Use of Temporally Validated Machine Learning Models To Predict Outcomes of Percutaneous Nephrolithotomy Using Data from the British Association of Urological Surgeons Percutaneous Nephrolithotomy Audit.

BACKGROUND AND OBJECTIVE: Machine learning (ML) is a subset of artificial intelligence that uses data to build algorithms to predict specific outcomes. Few ML studies have examined percutaneous nephrolithotomy (PCNL) outcomes. Our objective was to build, streamline, temporally validate, and use ML models for prediction of PCNL outcomes (intensive care admission, postoperative infection, transfusion, adjuvant treatment, postoperative complications, visceral injury, and stone-free status at follow-up) using a comprehensive national database (British Association of Urological Surgeons PCNL). METHODS: This was an ML study using data from a prospective national database. Extreme gradient boosting (XGB), deep neural network (DNN), and logistic regression (LR) models were built for each outcome of interest using complete cases only, imputed, and oversampled and imputed/oversampled data sets. All validation was performed with complete cases only. Temporal validation was performed with 2019 data only. A second round used a composite of the most important 11 variables in each model to build the final model for inclusion in the shiny application. We report statistics for prognostic accuracy. KEY FINDINGS AND LIMITATIONS: The database contains 12 810 patients. The final variables included were age, Charlson comorbidity index, preoperative haemoglobin, Guy's stone score, stone location, size of outer sheath, preoperative midstream urine result, primary puncture site, preoperative dimercapto-succinic acid scan, stone size, and image guidance (https://endourology.shinyapps.io/PCNL_Demographics/). The areas under the receiver operating characteristic curve was >0.6 in all cases. CONCLUSIONS AND CLINICAL IMPLICATIONS: This is the largest ML study on PCNL outcomes to date. The models are temporally valid and therefore can be implemented in clinical practice for patient-specific risk profiling. Further work will be conducted to externally validate the models. PATIENT SUMMARY: We applied artificial intelligence to data for patients who underwent a keyhole surgery to remove kidney stones and developed a model to predict outcomes for this procedure. Doctors could use this tool to advise patients about their risk of complications and the outcomes they can expect after this surgery.

Point-of-Care Disease Screening in Primary Care Using Saliva: A Biospectroscopy Approach for Lung Cancer and Prostate Cancer.

Saliva is a largely unexplored liquid biopsy that can be readily obtained noninvasively. Not dissimilar to blood plasma or serum, it contains a vast array of bioconstituents that may be associated with the absence or presence of a disease condition. Given its ease of access, the use of saliva is potentially ideal in a point-of-care screening or diagnostic test. Herein, we developed a swab "dip" test in saliva obtained from consenting patients participating in a lung cancer-screening programme being undertaken in north-west England. A total of 998 saliva samples (31 designated as lung-cancer positive and 17 as prostate-cancer positive) were taken in the order in which they entered the clinic (i.e., there was no selection of participants) during the course of this prospective screening programme. Samples (sterile Copan blue rayon swabs dipped in saliva) were analysed using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. In addition to unsupervised classification on resultant infrared (IR) spectra using principal component analysis (PCA), a range of feature selection/extraction algorithms were tested. Following preprocessing, the data were split between training (70% of samples, 22 lung-cancer positive versus 664 other) and test (30% of samples, 9 lung-cancer positive versus 284 other) sets. The training set was used for model construction and the test set was used for validation. The best model was the PCA-quadratic discriminant analysis (QDA) algorithm. This PCA-QDA model was built using 8 PCs (90.4% of explained variance) and resulted in 93% accuracy for training and 91% for testing, with clinical sensitivity at 100% and specificity at 91%. Additionally, for prostate cancer patients amongst the male cohort (n = 585), following preprocessing, the data were split between training (70% of samples, 12 prostate-cancer positive versus 399 other) and test (30% of samples, 5 prostate-cancer positive versus 171 other) sets. A PCA-QDA model, again the best model, was built using 5 PCs (84.2% of explained variance) and resulted in 97% accuracy for training and 93% for testing, with clinical sensitivity at 100% and specificity at 92%. These results point to a powerful new approach towards the capability to screen large cohorts of individuals in primary care settings for underlying malignant disease.

