Analysis of fibrinolytic shutdown in trauma patients with traumatic brain injury

BACKGROUND

Coagulation profiles following major trauma vary depending on injury pattern and degree of shock. The physiologic mechanisms involved in coagulation function at any given time are varied and remain poorly understood. Thromboelastography (TEG) has been used evaluate coagulation profiles in the trauma population with some reports demonstrating a spectrum of fibrinolysis to fibrinolytic shutdown on initial presentation. The objective of this study was to evaluate the fibrinolytic profile of patients with TBI using thromboelastography (TEG). We hypothesized that patients with TBI would demonstrate low fibrinolytic activity.

METHODS

All trauma activations at an ACS-verified level 1 trauma center received a TEG analysis upon arrival from December 2019 to June 2021. A retrospective review of the results and outcomes was conducted, and TBI patients were compared to patients without TBI. Linear regression was used to evaluate the effect of patient and injury factors on fibrinolysis. Hyperfibrinolysis was defined as LY30 ​> ​7.7%, physiologic fibrinolysis as LY30 0.6-7.7%, and fibrinolytic shutdown as LY30 ​< ​0.6%.

RESULTS

A total of 1369 patients received an admission TEG analysis. Patients with TBI had a significantly higher median ISS (16 vs. 8, p ​< ​0.001), lower median admission Glasgow Coma Scale (14 vs. 15, p ​< ​0.001), longer intensive care unit length of stay (3 vs. 2 days, p ​< ​0.0001), increased ventilator days (216 vs. 183, p ​< ​0.001), higher mortality (14.6% vs. 5.1%, p ​< ​0.001), but lower shock index (0.6 vs. 0.7, p ​< ​0.0001) compared to those without TBI. Median LY30 was found to be decreased in the TBI group (0.1 vs. 0.2, p ​= ​0.0006). Patients with TBI were found to have a higher rate of fibrinolytic shutdown compared those without TBI (68.7% vs. 63.5%, p ​= ​0.054). ISS, sex, and shock index were found to be predictive of LY30 on linear regression, but TBI was not (Β: 0.09, SE: 0.277, p ​= ​0.745). The rate of DVT/PE did not appear to be elevated in patients with TBI (0.8%) and without TBI (1.2%).

CONCLUSIONS

Trauma patients with and without TBI were found to have high rates of fibrinolytic shutdown. Although there was a high incidence of fibrinolytic shutdown, it did not appear to have an impact on the rate of thrombotic complications. The clinical significance of these results is unclear and differs significantly from recent reports which demonstrated that TBI is associated with a 25% rate of fibrinolytic shutdown. Further investigation is needed to better define the fibrinolytic pathway in patients with trauma and TBI to develop optimal treatment algorithms.

Panmixia in the American eel extends to its tropical range of distribution: Biological implications and policymaking challenges

The American eel (Anguilla rostrata) has long been regarded as a panmictic fish and has been confirmed as such in the northern part of its range. In this paper, we tested for the first time whether panmixia extends to the tropical range of the species. To do so, we first assembled a reference genome (975 Mbp, 19 chromosomes) combining long (PacBio and Nanopore and short (Illumina paired-end) reads technologies to support both this study and future research. To test for population structure, we estimated genotype likelihoods from low-coverage whole-genome sequencing of 460 American eels, collected at 21 sampling sites (in seven geographic regions) ranging from Canada to Trinidad and Tobago. We estimated genetic distance between regions, performed ADMIXTURE-like clustering analysis and multivariate analysis, and found no evidence of population structure, thus confirming that panmixia extends to the tropical range of the species. In addition, two genomic regions with putative inversions were observed, both geographically widespread and present at similar frequencies in all regions. We discuss the implications of lack of genetic population structure for the species. Our results are key for the future genomic research in the American eel and the implementation of conservation measures throughout its geographic range. Additionally, our results can be applied to fisheries management and aquaculture of the species.

Cholesterol granuloma of the breast: A case report

Cholesterol granuloma of the breast is a rare entity that can be indistinguishable from cancer on physical exam and imaging. We present the case of a 58-year-old woman who developed a new enhancing mass on high-risk screening magnetic resonance imaging (MRI). Interestingly, this mass developed in the same area as a previously noted benign-appearing inflammatory cyst that had been decreasing in size on MRI and mammogram over many years. Ultrasound-guided biopsy was performed which revealed cholesterol granuloma. We will discuss the nonspecific imaging findings and the characteristic histopathological features that confirm diagnosis.

