patients with spinal stenosis. This disorder, however, is often overlooked, which can lead to serious complications. Identification of tandem spinal stenosis is paramount as a first step in management and, although there is still no preferred intervention, both staged and simultaneous procedures have been shown to be effective. Surgeons may utilize a single, staged, or combined approach to decompression, always addressing cervical myelopathy as a priority.

Study Design: Retrospective case series., Objective: To evaluate if spine measurement software can simulate sagittal alignment following pedicle subtraction osteotomy (PSO)., Methods: We retrospectively reviewed consecutive adult spinal deformity patients who underwent lumbar PSO. Sagittal measurements were performed on preoperative lateral, standing radiographs. Sagittal measurements after simulated PSO were compared to actual postoperative measurements. A regression equation was developed using cases 1-7 to determine the amount of manual rotation required of each film to match the simulated sagittal vertical axis (SVA) to the actual postoperative SVA. The equation was then applied to cases 8-13., Results: For all 13 cases, the spine software accurately simulated lumbar lordosis, pelvic incidence lumbar lordosis mismatch, and T1 pelvic angle, with no significant differences between actual and simulated measurements. The pelvic tilt (PT), sacral slope (SS), thoracolumbar alignment (TL), thoracic kyphosis (TK), T9 spino-pelvic inclination (T9SPi), T1 spino-pelvic inclination (T1SPi), and SVA were inaccurately simulated. The PT, SS, T9SPi, T1SPi, and SVA all change with manual rotation of the film, and by using the regression equation developed with cases 1-7, we were able to improve the accuracy and decrease the variability of the simulated PT, SS, T9SPi, T1SPi, and SVA for cases 8-13., Conclusions: Dedicated spine measurement software can accurately simulate certain sagittal measurements, such as LL, PI-LL, and TPA, following PSO. A number of measurements, including PT, SS, TL, TK, T9SPi, T1SPi, and SVA were inaccurately simulated. Our preliminary algorithm improved the accuracy and decreased the variability of certain measurements, but requires future prospective studies for further validation., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Dr Samuel K. Cho has received personal fees from DePuy, Medtronic, Stryker, and Zimmer, all outside of the submitted work.

