16 to 34% of the population suffer from shoulder pain, the most common cause being rotator cuff tears. NICE guidance recommends using ultrasound scan (USS) or MRI to assess these patients, but does not specify which is preferable. This study assesses the accuracy of USS and MRI in rotator cuff tears in a DGH, to establish the most appropriate imaging modality. Patients who had at least two of shoulder ultrasound, MRI or arthroscopy within a seven month period (n=55) were included in this retrospective study. Sensitivity, Specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were calculated using arthroscopy as the true result, and kappa coefficients calculated for each pairing. 59 comparisons were made in total. Sensitivity for MRI in full supraspinatus tears was 0.83, and for USS 0.75. Specificity for MRI in these tears was 0.75, and for USS 0.83. Values were much lower in other tears, which occurred less frequently. USS and MRI completely agreed with each other 61.3% of the time. Both modalities were only completely accurate 50% of the time. Kappa coefficient between arthroscopy and MRI for supraspinatus tears was 0.658, and for USS was 0.615. There was no statistical difference between MRI and USS sensitivity or specificity (p=1), suggesting that one modality cannot be recommended over the other for full supraspinatus tears. They also do not tend to corroborate one another, suggesting that there is no benefit from doing both scans. Further research is needed to see how both modalities can be improved to increase their accuracy

FAI has been implicated in the progression of osteoarthritis (OA) and early detection may allow for treatment, which can slow or halt progression. FAI is a difficult condition to image and there is little objective evidence about imaging accuracy. We aim to measure the accuracy of five imaging modalities. Three blinded observers retrospectively reviewed five different modalities from two age and sex matched groups: A patient group referred to the outpatient clinic with a clinical diagnosis of FAI and a control group who had had CT scans of the pelvis for suspected trauma, where the Pelvic scan had been reported as showing no injuries. The imaging modalities were: Standard x-ray; Antero-Posterior, Lateral; Condition-specific x-ray projections; Dunn view, lateral internal rotation; Standard Computer Tomography (CT) multiplanar reconstruction (MPR); axial, sagittal and coronal; Condition-specific CT MPR; angled axial, angled coronal; 3D modelling; and surface rendered dynamic. We found marked variations in the sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictiive Value (NPV) for each of the following imaging modalities: Standard X-ray; Sensitivity 51.9; Specificity; 57.1; PPV; 40; NPV; 68.3 Special X-rays; Sensitivity; 66.7; Specificity; 57.1; PPV; 46.1; NPV; 75.7. Standard CT MPR; Sensitivity; 40.7; Specificity; 75.5; PPV; 47.8; NPV; 69.8 Special CT MPR; Sensitivity; 48.1; Specificity; 57.1; PPV; 46.4; NPV; 70.8 Dynamic 3D CT models; Sensitivity; 55.6; Specificity; 69.3; PPV; 42.8; and NPV; 71.8. The Dynamic 3D CT models (where the observer can manipulate the model in real time three dimension to control the perspective) proved to be the most accurate, closely followed by the special X-Ray views, which were also the most sensitive. The Standard CT MPRs were the most specific but had a low sensitivity. This is the first study to measure sensitivity, specificity and PPV and NPV for these imaging modalities in FAI. We recommend the use of condition-specific X-Ray views as well as 3D CT Models for optimal imaging accuracy in this condition. Standard X-Ray views and CTs proved less useful

Magnetic resonance imaging (MRI) is a useful diagnostic tool in evaluating meniscus pathology in the knee. Data from available literature suggests sensitivity and specificity rates around 90% when compared to the gold standard findings at knee arthroscopy. We sought to evaluate the sensitivity, specificity and precision rate (positive predictive value) of MRI at diagnosing meniscus tears within our unit. A retrospective audit of a total of 79 MRI reports and arthroscopic findings spanning a one year period was carried out. There were 66 positive MRI reports and 13 negative reports. There were 6 false positives 4 false negatives when compared to arthroscopic findings. The sensitivity of MRI for detecting meniscus tears was 93.7% with 60 out of 64 tears detected. All 4 false negatives also had at least grade III osteoarthritic changes at arthroscopy. Specificity was rather low at 60% with MRI reporting 6 tears (false positives) out of 15 patients who had no tears found at arthroscopy. The positive predictive value (precision rate) of MRI detecting tears was 90.9%. This data shows that MRI in our unit has a comparable high sensitivity to that in various literature making it a useful tool at ruling out disease with a negative result in the clinical setting. A more useful parameter in the clinical setting is its high precision rate when faced with a positive result. However, its specificity is much lower than that in most published data. A total of 6 tears on MRI turned out not to be on arthroscopy meaning patients could have been subjected to an avoidable invasive procedure in the absence of any other indication. This highlights the importance of obtaining reports from experienced musculoskeletal radiologists and the need for surgeons to review MRI images and match them to clinical information prior to subjecting patients to surgery