Methicillin-Resistant Staphylococcus aureus Nasal Swab Is Insufficient to Withhold Empiric Methicillin-Resistant Staphylococcus aureus Pneumonia Coverage in a Trauma Population

INTRODUCTION

Methicillin-resistant staphylococcus aureus (MRSA) nasal colonization is a predictor of MRSA pneumonia in intensive care unit (ICU) patients. Negative nasal swabs have shown up to a 97% negative predictive value for MRSA pneumonia in nontrauma populations, though little investigation has been pursued in trauma patients.

MATERIALS AND METHODS

All trauma patients admitted to the ICU from April 2018 to February 2019 were screened for MRSA colonization by nasal swab. Patients with suspicion for pneumonia underwent bronchoalveolar lavage or quantitative sputum culture and were started on empiric antibiotic therapy based on the swab result. Swab-positive patients were started on empiric MRSA coverage and swab-negative patients were not.

RESULTS

MRSA nasal swab screening was performed in 601 trauma ICU patients. Ninety-six patients subsequently underwent pneumonia workup and were started on an empiric antibiotic regimen based on nasal swab results. Seventeen (17.7%) patients were MRSA nasal swab positive on screening, and 22 (22.9%) patients subsequently had significant growth of MRSA on quantitative respiratory culture. The sensitivity of nasal swab was 50.0% and the specificity was 91.9%. Eleven patients had a negative MRSA nasal swab but a positive MRSA pneumonia (11.5%). Patients with inadequate antibiotic coverage had statistically longer hospital length of stay, ICU length of stay, ventilator days, and rates of unplanned intubation compared to patients with adequate antibiotic coverage.

CONCLUSIONS

Nasal swab screening was not sensitive enough in a trauma population with a high endemic incidence of MRSA colonization to warrant withholding empiric antibiotic MRSA coverage in patients with suspected pneumonia.

Analysis of Admission Thromboelastogram Profiles in 1369 Male and Female Trauma Patients

INTRODUCTION

Recent studies have demonstrated a hypercoagulable thromboelastrogram (TEG) in female trauma patients compared with males, conferring a possible survival advantage. We hypothesized that TEG profiles would reveal a relative hypercoagulable state in female compared with male trauma patients.

METHODS

A prospective review was conducted on all adult trauma patients admitted to the trauma service at an American College of Surgeons-verified level I trauma center from December 2019 to June 2021 who, per our institutional protocol, received a thrombelastotgraphy on their initial arrival to the trauma center if classified as a level I or II trauma activation. The thromboelastography values of male and female trauma patients were compared as the primary outcome variables of interest. The secondary outcomes investigated were hospital length of stay, surgical interventions, and ventilatory requirement.

RESULTS

A total of 1369 patients met inclusion criteria, with 878 (64.1%) male and 491 (35.9%) female. Female patients had a higher median alpha angle (74.8 versus 72.6°, P < 0.001), maximum amplitude (69.3 versus 66.2 mm, P < 0.001), and shorter median K time (1.0 versus 1.2 s, P < 0.001). Female patients had a shorter hospital length of stay (4 versus 5 d, P < 0.001), had a lower rate of surgical intervention (14.6% versus 25.5%, P < 0.001), and had lower rates of mechanical ventilation (19.3% versus 39.5%, P < 0.001).

CONCLUSIONS

Female trauma patients were found to have hypercoagulable indices on TEG at the time of initial trauma evaluation compared with males. Intrinsic differences in sex coagulation profiles should be further investigated to optimize modern resuscitation strategies.

Routine Lower Extremity Screening Ultrasound Protocols in Trauma Patients Are Not Cost Effective

BACKGROUND

Despite prophylaxis, deep vein thrombosis (DVT) and pulmonary embolism remain dreaded complications following traumatic injury and are associated with significant morbidity and mortality. Screening ultrasound (US) protocols have been employed in trauma centers for early detection of lower extremity (LE) deep venous thrombosis. We hypothesized that screening lower extremity venous duplex US would not prove cost effective in our trauma population who receives early pharmacologic prophylaxis.

METHODS

Data was collected for one year on all adult trauma patients admitted to the trauma service from December 2019 to 2020. DVT screening US was obtained at 3 days after admission for patients with long bone or pelvic fracture, spinal cord injury, immobility, and/or spinal fracture requiring surgery. Screening US was obtained at 7 days for all others and repeated weekly until discharge. Data was retrospectively collected and analyzed.