Background Context: Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been widely adopted as a fusion adjunct in spine surgery since its approval in 2002. A number of concerns regarding adverse effects and potentially devastating complications of rhBMP-2 use led to a Food and Drug Administration (FDA) advisory issued in 2008 cautioning its use, and a separate warning about its potential complications was published by The Spine Journal in 2011., Purpose: To compare trends of rhBMP-2 use in spine surgery after the FDA advisory in 2008 and The Spine Journal warning in 2011., Study Design: Retrospective cross-sectional study using a national database., Patient Sample: All patients from 2002 to 2013 who underwent spinal fusion surgery at an institution participating in the Nationwide Inpatient Sample (NIS)., Outcome Measures: Proportion of spinal fusion surgeries using rhBMP-2., Methods: We queried the NIS from 2002 to 2013 and used International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) procedure codes to identify spinal fusion procedures and those that used rhBMP-2. Procedures were subdivided into primary and revision fusions, and by region of the spine. Cervical and lumbosacral fusions were further stratified into anterior and posterior approaches. The percentage of cases using BMP was plotted across time. A linear regression was fit to the data from quarter 3 of 2008 (FDA advisory) through quarter 1 of 2011, and a separate regression was fit to the data from quarter 2 of 2011 (The Spine Journal warning) onward. The slopes of these regression lines were statistically compared to determine differences in trends. No funding was received to conduct this study, and no authors had any relevant conflicts of interest., Results: A total of 4,167,079 patients in the NIS underwent spinal fusion between 2002 and 2013. We found a greater decrease in rhBMP-2 use after The Spine Journal warning compared with the FDA advisory for all fusion procedures (p=.006), primary fusions (p=.006), and revision fusions (p=.004). Lumbosacral procedures also experienced a larger decline in rhBMP-2 use after The Spine Journal article as compared with the FDA warning (p=.0008). This pattern was observed for both anterior and posterior lumbosacral fusions (p≤.0001 for both). Anterior cervical fusion was the only procedure that demonstrated a decline in rhBMP-2 use after the FDA advisory that was statistically greater than after The Spine Journal article (p=.02)., Conclusions: Warnings sanctioned through the spine literature may have a greater influence on practice of the spine surgery community as compared with advisories issued by the FDA.Comprehensive guidelines regarding safe and effective use of rhBMP-2 must be established., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Study Design: Retrospective cohort study., Objective: To determine if patients fused with multi-rod constructs to the pelvis have a lower incidence of lumbosacral rod failure and pseudarthrosis than those fused with dual-rod constructs., Methods: We performed a retrospective review of consecutive adult spinal deformity patients who underwent long fusion to the pelvis. Inclusion criteria were >5 levels, primary fusion or revision for L5-S1 pseudarthrosis, and minimum 1-year follow-up. Revision patients with indications other than L5-S1 pseudarthrosis were excluded. One-year follow-up plain radiographs were reviewed for rod integrity, and computed tomography scan (CT) was obtained whenever rod breakage was observed. Dual-rod and multi-rod (3 or 4 rods) cohorts were statistically compared., Results: There were 31 patients with 15 in the dual-rod group and 16 in the multi-rod group, with average ages of 68 ± 9 and 63 ± 12 years, respectively. No patients in the multi-rod group experienced rod fracture, whereas 6 in the dual-rod group fractured a rod ( P = .007), with 4 occurring at the lumbosacral junction ( P = .04). CT scan in the 4 lumbosacral rod fracture cases, and surgical exploration in 3, confirmed pseudarthrosis and hypertrophic nonunion at the L5-S1 junction., Conclusion: Patients with dual-rod constructs had a statistically greater incidence of lumbosacral pseudarthrosis with implant failure than those with multi-rod constructs. CT and surgical exploration showed hypertrophic nonunion as opposed to oligo- or atrophic nonunion. This suggests that mechanical instability, not biology, is the main reason for failure, and could be addressed with the use of multi-rods., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Retrospective case series., Objective: To investigate which sagittal parameters contribute to a normal sagittal vertical axis (SVA) when there is a pelvic incidence-lumbar lordosis (PI-LL) mismatch >10° following adult spinal deformity (ASD) correction., Methods: We performed a retrospective review of ASD patients with >5 levels fused. Sagittal measurements between cohorts of postoperative PI-LL >10° and PI-LL<10° were compared. We correlated SVA to pelvic tilt (PT), thoracic kyphosis (TK), PI-LL, cervical lordosis (CL), and correlated the pre- to postoperative change in SVA to change in PT, change in TK, change in PI-LL, and change in CL. We also correlated SVA and the change in SVA to combined parameters of ((PI-LL) - PT + TK)., Results: We analyzed 52 patients with a mean age of 59 ± 16 years. In patients with a postoperative SVA <5cm, a smaller TK was seen when PI-LL >10° than when PI-LL<10° (15.45° vs 33.04°, P = .0004). Additionally, PT was larger when PI-LL >10° than when PI-LL <10° (25.73° vs 19.07°, P = .006). SVA correlated better with ((PI-LL) - PT + TK) ( R 2 = 0.51) than with PI-LL alone ( R 2 = 0.33). Lastly, there was no significant correlation between change in pre- to postoperative SVA with change in TK for all cases ( P = .73), but in cases where change in PI-LL was <10°, there was a significant correlation between change in TK and change in SVA ( P = .009)., Conclusion: Our results demonstrate that PT and TK, and not just PI-LL, play an important role in maintaining sagittal balance when there is a PI-LL mismatch >10°., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Retrospective cohort study., Objective: To compare perioperative characteristics of stand-alone cages and anterior cervical plates used for anterior cervical discectomy and fusion (ACDF)., Methods: We reviewed 40 adult patients who received a stand-alone cage for elective ACDF and matched them with 40 patients who received an anterior cervical plate. We statistically compared operative time, length of stay, proportion of ambulatory cases, overall complications necessitating a trip to the ED, readmission, or reoperation related to index procedure., Results: There were 21 women and 19 men in the plate cohort with average ages of 53 years ± 12 and 20 women and 20 men in the stand-alone group with an average age of 52 years ± 11. With no statistical difference in total number, the plate group experienced 4 short-term (within 90 days of discharge) complications, including 3 patients who visited the emergency department for dysphagia and 1 who visited the emergency department for severe back pain, while the stand-alone group experienced 0 complications. There was no significant difference in operative time between the stand-alone group (75.35 min) and the plate group (81.35 min; P = .37). There was a significant difference between the proportion of ambulatory cases in the stand-alone group (25) and the plate group (6; P < .0001)., Conclusion: Our results demonstrate that stand-alone cages have fewer complications compared to anterior plating, with a lower trend of incidence of postoperative dysphagia. Stand-alone cages may offer the advantage of sending patients home ambulatory after ACDF surgery., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Sheeraz A. Qureshi has the following disclosures: Paid consulting—Zimmer, Medtronic, Stryker, Orthofix Inc; IP royalties—Zimmer; Paid speaker—Globus Medical, Medtronic, Stryker. The other authors have no conflicts of interest to report.

