Measuring Proximal Tibial Metaphyseal Width and Lateral Epiphyseal Height Improves Determination of Remaining Growth in Children.

BACKGROUND: Accurate assessments of skeletal maturity is of critical importance to guide type and timing of orthopaedic surgical interventions. Several quantitative markers of the proximal tibia were recently developed using historical knee radiographs. The purpose of the present study was to determine which marker would be most effective in assessment of full-length radiographs in a modern pediatric patient population. METHODS: All full-length radiographs at our institutions between 2013 and 2018 were reviewed. Inclusion criteria for our study required that the child reached final height as defined by 2 consecutive unchanged heights, at least 6 months apart, after age 16 for boys and 14 for girls. Patients with metabolic bone disease, prior surgery such as epiphysiodesis, or previous infections around the knee were excluded. Summary statistics for each of the 3 proximal tibial ratios were calculated and multiple linear regression was performed with percent of growth remaining as a dependent variable. A recommended regression model is presented and evaluated. RESULTS: A total of 692 full-length radiographs met inclusion criteria. Proximal tibial ratios were calculated and averaged values for each percent of growth remaining was presented. Multiple linear regression demonstrated that using all 3 variables led to overfitting of the model so tibial metaphyseal width/lateral tibial epiphyseal height was selected as the optimal ratio for use by clinicians. The optimal model for determining growth was found to have R2=0.723 in the developmental set and R2=0.762 in an excluded validation set. CONCLUSIONS: This study demonstrates that the proximal tibial metaphyseal width/lateral tibial epiphyseal height is the ideal measurement for clinicians seeking to determine growth remaining in children. It presents average values between 0% and 25% of growth remaining. This study also develops and validates a multivariable regression model for determining percentage of growth remaining in children that will allow for quantitative determination of growth using full-length radiographs. LEVEL OF EVIDENCE: Level III.

Modification and application of the proximal humerus ossification system to adolescent idiopathic scoliosis patients.

PURPOSE: We have previously demonstrated that proximal humeral ossification patterns are reliable for assessing peak height velocity in growing patients. Here, we sought to modify the system by including medial physeal closure and evaluate whether this system combined with the Cobb angle correlates with progression to surgery in patients with adolescent idiopathic scoliosis. METHODS: We reviewed 616 radiographs from 79 children in a historical collection to integrate closure of the medial physis into novel stages 3A and 3B. We then analyzed radiographs from the initial presentation of 202 patients with adolescent idiopathic scoliosis who had either undergone surgery or completed monitoring at skeletal maturity. Summary statistics for the percentage of patients who progressed to the surgical range were calculated for each category of humerus and Cobb angle. RESULTS: The intra-observer and inter-observer ICC for assessment of the medial physis was 0.6 and 0.8, respectively. Only 3.4% of radiographs were unable to be assessed for medial humerus closure. The medial humerus physis begins to close about 1 year prior to the lateral physis and patients with a closing medial physis, but an open lateral physis were found to be the closest to PHV (0.7 years). Stratifying patients by Cobb angle and modified humerus stage yield categories with low and high risks of progression to the surgical range. CONCLUSION: The medial humerus can be accurately evaluated and integrated into a new modified proximal humerus ossification system. Patients with humerus stage 3A or below have a higher rate of progression to the surgical range than those with humerus stage 3B or above.

The Proximal Humeral Ossification System Improves Assessment of Maturity in Patients with Scoliosis.

BACKGROUND: We recently developed a classification system to assess skeletal maturity by scoring proximal humeral ossification in a similar way to the canonical Risser sign. The purpose of the present study was to determine whether our system can be used to reliably assess radiographs of the spine for modern patients with idiopathic scoliosis, whether it can be used in combination with the Sanders hand system, and whether the consideration of patient factors such as age, sex, and standing height improves the accuracy of predictions. METHODS: We retrospectively reviewed 414 randomized radiographs from 216 modern patients with scoliosis and measured reliability with use of the intraclass correlation coefficient (ICC). We then analyzed 606 proximal humeral radiographs for 70 children from a historical collection to determine the value of integrating multiple classification systems. The age of peak height velocity (PHV) was predicted with use of linear regression models, and performance was evaluated with use of tenfold cross-validation. RESULTS: The proximal humeral ossification system demonstrated excellent reliability in modern patients with scoliosis, with an ICC of 0.97 and 0.92 for intraobserver and interobserver comparisons, respectively. The use of our system in combination with the Sanders hand system yielded 7 categories prior to PHV and demonstrated better results compared with either system alone. Linear regression algorithms showed that integration of the proximal part of the humerus, patient factors, and other classification systems outperformed models based on canonical Risser and triradiate-closure methods. CONCLUSIONS: Humeral head ossification can be reliably assessed in modern patients with scoliosis. Furthermore, the system described here can be used in combination with other parameters such as the Sanders hand system, age, sex, and height to predict PHV and percent growth remaining with high accuracy. CLINICAL RELEVANCE: The proximal humeral ossification system can improve the prediction of PHV in patients with scoliosis on the basis of a standard spine radiograph without a hand radiograph for the determination of bone age. This increased accuracy for predicting maturity will allow physicians to better assess patient maturity relative to PHV and therefore can help to guide treatment decision-making without increasing radiation exposure, time, or cost. The present study demonstrates that assessment of the proximal humeral physis is a viable and valuable aid in the determination of skeletal maturity as obtained from radiographs of the spine that happen to include the shoulder in adolescent patients with idiopathic scoliosis.