RESULTS

Exactly 1365 patients met inclusion criteria with median ISS 12 (IQR, 9-17), median age 56 (IQR, 36-73 years), and with majority blunt injuries (90.7%). A total of 1369 screening US were performed finding 27 DVTs (2%). The total cost of screening for the year analyzed amounted to over $270,000 with 50.7 screening US needed to detect 1 DVT. This resulted in an average screening cost of over $10,000 for the detection of a single DVT.

DISCUSSION

In trauma patients receiving early pharmacologic prophylaxis, routine LE screening US protocols to detect LE DVT are not cost effective.

Traumatic brain injury patients with platelet inhibition receiving platelet transfusion demonstrate decreased need for neurosurgical intervention and decreased mortality

BACKGROUND

Platelet dysfunction is known to occur in patients with traumatic brain injury (TBI), and the correction of platelet dysfunction may prevent hemorrhagic progression in TBI. Thromboelastography with platelet mapping (TEG-PM; Haemonetics) evaluates the degree of platelet function inhibition through the adenosine diphosphate (ADP) and arachidonic acid (AA) pathways. We hypothesized that ADP and AA inhibition would improve with the transfusion of platelets in patients with TBI.

METHODS

A retrospective review was conducted at a Level I trauma center of all patients presenting with TBI from December 2019 to December 2020. Per a practice management guideline, a platelet mapping assay was obtained on all patients with TBI upon admission. If ADP or AA was found to be inhibited (>60%), the patient was transfused 1 unit of platelets and a repeat platelet mapping assay was ordered. Demographic data, laboratory values, and outcomes were analyzed.

RESULTS

Over the 13-month study period, 453 patients with TBI underwent TEG-PM with a protocol adherence rate of 66.5% resulting in a total of 147 patients who received platelets for ADP and/or AA inhibition; of those, 107 underwent repeat TEG-PM after platelets were administered. With the administration of platelets, ADP (p < 0.0001), AA (p < 0.0001), and MA (p = 0.0002) all significantly improved. Of 330 patients with TBI not taking antiplatelet medications, 50.9% showed inhibition in ADP and/or AA. If AA or ADP inhibition was noted on admission, mortality was increased (p = 0.0108). If ADP improved with platelet administration, the need for neurosurgical intervention was noted to decrease (p = 0.0182).

CONCLUSION

Patients with TBI and platelet inhibition may benefit from the administration of platelets to correct platelet dysfunction. Thromboelastography with platelet mapping may be implemented in the initial workup of patients presenting with TBI to assess platelet dysfunction and provide prognostic information, which may guide treatment.

LEVEL OF EVIDENCE

Therapeutic / Care Management, level III.

Abstract P3-03-19: Incidence and time to resolution of axillary adenopathy on mammography after COVID-19 vaccination