Signalling complexes are dynamic, multimolecular structures and sites for intracellular signal transduction. Although they play a crucial role in cellular activation, current research techniques fail to resolve their structure in intact cells. Here we present a multicolour, photoactivated localization microscopy approach for imaging multiple types of single molecules in fixed and live cells and statistical tools to determine the nanoscale organization, topology and synergy of molecular interactions in signalling complexes downstream of the T-cell antigen receptor. We observe that signalling complexes nucleated at the key adapter LAT show a hierarchical topology. The critical enzymes PLCγ1 and VAV1 localize to the centre of LAT-based complexes, and the adapter SLP-76 and actin molecules localize to the periphery. Conditional second-order statistics reveal a hierarchical network of synergic interactions between these molecules. Our results extend our understanding of the nanostructure of signalling complexes and are relevant to studying a wide range of multimolecular complexes.

Linker for Activation of T cells (LAT) is an adapter protein that is essential for T cell function. Knock-in mice with a LAT mutation impairing calcium flux develop a fatal CD4+ lymphoproliferative disease. miR-155 is a microRNA that is correlated with hyperproliferation in a number of cancers including lymphomas and leukemias and is overexpressed in mutant LAT T cells. To test whether miR-155 was merely indicative of T cell activation or whether it contributes to lymphoproliferative disease in mutant LAT mice, we interbred LAT mutant and miR-155-deficient mice. miR-155 deficiency markedly inhibited lymphoproliferative disease by stimulating BIM-dependent CD4+ T cell apoptosis, even though ERK activation and T cell proliferation were increased in double mutant CD4+ T cells. Bim/Bcl2l11 expression is activated by the forkhead transcription factor FOXO3. Using miR-155-deficient, LAT mutant T cells as a discovery tool, we found two connected pathways that impact the nuclear translocation and activation of FOXO3 in T cells. One pathway is mediated by the inositide phosphatase SHIP-1 and the serine/threonine kinases AKT and PDK1. The other pathway involves PAK1 and JNK kinase activation. We define crosstalk between the two pathways via the kinase mTOR, which stabilizes PAK1. This study establishes a role for PAK1 in T cell apoptosis, which contrasts to its previously identified role in T cell proliferation. Furthermore, miR-155 regulates the delicate balance between PAK1-mediated proliferation and apoptosis in T cells impacting lymphoid organ size and function.

The activation of the small guanosine triphosphatase Ras by the guanine nucleotide exchange factor (GEF) Sos1 (Son of Sevenless 1) is a central feature of many receptor-stimulated signaling pathways. In developing T cells (thymocytes), Sos1-dependent activation of extracellular signal-regulated kinase (ERK) is required to stimulate cellular proliferation and differentiation. We showed that in addition to its GEF activity, Sos1 acted as a scaffold to nucleate oligomerization of the T cell adaptor protein LAT (linker for activation of T cells) in vivo. The scaffold function of Sos1 depended on its ability to bind to the adaptor protein Grb2. Furthermore, the GEF activity of Sos1 and the Sos1-dependent oligomerization of LAT were separable functions in vivo. Whereas the GEF activity of Sos1 was required for optimal ERK phosphorylation in response to T cell receptor (TCR) stimulation, the Sos1-dependent oligomerization of LAT was required for maximal TCR-dependent phosphorylation and activation of phospholipase C-γ1 and Ca(2+) signaling. Finally, both of these Sos1 functions were required for early thymocyte proliferation. Whereas transgenic restoration of either the GEF activity or the LAT oligomerization functions of Sos1 alone failed to rescue thymocyte development in Sos1-deficient mice, simultaneous reconstitution of these two signals in the same cell restored normal T cell development. This ability of Sos1 to act both as a RasGEF and as a scaffold to nucleate Grb2-dependent adaptor oligomerization may also occur in other Grb2-dependent pathways, such as those activated by growth factor receptors.

Helper T cells from a mutant mouse model, LAT Y136F, hyper-proliferate and cause a severe lymphoproliferative disease that kills the mice by six months of age. LAT Y136F mice carry a tyrosine to phenylalanine mutation in the Linker for Activation of T cells (LAT) gene. This mutation leads to a number of changes in T cells that result in altered cytokine production including increased IL-4 production, increased proliferation, and decreased apoptosis. Hyper-proliferation of the mutant T cells contributes to lymphadenopathy, splenomegaly, and multi-organ T cell infiltration. miRNAs are short non-coding RNAs that regulate expression of cohorts of genes. This study investigates which miRNAs are expressed in LAT Y136F T cells and compares these to miRNAs expressed in wild type T cells that are undergoing proliferation in two other settings. The first setting is homeostatic proliferation, which was modeled by adoptive transfer of wild type T cells into T cell-deficient mice. The second setting is proliferation in response to infection, which was modeled by infection of wild type mice with the nematode H. polygyrus. By comparing miRNA expression in these three proliferative states (LAT Y136F hyper-proliferation, homeostatic proliferation and proliferation in response to H. polygyrus infection) to expression in wild type naïve CD4(+) T cells, we found miRNAs that were highly regulated in all three proliferative states (miR-21 and miR-146a) and some that were more specific to individual settings of proliferation such as those more specific for LAT Y136F lymphoproliferative disease (miR-669f, miR-155 and miR-466a/b). Future experiments that modulate levels of the miRNAs identified in this study may reveal the roles of these miRNAs in T cell proliferation and/or lymphoproliferative disease.

