Robotic Versus Navigation Assisted Posterior Lumbar Fusion: A National Database Study.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: Compare perioperative adverse events and reoperations between navigation-assisted and robotic-assisted posterior lumbar fusion. SUMMARY OF BACKGROUND DATA: Navigation has become increasingly utilized for posterior lumbar fusion (PLF). More recently, robotic assistance systems have been gaining traction. However, the incremental advantage of these systems has been unclear in the literature. METHODS: Patients undergoing one to three level PLF (with or without anterior or posterior interbody fusion) were identified from the 2015-2022 M161Ortho PearlDiver Database using CPT codes. Navigation assistance was identified based on CPT coding and robotic assistance was based on ICD-10 procedural coding. Navigation-assisted cases were matched 4:1 to robotic assisted patients based on age, sex, Elixhauser Comorbidity Index, number of levels fuse, and concomitant anterior fusion. Incidence of 90-day adverse outcomes were assessed and compared with multivariable logistical regression. Bonferroni correction was applied for multiple testing. Rate of reoperation was assessed using a Kaplan-Meier survival analysis. RESULTS: From 2015 to 2022, there has been a significant increase in both navigation and robotic assisted lumbar fusions, with navigation-assisted surgery being significantly more common. After matching, there were 2,401 navigation-assisted cases and 651 robotic-assisted cases. On multivariate analysis, there no significant differences in 90-day any, severe, or minor adverse events. There was a significant increase odd of readmissions in the robotic cohort (OR: 1.77, P<0.001). There were no differences in three-year reoperation rates between the navigation-assisted and robotic-assisted cohorts (95.8% versus 94.0%, P=0.30). CONCLUSIONS: As spinal navigation has been gaining popularity and robotic assistance is starting to be further utilized, the incremental advantage of different techniques may be questioned. While further study and technique evolution are ongoing, the current study was not able to demonstrate 90-day or 3-year incremental advantages for robotics relative to navigation based on the metrics evaluated.

Exact Integral Formulas for False Discovery Rate and the Variance of False Discovery Proportion.

Multiple hypothesis testing is an integral component of data analysis for large-scale technologies such as proteomics, transcriptomics, or metabolomics, for which the false discovery rate (FDR) and positive FDR (pFDR) have been accepted as error estimation and control measures. The pFDR is the expectation of false discovery proportion (FDP), which refers to the ratio of the number of null hypotheses to that of all rejected hypotheses. In practice, the expectation of ratio is approximated by the ratio of expectation; however, the conditions for transforming the former into the latter have not been investigated. This work derives exact integral expressions for the expectation (pFDR) and variance of FDP. The widely used approximation (ratio of expectations) is shown to be a particular case (in the limit of a large sample size) of the integral formula for pFDR. A recurrence formula is provided to compute the pFDR for a predefined number of null hypotheses. The variance of FDP was approximated for a practical application in peptide identification using forward and reversed protein sequences. The simulations demonstrate that the integral expression exhibits better accuracy than the approximate formula in the case of a small number of hypotheses. For large sample sizes, the pFDRs obtained by the integral expression and approximation do not differ substantially. Applications to proteomics data sets are included.

International Classification of Diseases Coding for Inflammatory Arthritides.

This quality improvement study investigates usage patterns of codes for inflammatory arthritides under International Statistical Classification of Diseases and Related Health Problems, Tenth Revision vs International Classification of Diseases, Ninth Revision.

A 10-year perspective on the question of whether surgeries for adolescent idiopathic scoliosis are "one and done"?