Background: This study reports incidence, timing, characteristics, and surveillance imaging of mammographic axillary adenopathy following COVID-19 vaccination. As COVID-19 immunizations continue, with possible booster vaccines upcoming, this study offers timing considerations and potential follow-up recommendations for breast imaging after vaccination. Methods: Retrospective analysis of patients (pts) who received at least one COVID-19 vaccine prior to screening (SM) or diagnostic mammography (DM) at Mayo Clinic Florida between January 15 to May 31, 2021. Vaccine-related information was queried by mammography technologists. Adenopathy was assessed by interpreting radiologists and follow-up studies were collated. Mammogram adenopathy included single enlarged node, multiple enlarged nodes, and adenopathy with soft tissue stranding. Ultrasound adenopathy included mildly prominent nodes with preserved fatty hila to rounded nodes with apparent loss of a fatty hilum. Wilcoxon rank-sum test and Fisher’s exact test were used to compare continuous and categorical variables, respectively. Multivariable logistic regression model was used to evaluate the association between days from vaccine and adenopathy. Results: Of 2349 pts, 34 (1.4%) had adenopathy (DM=6; SM=28) and 3 (0.1%) were symptomatic. Presence of axillary symptoms was associated with abnormal imaging (p&lt;0.001) with an odds ratio of 33 in multivariable model. Median time after vaccine for pts with adenopathy was significantly shorter at 14 days compared to 33 days for pts without adenopathy (p&lt;0.001). Incidence of adenopathy decreased as days from vaccine increased (3.4% for 0-14 days, 2.1% for 15-28 days, and 0.4% for &gt; 28 days, p&lt;0.001). After adjusting for being symptomatic, days from vaccine still had a significant impact on finding mammographic adenopathy (for each day after vaccine, OR=0.96, p&lt;0.001). No significant difference was seen based on age (p=0.66), vaccine brand (p=0.66), vaccine dose (p=0.18). ROC analysis to identify a cutoff value for presence/absence of adenopathy was 0.74 (95% CI 0.67-0.81) at 22.5 days following vaccination. Additional imaging with mammogram and/or ultrasound was requested for 31 pts. These included no follow-up (n=4, 12.9%), repeat ultrasound with or without mammogram in 1-3 months (n=26, 83.9%), and biopsy (n=1, 3.2%, pt with ipsilateral breast cancer with negative results, presumably vaccine induced). To date, all pts who underwent surveillance imaging demonstrated normalization of lymph node appearance. The median time for abnormal imaging related to adenopathy to return to BI-RADS 1 or 2 was 84 (range 13-157) days. Conclusion: The incidence of COVID-19 vaccine-induced adenopathy in this study (1.4%) appeared to be lower than self-reported axillary swelling in COVID-19 vaccine trials (16%) but is still higher than the reported incidence of adenopathy on an otherwise normal SM (0.02-0.04%). The incidence of adenopathy decreased significantly over time and was not present in most pts 28 days after the vaccine. In patients with abnormal adenopathy, followup imaging showed resolution of vaccine-induced adenopathy in most patients by 3 months.

Adenopathy(N=34)No Adenopathy (N=2315)P valueAge0.66N342314Median (Range)63.5 (35.0, 83.0)64.0 (30.0, 94.0)Q1, Q351.5, 72.555.0, 71.0Exam type&lt;0.001DM6 (13.3%)39 (86.7%)SM28 (1.2%)2276 (98.8%)Symptomatic&lt;0.001Missing032Yes3 (23.1%)10 (76.9%)No31 (1.3%)2273 (98.7%)Vaccine brand0.66Missing119mRNA-127319 (1.7%)1117 (98.3%)BNT162b214 (1.2%)1138 (98.8%)Other0 (0.0%)41 (100.0%)Vaccine dose0.18Missing0181st9 (2.2%)409 (97.8%)2nd25 (1.3%)1888 (98.7%)Days from vaccine&lt;0.001Median (Range)14.0 (1.0, 91.0)33.0 (0.0, 239.0)Q1, Q38.2, 20.816.0, 61.0Days from Vaccine&lt;0.0010-1418 (3.4%)519 (96.6%)15-2811 (2.1%)513 (97.9%)&gt;285 (0.4%)1283 (99.6%)

Citation Format: Kristin Robinson, Santo Maimone, Pooja P Advani, Zhuo Li, Denise Gococo-Benore, Neda Qosja, Ashita Mummareddy, Ahmed M Ashai, Annamaria Wilhelm, Robert Maxwell, Martha Wasserman, Neema Patel, Andrey Morozov, Saranya Chumsri. Incidence and time to resolution of axillary adenopathy on mammography after COVID-19 vaccination [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-03-19.

A Comparison of Prehospital Nonphysician and Hospital Physician Placed Tube Thoracostomy

BACKGROUND

Prehospital chest decompression can be a lifesaving procedure in severe chest trauma. Studies investigating prehospital chest decompression are mostly European where physicians are assigned to prehospital care units. This report is one of the first to compare demographics and outcomes in patients undergoing prehospital chest decompression by trained aeromedical nonphysician personnel to hospital chest decompression by physicians.

METHODS

Prehospital tube thoracostomy (PTT) patients were identified from January 2014 to January 2019 and were matched in a 1:2 ratio based on age, Injury Severity Score (ISS), and chest Abbreviated Injury Score (AIS) to patients who underwent hospital tube thoracostomy (HTT) within 24 hours of admission.

RESULTS

Forty-nine PTT patients were matched to 98 HTT patients. PTT patients had lower admission Glasgow Coma Scale (GCS), a higher rate of pre-chest tube needle decompression, and higher level 1 trauma activation. PTT were placed sooner (21.9 vs 157.0 minutes, P < .001). Rates of tube malposition, organ injury, tube dislodgement, empyema, and hospital-acquired pneumonia over the course of hospital admission were not significantly different between the 2 groups. PTT patients had longer intensive care unit length of stay (LOS), but similar hospital LOS, and overall mortality.