Mice expressing a germline mutation in the phospholipase C-γ1-binding site of linker for activation of T cells (LAT) show progressive lymphoproliferation and ultimately die at 4-6 mo age. The hyperactivated T cells in these mice show defective TCR-induced calcium flux but enhanced Ras/ERK activation, which is critical for disease progression. Despite the loss of LAT-dependent phospholipase C-γ1 binding and activation, genetic analysis revealed RasGRP1, and not Sos1 or Sos2, to be the major Ras guanine exchange factor responsible for ERK activation and the lymphoproliferative phenotype in these mice. Analysis of isolated CD4(+) T cells from LAT-Y136F mice showed altered proximal TCR-dependent kinase signaling, which activated a Zap70- and LAT-independent pathway. Moreover, LAT-Y136F T cells showed ERK activation that was dependent on Lck and/or Fyn, protein kinase C-θ, and RasGRP1. These data demonstrate a novel route to Ras activation in vivo in a pathological setting.

Thymocytes must transit at least two distinct developmental checkpoints, governed by signals that emanate from either the pre-T cell receptor (pre-TCR) or the TCR to the small G protein Ras before emerging as functional T lymphocytes. Recent studies have shown a role for the Ras guanine exchange factor (RasGEF) Sos1 at the pre-TCR checkpoint. At the second checkpoint, the quality of signaling through the TCR is interrogated to ensure the production of an appropriate T cell repertoire. Although RasGRP1 is the only confirmed RasGEF required at the TCR checkpoint, current models suggest that the intensity and character of Ras activation, facilitated by both Sos and RasGRP1, will govern the boundary between survival (positive selection) and death (negative selection) at this stage. Using mouse models, we have assessed the independent and combined roles for the RasGEFs Sos1, Sos2, and RasGRP1 during thymocyte development. Although Sos1 was the dominant RasGEF at the pre-TCR checkpoint, combined Sos1/RasGRP1 deletion was required to effectively block development at this stage. Conversely, while RasGRP1 deletion efficiently blocked positive selection, combined RasGRP1/Sos1 deletion was required to block negative selection. This functional redundancy in RasGEFs during negative selection may act as a failsafe mechanism ensuring appropriate central tolerance.

Receptor-regulated cellular signaling often is mediated by formation of transient, heterogeneous protein complexes of undefined structure. We used single and two-color photoactivated localization microscopy to study complexes downstream of the T cell antigen receptor (TCR) in single-molecule detail at the plasma membrane of intact T cells. The kinase ZAP-70 distributed completely with the TCRζ chain and both partially mixed with the adaptor LAT in activated cells, thus showing localized activation of LAT by TCR-coupled ZAP-70. In resting and activated cells, LAT primarily resided in nanoscale clusters as small as dimers whose formation depended on protein-protein and protein-lipid interactions. Surprisingly, the adaptor SLP-76 localized to the periphery of LAT clusters. This nanoscale structure depended on polymerized actin and its disruption affected TCR-dependent cell function. These results extend our understanding of the mechanism of T cell activation and the formation and organization of TCR-mediated signaling complexes, findings also relevant to other receptor systems., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Over the past 30 years, tubewells have become a ubiquitous source of potable groundwater in South Asia. Considered safer than surface water, groundwater naturally contains minerals that may impact human health; however, few data exist on tubewell water mineral content or its association with human nutritional or health conditions. We surveyed iron concentration in tubewell water across a 435 km2, contiguous, rural area in northwestern Bangladesh to map and quantify levels of iron in drinking water. One tubewell was randomly sampled from each of 948 adjacent grid cells 675 m2 in size. Water sampling was standardized and iron concentration measured using a field-based colorimetric kit. The median (interquartile range) concentration of iron in tubewell water was 7.6 (1.6, 17.6) mg l(-1). There was high geographic variation (range of 0-46.5 mg l(-1)), and iron in only 3% of surveyed tubewells fell below the WHO aesthetic cut-off of 0.3 mg l(-1) suggesting elevated levels of iron throughout the area. Villagers accurately perceived groundwater iron concentration, based on a 4-point ('none', 'a little', 'medium', 'a lot') scale (p<0.001). Water source iron content can be readily quantified in population settings offering the potential to evaluate the health relevance of groundwater iron exposure in rural communities.