ATR-FTIR Spectroscopy with Chemometrics for Analysis of Saliva Samples Obtained in a Lung-Cancer-Screening Programme: Application of Swabs as a Paradigm for High Throughput in a Clinical Setting.

There is an increasing need for inexpensive and rapid screening tests in point-of-care clinical oncology settings. Herein, we develop a swab "dip" test in saliva obtained from consenting patients participating in a lung-cancer-screening programme being undertaken in North West England. In a pilot study, a total of 211 saliva samples (n = 170 benign, 41 designated cancer-positive) were randomly taken during the course of this prospective lung-cancer-screening programme. The samples (sterile Copan blue rayon swabs dipped in saliva) were analysed using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. An exploratory analysis using principal component analysis (PCA,) with or without linear discriminant analysis (LDA), was then undertaken. Three pairwise comparisons were undertaken including: (1) benign vs. cancer following swab analysis; (2) benign vs. cancer following swab analysis with the subtraction of dry swab spectra; and (3) benign vs. cancer following swab analysis with the subtraction of wet swab spectra. Consistent and remarkably similar patterns of clustering for the benign control vs. cancer categories, irrespective of whether the swab plus saliva sample was analysed or whether there was a subtraction of wet or dry swab spectra, was observed. In each case, MANOVA demonstrated that this segregation of categories is highly significant. A k-NN (using three nearest neighbours) machine-learning algorithm also showed that the specificity (90%) and sensitivity (75%) are consistent for each pairwise comparison. In detailed analyses, the swab as a substrate did not alter the level of spectral discrimination between benign control vs. cancer saliva samples. These results demonstrate a novel swab "dip" test using saliva as a biofluid that is highly applicable to be rolled out into a larger lung-cancer-screening programme.

Enabling national improvement in quality of care for renal colic.

OBJECTIVES: To report the results of a clinical audit conducted by the British Association of Urological Surgeons (BAUS) of ureteric stone care pathways, with results reported with reference to national quality standards. PATIENTS AND METHODS: The BAUS conducted a clinical audit of all patients presenting as an emergency to 107 hospitals in England during November 2020 with ureteric stones. All patients were followed up until 31 March 2021 and the inpatient and outpatient management received was recorded. RESULTS: Data for 2192 patients across 117 units were submitted. The median (interquartile range [IQR]) number of patients per unit was 16 (9-27); 70% of patients were male and the median (IQR) patient age was 46 (34-59) years. Initial management was conservative treatment for 70% of patients. Overall, primary shockwave lithotripsy was performed in 34% of patients and primary ureteroscopy in 23% of cases when surgical intervention was required to treat the stone. However, 40% of patients in whom active intervention was appropriate underwent placement of a temporizing ureteric stent rather than undergo definitive surgical intervention at the outset. Female patients were less likely to have a computed tomography (CT) scan of the kidneys, ureters and bladder performed within 24 h of presentation (13% vs 7.3% for men [chi-squared P = 0.01]) and to be given correct analgesia (66% vs 73% for men [chi-squared P = 0.03]). Patients aged 60 years or older were also significantly less likely to be offered nonsteroidal anti-inflammatory drug analgesia appropriately. In total, 87% of patients had their calcium measured within the last 2 years and 73% of patients had evidence of being offered stone prevention diet and fluid advice. CONCLUSIONS: The audit demonstrates that the National Institute of Health and Care Excellence Quality Standards are both measurable and achievable. However, there was considerable variation in the delivery of these standards, including with regard to sex and age, highlighting inequalities for patient care across the UK.

Biplanar Videoradiography Dataset for Model-based Pose Estimation Development and New User Training.