DISCUSSION

This report demonstrates that PTT is performed sooner than hospital placed tubes. Complication rates associated with tube thoracostomy and patient outcomes were not statistically different between PTT and HTT groups.

Measuring the impact of varying denominator definitions on standardized antibiotic consumption rates: implications for antimicrobial stewardship programmes

Objectives

To quantify the impact of varying the at-risk days definition on the overall report of at-risk days and on the calculated standardized consumption rates (SCRs) for piperacillin/tazobactam, amikacin, daptomycin and vancomycin.

Methods

Data were evaluated for two system hospitals, an 894 bed academic centre and a 114 bed community hospital. Aggregate inpatient antibiotic administration and occupancy data were extracted from electronic databases at the facility-wide level. Occupancy data were reported from admission-discharge-transfer systems. At-risk days were defined as hospital days present (DP), patient days (PD), persons present (PP) and billing days (BD). Inpatient antimicrobial days of therapy (DOT) across four major antimicrobial agents were used to calculate facility-wide SCRs using each denominator and were evaluated by least-squares regression and R2 values.

Results

Within the 894 bed academic hospital, the average monthly facility-wide days were 28 424, 22 198, 15 957 and 14 789 by the DP, PP, PD and BD definitions, respectively. Within the 114 bed community hospital, the average monthly facility-wide days were 5175, 3523 and 2816 by the DP, PP and PD definitions, respectively. Strong concordance was observed between facility-wide SCRs using the DP and PP definitions in both the academic (R2 = 0.99, y = 0.78x - 0.001) and community (R2 = 0.99, y = 0.68x - 0.03) centres across all four inpatient antibiotics evaluated. In an analysis of piperacillin/tazobactam SCRs, rates were over-predicted by 28%-93% at the facility-wide level across centres using alternative denominators.

Conclusions

We found that data source and definitions of at-risk denominator days meaningfully impact antibiotic SCRs. Centres should carefully consider these potential sources of variation when setting consumption benchmarks and internally evaluating use.

[Superior canal dehiscence syndrome : Diagnosis with vestibular evoked myogenic potentials and fremitus nystagmus. German version]

BACKGROUND

Superior canal dehiscence syndrome (SCDS) is a relatively rare neurotological disorder that is characterized by a heterogeneous clinical picture. Recently, vestibular evoked myogenic potential (VEMP) measurementwas established for the diagnosis of SCDS. In the present study, a case series of patients with SCDS were analyzed, with a focus on VEMP.

METHODS

Four patients with SCDS were prospectively examined with ocular VEMP (oVEMP) and cervical VEMP (cVEMP). The clinical features and the standard audiovestibular test battery results are summarized and analyzed. The diagnostic accuracy of VEMP testing is evaluated.

RESULTS

The increased oVEMP amplitudes had a specificity of 100% in this patient population. All patients had normal caloric function and head impulse testing. The Tullio sign was observed in two patients. Three patients had autophony. The airbone gap was not greater than 10 dB in any of the patients. Two patients had marked fremitus nystagmus. All patients had a bony dehiscence of the superior semicircular canal on computed tomography imaging.

CONCLUSION

The subjective and clinical features in this case series of SCDS patients were heterogeneous. However, objective oVEMP testing had the highest diagnostic value. Furthermore, we describe a new diagnostic clinical sign: fremitus nystagmus.

Guidelines for Biosafety in Teaching Laboratories Version 2.0: A Revised and Updated Manual for 2019

The original Guidelines for Biosafety in Teaching Laboratories were developed in 2012 in response to an outbreak of Salmonella Typhimurium tracked by the Centers for Disease Control and Prevention (CDC) that originated from clinical and teaching microbiology laboratories. In the 7 years since the publication of the guidelines, there have been two subsequent CDC-reported Salmonella outbreaks originating from clinical and teaching microbiology laboratories. Use of and issues with the guidelines by ASM members have been tracked by various means since publication, and in 2018 it became apparent that an update of the guidelines was necessary. The Education Board of the American Society for Microbiology charged this task force with updating the guidelines based on the accumulated information. While the guidelines should look familiar, users will find that the originally separate BSL1 and BSL2 guidelines have been rolled into one document, to help eliminate redundancy and confusion. In addition, sections on risk assessment and service animals in the teaching laboratory have been added. These updated guidelines should help clarify many of the issues for which users expressed problems with the original guidelines.