Aims: Multiple nerve repair by means of a Y-shaped nerve guide represents a good model for studying the specificity of peripheral nerve fiber regeneration. Here we have employed this model for investigating the specificity of axonal regeneration in mixed nerves of the rat forelimb model. Specificity of nerve regeneration can be defined as the ability of the nerve fibers of a peripheral nerve, after a lesion. Tree types of specificity on nerve regeneration has been postulated: “tissue specificity” (the preferential reinnervation of distal nerve tissue versus other types of tissue), topographic specificity (regenerating nerve fibers are preferentially attracted by analogous distal pathways (e.g. preferential regeneration along tibial nerve pathways by tibial nerve fibers), and end-organ specificity, which is the hypothesis that distal end-organs (muscle vs. sensory targets) specifically attracts the respective (motor vs. sensory) regenerating nerve fibers. Exists no agreement regarding the presence and features of the two last type of specificity. Methods: The left median and ulnar nerves, in adult female rats, were transected and repaired with a 14-mm Y-shaped conduit. The proximal end of the Y-shaped conduit was sutured to the proximal stump of either the median nerve or the ulnar nerve. Ten months after surgery, rats were tested for functional recovery of each median and ulnar nerve. Quantitative morphology of regenerated myelinated nerve fibers was then carried out by the two-dimensional disector technique. Results: Results showed that partial recovery of both median and ulnar nerve motor function was regained in all experimental groups. Performance in the grasping test was significantly lower when the ulnar nerve was used as the proximal stump. Ulnar test assessment showed no significant difference between the two Y-shaped repair groups. The number of regenerated nerve fibers was significantly higher in the median nerve irrespectively of the donor nerve, maintaining the same proportion of myelinated fibers between the two nerves (about 60% median and 40% ulnar). On the other hand, nerve fiber size and myelin thickness were significantly larger in both distal nerves when the median nerve was used as the proximal donor nerve stump. G-ratio and myelin thickness/ axon diameter ratio returned to normal values in all experimental groups. Conlusions: These results demonstrate that combined Y-shaped-tubulization repair of median and ulnar nerves permits the functional recovery of both nerves, independently from the proximal donor nerve employed, and that tissue, and not topographic, specificity guides nerve fiber regeneration in major forelimb mixed nerves of rats

Abstract

Aims

The sensitivity and specificity of electrodiagnostic parameters in diagnosing carpal tunnel syndrome (CTS) have been reported differently, and this study aims to address this gap.

Aims: We aim to investigate how often we needed extensive investigations to reach a speciþc diagnosis and whether we could identify symptoms and signs predictive of such diagnosis. Methods: We analysed the records of 60 children referred to our specialist clinics complaining of back pain. We statistically analysed the speciþcity of 9 parameters from history and clinical examination to predict the þnal diagnosis and checked the correlation between initial clinical diagnosis and þnal diagnosis following extensive investigations such as bone scan, CT and MRI scan. Results: The mean age of our group of patients was 12.3 years (range=3–18 years). We failed to reach a speciþc initial diagnosis after history taking, clinical examination and simple X-rays of the spine in 33 patients (55%). By the completion of investigations a speciþc diagnosis was not reached in only 18 (35%), and the difference was signiþcant compared to the other 65% (chi square(1)=4.41, p< 0.05). In 15 children specialist investigations clariþed a diagnosis of spondylolysis, Scheuermannñs disease and tumour. A hypothesised set of 9 clinical symptoms and signs was not predictive of speciþcity of initial clinical diagnosis (RL 2=0.12, chi square (9)=10.07, p> 0.05), but was predictive of þnal diagnosis (RL 2=0.35, chi square(9)=22.88, p< 0.01). A speciþc diagnosis was less likely in the presence of activity related pain or intermittent pain. There was a high degree of correlation between initial clinical diagnosis and þnal diagnosis. (phi=0.70, chi square(1)=25.07, p< 0.001). Conclusions: For about half our group of children, back pain was not a speciþc symptom. A set of common set of clinical symptoms and signs did not initially predict speciþcity. Based on these initial þndings we should continue to investigate in depth any referred child with back pain.