PURPOSE: Posterior scoliosis fusion (PSF) for adolescent idiopathic scoliosis (AIS) is considered a highly successful surgery with excellent outcomes. However, especially as many patients "graduate" from their pediatric surgeons, there is the need to quantify the long-term outcomes of such surgeries. METHODS: The 2010-2022 Pearldiver M161 dataset was queried for those who were 10 to 18 years old with AIS undergoing PSF with at least 10 years follow-up. Patient characteristics were abstracted. Reoperations were identified based on coding for any subsequent thoracic/lumbar surgery/revision. The 10-year reoperation rate and reasons for reoperation were determined, and multivariate regression was performed to determine risk factors. RESULTS: In total, 3,373 AIS PSF patients were identified. Of the study cohort, 324 (9.6%) underwent reoperation within 10-years with an interquartile range for timing of surgery of 81-658 days, of which 29.6% were done for infection. Reoperations were done within the first three months for 152 (46.9% of reoperations), three months to 2 years for 97 (29.9%), and 2 years to 10 years for 74 (22.8%). Based on multivariate regression, need for reoperation was associated with male sex (OR: 1.70), asthma (OR: 1.36) and greater than thirteen segments of instrumentation (OR: 1.48) (p < 0.05 for each) but not age, other comorbidities, or insurance. CONCLUSIONS: The current study of a large national AIS PSF population found 9.6% to undergo reoperation in the 10 years following their index operation. Although specifics about the curve pattern could not be determined, the reoperation incidence and correlation with specific risk factors are notable and important for patient counselling.

Osteochondral Allograft or Autograft Transplantation of the Femoral Head Leads to Improvement in Outcomes but Variable Survivorship: A Systematic Review.

PURPOSE: To review patient-reported outcomes (PROs) and survivorship in patients undergoing osteochondral autograft or allograft transplantation (OAT) of the femoral head. METHODS: PubMed, Cochrane Center for Register of Controlled Trials, and Scopus databases were searched in November 2022 with an updated search extending to December 2023 using criteria from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and the following keywords: (hip OR femoral head) AND (mosaicplasty OR osteochondral allograft OR osteochondral autograft OR osteochondral lesion). Articles were included if they evaluated postoperative PROs in patients who underwent OAT of the femoral head and had a study size of 5 or more hips (n ≥ 5). Survivorship was defined as freedom from conversion to total hip arthroplasty. For PROs evaluated in 3 studies or more, forest plots were created and I2 was calculated. RESULTS: Twelve studies were included in this review, with a total of 156 hips and a mean follow-up time ranging between 16.8 and 222 months. In total, 104 (66.7%) hips were male while 52 (33.3%) were female. Age of patients ranged from 17.0 to 35.4 years, while body mass index ranged from 23.3 to 28.1. Eight studies reported on osteochondral autograft transplantation and 4 studies on osteochondral allograft transplantation. Three studies reported significant improvement in at least 1 PRO. Survivorship ranged from 61.5% to 96% at minimum 2-year follow-up and from 57.1% to 91% at minimum 5-year follow-up. At a follow-up of less than 5 years, osteochondral allograft transplantation studies showed 70% to 87.5% survivorship, while autograft varied from 61.54% to 96%. CONCLUSIONS: Patients with osteochondral lesions of the femoral head who underwent osteochondral autograft or allograft transplantation demonstrated improved PROs but variable survivorship rates. LEVEL OF EVIDENCE: Level IV, systematic review of Level IV studies.

Are Medical School Curricula Adapting With Their Students? A Survey on How Medical Students Study and How it Relates to USMLE Step 1 Scores.

OBJECTIVES: Over the years, medical schools have evolved their curricula in response to the medical field, faculty, and students. The current study aims to examine how medical students study, what resources they most commonly use, and how it relates to United States Medical Licensing Examination (USMLE) Step 1 scores. METHODS: A cross-sectional survey study of United States medical students was distributed via social media, GroupMe school chats, and school listservs from September 8, 2020, to December 12, 2020. The survey gathered data including, demographic and school information, resources students, time spent using each resource, and USMLE Step 1 scores. RESULTS: The survey was completed by 560 students from 102 different United States medical schools. Study guides as online resources (83.2%) were mostly used, lecture (82.5%), Anki (spaced repetition flashcards, 68.3%), and school-organized sessions (workshops, labs, and small groups) (60.7%). Of the students surveyed, 90% attended schools with a recorded lecture option. Only 54% of these students watched their lectures live. When watched online, the average watching speed was 1.75 ± 0.4× with a mode of 2× speed. In examining different medical school styles, schools with a 1.5-year preclinical curriculum had higher USMLE Step 1 scores (244.5 ± 15.6 vs 236.9 ± 16.2, P-score = .024) compared to schools that did not (1- or 2-year preclinical curriculum). CONCLUSION: Medical students seem to be using third-party resources in addition to their medical school curriculums. Because students are already broadly using these, medical schools could allow their curriculums to reference, require, or complement third-party online resources. Additionally, because of their increased cost, medical schools could consider ways to alleviate the cost on medical students as a means of equitable support. Lastly, Step 1 scores significantly correlated with schools with a 1.5-year preclinical curriculum, although the exact reasoning for this remains uncertain.