Ten-year survival and seven-year functional results of cementless Oxford unicompartmental knee replacement: A prospective consecutive series of our first 1000 cases

BACKGROUND

Cementless fixation is an alternative to cemented unicompartmental knee replacement (UKR), with several advantages over cementation. This study reports the ten-year survival and seven-year clinical outcome of cementless Oxford unicompartmental knee replacement (OUKR).

METHODS

This prospective study describes the clinical outcome and survival of the first 1000 consecutive cementless medial OUKRs implanted at two centres for recommended indications.

RESULTS

The 10-year survival was 97% (CI 95%: 92-100%), with 25 knees being revised. The commonest reason for revision was progression of arthritis laterally, which occurred in nine knees, followed by primary dislocation of the bearing, which occurred in six knees. There were two dislocations secondary to trauma and a ruptured ACL, and two tibial plateau fractures. Although there were no definite cases of aseptic loosening, two early revisions were related to tibial fixation: one for pain and a radiolucent line and one for incomplete seating of the component with a radiolucent line. There were four revisions for pain, but the cause of the pain was uncertain: in one there was tibial overhang and in two there was patellofemoral degeneration, which possibly contributed to the pain. There were no deep infections. The mean OKS improved from 23 (SD 8) to 42 (SD 7) at a mean follow-up of 7.0 years (p < 0.001). There was no significant difference in survival or clinical outcome between the designer and independent centre.

CONCLUSIONS

The cementless OUKR is a safe and reproducible procedure with excellent 10-year survival and clinical results in the hands of both designer and independent surgeons.

The five-year radiological results of the uncemented Oxford medial compartment knee arthroplasty

This study reports on the first 150 consecutive Oxford cementless unicompartmental knee arthroplasties (UKA) performed in an independent centre (126 patients). All eligible patients had functional scores (Oxford knee score and high activity arthroplasty score) recorded pre-operatively and at two- and five-years of follow-up. Fluoroscopically aligned radiographs were taken at five years and analysed for any evidence of radiolucent lines (RLLs), subsidence or loosening. The mean age of the cohort was 63.6 years (39 to 86) with 81 (53.1%) males. Excellent functional scores were maintained at five years and there were no progressive RLLs demonstrated on radiographs. Two patients underwent revision to a total knee arthroplasty giving a revision rate of 0.23/100 (95% confidence interval 0.03 to 0.84) component years with overall component survivorship of 98.7% at five years. There were a further four patients who underwent further surgery on the same knee, two underwent bearing exchanges for dislocation and two underwent lateral UKAs for disease progression. This was a marked improvement from other UKAs reported in New Zealand Joint Registry data and supports the designing centre's early results.

Depolymerization Kinetics of Glass-Forming Chalcogenide Melts. Coherence TYansfer NMR Studies of Phosphorus Selenide

The kinetics of the depolymerization of a glass-forming phosphorus selenide melt containing 48 at.% phosphorus have been studied using one- and two-dimensional coherence transfer spectroscopic methods. The depolymerization leads to the creation of molecular P4Se3. Two-dimensional spectroscopy indicates that these units are in slow exchange with the residual polymeric matrix, and corresponding rate constants are extracted from temperature dependent one-dimensional coherence transfer experiments. The results are quantitatively consistent with previous temperature-dependent NMR lineshape studies, yielding an activation energy of 109 kJ/mol

Temporal trends and geographical variation in the use of subacromial decompression and rotator cuff repair of the shoulder in England

We explored the trends over time and the geographical variation in the use of subacromial decompression and rotator cuff repair in 152 local health areas (Primary Care Trusts) across England. The diagnostic and procedure codes of patients undergoing certain elective shoulder operations between 2000/2001 and 2009/2010 were extracted from the Hospital Episode Statistics database. They were grouped as 1) subacromial decompression only, 2) subacromial decompression with rotator cuff repair, and 3) rotator cuff repair only. The number of patients undergoing subacromial decompression alone rose by 746.4% from 2523 in 2000/2001 (5.2/100 000 (95% confidence interval (CI) 5.0 to 5.4) to 21 355 in 2009/2010 (40.2/100 000 (95% CI 39.7 to 40.8)). Operations for rotator cuff repair alone peaked in 2008/2009 (4.7/100 000 (95% CI 4.5 to 4.8)) and declined considerably in 2009/2010 (2.6/100 000 (95% CI 2.5 to 2.7)). Given the lack of evidence for the effectiveness of these operations and the significant increase in the number of procedures being performed in England and elsewhere, there is an urgent need for well-designed clinical trials to determine evidence of clinical effectiveness.