Management of Degenerative Spondylolisthesis: Analysis of a Questionnaire Study, Correlation With a National Sample, and Perioperative Outcomes of Treatment Options.

BACKGROUND: Surgical treatment for lumbar degenerative spondylolisthesis has been shown to provide better long-term outcomes than conservative treatment. However, there is variation in surgical approaches employed by surgeons. This study investigates current surgical practice patterns and compares perioperative outcomes of 3 common surgical treatments for this pathology. METHODS: A survey was administered to surgeons who attended the Lumbar Spine Research Society (LSRS) meeting in 2014. Data were extracted from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) from 2005 to 2014 to characterize the same responses. The 2 data sets were compared. Perioperative outcomes of those in the ACS-NSQIP posterior fusion subcohorts were characterized and compared. RESULTS: Posterior surgical approaches utilized by surgeons who responded to the LSRS survey were similar to those captured by ACS-NSQIP where 72% of those with degenerative spondylolisthesis were fused. Of those that were fused, 8% had an uninstrumented posterior fusion, 33% had an instrumented posterior fusion, and 59% had an instrumented posterior fusion with interbody. On multivariate analysis, there was no difference in risk of postoperative adverse events, readmission, or length of stay between these 3 common types of fusion. CONCLUSIONS: Practice patterns for the posterior management of lumbar degenerative spondylolisthesis were similar between LSRS survey responses and ACS-NSQIP data. The ACS-NSQIP perioperative outcome measures assessed were similar regardless of surgical technique. These findings highlight that cost-benefit considerations and longer-term outcomes have to be the measures by which surgical technique is chosen for degenerative spondylolisthesis.

Incidence and considerations of 90-day readmissions following posterior lumbar fusion.

BACKGROUND CONTEXT: Posterior lumbar fusion (PLF) is a commonly performed procedure. The evolution of bundled payment plans is beginning to require physicians to more closely consider patient outcomes up to 90 days after an operation. Current quality metrics and other databases often consider only 30 postoperative days. The relatively new Healthcare Cost and Utilization Project Nationwide Readmissions Database (HCUP-NRD) tracks patient-linked hospital admissions data for up to one calendar year. PURPOSE: To identify readmission rates within 90 days of discharge following PLF and to put this in context of 30 day readmission and baseline readmission rates. STUDY DESIGN: Retrospective study of patients in the HCUP-NRD. PATIENT SAMPLE: Any patient undergoing PLF performed in the first 9 months of 2013 were identified in the HCUP-NRD. OUTCOME MEASURES: Readmission patterns up to a full calendar year after discharge. METHODS: PLFs performed in the first 9 months of 2013 were identified in the HCUP-NRD. Patient demographics and readmissions were tracked for 90 days after discharge. To estimate the average admission rate in an untreated population, the average daily admission rate in the last quarter of the year was calculated for a subset of PLF patients who had their operation in the first quarter of the year. This study was deemed exempt by the institution's Human Investigation Committee. RESULTS: Of 26,727 PLFs, 1,580 patients (5.91%) were readmitted within 30 days of discharge and 2,603 patients (9.74%) were readmitted within 90 days of discharge. Of all readmissions within 90 days, 54.56% occurred in the first 30 days. However, if only counting readmissions above the baseline admission rate of a matched population from the 4th quarter of the year (0.08% of population/day), 89.78% of 90 day readmissions occurred within the first 30 days. CONCLUSIONS: The current study delineates readmission rates after PLF and puts this in the context of 30-day readmission rates and baseline readmission rates for those undergoing PLF. These results are important for patient counseling, planning, and preparing for potential bundled payments in spine surgery.

Changes in Proximal Femoral Shape During Fetal Development.