Editorial Commentary: Irreparable, Symptomatic, Hip Labral Tears Should Be Reconstructed in Patients without Osteoarthritis. However, Comparison of the Two, as Well as Allograft versus Autograft Reconstruction, Is Challenging.

Hip acetabular labrum plays a chondroprotective role by maintaining stability, providing a suction seal, and contributing to load distribution. In symptomatic patients without osteoarthritis, arthroscopic labral repair has strong clinical and biomechanical data to support its use. For irreparable tears, the labrum should be reconstructed. Biomechanically, labral reconstruction does not demonstrate superiority when compared to labral repair or the intact native labrum state. However, it is superior to labral excision. One challenge in making these comparisons is the heterogeneity in surgical technique. Labral reconstruction techniques can vary significantly. In terms of reconstruction, allograft offers the advantage of no donor site morbidity, but availability, costs, and risks must be considered. Autograft use is limited by donor site morbidity and increased operative time. Direct comparisons again show no clear evidence to suggest superiority of one over the other.

Anterior Cervical Discectomy and Fusion Outcomes in Patients With and Without Bariatric Surgery-Weight Loss Does Make a Difference.

STUDY DESIGN: A retrospective comparative cohort study. OBJECTIVE: To compare outcomes of elective non-obese anterior cervical discectomy and fusion (ACDF) patients with those that underwent bariatric surgery (BS). SUMMARY OF BACKGROUND DATA: Morbid obesity (MO) has been associated with an increased risk of complications following procedures such as elective ACDF. While pre-emptive BS has been considered for those with MO (body mass index [BMI] ≥35 kg/m 2 ), the impact of this intervention on BMI and its resultant correlation with surgical outcomes remains limited. METHODS: The PearlDiver 2010-Q1 2020 MSpine database was used to identify patients undergoing elective isolated ACDF. Three sub-cohorts were defined as follows: (1) Non-obese controls without a history of BS, (2) patients with BS procedure within two years with a BMI <35 kg/m 2 (BS+MO-), and (3) patients with BS procedure within the two years with a BMI ≥35 kg/m 2 (BS+MO+). Univariate and multivariate regression analyses were performed to compare 90-day adverse event rates adjusting for age, sex, Elixhauser Comorbidity Index, and length of stay. Kaplan-Meier analysis was performed to assess five-year cervical reoperation rates. RESULTS: Of 160,166 elective ACDF patients, prior BS was identified for 479. Of these, 136 patients were BS+MO- and 343 were BS+MO+. On multivariate analysis, BS+MO- were not at increased odds of adverse events, but BS+MO+ were at greater odds of 90-day pulmonary embolism (odds ratio 3.28, P =0.043), wound dehiscence (5.02, P <0.001), hematomas (2.52, P =0.042), and overall minor adverse events (1.61, P =0.011) compared with controls. Five-year reoperation rates were not significantly different between the groups. CONCLUSION: Twenty-eight percent of those with BS before ACDF fell out of the categorization of MO. Among this group, the odds of adverse events were similar to non-obese patients. These findings suggest that the psychological preparation and BS alone are insufficient to reduce the risk of adverse events after ACDF. Weight reduction must be achieved as well, ideally moving patients out of the BMI range for morbid obesity.

Incidence, Timing, and Predictors of Hip Dislocation After Primary Total Hip Arthroplasty for Osteoarthritis.