The effect of the Oxford uncemented medial compartment arthroplasty on the bone mineral density and content of the proximal tibia

We studied the bone mineral density (BMD) and the bone mineral content (BMC) of the proximal tibia in patients with a well-functioning uncemented Oxford medial compartment arthroplasty using the Lunar iDXA bone densitometer. Our hypothesis was that there would be decreased BMD and BMC adjacent to the tibial base plate and increased BMD and BMC at the tip of the keel.

There were 79 consecutive patients (33 men, 46 women) with a mean age of 65 years (44 to 84) with a minimum two-year follow-up (mean 2.6 years (2.0 to 5.0)) after unilateral arthroplasty, who were scanned using a validated standard protocol where seven regions of interest (ROI) were examined and compared with the contralateral normal knee. All had well-functioning knees with a mean Oxford knee score of 43 (14 to 48) and mean Knee Society function score of 90 (20 to 100), showing a correlation with the increasing scores and higher BMC and BMD values in ROI 2 in the non-implanted knee relative to the implanted knee (p = 0.013 and p = 0.015, respectively).

The absolute and percentage changes in BMD and BMC were decreased in all ROIs in the implanted knee compared with the non-implanted knee, but this did not reach statistical significance. Bone loss was markedly less than reported losses with total knee replacement.

There was no significant association with side, although there was a tendency for the BMC to decrease with age in men. The BMC was less in the implanted side relative to the non-implanted side in men compared with women in ROI 2 (p = 0.027), ROI 3 (p = 0.049) and ROI 4 (p = 0.029).

The uncemented Oxford medial compartment arthroplasty appears to allow relative preservation of the BMC and BMD of the proximal tibia, suggesting that the implant acts more physiologically than total knee replacement. Peri-prosthetic bone loss is an important factor in assessing long-term implant stability and survival, and the results of this study are encouraging for the long-term outcome of this arthroplasty.

Cite this article: Bone Joint J 2013;95-B:1480–3.

Oviposition site selection in Aedes albopictus (Diptera: Culicidae): are the effects of predation risk and food level independent?

For organisms lacking parental care and where larval dispersal is limited, oviposition site selection decisions are critical fitness-enhancing choices. However, studies usually do not consider the interdependence of the two. In this study, we evaluated the effect of food level on the oviposition behavior of Aedes albopictus (Skuse) in the presence or the absence of a nonlethal predator (caged dragonfly nymph). We also attempted to quantify the perceived cost of predation to ovipositioning mosquitoes. Mosquitoes were presented with oviposition cups containing four levels of larval food (fermented leaf infusion) with or without a caged libellulid nymph. By titrating larval food, we estimated the amount of food needed to attract the female mosquito to oviposit in the riskier habitat. As expected, oviposition rate increased with food level and decreased in the presence of a predator. However, the effect of food level did not differ between predator treatments. By calculating the difference in the amount of food for points of equal oviposition rate in the predator-present and predator-absent regression lines, we estimated the cost of predation risk to be 1950 colony-forming-units per milliliter. Our study demonstrated the importance of considering the possible interdependence of predation risk and food abundance for oviposition-site-seeking insects. This study also quantified the perceived cost of predation and found it to be relatively low, a fact with positive implications for biological control.

Computer simulations of particle-bubble interactions and particle sliding using Discrete Element Method

Three dimensional Discrete Element Method (DEM) computer simulations have been carried out to analyse the kinetics of collision of multiple particles against a stationary bubble and the sliding of the particles over the bubble surface. This is the first time that a computational analysis of the sliding time and particle packing arrangements of multiple particles on the surface of a bubble has been carried out. The collision kinetics of monodisperse (33 μm in radius) and polydisperse (12-33 μm in radius) particle systems have been analysed in terms of the time taken by 10%, 50% and 100% of the particles to collide against the bubble. The dependencies of these collision times on the strength of hydrophobic interactions follow relationships close to power laws. However, minimal sensitivity of the collision times to particle size was found when linear and square relationships of the hydrophobic force with particles radius were considered. The sliding time for single particles has corroborated published theoretical expressions. Finally, a good qualitative comparison with experiments has been observed with respect to the particle packing at the bottom of the bubble after sliding demonstrating the usefulness of computer simulations in the studies of particle-bubble systems.