Measuring the motion of the small foot bones is critical for understanding pathological loss of function. Biplanar videoradiography is well-suited to measure in vivo bone motion, but challenges arise when estimating the rotation and translation (pose) of each bone. The bone's pose is typically estimated with marker- or model-based methods. Marker-based methods are highly accurate but uncommon in vivo due to their invasiveness. Model-based methods are more common but are currently less accurate as they rely on user input and lab-specific algorithms. This work presents a rare in vivo dataset of the calcaneus, talus, and tibia poses, as measured with marker-based methods during running and hopping. A method is included to train users to improve their initial guesses into model-based pose estimation software, using marker-based visual feedback. New operators were able to estimate bone poses within 2° of rotation and 1 mm of translation of the marker-based pose, similar to an expert user of the model-based software, and representing a substantial improvement over previously reported inter-operator variability. Further, this dataset can be used to validate other model-based pose estimation software. Ultimately, sharing this dataset will improve the speed and accuracy with which users can measure bone poses from biplanar videoradiography.

UK national bladder outlet obstruction surgery snapshot audit.

OBJECTIVES: To determine the preoperative assessment and perioperative outcomes of men undergoing bladder outlet obstruction (BOO) surgery in the UK. PATIENTS AND METHODS: A retrospective cohort study was conducted of all men undergoing BOO surgery in 105 UK hospitals over a 1-month period. The study included 1456 men, of whom 42% were catheter dependent prior to undergoing surgery. RESULTS: There was no evidence that a frequency-volume chart or urinary symptom questionnaire had been completed in 73% or 50% of men, respectively in the non-catheter-dependent group. Bipolar transurethral resection of the prostate (TURP) was the most common BOO surgical procedure performed (38%). Monopolar TURP was the next most prevalent modality (23%); however, minimally invasive BOO surgical procedures combined accounted for 17% of all procedures performed. Of the cohort 5% of men had complications within 30 days of surgery, only 1% had Clavien-Dindo Grade ≥III complications. Less than 1% of the cohort received a blood transfusion after BOO surgery and 2% were re-admitted to hospital after their BOO surgery. In total only 4% of the whole cohort were catheter dependent after BOO surgery. Pre- and postoperative paired International Prostate Symptom Score scores reviewed suggest that minimally invasive surgical procedures achieved comparable levels of improvement in both symptoms and bother at 3 months postoperatively in men who were not catheter dependent preoperatively. CONCLUSIONS: There has been a substantial shift in the available choice of procedure for BOO surgery around the UK in recent years. However, men can be reassured that overall BOO surgery treatments are safe and effective. Evidence of adherence to guidelines in the preoperative assessment of men with lower urinary tract symptoms undergoing surgery was poorly documented and must be improved.

Barriers to Integration of Primary Care into Emergency Care: Experiences in Germany.

INTRODUCTION: In response to emergency department over-crowding primary care practitioners (PCPs) have been incorporated into care pathways to provide integrated care. We consider why a pilot project of PCP-led streaming in a German emergency department failed, the challenges encountered transplanting models between differing systems and cultures, and if the concept constitutes integrated care. THEORY AND METHODS: The original design was a mixed methods data gather around PCP-streaming of non-urgent self-referrers in an emergency department. RESULTS: The demand for the PCP-streaming was low, which was at odds with pre-study estimates. The study was stopped prematurely without adequate data; this is an opinion-based article. DISCUSSION: A fundamental of emergency care is a central emergency department. An emergency department can be the fulcrum from which urgent inter-disciplinary hospital care is initiated and coordinated. Objective triage is fundamental to this and regional healthcare planning. With such fundamentals in place, PCP integration has the potential to facilitate and provide integrated care. Relevant elements of the Rainbow Model of Integrated Care frame the discussion. CONCLUSION: The key element deficient in each barrier to our project, yet present in successful studies, was normative integration.

A comparison of centre of pressure behaviour and ground reaction force magnitudes when individuals walk overground and on an instrumented treadmill.