INTRODUCTION: Total hip arthroplasty (THA) may be complicated by dislocation. The incidence of and risk factors for dislocation are incompletely understood. This study aimed to determine the incidence and predictors of hip dislocation within 2 years of primary THA. METHODS: The 2010 to 2020 PearlDiver MHip database was used to identify patients undergoing primary THA for osteoarthritis with a minimum of 2 years of postoperative data. Dislocation was identified by associated codes. Age, sex, body mass index, Elixhauser Comorbidity Index, fixation method, and bearing surface were compared for patients with dislocation versus control subjects by multivariate regression. Timing and cumulative incidence of dislocation were assessed. RESULTS: Among 155,185 primary THAs, dislocation occurred within 2 years in 3,630 (2.3%). By multivariate analysis, dislocation was associated with younger age (<65 years), female sex, body mass index < 20, higher Elixhauser Comorbidity Index, cemented prosthesis, and use of metal-on-poly or metal-on-metal implants ( P< 0.05 for each). Among patients who experienced at least one dislocation, 52% of first-time dislocations occurred in the first 3 months; 57% had more than one and 11% experienced >5 postoperative dislocation events. Revision surgery was done within 2 years of index THA for 45.6% of those experiencing dislocation versus 1.8% of those who did not ( P < 0.001). CONCLUSION: This study found that 2.3% of a large cohort of primary THA patients experienced dislocation within 2 years, identified risk factors for dislocation, and demonstrated that most patients experiencing dislocation had recurrent episodes of instability and were more likely to require revision surgery.

Single-level posterior lumbar fusions in patients with Ehlers Danlos Syndrome not found to be associated with increased postoperative adverse events or five-year reoperations.

Background: Ehlers Danlos Syndrome (EDS) is a rare connective tissue disorder that results from mutations in collagen genes. Potentially related to laxity and resultant degenerative changes, adult EDS patients may require posterior lumbar fusion (PLF). However, with low numbers, adequately powered outcome studies have been limited. The purpose of this study was to investigate risk of complications, readmissions and reoperations in adult patients with EDS following single-level PLF. Methods: A retrospective study using the 2010 to 2020 MSpine Pearldiver dataset was performed. Adult patients undergoing single-level PLF (excluding any with anterior procedures) with and without EDS for which at least 90-day follow up was available were identified. Any cases performed for trauma, tumor, or infection were excluded.Single-level PLF EDS patients were then matched 1:4 with PLF non-EDS patients based on age, sex, and Elixhauser Comorbidity Index (ECI). Rates of ninety-day any, severe, and minor adverse events as well as readmissions were tabulated and compared with chi-square tests. Multivariate logistical regression was then performed (controlling for age, sex, and ECI).Reoperation surgeries over five years were assessed, Kaplan-Meier survival curves generated, and curves of those with and without EDS were compared with log rank test. Results: In total, there were 170,100 single-level PLF case identified, of which 242 (0.14%) had EDS. After matching, there were 957 without EDS and 239 with EDS. On multivariate regression, there were no significant differences in 90-day any, severe, or minor adverse events, or readmissions (p>0.05 for each). Over five years, there were also not significant differences in rates of reoperation (p> 0.05). Conclusions: For EDS patients undergoing PLF, the current study identified similar 90-day adverse events and 5-year reoperation rates compared to those without EDS. These findings may be useful for patient counseling and surgical planning for those with this rare condition.

Marfan syndrome and adolescent idiopathic scoliosis patients have similar 90-day postoperative outcomes and 5-year reoperation rates after spinal deformity surgery.

PURPOSE: Outcomes after spinal deformity surgery in patients with Marfan syndrome (MFS) are poorly characterized given the rarity of the condition. Updated analyses from nationally representative samples, and comparison to outcomes after more commonly performed procedures for conditions such as adolescent idiopathic scoliosis (AIS) could help define the relative risks. METHODS: Using the 2010-2020 PearlDiver administrative databases, patients who underwent posterior spinal fusion for > 7 segments were extracted. MFS patients were matched 1:4 to AIS patients based on age, sex, and Elixhauer comorbidity index (ECI). Ninety-day outcomes and 5-year reoperation rates were compared. Significance was set at p < 0.05. RESULTS: In total, 206 MFS patients were matched to 825 AIS patients. After adjusting for age, sex, and ECI, multivariate odds ratios (OR) for 90-day any, serious, and minor adverse events, as well as readmissions, were not significantly different for those with MFS compared to those with AIS (p > 0.05 for each). Five-year reoperation rates were also not significantly different (13.1% for the MFS cohort and 13.0% for the AIS cohort (no difference by log-rank, p = 0.9). CONCLUSION: While deformity surgery is much less commonly performed for MFS than AIS, it is not uncommonly considered for patients with this condition. Despite some known technical challenges for MFS deformity surgery, the current study leveraged a large, national database to find that 90-day adverse events and 5-year reoperations were not different for matched MFS and AIS patients undergoing deformity surgery. For select patients, these findings should be useful for surgical planning and patient counseling.