BACKGROUND: Walker and Goldsmith's classic article on fetal hip joint development reported that neck/shaft angle did not change from 12 weeks of gestational age through term while version increased from 0 to 40 degrees. This suggests no change in coronal alignment during development, a conclusion we dispute. By re-examining their data, we found that the true neck/shaft angle (tNSA) decreased by 7.5 degrees as version increased by 40 degrees from 12 weeks of gestational age to term. METHODS: Four investigators measured both femoral version and neck-shaft angle from photographs published by the authors of femurs at multiple stages of maturation from 12 weeks of gestational age to term. The tNSAs and inclination angles were calculated for each femur illustrated using previously validated formula. Changes in the morphology of the femur over time were analyzed using a Student t test. Interobserver and intraobserver reliability were also determined by the Pearson R coefficient. RESULTS: As reported by Walker and Goldsmith, apparent neck/shaft angle (aNSA) did not significantly change during maturation, whereas version increased by 40 degrees. However, tNSA decreased by 7.5 degrees during maturation, while the inclination increased by 32 degrees over the same period. This paper demonstrates angular changes in both the coronal and transverse planes with a 4:1 ratio of angular change in the transverse and coronal planes respectively. Interobserver Pearson coefficient R=0.98 and an intraobserver Pearson coefficient R=0.99. CONCLUSIONS: Although Walker and Goldsmith reported angular changes only in the transverse plane, we conclude that they identified angular changes in both the coronal and transverse planes. Here we show it is mathematically necessary for tNSA to decrease, if aNSA remains constant as version increases. CLINICAL RELEVANCE: A reader who is not well versed in the difference between aNSA and tNSA or version and inclination cannot appreciate what Walker and Goldsmith presented. Surgeons operating on the proximal femur also benefit from understanding these distinctions.

Adverse Events Following Posterior Lumbar Fusion: A Comparison of Spine Surgeons Perceptions and Reported Data for Rates and Risk Factors.

BACKGROUND: Postoperative complications and risks factors for adverse events play an important role in both decision making and patient expectation setting. The present study serves to contrast surgeons' perceived and reported rates of postoperative adverse events following posterior lumbar fusion (PLF) and to assess the accuracy of predicting the impact of patient factors on such outcomes. METHODS: A survey investigating perceived rates of adverse events and the impact of patient risk factors on them following PLF for degenerative conditions was distributed to spine surgeons at the Lumbar Spine Research Society (LSRS) 2016 annual meeting. For comparison, the corresponding rates and patient risk factors were assessed in patients undergoing elective PLF from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) data years 2011-2014. RESULTS: From the survey, there were 53 responses (response rate of 79%) from attending physicians at LSRS. From NSQIP, there were 16,589 patients who met the inclusion criteria. Adverse event rates estimated by the surgeons at LSRS were close to those determined by NSQIP data (no greater than 2.81% different). The largest differences were for deep vein thrombosis (overestimation of 2.81%, P < .001), anemia requiring transfusion (overestimation of 2.47%, P = .018), and urinary tract infection (overestimation of 2.29%, P < .001). Similarly, the estimated impact of patient factors was similar to the data (within relative risk of 2.02). The largest differences were for current smoking (overestimation of 2.02 relative risk, P < .001), insulin dependent diabetes (overestimation of 1.36, P < .001), and obesity (overestimation of 1.35, P < .001). CONCLUSIONS: The current study noted that surgeon estimates were relatively close to national numbers for estimating the adverse events and impact of patient factors on such outcomes after PLF for degenerative conditions. The estimates are roughly appropriate with a bias toward overestimation for planning and expectation setting.

Predicting Adverse Outcomes After Total Hip Arthroplasty: A Comparison of Demographics, the American Society of Anesthesiologists class, the Modified Charlson Comorbidity Index, and the Modified Frailty Index.

INTRODUCTION: No known study has compared the predictive power of the American Society of Anesthesiologists (ASA) class, modified Charlson Comorbidity Index, modified Frailty Index, and demographic characteristics for general health complications after total hip arthroplasty (THA). METHODS: Comorbidity indices and demographics from National Surgical Quality Improvement Program THA patients were evaluated for discriminative ability in predicting adverse outcomes using the area under the curve analysis from the receiver operating characteristic curves. Perioperative outcomes included any adverse event, severe adverse events, minor adverse events, extended hospital stay, and discharge to higher-level care. RESULTS: In total, 64,792 THA patients were identified. The most predictive comorbidity index was ASA, and demographic factor was age. Of these, age had the greatest discriminative ability for four of the five adverse outcomes. CONCLUSION: For THA, easily obtained patient ASA and age are more predictive of perioperative adverse outcomes than the more complex and numerically tabulated modified Charlson Comorbidity Index and modified Frailty Index.

Humeral Head Ossification Predicts Peak Height Velocity Timing and Percentage of Growth Remaining in Children.