BACKGROUND: Instrumented treadmills facilitate analysis of consecutive strides in ways that typical overground gait data collections cannot. Researchers have quantified differences between joint kinetic measures whilst walking on an instrumented treadmill compared to those walking overground. The reason for such differences has not yet been established. RESEARCH QUESTION: Can we identify the source or sources of these errors by comparing centre of pressure and ground reaction force measurements recorded on a treadmill to those collected overground? METHODS: Kinematic and kinetic data were recorded while nineteen individuals walked continuously at their self-selected walking speed overground and on a treadmill. Comparisons of the centre of pressure and ground reaction forces were made between the two conditions using 2-tailed paired t-tests and Cohen's d effect size. RESULTS: The results indicated that participants had significantly faster backwards, lateral and medial centre of pressure velocities when walking on a treadmill compared to when they were walking overground. Additionally, participants also had significantly reduced peak propulsive ground reaction forces when walking on a treadmill than walking overground. SIGNIFICANCE: These results suggest that shear forces caused by the belts sliding over the treadmill force platforms affect the centre of pressure during early stance, and the minimal acceleration of a participant's centre of mass during treadmill walking results in reduced propulsive force during late stance. Therefore, care should be taken during studies when comparing kinetic gait variables between overground and treadmill walking.

Growth of Non-Halophilic Bacteria in the Sodium-Magnesium-Sulfate-Chloride Ion System: Unravelling the Complexities of Ion Interactions in Terrestrial and Extraterrestrial Aqueous Environments.

Motivated by an interest in understanding the habitability of aqueous environments on Earth and in extraterrestrial settings, this study investigated the influence of ions in an artificial sodium-magnesium-sulfate-chloride ion system on the growth parameters (lag phase, growth rate, and final cell concentration) of bacteria. These four ions, in different combinations, are key components of many aqueous environments on Earth and elsewhere. We investigated non-halophilic bacteria deliberately to remove the bias of prior adaptations to high concentrations of selected ions so that we could compare the effects of different ions. We tested the hypothesis that water activity determined the growth parameters independent of the ion types. Neither water activity or ionic strength alone could predict growth. However, when ionic strengths were matched, many differences in growth parameters could be explained by the water activity. We suggest that species-specific effects (caused by differences in biochemical and physiological influences), the role of individual ions in cellular processes, and potentially the chaotropicity and kosmotropicity of solutions influenced the growth. Our data show that although extreme combinations of these ions allow for general predictions on the habitability of extraterrestrial aqueous environments, a complex interplay of ionic effects influences the growth and thus the adaptations required for given ion combinations. The data also show that an accurate quantification of the habitability of ocean worlds, such as Europa and Enceladus, can only be made when samples are obtained from these water bodies and the ion combinations are determined.

Cost analysis of ureteroscopy (URS) vs extracorporeal shockwave lithotripsy (ESWL) in the management of ureteric stones <10 mm in adults: a UK perspective.

OBJECTIVES: To compare the total cost of a treatment strategy starting with ureteroscopy (URS) vs a strategy starting with extracorporeal shockwave lithotripsy (ESWL). METHODS: For ureteric stones of <10 mm, URS or ESWL are the main treatment options that are considered. Although the interventions differ, the goal of the interventions is to achieve a stone-free status. A systematic review and meta-analysis undertaken as part of the National Institute for Health and Care Excellence (NICE) guideline on 'Renal and ureteric stones: assessment and management' identified URS as more effective, in terms of getting people stone free, but has a higher probability of re-admission and adverse events (AEs) that contributes to downstream resource use. ESWL is initially less costly, but lower effectiveness means a greater need for repeat or ancillary procedures in order to get a patient stone free. Given these trade-offs between benefits and costs, a cost analysis of URS and ESWL was undertaken as part of the NICE guideline, using evidence from the literature of effectiveness, re-admission and AEs. The NICE guideline meta-analysis showed a lot of heterogeneity and differences in how outcomes were reported between studies. The costing analysis, therefore only used studies where: (i) patients were rendered stone free, and (ii) where effectiveness, was based on the first-line (initial) procedures. Exploratory quality adjusted life year (QALY) work was also undertaken to identify the QALY and quality of life (QoL) differences required for the most expensive intervention to be cost effective, based on the assumption that the difference in effectiveness between the initial procedures would be the main source of the QALY gain between the two strategies. RESULTS: The URS strategy was more costly overall than the ESWL strategy (incremental cost of £2387 [pounds sterling]). Sensitivity analysis varying the initial effectiveness of ESWL treatment (between the base case value of 82% and 40%) showed that URS would still be a more costly strategy even if the initial session of ESWL only had a success probability of 40%. A two-way sensitivity analysis as part of the exploratory QALY work showed that ESWL would have to have very low effectiveness and people would have to wait for further treatment for many weeks (following a failed ESWL treatment) for there to be feasible QoL gains to justify the additional cost of the URS strategy. CONCLUSIONS: ESWL is less effective at initial stone clearance and therefore requires more ancillary interventions than URS. However, the magnitude of the difference in costs means URS is unlikely to be cost effective intervention at a population level for first-line treatment, implying ESWL should be the first choice treatment.