Background: The diagnosis of implant-associated infections is difficult due to organisms attached to surfaces as biofilms. We hypothesize that diagnosis can be improved by removing biofilm microorganisms from implant surface by sonication, followed by Gram stain, culture and calorimetric detection in sonication fluid.

Methods: We prospectively included adult patients from May 2005 until December 2006 from whom an orthopedic implant (joint prosthesis or internal fixation device) was removed for any reason. Removed implants were vortexed and sonicated in solid containers 5 min at 40 kHz in 100 to 400 ml Ringer’s solution. The resulting sonicate was plated and incubated on aerobic and anaerobic blood agar and aliquots were in parallel incubated at 37°C for 3 days in an isothermal calorimeter TAM III (TA Instruments, New Castle, DE). Gram stain was performed on sonicates centrifuged at 5000 g for 10 min. Definitive infection diagnosis was of the implant was defined if purulence surrounding the implant, or growth of the same microorganism in ≥2 synovial fluid or intraoperative tissue specimens, or acute inflammation in histopathology, or a sinus tract was present. Sonicate culture was defined positive if > 10 cfu (colony forming units) grew/ml sonicate. Calorimetry was defined positive if heat flow rate increased ≥10 μW above baseline (detection limit ~0.3 μW).

Results: 846 implants (367 joint prostheses and 479 internal fixation devices) were studied, of which 171 (20%) were infected and 675 (80%) were aseptic cases. The sensitivity of intraoperative tissue cultures was 74%, of sonicate culture 89%, of sonicate Gram stain 51%, of sonicate calorimetry 96%. The specificity of all specimens was ≥95%.

Conclusion: Sonicate culture and calorimetry were more sensitive than intraoperative tissue cultures for diagnosing implant infections. With Gram stain of centrifuged sonicate, infection was diagnosed in > 50% cases. Sonicate culture and calorimetry may replace the current approach using multiple intraoperative periprosthetic tissue specimens, whenever the implant or part of it is removed.

ARMD (Adverse Reaction to Metal Debris) is an increasingly recognised complication of metal on metal hip replacements. The MHRA (Medical and Healthcare Related Devices Agency) have advised a blood cobalt or chromium level above 7 mg/L is a threshold for further investigation, stating that “low levels are reassuring and strongly predict not having an adverse outcome”. Cross-sectional imaging should be performed when levels are above 7 mg/L. We have performed a study investigating the specificity and sensitivity of chromium and cobalt metal ion levels as a screening measure for ARMD.

79 ASR hip replacements were performed at our hospital and 75 (95%) of these underwent a Metal Artefact Reduction Sequence (MARS) MRI scan. All patients (64 hips) who had not undergone revision were invited to take part in this study. 57 patients with 62 hip replacements completed hip and activity scores, had blood cobalt and chromium ion level measurements and 3D-CT to measure acetabular component position.

Acetabular component inclination (>50 degrees), small head size (< 51mm) and female gender were significantly correlated with raised chromium (Cr) and cobalt (Co) ion levels. An ARMD was detected using MRI in 18 (29%) of the hips in this study. The incidence of ARMD was significantly higher when chromium concentration was above 7 mg/l (p = 0.02). Chromium ion levels >7 mg/L had a sensitivity of 56% and specificity of 83% for ARMD, and cobalt ion levels >7 mg/L 56% and 76% respectively. 40 patients had cobalt levels <7 mg/L and 33 had chromium levels <7 mg/L, but 8 of these had an ARMD on MRI. All 8 patients had minimal symptoms (Oxford Hip Score ≥ 44 out of 48).

The Medicines and Healthcare Products Regulatory Agency (MHRA) has recommended that cobalt and chromium levels be measured in patients with a metal-on-metal hip replacement and cross-sectional imaging performed when these levels are above 7 μg/L. This study has shown that by using this threshold, in patients with this implant combination, the sensitivity and specificity for the detection of ARMD is low and patients with soft tissue disease may be missed. Furthermore the presence of MRI detected ARMD, in the absence of significant clinical symptoms and with metal ion levels <7 μg/L is of concern.