BACKGROUND: Understanding skeletal maturity is important in the management of idiopathic scoliosis. Iliac apophysis, triradiate cartilage, hand, and calcaneal ossification patterns have previously been described to assess both peak height velocity (PHV) and percent growth remaining; however, these markers may not be present on standard spine radiographs. The purpose of this study was to describe a novel maturity assessment method based on proximal humeral epiphyseal ossification patterns. METHODS: Ninety-four children were followed at least annually throughout growth with serial radiographs and physical examinations. The PHV of each child was determined by measuring the change in height observed at each visit and adjusting for the interval between visits. Percent growth remaining was determined by comparing current to final standing height. The humeral head periphyseal ossification was grouped into stages by 8 investigators ranging from medical student to attending surgeon. RESULTS: The morphologic changes involving the proximal humeral physis were categorized into 5 stages based on development of the humeral head epiphysis and fusion of the lateral margin of the physis. Our novel classification scheme was well distributed around the PHV and reliably correlated with age of peak growth and percent growth remaining with >70% nonoverlapping interquartile ranges. Furthermore, the scheme was extremely reliable with intraclass correlation coefficients of 0.96 and 0.95 for intraobserver and interobserver comparisons, respectively. CONCLUSIONS: The humeral head classification system described here was strongly correlated with age of PHV as well as percentage growth remaining. Furthermore, the staging system was extremely reliable in both interobserver and intraobserver correlations suggesting that it can be easily generalized. CLINICAL RELEVANCE: As a view of the humeral head is almost always present on standard scoliosis spine x-ray at our institution, our classification can be easily adapted by surgeons to gain additional insight into skeletal maturity of patients with scoliosis. We believe that our method will significantly improve the evaluation of the child with scoliosis without increasing radiation exposure, time, or cost.

General Health Adverse Events Within 30 Days Following Anterior Cervical Discectomy and Fusion in US Patients: A Comparison of Spine Surgeons' Perceptions and Reported Data for Rates and Risk Factors.

STUDY DESIGN: Survey study and retrospective review of prospective data. OBJECTIVES: To contrast surgeons' perceptions and reported national data regarding the rates of postoperative adverse events following anterior cervical discectomy and fusion (ACDF) and to assess the accuracy of surgeons in predicting the impact of patient factors on such outcomes. METHODS: A survey investigating perceived rates of perioperative complications and the perceived effect of patient risk factors on the occurrence of complications following ACDF was distributed to spine surgeons at the Cervical Spine Research Society (CSRS) 2015 Annual Meeting. The equivalent reported rates of adverse events and impacts of patient risk factors on such complications were assessed in patients undergoing elective ACDF from the National Surgical Quality Improvement Program (NSQIP). RESULTS: There were 110 completed surveys from attending physicians at CSRS (response rate = 44%). There were 18 019 patients who met inclusion criteria in NSQIP years 2011 to 2014. The rates of 11 out of 17 (65%) postoperative adverse events were mildly overestimated by surgeons responding to the CSRS questionnaire in comparison to reported NSQIP data (overestimates ranged from 0.24% to 1.50%). The rates of 2 out of 17 (12%) postoperative adverse events were mildly underestimated by surgeons (range = 0.08% to 1.2%). The impacts of 5 out of 10 (50%) patient factors were overestimated by surgeons (range relative risk = 0.56 to 1.48). CONCLUSIONS: Surgeon estimates of risk factors for and rates of adverse events following ACDF procedures were reasonably nearer to national data. Despite an overall tendency toward overestimation, surgeons' assessments are roughly appropriate for surgical planning, expectation setting, and quality improvement initiatives.

Longer Operative Time Is Associated With Increased Adverse Events After Anterior Cervical Diskectomy and Fusion: 15-Minute Intervals Matter.

Little is known about the impact of operative time, as an independent and interval variable, on general health perioperative outcomes following anterior cervical diskectomy and fusion. Therefore, patients undergoing a 1-level anterior cervical diskectomy and fusion were identified in the American College of Surgeons National Surgical Quality Improvement Program. Operative time (as an interval variable) was tested for association with perioperative outcomes using a multivariate regression that was adjusted for differences in baseline characteristics. A total of 15,241 patients were included. Increased surgical duration was consistently correlated with a rise in any adverse event postoperatively, with each additional 15 minutes of operating time raising the risk for having any adverse event by an average of 10% (99.64% confidence interval, 3%-17%, P<.001). In fact, 15-minute increases in surgical duration were associated with incremental increases in the rates of venous thromboembolism, sepsis, unplanned intubation, extended length of hospital stay, and hospital readmission. Greater operative time, despite controlling for other patient variables, increases the risk for overall postoperative adverse events and multiple individual adverse outcomes. This increased risk may be attributed to anesthetic effects, physiologic stresses, and surgical site issues. Although it is difficult to fully isolate operative time as an independent variable because it may be closely related to the complexity of the surgical pathology being addressed, the current study suggests that surgeons should maximize operative efficiency as possible (potentially using strategies that have been shown to improve operative time in the 15-minute magnitude), without compromising the technical components of the procedure. [Orthopedics. 2018; 41(4):e483-e488.].

Missing data treatments matter: an analysis of multiple imputation for anterior cervical discectomy and fusion procedures.