Clinical and Patient-reported Outcome Measures in Men Referred for Consideration of Surgery to Treat Lower Urinary Tract Symptoms: Baseline Results and Diagnostic Findings of the Urodynamics for Prostate Surgery Trial; Randomised Evaluation of Assessment Methods (UPSTREAM).

BACKGROUND: Clinical evaluation of male lower urinary tract symptoms (MLUTS) in secondary care uses a range of assessments. It is unknown how MLUTS evaluation influences outcome of therapy recommendations and choice, notably urodynamics (UDS; filling cystometry and pressure flow studies). OBJECTIVE: To report participants' sociodemographic and clinical characteristics, and initial diagnostic findings of the Urodynamics for Prostate Surgery Trial; Randomised Evaluation of Assessment Methods (UPSTREAM). UPSTREAM is a randomised controlled trial evaluating whether symptoms are noninferior and surgery rates are lower if UDS is included. DESIGN, SETTING, AND PARTICIPANTS: A total of 820 men (≥18 yr of age) seeking treatment for bothersome LUTS were recruited from 26 National Health Service hospital urology departments. INTERVENTION: Care pathway based on routine, noninvasive tests (control) or routine care plus UDS (intervention arm). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome is International Prostate Symptom Score (IPSS) and the key secondary outcome is surgery rates 18 mo after randomisation. International Consultation on Incontinence Questionnaires were captured for MLUTS, sexual function, and UDS satisfaction. Baseline clinical and patient-reported outcome measures (PROMs), and UDS findings were informally compared between arms. Trends across age groups for urinary and sexual PROMs were evaluated with a Cuzick's test, and questionnaire items were compared using Pearson's correlation coefficient. RESULTS AND LIMITATIONS: Storage LUTS, notably nocturia, and impaired sexual function are prominent in men being assessed for surgery. Sociodemographic and clinical evaluations were similar between arms. Overall mean IPSS and quality of life scores were 18.94 and 4.13, respectively. Trends were found across age groups, with older men suffering from higher rates of incontinence, nocturia, and erectile dysfunction, and younger men suffering from increased daytime frequency and voiding symptoms. Men undergoing UDS testing expressed high satisfaction with the procedure. CONCLUSIONS: Men being considered for surgery have additional clinical features that may affect treatment decision making and outcomes, notably storage LUTS and impaired sexual function. PATIENT SUMMARY: We describe initial assessment findings from a large clinical study of the treatment pathway for men suffering with bothersome urinary symptoms who were referred to hospital for further treatment, potentially including surgery. We report the patient characteristics and diagnostic test results, including symptom questionnaires, bladder diaries, flow rate tests, and urodynamics.

A Low-Diversity Microbiota Inhabits Extreme Terrestrial Basaltic Terrains and Their Fumaroles: Implications for the Exploration of Mars.