MoM implants at risk of failure are associated with raised cobalt and chromium levels. However metal ion analysis alone is not reliable as a screening tool for ARMD, which is often clinically “silent”. We recommend the routine use of MARS MRI as the safest method of ARMD diagnosis in patients with MoM implants.

Background. Masses are not uncommon in the foot and ankle. Most of these masses are benign, often leading clinicians to underestimate their potential for malignancy. Methods. We conducted a retrospective review of our clinical records, on patients with histologically confirmed musculoskeletal tumours of the foot and ankle, treated in a single nstitution between 2010 and 2019. The maximum diameter of each lesion was determined through MRI or Ultrasound analysis in centimeters. To develop a scoring system we compared the risk of malignancy with five criteria: site (proximal or distal to the first TMTJ), gender, age, composition and the diameter as observed. Results. Our study included 496 patients, of whom 39 (7.9%) were identified as having malignancies. The incidence of malignancy demonstrated an increased propensity among male patients, patients over 50 years of age and lesions located proximal to the TMTJ. A ROC Analysis determined that lesions measuring over 2.85 cm had an increased risk of malignancy, with a PPV of 31.1%, a NPV of 94.2%, a Sensitivity of 0.82, and a Specificity of 0.62. These identified patterns of risk were employed to formulate a scoring system, aimed at facilitating informed clinical judgment in the referral of patients to regional tumor services. Conclusion. The new OxFAT scoring system highlights the importance of lesion size, site, age and gender of the patient in determining the risk of malignancy in lump in the foot and ankle. We propose this new scoring system to aid health care professionals in managing these patients. Based on our results any patient with a foot or ankle mass of less than 2.85cm, an OxFAT score < 4/7 and no malignant or sinister features on MRI or USS can be managed locally with excision biopsy. All other patients should be referred urgently to a Regional Tumour Service

Introduction and purpose: To assess the diagnostic usefulness of MRI to diagnose ACL lesions using quantitative instead of qualitative parameters. Materials and methods: A retrospective study was made of the MRIs of a group of 50 patients with an athroscopically confirmed ACL tear and a control group of 50 patients with meniscal lesions and with an arthroscopic confirmation that they had a normal ACL. Multiple MRI findings were studied in order to evaluate their sensitivity and Specificity to detect an ACL lesion. Special emphasis was placed on 3 quantitative parameters, including a simplified method to measure the angle between the ACL and the tibial plateau. Results: Using 45° as a cutoff value, the ACL/tibial plateau angle yielded a sensitivity and Specificity of 100%. With a 0° cutoff value, the angle together with Blumensaat’s line showed a sensitivity of 90% and a Specificity of 98%. With a cutoff value of 115°, the PCL angle showed a sensitivity of 70% and a Specificity of 82%. Conclusions: The quantitative parameters studied are valuable to predict ACL lesions and can increase both the sensitivity and Specificity of MRI images. The ACL/ tibial plateau angle can be measured easily using a single MRI image and can be regarded as the best clue to diagnose ACL lesions

Introduction: Ankle sprain is one of the common presentations in Accident and Emergency. Accurate diagnosis is critical and sometime difficult without special investigation such as Magnetic Resonance Imaging (MRI) or arthroscopy. Aim: The purpose of this project was to evaluate magnetic resonance imaging (MRI) accuracy for diagnosing and defining ankle pathology. Method: Retrospective review of 36 patients who underwent both MRI and Arthroscopy. All cases were seen by single orthopaedic surgeon with special interest in foot and ankle surgery. MRI scan were reviewed by consultant radiologist at our institute. Arthroscopy was used as a standard for comparing MRI results. Sensitivity and Specificity was calculated by qualified statistician. Results: For osteochondral lesion the Sensitivity of 85.7 %, Specificity of 93.3% and Accuracy of 89.7% was noticed. Anterior and posterior tibiofibular ligament (ATFL and PTFL) pathology had a Sensitivity of 100 %, Specificity of 100% and Accuracy of 100%, while anterior inferior tibiofibular ligament pathology had a Sensitivity of 66.6 %, Specificity of 95% and Accuracy of 86.6%. Conclusion: Although MRI is a useful tool in exclusion of pathological condition its sensitivity and accuracy in diagnosing ligament injury is not encouraging