BACKGROUND CONTEXT: The presence of missing data is a limitation of large datasets, including the National Surgical Quality Improvement Program (NSQIP). In addressing this issue, most studies use complete case analysis, which excludes cases with missing data, thus potentially introducing selection bias. Multiple imputation, a statistically rigorous approach that approximates missing data and preserves sample size, may be an improvement over complete case analysis. PURPOSE: The present study aims to evaluate the impact of using multiple imputation in comparison with complete case analysis for assessing the associations between preoperative laboratory values and adverse outcomes following anterior cervical discectomy and fusion (ACDF) procedures. STUDY DESIGN/SETTING: This is a retrospective review of prospectively collected data. PATIENT SAMPLE: Patients undergoing one-level ACDF were identified in NSQIP 2012-2015. OUTCOME MEASURES: Perioperative adverse outcome variables assessed included the occurrence of any adverse event, severe adverse events, and hospital readmission. METHODS: Missing preoperative albumin and hematocrit values were handled using complete case analysis and multiple imputation. These preoperative laboratory levels were then tested for associations with 30-day postoperative outcomes using logistic regression. RESULTS: A total of 11,999 patients were included. Of this cohort, 63.5% of patients had missing preoperative albumin and 9.9% had missing preoperative hematocrit. When using complete case analysis, only 4,311 patients were studied. The removed patients were significantly younger, healthier, of a common body mass index, and male. Logistic regression analysis failed to identify either preoperative hypoalbuminemia or preoperative anemia as significantly associated with adverse outcomes. When employing multiple imputation, all 11,999 patients were included. Preoperative hypoalbuminemia was significantly associated with the occurrence of any adverse event and severe adverse events. Preoperative anemia was significantly associated with the occurrence of any adverse event, severe adverse events, and hospital readmission. CONCLUSIONS: Multiple imputation is a rigorous statistical procedure that is being increasingly used to address missing values in large datasets. Using this technique for ACDF avoided the loss of cases that may have affected the representativeness and power of the study and led to different results than complete case analysis. Multiple imputation should be considered for future spine studies.

Discriminative Ability for Adverse Outcomes After Surgical Management of Hip Fractures: A Comparison of the Charlson Comorbidity Index, Elixhauser Comorbidity Measure, and Modified Frailty Index.

OBJECTIVES: The Charlson comorbidity index (CCI), Elixhauser comorbidity measure (ECM), and modified frailty index (mFI) have been associated with mortality after hip fracture. The present study compares the clinically informative discriminative ability of CCI, ECM, and mFI, as well as demographic characteristics for predicting in-hospital adverse outcomes after surgical management of hip fractures. METHODS: Patients undergoing hip fracture surgery were selected from the 2013 National Inpatient Sample. The discriminative ability of CCI, ECM, and mFI, as well as demographic factors for adverse outcomes were assessed using the area under the curve analysis from receiver operating characteristic curves. Outcomes included the occurrence of any adverse event, death, severe adverse events, minor adverse events, and extended hospital stay. RESULTS: In total, 49,738 patients were included (mean age: 82 years). In comparison with CCI and mFI, ECM had the significantly largest discriminative ability for the occurrence of all outcomes. Among demographic factors, age had the sole or shared the significantly largest discriminative ability for all adverse outcomes except extended hospital stay. The best performing comorbidity index (ECM) outperformed the best performing demographic factor (age) for all outcomes. CONCLUSION: Among both comorbidity indices and demographic factors, the ECM had the best overall discriminative ability for adverse outcomes after surgical management of hip fractures. The use of this index in correctly identifying patients at risk for postoperative complications may help set appropriate patient expectations, assist in optimizing prophylaxis regimens for medical management, and adjust reimbursements. More widespread use of this measure for hip fracture studies may be appropriately considered. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The Rothman Index Is Associated With Postdischarge Adverse Events After Hip Fracture Surgery in Geriatric Patients.

