Aim. Diagnosis of periprosthetic joint infection (PJI) is challenging given the limitations of available diagnostic tests. Recently, several studies have shown a role of the long pentraxin PTX3 as a biomarker in inflammatory diseases and infections. This single-center prospective diagnostic study evaluated the diagnostic ability of synovial fluid and serum PTX3 for the infection of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Method. Consecutive patients undergoing revision surgery for painful THA or TKA were enrolled. Patients with antibiotic therapy suspended for less than 2 weeks prior to surgery and patients eligible for metal-on-metal implant revision or spacer removal and prosthesis re-implantation were excluded. Quantitative assessment of synovial fluid and serum PTX3 was performed with ELISA method. Musculoskeletal Infection Society (MSIS) criteria were used as reference standard for diagnosis of PJI. Continuous data values were compared for statistical significance with univariate unpaired, 2-tailed Student's t-tests. Receiver operating characteristic (ROC) curve analyses was performed to assess the ability of serum and synovial fluid PTX3 concentration to determine the presence of PJI. Youden's J statistic was used to determine optimum threshold values for the diagnosis of infection. Sensitivity (Se), specificity (Sp), positive (PPV) and negative (NPV) predictive values, positive (LR+) and negative (LR-) likelihood ratio, area under the ROC curve (AUC) were calculated. Results. One-hundred fifteen patients (M:F=49:66) with a mean age of 62 years (40–79) underwent revision of THA (n=99) or TKA (n=16). According with MSIS criteria, 18 cases were categorized as septic and 97 as aseptic revisions. The average synovial fluid concentration of PTX3 was significantly higher in patients with PJI compared to patients undergoing aseptic revision (24,3 ng/dL vs 3,64 ng/dL; P=0.002). There was no significant difference in terms of serum concentration of PTX3 between the two groups. Synovial fluid PTX3 demonstrated an AUC of 0.96 (95%IC 0.89–0.98) with Se 94%, Sp 90%, PPV 67%, NPV 100%, LR+ 9.4 and LR- 0.06 for a threshold value of 4.5 ng/dL. Serum PTX3 demonstrated an AUC of 0.70 (95%IC 0.51–0.87) with Se 72%, Sp 67%, PPV 30%, NPV 93%, LR+ 2.2 and LR- 0.42 for a threshold value of 4.5 ng/dL. Conclusions. In patients undergoing revision surgery for painful THA or TKA, synovial PTX3 demonstrated a strong diagnostic ability for PJI. Synovial PTX3 could represent a more useful biomarker for detection of PJI compared with serum PTX3

Spinopelvic mobility describes the change in lumbar lordosis and pelvic tilt from standing to sitting position. For 1° of posterior pelvic tilt, functional cup anteversion increases by 0.75° after total hip arthroplasty (THA). Thus, spinopelvic mobility is of high clinical relevance regarding the risk of implant impingement and dislocation.

Our study aimed to 1) determine the proportion of OA-patients with stiff, normal or hypermobile spino-pelvic mobility and 2) to identify clinical or static standing radiographic parameters predicting spinopelvic mobility.

This prospective diagnostic cohort study followed 122 consecutive patients with end-stage osteoarthritis awaiting THA. Preoperatively, the Oxford Hip Score, Oswestry Disability Index and Schober's test were assessed in a standardized clinical examination. Lateral view radiographs were taken of the lumbar spine, pelvis and proximal femur using EOS© in standing position and with femurs parallel to the floor in order to achieve a 90°-seated position. Radiographic measurements were performed for the lumbar lordosis angle (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI) and pelvic-femoral-angle (PFA). The difference in PT between standing and seated allowed for patient classification based on spino-pelvic mobility into stiff (±30°).

From the standing to the sitting position, the pelvis tilted backwards by a mean of 19.6° (SD 11.6) and the hip was flexed by a mean of 57° (SD 17). Change in pelvic tilt correlated inversely with change in hip flexion.

Spinopelvic mobility is highly variable in patients awaiting THA and we could not identify any clinical or static standing radiographic parameter predicting the change in pelvic tilt from standing to sitting position. In order to identify patients with stiff or hypermobile spinopelvic mobility, we recommend performing lateral view radiographs of the lumbar spine, pelvis and proximal femur in all patients awaiting THA. Thereafter, implants and combined cup inclination/anteversion can be individually chosen to minimize the risk of dislocation.

No predictors could be identified. We recommend performing sitting and standing lateral view radiographs of the lumbar spine and pelvis to determine spinopelvic mobility in patients awaiting THA.

Specific and rapid detection methods for spinal tuberculosis, with sufficient sensitivity in HIV-1 co-infected individuals, are needed, to ensure early initiation of appropriate treatment to prevent physical disability and neurological fallout. In addition, understanding the systemic and local pathophysiology of spinal tuberculosis, and its interaction with HIV-1 infection, is crucial to guide future therapeutic interventions. We prospectively enrolled adult patients presenting with signs and symptoms of suspected spinal tuberculosis, at Groote Schuur Hospital, between November 2020 and December 2021. TB diagnostic testing was performed on open and CT-guided spinal biopsies using Xpert MTB/RIF Ultra compared to gold standards TB culture and histology. A highly sensitive droplet digital PCR assay for detecting and quantifying Mycobacterium tuberculosis complex (MTBC) and HIV-1 DNA was tested. Plasma inflammatory proteins were measured to assess systemic inflammation. Xpert Ultra had a high sensitivity of 94.7% and specificity of 100% for STB against TB culture and histology in both open and CT-guided biopsy samples. The ddPCR assay confirmed TB detection in 94% of patients with positive Xpert Ultra results. Four patients with negative TB diagnostic results had MTBC DNA detected by ddPCR. HIV-1 DNA was detected in the spinal tissues from all HIV-1-infected patients. MTBC DNA levels were significantly higher in HIV-1-co-infected spinal tissue samples (p< 0.01). We identified four biomarkers significantly associated with higher bacterial burden at the disease site (p< 0.01). Xpert Ultra and MTBC ddPCR improve the detection of STB. DdPCR can be utilized as an additional, highly sensitive tool for detecting and quantifying Mtb, in pathological samples that may be paucibacillary. These findings provide novel diagnostic and pathophysiologic insight into STB, in the context of HIV-1 infection, and provide rationale to include these tests in hospital and research settings for patients from communities burdened by TB and HIV-1