A major objective in the exploration of Mars is to test the hypothesis that the planet hosted life. Even in the absence of life, the mapping of habitable and uninhabitable environments is an essential task in developing a complete understanding of the geological and aqueous history of Mars and, as a consequence, understanding what factors caused Earth to take a different trajectory of biological potential. We carried out the aseptic collection of samples and comparison of the bacterial and archaeal communities associated with basaltic fumaroles and rocks of varying weathering states in Hawai'i to test four hypotheses concerning the diversity of life in these environments. Using high-throughput sequencing, we found that all these materials are inhabited by a low-diversity biota. Multivariate analyses of bacterial community data showed a clear separation between sites that have active fumaroles and other sites that comprised relict fumaroles, unaltered, and syn-emplacement basalts. Contrary to our hypothesis that high water flow environments, such as fumaroles with active mineral leaching, would be sites of high biological diversity, alpha diversity was lower in active fumaroles compared to relict or nonfumarolic sites, potentially due to high-temperature constraints on microbial diversity in fumarolic sites. A comparison of these data with communities inhabiting unaltered and weathered basaltic rocks in Idaho suggests that bacterial taxon composition of basaltic materials varies between sites, although the archaeal communities were similar in Hawai'i and Idaho. The taxa present in both sites suggest that most of them obtain organic carbon compounds from the atmosphere and from phototrophs and that some of them, including archaeal taxa, cycle fixed nitrogen. The low diversity shows that, on Earth, extreme basaltic terrains are environments on the edge of sustaining life with implications for the biological potential of similar environments on Mars and their exploration by robots and humans.

Extra-Anatomic Stents in Ureteric Obstruction: Our Experience.

OBJECTIVES: To present our experience of the Detour extra-anatomic stent (EAS; Porges-Coloplast, Denmark) to bypass ureteric obstruction. Use of the EAS is indicated in patients with complex ureteric strictures or malignant disease, where long-term nephrostomy drainage is undesirable. MATERIALS AND METHODS: Between December 2001 and October 2017, 20 Detour EAS were implanted into 13 patients. The primary indication was ureteric obstruction or injury secondary to metastatic malignancy, or from treatment for malignancy. Five patients required bilateral EAS, with two patients having bilateral EAS following initial unilateral insertion. In 11 patients, the stent was inserted into their bladder, with 2 diverted into a double-barreled stoma. The mean age at the time of implantation was 64 years (range: 50-83 years), and the median follow-up was 12 months (range: 1.5-42 months). RESULTS: Four patients required stent revision for urinary leaks, and two developed recurrent urinary tract infections in their stent requiring intravenous antibiotics. All EAS continued to drain successfully following treatment or revision. One patient died due to complications from dislodgement of the stent, leading to laparotomy and intra-abdominal sepsis. Seven patients died due to progression of metastatic malignant disease, and the Detour EAS was functioning in all seven at time of death. The remaining five patients are well with functioning Detour EAS. CONCLUSIONS: The Detour EAS system provides a suitable alternative option for urinary diversion, affording a good quality of life to carefully selected patients with multiple comorbidities and malignant disease.

Electromagnetically tracked personalized templates for surgical navigation.

PURPOSE: An electromagnetic (EM) surgical tracking system was developed for orthopedic navigation. The reportedly poor accuracy of point-based EM navigation was improved by using anatomical impressions, which were EM-tracked personalized templates. Lines, rather than points, were consistently used for calibration and error evaluation. METHODS: Technical accuracy was tested using models derived from CT scans of ten cadaver shoulders. Tracked impressions were first designed, calibrated, and tested using lines as fiducial objects. Next, tracked impressions were tested against EM point-based navigation and optical point-based navigation, in environments that were either relatively empty or that included surgical instruments. Finally, a tracked impression was tested on a cadaver forearm in a simulated fracture-repair task. RESULTS: Calibration of anatomical impressions to EM tracking was highly accurate, with mean fiducial localization errors in positions of 0.3 mm and in angles of [Formula: see text]. Technical accuracy on physical shoulder models was also highly accurate; in an EM field with surgical instruments, the mean of target registration errors in positions was 2.2 mm and in angles was [Formula: see text]. Preclinical accuracy in a cadaver forearm in positions was 0.4 mm and in angles was [Formula: see text]. The technical accuracy was significantly better than point-based navigation, whether by EM tracking or by optical tracking. The preclinical accuracy was comparable to that achieved by point-based optical navigation. CONCLUSIONS: EM-tracked impressions-a hybrid of personalized templates and EM navigation-are a promising technology for orthopedic applications. The two technical contributions are the novel hybrid navigation and the consistent use of lines as fiducial objects, replacing traditional point-based computations. The accuracy improvement was attributed to the combination of physical surfaces and line directions in the processes of calibration and registration. The technical studies and preclinical trial suggest that EM-tracked impressions are an accurate, ergonomic innovation in image-guided orthopedic surgery.