Adverse Events After Posterior Lumbar Fusion Are Not Sufficiently Characterized With 30-day Follow-up: A Database Study.

INTRODUCTION: Many studies track outcomes after procedures, such as posterior lumbar fusion (PLF), for only 30 days because of database limitations. However, adverse events may not have plateaued by this time. Thus, this study used an alternate database to evaluate the timing of adverse events for 90 days after PLF. METHODS: Adult PLF patients were identified from the 2010 to 2020 Q2 M53Ortho PearlDiver administrative data set. Ninety-day rates of multiple adverse events were determined. The time of diagnosis for each event in the 90-day postoperative period was determined. Data were dichotomized by occurrence in days 0 to 30 and 31 to 90. Median, interquartile range, and middle 80% for the time of diagnosis were determined for each adverse event. RESULTS: Of 51,915 patients undergoing PLF, 7,141 (13.8%) had an adverse event within 90 days of PLF. Of these, 5,174 (72.5%) experienced an event within 30 days and 2,544 (35.6%) after 30 days. For individual adverse outcomes studied, the percent that occurred 31 to 90 days after surgery ranged from 9% to 42%. The time of diagnosis (median; interquartile range; middle 80%) for each adverse event was as follows: transfusion (2 days; 2 to 5 days; 1 to 26 days), acute kidney injury (9; 2 to 29; 1 to 60), hematoma (9; 4 to 20; 3 to 39), cardiac event (11; 3 to 43; 1 to 71), pneumonia (12; 4 to 38; 2 to 68), venous thromboembolism (15; 6 to 33; 3 to 62), sepsis (19; 9 to 39; 4 to 63), surgical site infection (21; 14 to 34; 8 to 48), urinary tract infection (22; 8 to 49; 4 to 72), and wound dehiscence (27; 17 to 39; 9 to 54). DISCUSSION: This study highlights the importance of looking past the 30-day mark for adverse events after PLF because approximately one-third of adverse events in this study were diagnosed 31 to 90 days after surgery. This can affect research studies, patient counseling about the incidence of specific adverse events, and the development of mechanisms for surveillance at key time points.

Emergency Department Visits Within 90 Days of Anterior Cruciate Ligament Reconstruction.