Aim. The clinical relevance of microbial DNA detected via next-generation sequencing (NGS) remains unknown. This multicenter study was conceived to: 1) identify species on NGS that may predict periprosthetic joint infection (PJI), then 2) build a predictive model for PJI in a developmental cohort, and 3) validate predictive utility of the model in a separate multi-institutional cohort. Method. Fifteen institutions prospectively collected samples from 194 revision TKA and 184 revision THA between 2017–2019. Synovial fluid, tissue and swabs were obtained intraoperatively and sent to MicrogenDx (Lubbock, TX) for NGS analysis. Reimplantations were excluded. Patients were classified per the 2018 ICM definition of PJI. DNA analysis of community similarities (ANCOM) was used to identify 17 bacterial species of 294 (W-value>50) for differentiating infected vs. noninfected cases. Logistic regression with LASSO selection and random-forest algorithms were then used to build a model for predicting PJI. ICM classification was the response variable (gold-standard) and species identified through ANCOM were predictors. Patients were randomly allocated 1:1 into training and validation sets. Using the training set, a model for PJI diagnosis was generated. The entire model-building procedure and validation was iterated 1000 times. Results. The model's assignment accuracy was 75.9%. There was high accuracy in true-negative and false-negative classification using this model, which has previously been a criticism of NGS. Specificity was 97.1%, PPV 75.0% and NPV 76.2%. On comparison of abundance between ICM-positive and ICM-negative patients, Staphylococcus aureus was the strongest contributor (F=0.99) to model predictive power. In contrast, Cutibacterium acnes was less predictive (F=0.309) and abundant across infected and noninfected revisions. Discussion. This is the first study to utilize predictive algorithms on a large multicenter dataset to transform analytic NGS data into a clinically relevant diagnostic model. Our collaborative findings suggest NGS may be an independent adjunct for PJI diagnosis, while also facilitating pathogen identification. Future work applying machine-learning will improve accuracy and utility of NGS

Aim. Synovial fluid investigation is the best alternative to diagnose prosthetic joint infection (PJI) before adequate microbiological/histology sampling during revision surgery. Although accurate preoperative diagnosis is certainly recommended, puncturing every patient before revision arthroplasty raises concerns about safety and feasibility issues especially in difficult to access joint (e.g., hip), that often require OR time and fluoroscopy/ultrasound guidance. Currently there is no clear guidelines regarding optimal indications to perform preoperative joint aspiration to diagnose PJI before revision surgery. The main goal of this study is to determine the accuracy of our institutional criteria using the new European Bone and Joint Infection Society (EBJIS) PJI definition. Method. We retrospectively evaluated every single- or first-stage for presumed aseptic or known infected revision total hip/knee arthroplasty procedures between 2013–2020. Preoperative clinical and laboratory features were systematically scrutinized. Cases with insufficient information for accurate final PJI diagnosis (i.e., no perioperative synovial fluid examination or no multiple cultures including sonication of removed implant) were excluded. Preoperative joint aspiration is recommended in our institution if any of the following criteria are met: 1) elevated CRP and/or ESR; 2) early failure (<2 years) or repeat failure; 3) high clinical suspicion/risk factors are present. Performance of such criteria were compared against final postoperative EBJIS definition PJI diagnosis. Results. A total of 364 revision THAs or TKAs were performed during the study period. After excluding 258 cases with insufficient information, a total of 106 patients were ultimately included. 38 (35,8 %) were classified as confirmed infections, 10 (9.4 %) as likely infected and 58 (54.7%) as infection unlikely. Of those, 37 confirmed infection cases, 9 likely infected cases and 32 infection unlikely cases did have indication for preoperative synovial fluid collection before revision surgery. Institutional criteria showed 95.8 % Sensitivity, 44.83 % Specificity, 92.9 % Negative Predictive Value (NPV) and 59 % Positive Predictive Value (PPV). Conclusions. Sensitivity and NPV of the aforementioned institutional criteria are very high even with the use of the more sensitive EBJIS PJI definition. As such they seem to be a valid alternative in selecting patients that should be punctured before revision arthroplasty. They identify the vast majority of infected patients while saving a significant number of patients from unnecessary procedures