Returning to contingency: the forward trauma team.

During Herrick 19, Main Operating Base Price Role 1 treatment facility saw one of the busiest periods of Role 1 trauma care within the British Afghanistan campaign. Within 5 months 73 trauma casualties were treated, 48 of whom were category A. This article shares the experiences of this Role 1 and its unusual context, and discusses the relevance with regard to future medical planning. The focus is on the human element; a fundamental of all military operations yet one that is often overlooked. We consider the team construct and the team members of Role 1 and suggest how this team and its leaders can be optimally prepared, supported and maintained, and then safely disassembled. We also consider how best this team can be placed within the battle group formation in order to provide the highest standard of care.

Personalized Guides for Registration in Surgical Navigation.

Personalized guides are increasingly used in orthopedic procedures but do not provide for intraoperative re-planning. This work presents a tracked guide that used physical registration to provide an anatomy-to-tracking coordinate frame transformation for surgical navigation. In a study using seven femoral models derived from clinical CT scans used for hip resurfacing, a guide characterization FRE of 0.4°±0.2°, drill-path drill-path angular TRE of 0.9°±0.4° and a positional TRE of 1.2mm±0.4mm were found; these values are comparable to conventional optical tracking accuracy. This novel use of a tracked guide may be particularly applicable to procedures that require a small surgical exposure, or when operating on anatomical regions with small bones that are difficult to track or reliably register.

A Toroidal Probe for Measuring Surgically Exposed Joint Centers.

Maintaining the hip center can improve the success of a total hip arthroplasty. A novel probe design, based on mating a toroid with a sphere, was used for kinematic measurements of the femoral head center and implant center in a pre-clinical study of hip joints. In an electromagnetically tracked implementation tested in a laboratory environment, the device measured a spherical center to within 1.2±0.2 mm in a technical validation. Applied to a plastic model of a cadaveric femur, the center of the femoral head was measured to 1.8±0.4 mm and the implant was measured to within 1.5±0.5 mm. Because leg length changes and offset changes in conventional hip arthroplasty can be as much as 16 mm, this device has relatively high accuracy that may improve implant localization for the hip.

Adrenal surgery in England: better outcomes in high-volume practices.

AIMS AND BACKGROUND: Adrenal surgery is performed by a variety of surgical specialities in differing environments and volumes. International data suggest that there is a correlation between adrenal surgery volume and outcomes but there are no UK data to support this or UK surgical guidelines. A multidisciplinary team representing the stakeholders in adrenal disease is preparing a national guidance on adrenal surgery. A review of the outcomes for adrenal surgery in England was performed to correlate outcomes with the volume of surgeon practice. METHODS: Hospital Episode Statistics (HES) data for the National Health Service (NHS) in England in the tax year 2013-2014 were examined for adrenal surgery. Length of hospital stay and rate of postoperative readmission were assessed as surrogate quality markers and a comparison made between 'high-' and 'low-' volume surgeons. RESULTS: A total of 795 adult adrenalectomies were performed by 222 different surgeons with a range of between 1 and 34 adrenalectomies performed per surgeon. Only thirty-six (16%) adrenal surgeons performed 6 or more adrenalectomies. A total of 186 surgeons (84%) performed a median of one adrenalectomy a year. Length of stay and readmission rate within thirty days of operation was 60% longer and 47% higher, respectively, when performed by low-volume surgeons. CONCLUSION: The current provision of adrenal surgery in the UK is not in the best interests of patients and is not cost-effective for the NHS. Adrenal surgery is best performed by higher volume surgeons in centres with dedicated adrenal multidisciplinary teams expert in all aspects of care of the adrenal patient.