Background: Emergency department (ED) visits after orthopaedic surgery such as anterior cruciate ligament reconstruction (ACLR) affect patients and health care systems and should be better understood. Purpose: To determine the incidence, predictors, and reasons for ED visits within 90 days after ACLR. Study Design: Descriptive epidemiologic study. Methods: Patients who had undergone ACLR between 2010 and 2020 were identified in a national database, and 90-day ED visits, readmissions, risk factors, and primary diagnoses for visits were determined. One-year postoperative data were used to establish baseline weekly ED visits for the cohort. Patient age, sex, Elixhauser comorbidity index, region of the country (Northeast, Midwest, West, South), and insurance coverage (Medicare, Medicaid, and commercial) were extracted, and these variables were compared using univariate analysis and multivariate logistic regression. Results: Out of 81,179 patients, ED visits were identified for 6764 (8.3%), and readmissions were identified for 592 (0.7%). Overall, 5300 patients had 1 ED visit, 1020 patients had 2 visits, 275 patients had 3 visits, and 169 patients had ≥4 or more visits; visits occurred within 2 weeks of surgery 38% of the time. Notably, weekly visits returned to baseline at week 3. Independent predictors of ED utilization from multivariate analysis were insurance type (relative to commercial insurance: Medicaid [odds ratio [OR], 2.41; 95% CI, 2.23-2.60] and Medicare [OR, 1.38; 95% CI, 1.19-1.60]), higher Elixhauser comorbidity index (per 2-point increase: OR, 2.24; 95% CI, 2.18-2.29), younger age (per 10-year decrease: OR, 1.23; 95% CI, 1.21-1.24), female sex (OR, 1.05; 95% CI, 1.02-1.08), and region of the country (relative to the West: Midwest [OR, 1.33; 95% CI, 1.26-1.39], Northeast [OR, 1.24; 95% CI, 1.18-1.30], and South [OR, 1.17; 95% CI, 1.12-1.23]). In the first 2 weeks, 67.5% of ED visits were for issues involving the surgical site, most commonly surgical-site pain (29% of all visits). In the total 90-day period, 39.4% of visits involved the surgical site. Conclusion: Within 90 days of ACLR, >8% of patients visited the ED, while 0.7% were readmitted. ED visits increased in the first 2 postoperative weeks and returned to baseline rates around week 3. Within the first 2 weeks, two-thirds of visits involved the surgical site. Younger patients, patients with greater comorbidity burden, those in certain regions of the country, and those with Medicaid had greater odds of ED utilization.

Clinical outcomes following one-, two-, three-, and four-level anterior cervical discectomy and fusion: a national database study.

BACKGROUND CONTEXT: Anterior cervical discectomy and fusion (ACDF) is a common surgical procedure. There is markedly less data on outcomes after three- and four-level cases than one- and two-level cases. PURPOSE: To compare perioperative 90-day adverse events and 5-year reoperation rates between isolated one-, two-, three-, and four-level ACDF cases. STUDY DESIGN/SETTING: Retrospective review of a large national database. PATIENT SAMPLE: Overall, 97,081 patients undergoing ACDF were identified, of which one-level cases were 42,382 (43.7%), two-level cases were 24,055 (24.8%), three-level cases were 28,293 (29.1%), and four-level cases were 2,361 (2.4%). OUTCOME MEASURES: Ninety-day adverse events and 5-year reoperation rates. METHODS: The 2010 to Q1 2020 PearlDiver database was queried to identify patients who underwent elective ACDF for degenerative pathology without corpectomy or concomitant posterior procedures. Univariate and multivariate analyses were performed to compare outcomes of subcohorts with varying number of levels addressed by ACDF. RESULTS: Of the 97,081 cases identified, patient characteristics and complication rates differed between the cohorts defined by levels treated. Univariate analyses revealed statistically different rates of 90-day any, serious, and minor adverse event rates between the groups, but the differences were all less than 2.5%. Readmission rates were statistically different by 2.9%, dysphagia by 3.2%, and prolonged length of stay by 6.3%.By multivariate analyses, three-level ACDF cases were not found to have greater 90-day adverse outcomes than two-level cases. Four-level ACDF cases were found to have significantly greater odds ratios of readmission, dysphagia, and prolonged length of stay (relative to one-level cases, OR 1.28, 1.63, and 1.97, respectively) but not other 90-day adverse events. Reoperation rates at five years for one-, two-, three-, and four-level cases were 13.0%, 13.5%, 15.0%, and 22.1%, respectively (log-rank p<.001). CONCLUSIONS: The current study represents one of the largest comparative studies of patients undergoing one-, two-, three-, and four-level ACDF. While odds of 90-day adverse events were not greater for three- versus two-level cases, four-level cases had several that were higher odds than one-level cases. Reoperation and dysphagia rates were higher for four-level cases than lesser levels. While these outcomes were found to be acceptable, they should help guide hospital planning and patient counseling.

Admission NarxCare Narcotic Scores Are Associated With Increased Odds of Readmission and Prolonged Length of Hospital Stay After Primary Elective Total Knee Arthroplasty.