BACKGROUND: The Rothman Index is a comprehensive measure of overall patient status in the inpatient setting already in use at many medical centers. It ranges from 100 (best score) to -91 (worst score) and is calculated based on 26 variables encompassing vital signs, routine laboratory values, and organ system assessments from nursing rounds from the electronic medical record. Past research has shown an association of Rothman Index with complications, readmission, and death in certain populations, but it has not been evaluated in geriatric patients with hip fractures, a potentially vulnerable patient population. QUESTIONS/PURPOSES: (1) Is there an association between Rothman Index scores and postdischarge adverse events in a population aged 65 years and older with hip fractures? (2) What is the discriminative ability of Rothman Index scores in determining which patients will or will not experience these adverse events? (3) Are there Rothman Index thresholds associated with increased incidence of postdischarge adverse outcomes? METHODS: One thousand two hundred fourteen patients aged 65 years and older who underwent hip fracture surgery at an academic medical center between 2013 and 2016 were identified. Demographic and comorbidity characteristics were characterized, and 30-day postdischarge adverse events were calculated. The associations between a 10-unit change in Rothman Index scores and postdischarge adverse events, mortality, and readmission were determined. American Society of Anesthesiologists (ASA) class was used as a measure of comorbidity because prior research has shown its performance to be equivalent or superior to that of calculated comorbidity measures in this data set. We assessed the ability of Rothman Index scores to determine which patients experienced adverse events. Finally, Rothman Index thresholds were assessed for an association with increased incidence of postdischarge adverse outcomes. RESULTS: We found a strong association between Rothman Index scores and postdischarge adverse events (lowest score: odds ratio [OR] = 1.29 [1.18-1.41], p < 0.001; latest score: OR = 1.37 [1.24-1.52], p < 0.001) after controlling for age, sex, body mass index, ASA class, and surgical procedure performed. The discriminative ability of lowest and latest Rothman Index scores was better than those of age, sex, and ASA class for any adverse event (lowest value: area under the curve [AUC] = 0.641; 95% confidence interval [CI], 0.601-0.681; latest value: AUC = 0.640; 95% CI, 0.600-0.680); age (0.534; 95% CI, 0.493-0.575, p < 0.001 for both), male sex (0.552; 95% CI, 0.518-0.585, p = 0.001 for both), and ASA class (0.578; 95% CI, 0.542-0.614; p = 0.004 for lowest Rothman Index, p = 0.006 for latest Rothman Index). There was never a difference when comparing lowest Rothman Index value and latest Rothman Index value for any of the outcomes (Table 5). Patients experienced increased rates of postdischarge adverse events and mortality with a lowest Rothman Index of ≤ 35 (p < 0.05) or latest Rothman Index of ≤ 55 (p < 0.05). CONCLUSIONS: The Rothman Index provides an objective method of assessing perioperative risk in the setting of hip fracture surgery in patients older than age 65 years and is more accurate than demographic measures or ASA class. Furthermore, there are Rothman Index thresholds that can be used to identify patients at increased risk of complications. Physicians can use this tool to monitor the condition of patients with hip fracture, recognize patients at high risk of adverse events to consider changing their plan of care, and counsel patients and families. Further investigation is needed to determine whether interventions based on Rothman Index values contribute to improved outcomes or value of hip fracture care. LEVEL OF EVIDENCE: Level II, diagnostic study.

Discrepancies in the Definition of "Outpatient" Surgeries and Their Effect on Study Outcomes Related to ACDF and Lumbar Discectomy Procedures: A Retrospective Analysis of 45,204 Cases.

STUDY DESIGN: This is a retrospective study. OBJECTIVE: To study the differences in definition of "inpatient" and "outpatient" [stated status vs. actual length of stay (LOS)], and the effect of defining populations based on the different definitions, for anterior cervical discectomy and fusion (ACDF) and lumbar discectomy procedures in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. SUMMARY OF BACKGROUND DATA: There has been an overall trend toward performing ACDF and lumbar discectomy in the outpatient setting. However, with the possibility of patients who underwent outpatient surgery staying overnight or longer at the hospital under "observation" status, the distinction of "inpatient" and "outpatient" is not clear. MATERIALS AND METHODS: Patients who underwent ACDF or lumbar discectomy in the 2005-2014 ACS-NSQIP database were identified. Outpatient procedures were defined in 1 of 2 ways: either as being termed "outpatient" or hospital LOS=0. Differences in definitions were studied. Further, to evaluate the effect of the different definitions, 30-day outcomes were compared between "inpatient" and "outpatient" and between LOS>0 and LOS=0 for ACDF patients. RESULTS: Of the 4123 "outpatient" ACDF patients, 919 had LOS=0, whereas 3204 had LOS>0. Of the 13,210 "inpatient" ACDF patients, 337 had LOS=0, whereas 12,873 had LOS>0. Of the 15,166 "outpatient" lumbar discectomy patients, 8968 had LOS=0, whereas 6198 had LOS>0. Of the 12,705 "inpatient" lumbar discectomy patients, 814 had LOS=0, whereas 11,891 had LOS>0. On multivariate analysis of ACDF patients, when comparing "inpatient" with "outpatient" and "LOS>0" with "LOS=0" there were differences in risks for adverse outcomes based on the definition of outpatient status. CONCLUSIONS: When evaluating the ACS-NSQIP population, ACDF and lumbar discectomy procedures recorded as "outpatient" can be misleading and often did not correlate with same day discharge. These findings have significant impact on the interpretation of existing studies and define an area that needs clarification for future studies. LEVEL OF EVIDENCE: Level 3.

High Publication Rate of Abstracts Presented at Lumbar Spine Research Society Meetings.