Aim. Metagenomic nanopore sequencing is demonstrating potential as a tool for diagnosis of infections directly from clinical samples. We have previously shown nanopore sequencing can be used to determine the causative bacterial species in prosthetic joint infections (PJI). However, to make predictions regarding antimicrobial resistance, human DNA contamination must be reduced so a greater proportion of sequence data corresponds to the microbial portion of the DNA extract. Here, we utilise selective DNA extraction from sonication fluid samples to begin to make predictions regarding antimicrobial resistance in PJI. Method. We investigated host cell DNA depletion with 5% saponin selective human cell lysis followed by nuclease digestion. Subsequently, bacterial cells were mechanically lysed before DNA extraction. Sequencing libraries from samples treated with and without saponin were prepared with a Rapid PCR Barcoding Kit. 1. and sequenced in multiplexes of 2–8 samples/flowcell on a GridION. Sequencing reads were analysed using the CRuMPIT pipeline and thresholds to indicate presence of a specific bacterial genus/species were investigated. Antimicrobial resistance determinants were detected using previously published sequences specifically for Staphylococcus aureus, as an example organism frequently causing PJI. Results. 247 DNA extracts from 115 sonication fluids plus controls were subjected to metagenomic sequencing, comprising extracts from 67 culture-positive (10 of which were culture-positive at <50 CFU/ml) and 48 culture-negative samples. 5% saponin depleted human DNA contamination, reducing the number of human sequenced bases to a median 12% from 98% in comparison to 5μm filtration without saponin. In 11 samples 5% saponin depleted human bases by <12% in comparison to 5μm filtration, which may be indicative of incomplete depletion. Bacteria observed in sonication fluid culture were identified to species-level in 49/65 (75%) cases, and to genus-level in 51/65 (78%). Specificity of sequencing was 103/114 (90%). Sequencing made a completely successful prediction of antimicrobial susceptibility in 8/19 S. aureus culture-positive samples treated with 5% saponin, and a partial prediction in 5/19 for the 8 antibiotics investigated. Without 5% saponin treatment sequencing could only detect a limited number of AMR determinants in 3/19 samples. Sequencing correctly predicted 13/15 (87%) resistant and 74/74 (100%) susceptible phenotypes where sufficient sequence data were available. Conclusions. Nanopore metagenomic sequencing can provide species identification in PJI. Additionally, depletion of human DNA improves depth of coverage and allows detection of antimicrobial resistance determinants, demonstrating as a proof of principle that nanopore sequencing could potentially provide a complete diagnostic tool in PJI. 1. Oxford Nanopore Technologies

Objectives. In this prospective cohort study, we investigated whether patient-specific finite element (FE) models can identify patients at risk of a pathological femoral fracture resulting from metastatic bone disease, and compared these FE predictions with clinical assessments by experienced clinicians. Methods. A total of 39 patients with non-fractured femoral metastatic lesions who were irradiated for pain were included from three radiotherapy institutes. During follow-up, nine pathological fractures occurred in seven patients. Quantitative CT-based FE models were generated for all patients. Femoral failure load was calculated and compared between the fractured and non-fractured femurs. Due to inter-scanner differences, patients were analyzed separately for the three institutes. In addition, the FE-based predictions were compared with fracture risk assessments by experienced clinicians. Results. In institute 1, median failure load was significantly lower for patients who sustained a fracture than for patients with no fractures. In institutes 2 and 3, the number of patients with a fracture was too low to make a clear distinction. Fracture locations were well predicted by the FE model when compared with post-fracture radiographs. The FE model was more accurate in identifying patients with a high fracture risk compared with experienced clinicians, with a sensitivity of 89% versus 0% to 33% for clinical assessments. Specificity was 79% for the FE models versus 84% to 95% for clinical assessments. Conclusion. FE models can be a valuable tool to improve clinical fracture risk predictions in metastatic bone disease. Future work in a larger patient population should confirm the higher predictive power of FE models compared with current clinical guidelines. Cite this article: F. Eggermont, L. C. Derikx, N. Verdonschot, I. C. M. van der Geest, M. A. A. de Jong, A. Snyers, Y. M. van der Linden, E. Tanck. Can patient-specific finite element models better predict fractures in metastatic bone disease than experienced clinicians? Towards computational modelling in daily clinical practice. Bone Joint Res 2018;7:430–439. DOI: 10.1302/2046-3758.76.BJR-2017-0325.R2