31P Dipolar NMR Approaches Towards the Development of Structural Principles in Non-Oxidic Glasses

While the utility of solid state NMR to provide structural information in amorphous systems is well established in silicate and borate glasses, the systematic application of modern NMR techniques to non-oxidic systems has just begun. One of the central issues in these types of glasses is the question of the chemical bond distribution and the existence of short range order. The present study utilizes the selective measurement of homonuclear 31p.31P dipole-dipole couplings via spin echo decay to address this issue in the glass systems P-Se, PSe- Ge and CdGeAs2-xPx. The results indicate that the first two systems are characterized by a high degree of chemical ordering. The chemical bond distribution in CdGeAs2-xPx glasses is found to deviate considerably from that in the stoichiometry-analog crystalline materials.

Bowstringing as a complication of deep brain stimulation: case report

OBJECTIVE

This retrospective case series describes bowstringing as a complication of deep brain stimulator implantation for Parkinson's disease, defined as abnormal tethering of leads between the pulse generator and stimulating electrode, associated with contracture of the patient's neck over the extension cable. There are no previous reports of this specific complication, which presumably has been more broadly classified under hardware-related complications.

CLINICAL PRESENTATION

Bowstringing may result in discomfort, restriction of movements, and/or equipment malfunction. Patients were identified by postoperative surveillance in clinic and by review of our database of Parkinson's disease patients who had undergone subthalamic nucleus deep brain stimulator placement. The incidence of this complication was 2.6% (6/228) in our overall clinic population, composed of 0% (0/181) of patients who received a Soletra pulse generator and 12.7% (6/47) of patients who received a Kinetra pulse generator.

INTERVENTION

The proportion of patients with bowstringing requiring operative revision was 83% (5/6), with 60% (3/5) patients undergoing conversion to single-channel pulse generators and 40% (2/5) undergoing revision of the original dual-channel pulse generator.

CONCLUSION

Factors associated with bowstringing include the use of dual-channel pulse generators and scar lysis complicated by seroma or infection. The mean time from implantation to bowstringing was 8.6 months with a range of 0.5 to 22 months. Bowstringing is a rare but potentially serious complication, and further study is needed to accurately predict and avoid this problem.

Synapse regression in depression: the role of 5-HT receptors in modulating NMDA receptor function and synaptic plasticity

Depression is accompanied by an increase in activity in the amygdala and a decrease in the rostral anterior cingulate cortex (rACC), with the former attributed to a failure of the latter to exert its normal inhibitory influence. This failure is likely due to regression of synaptic connections between the rACC and the amygdala, a process reversed in part by selective serotonin reuptake inhibitors (SSRIs). The present work presents a hypothesis as to how SSRIs might bring about this process and hence normalization of activity, at least in patients that are responsive to SSRIs. Serotonin receptors of the excitatory 5-HT(2A)R class increase N-methyl-D-aspartate receptor (NMDAR) efficacy, while those of the inhibitory 5-HT(1A)R class decrease NMDAR efficacy. A decrease of 5-HT transporter (5-HTT) efficacy, either during human development through functional polymorphisms, or in animals through 5-HTT transgenic knockouts, is accompanied by a decrease in 5-HT(1A)R and hence an increase in excitability and NMDAR efficacy which drives an increase in synaptic spines in the amygdala. As the limbic region of the brain normally possesses high levels of 5-HT(1A)R the effect of loss of these is to increase excitation in this region, as is observed. Changes in the level of extracellular 5-HT in adult animals also modulates the density of synaptic spines, with these increasing with an increase in 5-HT, possibly as a consequence of increases in 5-HT(2A)R activity over that of 5-HT(1A)R. Increasing extracellular levels of 5-HT with SSRIs would then lead to an increase in excitability and in synaptic spines for afferents in the dorsal rostral anterior cingulate cortex but not in the ventral regions such as the amygdala that have few 5-HT(2A)R. This allows dorsal regions to once more exert their inhibitory influence over ventral regions. In this way, SSRIs may exert their effect in normalizing dorsal hypometabolism and ventral hypermetabolism in those suffering from depression.