BACKGROUND: Although publication rates from multiple orthopedic research conferences have been published in the literature, the publication rates of abstracts presented at the Lumbar Spine Research Society (LSRS) meetings have never been reported. The purpose of this study is to evaluate the publication rates from the LSRS annual meeting years 2008-2012 and then to compare those rates with that of other spine research society meetings. METHODS: Podium presentations from 2008 to 2012 and poster presentations from 2010 to 2012 were reviewed. For each presentation, a PubMed search was performed to determine if a full-text publication existed. χ2 tests were used to compare LSRS publication rates to those of other spine meetings. In addition, impact of published articles was evaluated by average citation count and average journal impact factor. RESULTS: From 2008 to 2012, a total of 332 podium and poster presentations were identified. The overall publication rate was 55.1% (183/332). For podium presentations, this was greatest in 2012 (66.0%) and lowest in 2008 (51.5%). For poster presentations, this was greatest in 2012 (53.6%) and lowest in 2010 (25.0%). The publication rate of presentations is statistically greater than the publication rates of Eurospine (37.8%, P < .001), North American Spine Society (40.0%, P < .001), The International Society for the Study of the Lumbar Spine (45.0%, P = .012), and the Scoliosis Research Society (47.0%, P = .042) but not statistically different than that of Cervical Spine Research Society (65.7%, P = .059). In addition, the average citation count per published article categorized by year ranged from 13 to 31. The average journal impact factor of published articles categorized by year ranged from 2.31 to 2.55. CONCLUSIONS: While LSRS is a relatively young society, these findings point to the high quality of presentations at this scientific meeting. These findings speak to the scientific rigor of presentations at LSRS. CLINICAL RELEVANCE: This study helps clinicians and scientists gauge the quality of a research meeting and make informed choices on which gatherings to attend.

Systematic Changes in the National Surgical Quality Improvement Program Database Over the Years Can Affect Comorbidity Indices Such as the Modified Frailty Index and Modified Charlson Comorbidity Index for Lumbar Fusion Studies.

STUDY DESIGN: Retrospective cohort study of prospectively collected data. OBJECTIVE: The aim of this study was to investigate the influence of changes in the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database over the years on the calculation of the modified Frailty Index (mFI) and the modified Charlson Comorbidity Index (mCCI) for posterior lumbar fusion studies. SUMMARY OF BACKGROUND DATA: Multiple studies have utilized the mFI and/or mCCI and showed them to be predictors of adverse postoperative outcomes. However, changes in the NSQIP database have resulted in definition changes and/or missing data for many of the variables included in these indices. No studies have assessed the influence of different methods of treating missing values when calculating these indices on such studies. METHODS: Elective posterior lumbar fusions were identified in NSQIP from 2005 to 2014. The mFI was calculated for each patient using three methods: treating conditions for which data was missing as not present, dropping patients with missing values, and normalizing by dividing the raw score by the number of variables collected. The mCCI was calculated by the first two of these methods. Mean American Society of Anesthesiologists (ASA) scores used for comparison. RESULTS: In total, 19,755 patients were identified. Mean ASA score increased between 2005 and 2014 from 2.27 to 2.50 (+10.1%). For each of the methods of data handling noted above, mean mFI over the years studied increased by 33.3%, could not be calculated, and increased by 183.3%, respectively. Mean mCCI increased by 31.2% and could not be calculated respectively. CONCLUSION: Systematic changes in the NSQIP database have resulted in missing data for many of the variables included in the mFI and the mCCI and may affect studies utilizing these indices. These changes can be understood in the context of ASA trends, and raise questions regarding the use of these indices with data available in later NSQIP years. LEVEL OF EVIDENCE: 3.

Inaccuracies in ICD Coding for Obesity Would Be Expected to Bias Administrative Database Spine Studies Toward Overestimating the Impact of Obesity on Perioperative Adverse Outcomes.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To determine if International Classification of Diseases (ICD) coding for obesity is biased toward certain subgroups and how potential bias may influence the outcomes of database research in spine. SUMMARY OF BACKGROUND DATA: There has been increased use of national databases using administrative data in the spine surgery literature. Past research demonstrates that sensitivity of ICD codes for obesity is poor, but it is unknown if such inaccuracies are systematically biased and if they may bias studies utilizing such data. METHODS: Patients who underwent elective posterior lumbar fusion, 2013 to 2016, at a large academic hospital were identified. All ICD codes assigned to the encounter were obtained. Body mass index (BMI) was calculated based on height and weight. The sensitivity of ICD coding for obesity was calculated. Sensitivity was compared for subgroups defined by demographic, comorbidity, intraoperative, and postoperative factors. The association of obesity (as defined by BMI≥30 and ICD coding) with 30-day postoperative adverse events was tested with multivariate regression. RESULTS: The study included 796 patients. The overall sensitivity of ICD coding for obesity was 42.5%. The sensitivity of ICD coding for obesity was significantly higher in patients with greater BMI, diabetes, American Society of Anesthesiologists class≥III, increased length of stay, venous thromboembolism, any adverse event, and major adverse event. Multivariate analysis for determining outcomes of increased risk with obesity as defined by ICD coding included venous thromboembolism, major adverse events, and any adverse events. However, multivariate analysis for determining outcomes of increased risk with obesity defined by BMI did not yield any positive associations. CONCLUSION: ICD codes for obesity are more commonly assigned to patients with other comorbidities or postoperative complications. Further, use of such nonrandomly assigned ICD codes for obesity has the potential to skew studies to suggest greater associated adverse events than calculated BMI would demonstrate. LEVEL OF EVIDENCE: 3.