The aim of this study was to produce estimates of specificity and predictive value of presenting symptoms and signs of paediatric bone cancer, a rare and frequently misdiagnosed condition, to aid clinical decision-making in primary care. A systematic literature review plus questionnaire to primary care physicians were carried out to determine frequency of bone cancer symptoms in both cancer and the benign conditions as which cancer is misdiagnosed. Literature sources – Ovid MEDLINE (1950-May 2008), EMBASE (1980-May 2008) and AMED (Allied and Alternative Medicine) (1985-May 2008). Literature review methods – We included systematic reviews, cohort studies or case series (where n ≥ 10), reporting frequency of symptoms and signs at initial presentation, as originally recorded in case notes or observed by the authors, in subjects aged 0–18 years. Disease incidence data was taken from retrospective and prospective studies from 1980 onwards which recorded incidence over a defined time period, in a large pre-defined population within Europe, North America or Australia. Questionnaire respondents – 32 general practitioners and paediatric Accident & Emergency physicians throughout Scotland and England. Positive predictive values (PPVs) for bone cancer symptoms range from 0.003 to 0.034% (percentage of children presenting with symptom who have cancer). Specificity (percentage of children without cancer who do not have the symptom) varies considerably between symptoms and ranges from 24% (tenderness) to 95% (weight loss). Specificity can be improved by looking for combinations of symptoms. Weight loss and fever are the features with both highest specificity and highest PPV. Bone cancer symptoms, even those with high specificity for cancer, have low positive predictive value. We suggest that diagnosis based on initial presentation to primary care is intrinsically difficult and that delay in diagnosis is not unreasonable if it is to make use of time as a diagnostic aid

Introduction. Prospective comparative study to evaluate the efficacy of the ultrasound diagnosis vs MRI in rupture of the Triangular fibrocartilage with arthroscopic confirmation. Material and methods. 55 patients presenting clinical wrist pain were studied from January’2004 untill september 2006. Our patient selection was composed by 30 men and 25 women, and the age range was 17 to 70 years old. 40 were Right-handed and 15 Left-Handed. Patients presented wrist pain related to several disorders. Our protocol included Sonography with a 11–MHz linear array probe using real-time compound spatial imaging and 1T-MRI studies. Wrist arthroscopy was performed in all of them. Results. 67 % of our patients presented Triangular fibrocartilage rupture at arthroscopy. The distribution of our patients related to the complementary tests was:. - Arthroscopy (+) 37 cases out of 50 (64%). - Ultrasound (+) 21 out of 37 (+ Art)). - MRI (+) 22 out of 37 (+ Art). According to this results we can easily calculate the sensibility/specificity and PPV/PNV of both tests:. - Ultrasound Sensibility/Specificity: 58,3 %/36,8 %. - MRI Sensibility/Specificity: 61 %/47 %. - Ultrasound PPV/PNV: 58 %/31,8 %. - MRI PPV/PNV: 68 %/37 %. Conclusions. Due to the results we obtained in our study, we can consider ultrasound as sensible and specific as MRI at diagnosis for the rupture of the Triangular fibrocartilage. In our opinion we conclude that neither MRI nor ultrasound results should be considered satisfactory for a proper diagnosis. This could be sorted out by the use of more resolutive MRI and ultrasound equipments