INTRODUCTION: The association of preoperative narcotic use with postoperative outcomes after primary elective total knee arthroplasty (TKA) has remained poorly characterized. The NarxCare platform analyzes patients' state Prescription Drug Monitoring Program records to assign numerical scores that approximate a patient's overall opioid usage. The present study investigated the utility of admission NarxCare narcotic scores in predicting the odds of adverse events (AEs) after primary elective TKA. METHODS: Elective primary TKA patients performed at a single institution between October 2017 and May 2020 were evaluated. NarxCare narcotic scores at the time of admission, patient characteristics, 30-day AEs, readmissions, revision surgeries, and mortality were abstracted. Elective TKA patients were binned based on admission NarxCare narcotic scores. The odds of experiencing adverse outcomes were compared. RESULTS: In total, 1136 patients met the criteria for inclusion in the study (Narx Score 0: n = 293 [25.8%], 1 to 99: n = 253 [22.3%], 100 to 299: n = 368 [32.4%], 300 to 499: n = 161 [14.2%], and 500+: n = 61 [5.37%]). By logistic regression, patients with higher admission narcotic scores tended to have a dose-dependent increase in the odds of prolonged length of hospital stay, readmission within 30 days, and aggregated AEs. DISCUSSION: Admission narcotic scores may be used to predict readmission and to stratify TKA patients by risk of AEs.

Synaptojanin1 deficiency upregulates basal autophagosome formation in astrocytes.

Macroautophagy dysregulation is implicated in multiple neurological disorders, such as Parkinson's disease. While autophagy pathways are heavily researched in heterologous cells and neurons, regulation of autophagy in the astrocyte, the most abundant cell type in the mammalian brain, is less well understood. Missense mutations in the Synj1 gene encoding Synaptojanin1 (Synj1), a neuron-enriched lipid phosphatase, have been linked to Parkinsonism with seizures. Our previous study showed that the Synj1 haploinsufficient (Synj1+/-) mouse exhibits age-dependent autophagy impairment in multiple brain regions. Here, we used cultured astrocytes from Synj1-deficient mice to investigate its role in astrocyte autophagy. We report that Synj1 is expressed in low levels in astrocytes and represses basal autophagosome formation. We demonstrate using cellular imaging that Synj1-deficient astrocytes exhibit hyperactive autophagosome formation, represented by an increase in the size and number of GFP-microtubule-associated protein 1A/1B-light chain 3 structures. Interestingly, Synj1 deficiency is also associated with an impairment in stress-induced autophagy clearance. We show, for the first time, that the Parkinsonism-associated R839C mutation impacts autophagy in astrocytes. The impact of this mutation on the phosphatase function of Synj1 resulted in elevated basal autophagosome formation that mimics Synj1 deletion. We found that the membrane expression of the astrocyte-specific glucose transporter GluT-1 was reduced in Synj1-deficient astrocytes. Consistently, AMP-activated protein kinase activity was elevated, suggesting altered glucose sensing in Synj1-deficient astrocytes. Expressing exogenous GluT-1 in Synj1-deficient astrocytes reversed the autophagy impairment, supporting a role for Synj1 in regulating astrocyte autophagy via disrupting glucose-sensing pathways. Thus, our work suggests a novel mechanism for Synj1-related Parkinsonism involving astrocyte dysfunction.

Technical Note: Using virtual noncontrast images from dual-energy CT to eliminate the need of precontrast CT for x-ray radiation treatment planning of abdominal tumors†.

PURPOSE: Radiation therapy (RT) planning frequently utilizes contrast-enhanced CT. However, dose calculations should not be performed on a contrast-enhanced CT because the patient will not receive bolus during treatment. It is typical to acquire CT twice during RT simulation: once before injection of bolus and once after. The registration between these datasets introduces errors. In this work, we investigate the use of virtual noncontrast images (VNC) derived from dual-energy CT (DECT) to eliminate the precontrast CT and the registration error. METHODS: CT datasets, including conventional 120 kVp pre- and postcontrast CTs and postcontrast DECT, acquired for ten pancreatic cancer patients were evaluated. The DECTs were acquired simultaneously using a dual source (DS) CT simulator. VNC and virtual mono-energetic images (VMI) were derived from DECTs. Gross tumor volumes (GTV), planning target volumes (PTV), and organs at risks (OAR) were delineated on the postcontrast CT and then populated to the precontrast CT and the VNC. An IMRT plan (50.4 Gy in 28 fractions) was then optimized on the precontrast CT. Dose distributions were recalculated on the VNC images. Contours from the pre- and postcontrast CTs and the dose distributions based on both were compared. RESULTS: On average, the distance of centroids of the populated duodenum contours on precontrast CT differed by 6.0 ± 4.0 mm from those on postcontrast CTs. The dose distributions on the precontrast CT and VNC were almost identical. The PTV mean and maximum doses differed by 0.1% and 0.2% between the two plans, respectively. CONCLUSION: The VNC derived from DECT can be used to replace the conventional precontrast CT scan for RT planning, eliminating the need for an additional precontrast CT scan and eliminating the registration errors. Thus, VNC can become an important asset to the future of RT.