Total Disc Arthroplasty Versus Anterior Interbody Fusion in the Lumbar Spine Have Relatively a Few Differences in Readmission and Short-term Adverse Events.

STUDY DESIGN: Retrospective matched cohort study of prospectively collected data. OBJECTIVE: To compare rates of adverse events and readmission between lumbar total disc arthroplasty (TDA) and anterior lumbar interbody fusion (ALIF) using the American College of Surgeons National Surgical Quality Improvement Program database. SUMMARY OF BACKGROUND DATA: TDA and ALIF may be considered for similar degenerative indications. However, there have been a few large-cohort comparison studies of short-term clinical outcomes for these procedures. METHODS: The 2011-2015 NSQIP databases were retrospectively queried to identify patients who underwent elective stand-alone ALIF and TDA. After propensity matching, the association of procedure type with adverse events and readmission was determined using McNemar's test. Operative time and postoperative length of stay (LOS) were compared using multivariate linear regression. Risk factors for adverse events were determined using multivariate Poisson regression. RESULTS: In total, 1801 ALIF and 255 TDA patients were identified. After matching with propensity scores, there were no significant differences in the rates of any adverse event, serious adverse events, individual adverse events, or readmission other than blood transfusion, which occurred more frequently in the ALIF cohort (3.92% vs. 0.39%, P = 0.007). Operative time was not significantly different between the two cohorts, but postoperative LOS was significantly longer for ALIF cases (+0.28 days, P < 0.001). When evaluating 10 preoperative variables as potential risk factors for adverse events and readmission after TDA and ALIF, the majority of results were similar. CONCLUSION: The only identified differences in perioperative outcomes between TDA and ALIF were a 3.53% higher incidence of blood transfusion and 0.28-day longer LOS for the ALIF group. These results suggest overall similar short-term general-health outcomes between the two groups, and that the choice between the two procedures, for the appropriately selected patient, should be based on longer-term functional outcomes. LEVEL OF EVIDENCE: 3.

Risk factors and pharmacologic prophylaxis for venous thromboembolism in elective spine surgery.

BACKGROUND CONTEXT: Venous thromboembolism (VTE) is a known complication after spine surgery, but prophylaxis guidelines are ambiguous for patients undergoing elective spine surgery. PURPOSE: The objective of this study was to characterize the incidence and risk factors for VTE and the association of pharmacologic prophylaxis with VTE and bleeding complications after elective spine surgery. STUDY DESIGN/SETTING: This is a retrospective cohort study of patients undergoing elective spine surgery in the National Surgical Quality Improvement Program (NSQIP) database and a retrospective cohort analysis at an academic medical center. PATIENT SAMPLE: This study included 109,609 patients in the NSQIP database from 2005 to 2014 and 2,855 patients at the authors' institution from January 2013 to March 2016 who underwent elective spine surgery. OUTCOME MEASURES: The incidence and risk factors for VTE were assessed in both cohorts based on the NSQIP criteria. The incidence of bleeding complications requiring reoperation was assessed based on operative reports in the institutional cohort. MATERIALS AND METHODS: Associations of patient and procedure factors with VTE were characterized in the NSQIP population. In the single-institution cohort, in addition to NSQIP variables, a chart review was completed to determine the use of VTE prophylaxis, the history of prior VTE, and the incidence of hematoma requiring reoperation. The association of patient and procedure variables, including pharmacologic prophylaxis and history of prior VTE, with VTE and hematoma requiring reoperation were determined with multivariate regression. RESULTS: Among 109,609 elective spine surgery patients in NSQIP, independent risk factors for VTE were greater age, male gender, increasing body mass index, dependent functional status, lumbar spine surgery, longer operative time, perioperative blood transfusion, longer length of stay, and other postoperative complications. There were 2,855 patients included in the institutional cohort. Pharmacologic prophylaxis was performed in 56.3% of the institutional patients, of whom 97.1% received unfractionated heparin. When controlling for patient and procedural variables, pharmacologic prophylaxis did not significantly influence the rate of VTE, but was associated with a significant increase in hematoma requiring a return to the operating room (relative risk=7.37, p=.048). CONCLUSIONS: Pharmacologic prophylaxis, primarily with unfractionated heparin, after elective spine surgery was not associated with a significant reduction in VTE. However, there was a significant increase in postoperative hematoma requiring reoperation among patients undergoing prophylaxis. This raises questions about the routine use of unfractionated heparin for VTE prophylaxis and supports the need for further consideration of risks and benefits of chemoprophylaxis after elective spine surgery.