Background: The presence of bacteria forming biofilms or prior antimicrobial use has been shown to reduce the sensitivity of the standard technique (PT cultures) in patients with infection of orthopedic implants. Culturing fluid resulting from sonication (FRS) of prosthesis could improve the microbiologic diagnosis. Objective: To analyze the diagnostic validity of culturing FRS of different orthopedic implants and PT culture. Methods: Between Jan 2007 and Apr 2008, patients undergoing knee or hip prosthesis removal, and those with ostheosyntesis or spinal instrumentation removal, were prospectively included (44 hip prosthesis, 63 knee prosthesis, 91 osteosynthesis and 14 spinal instrumentations). 5 PT specimens were collected for culture. Removed implants were sonicated during 5 min. (40Hz). Both, PT and FRS, were inoculated in aerobic agar (Chocolate Polyvitex), anaerobic agar (Schaedler + 5% blood) and in thioglycolat, for 7 days. Positive culture cut-off was defined as growing of > 5 CFU. Clinical diagnosis of prosthetic-joint infection was made as commonly accepted. Previous antimicrobial therapy was assessed. Diagnostic validity was calculated for both culturing methods. Sensitivity of methods was compared by Chi-square test (SPSS 15.0). Results: 212 cases were included. Diagnostic of infection was made in 17 hip prosthesis (THA), 20 knee prosthesis (TKA), 24 osteosynthesis (OS) and 6 spinal fusions (SI). Tissue culture was positive in 9 THA, 11 TKA 18 OS and 4 SI. Sonication culture was positive in 14 THA, 18TKA, 23 Os and 6 SI. Tissue culture: Sensibility: THA53%, TKA 55%, OS 75% and SI 66%. Specificity: THA 96%, TKA 100%, OS 96%, SI 100%. Sonications: Sensibility: THA 82%, TKA 90%, OS 95% and SI 100%. Specificity: THA 96%, TKA 100%, OS 92%, SI 100%. Statistical differences favoring sonication were found in sensitivity in knee arthroplasty and osteosynthesis implants. 6 patients received antibiotics for > 7 days before implant was removed. Sonication culture was positive in 4 of them whereas only one standard culture yielded positive. Conclusions: FRS cultures are more sensitive than PT cultures. Sensitivity of the method depends on which device is evaluated. Sonication also improves sensitivity of culture after preoperative antimicrobial therapy

Introduction. Next generation sequencing (NGS) has been shown to facilitate detection of microbes in a clinical sample, particularly in the setting of culture-negative periprosthetic joint infection (PJI). However, it is unknown whether every microbial DNA signal detected by NGS is clinically relevant. This multi-institutional study was conceived to 1) identify species detected by NGS that may predict PJI, then 2) build a predictive model for PJI in a developmental cohort; and 3) validate the predictive utility of the model in a separate multi-institutional cohort. Methods. This multicenter investigation involving 15 academic institutions prospectively collected samples from 194 revision total knee arthroplasties (TKA) and 184 revision hip arthroplasties (THA) between 2017–2019. Patients undergoing reimplantation or spacer exchange procedures were excluded. Synovial fluid, deep tissue and swabs were obtained at the time of surgery and shipped to MicrogenDx (Lubbock, TX) for NGS analysis. Deep tissue specimens were also sent to the institutional labs for culture. All patients were classified per the 2018 Consensus definition of PJI. Microbial DNA analysis of community similarities (ANCOM) was used to identify 17 candidate bacterial species out of 294 (W-value >50) for differentiating infected vs. noninfected cases. Logistic Regression with LASSO model selection and random forest algorithms were then used to build a model for predicting PJI. For this analysis, ICM classification was the response variable (gold standard) and the species identified through ANCOM were the predictor variables. Recruited cases were randomly split in half, with one half designated as the training set, and the other half as the validation set. Using the training set, a model for PJI diagnosis was generated. The optimal resulting model was then tested for prediction ability with the validation set. The entire model-building procedure and validation was iterated 1000 times. From the model set, distributions of overall assignment rate, specificity, sensitivity, positive predictive value (PPV) and negative predicative value (NPV) were assessed. Results. The overall predictive accuracy achieved in the model was 75.9% (Figure 1). There was a high accuracy in true-negative and false-negative classification of patients using this predictive model (Figure 2), which has previously been a criticism of NGS interpretation and reporting. Specificity was 97.1%, PPV was 75.0%, and NPV was 76.2%. On comparison of the distribution of abundances between ICM-positive and ICM-negative patients, Staphylococcus aureus was the strongest contributor (F=0.99) to the predictive power of the model (Figure 3). In contrast, Cutibacterium acnes was less predictive (F=0.309) and noted to be abundant across both infected and noninfected revision TJA samples. Discussion. This study is the first to utilize predictive modeling algorithms on a large prospective multicenter database in order to transform analytic NGS data into a clinically relevant diagnostic signal. Our collaborative findings suggest the microbial DNA signal identified on NGS may be an independent useful adjunct for the diagnosis of PJI, as well as help identify causative organisms. Further work applying artificial intelligence tools will improve accuracy, predictive power and clinical utility of high-throughput sequencing technology. For figures, tables, or references, please contact authors directly