Improving Structure Delineation for Radiation Therapy Planning Using Dual-Energy CT.

PURPOSE: We present the advantages of using dual-energy CT (DECT) for radiation therapy (RT) planning based on our clinical experience. METHODS: DECT data acquired for 20 representative patients of different tumor sites and/or clinical situations with dual-source simultaneous scanning (Drive, Siemens) and single-source sequential scanning (Definition, Siemens) using 80 and 140-kVp X-ray beams were analyzed. The data were used to derive iodine maps, fat maps, and mono-energetic images (MEIs) from 40 to 190 keV to exploit the energy dependence of X-ray attenuation. The advantages of using these DECT-derived images for RT planning were investigated. RESULTS: When comparing 40 keV MEIs to conventional 120-kVp CT, soft tissue contrast between the duodenum and pancreatic head was enhanced by a factor of 2.8. For a cholangiocarcinoma patient, contrast between tumor and surrounding tissue was increased by 96 HU and contrast-to-noise ratio was increased by up to 60% for 40 keV MEIs compared to conventional CT. Simultaneous dual-source DECT also preserved spatial resolution in comparison to sequential DECT as evidenced by the identification of vasculature in a pancreas patient. Volume of artifacts for five patients with titanium implants was reduced by over 95% for 190 keV MEIs compared to 120-kVp CT images. A 367-cm3 region of photon starvation was identified by low CT numbers in the soft tissue of a mantle patient in a conventional CT scan but was eliminated in a 190 keV MEI. Fat maps enhanced image contrast as demonstrated by a meningioma patient. CONCLUSION: The use of DECT for RT simulation offers clinically meaningful advantages through improved simulation workflow and enhanced structure delineation for RT planning.

Parkinson's disease detection from 20-step walking tests using inertial sensors of a smartphone: Machine learning approach based on an observational case-control study.

Parkinson's disease (PD) is a neurodegenerative disease inducing dystrophy of the motor system. Automatic movement analysis systems have potential in improving patient care by enabling personalized and more accurate adjust of treatment. These systems utilize machine learning to classify the movement properties based on the features derived from the signals. Smartphones can provide an inexpensive measurement platform with their built-in sensors for movement assessment. This study compared three feature selection and nine classification methods for identifying PD patients from control subjects based on accelerometer and gyroscope signals measured with a smartphone during a 20-step walking test. Minimum Redundancy Maximum Relevance (mRMR) and sequential feature selection with both forward (SFS) and backward (SBS) propagation directions were used in this study. The number of selected features was narrowed down from 201 to 4-15 features by applying SFS and mRMR methods. From the methods compared in this study, the highest accuracy for individual steps was achieved with SFS (7 features) and Naive Bayes classifier (accuracy 75.3%), and the second highest accuracy with SFS (4 features) and k Nearest neighbours (accuracy 75.1%). Leave-one-subject-out cross-validation was used in the analysis. For the overall classification of each subject, which was based on the majority vote of the classified steps, k Nearest Neighbors provided the most accurate result with an accuracy of 84.5% and an error rate of 15.5%. This study shows the differences in feature selection methods and classifiers and provides generalizations for optimizing methodologies for smartphone-based monitoring of PD patients. The results are promising for further developing the analysis system for longer measurements carried out in free-living conditions.