Aim. Diagnosing low-grade periprosthetic joint infections (PJI) can be very challenging due to low-virulent microorganisms capable of forming biofilm. Clinical signs can be subtle and may be similar to those of aseptic failure. To minimize morbidity and mortality and to preserve quality of life, accurate diagnosis is essential. The aim of this study was to assess the performance of various diagnostic tests in diagnosing low-grade PJI. Methods. Patients undergoing revision surgery after total hip and knee arthroplasty were included in this retrospective cohort study. A standardized diagnostic workup was performed using the components of the 2021 European Bone and Joint Infection Society (EBJIS) definition of PJI. For statistical analyses, the respective test was excluded from the infection definition to eliminate incorporation bias. Receiver-operating-characteristic curves were used to calculate the diagnostic performance of each test, and their area-under-the-curves (AUC) were compared using the z-test. Results. 422 patients undergoing revision surgery after total hip and knee arthroplasty were included in this study. 208 cases (49.3%) were diagnosed as septic. Of those, 60 infections (28.8%) were defined as low-grade PJI (symptoms >4 weeks and caused by low-virulent microorganisms (e. g. coagulase-negative staphylococci, Cutibacterium spp., enterococci and Actinomyces)). Performances of the different test methods are listed in Table 1. Synovial fluid (SF) - WBC (white blood cell count) >3000G/L (0.902), SF - %PMN (percentage of polymorphonuclear neutrophils) > 65% (0.959), histology (0.948), and frozen section (0.925) showed the best AUCs. Conclusion. The confirmatory criteria according to the EBJIS definition showed almost ideal performances in ruling-in PJI (>99% specificity). Histology and synovial fluid cell count (SF-WBC and SF-%PMN) showed excellent accuracies for diagnosing low-grade PJI. However, a reduced immune reaction in these cases may necessitate lower cut-off values. Intraoperative frozen section may be valuable in cases with inconclusive preoperative diagnosis. For any tables or figures, please contact the authors directly

Aim. Periprosthetic joint infection (PJI) is one of the main reasons for revision surgery after primary unicompartmental knee arthroplasty (UKA), total knee arthroplasty (TKA) or total hip arthroplasty (THA). Currently the MSIS and EBJIS criteria sets are considered to be the gold standards in determining PJI. These criteria sets are complex and contain tests that are time-consuming and many are rather costly. Therefore, further research is indicated to find a simpler but equally reliable diagnostic test. In this study we evaluated the additional value of calprotectine measurement in synovial fluid in patients undergoing hip and knee (revision) arthroplasty following routine work-up. Method. In a retrospective cohort study, we analyzed 182 synovial fluid samples from 143 patients with suspected PJI after UKA, TKA, THA or revision arthroplasty. Twenty-six of those cases were classified as PJI according to the MSIS and EBJIS criteria. Subsequently, synovial calprotectin was determined, using a lateral flow assay and two cut-off thresholds of ≥14 mg/L and ≥50 mg/L. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of synovial calprotectin was determined. Results. When applying the MSIS and EBJIS criteria and a calprotectin level ≥14 mg/L, synovial calprotectin revealed an area under the curve of 0.96 (95% CI 0.90-1.00), with 92.3% sensitivity and 100% specificity. The PPV and NPV were 100% and 92.9% respectively. When applying the MSIS and EBJIS criteria and a calprotectin level ≥ 50 mg/L, synovial calprotectin revealed an area under the curve of 0.94 (95% CI 0.87-1.00), with 88.5% sensitivity and 100% specificity. The PPV and NPV were 100% and 89.7% respectively. Conclusions. The value of calprotectin in synovial fluid gives valuable information with a single test result, resulting in high predictive value in the diagnosis of PJI after hip or knee arthroplasty and should seriously be considered as part of PJI diagnostics in an outpatient clinical setting. The high specificity can help rule in patients that are suspected of PJI. Therefor this test can be helpful in a preop diagnostic work-up to avoid unnecessary revisions in patients with well-placed and well-fixed arthroplasties with a suspected PJI. These conclusions are independent of which criteria set was used as a gold standard

The diagnosis of infection following shoulder arthroplasty is notoriously difficult. The prevalence of prosthetic shoulder infection after arthroplasty ranges from 3.9 – 15.4% and the most common infective organism is Cutibacterium acnes. Current preoperative diagnostic tests fail to provide a reliable means of diagnosis including WBC, ESR, CRP and joint aspiration. Fluoroscopic-guided percutaneous synovial biopsy (PSB) has previously been reported in the context of a pilot study and demonstrated promising results. The purpose of this study was to determine the diagnostic accuracy of percutaneous synovial biopsy compared with open culture results (gold standard). This was a multicenter prospective cohort study involving four sites and 98 patients who underwent revision shoulder arthroplasty. The cohort was 60% female with a mean age was 65 years (range 36-83 years). Enrollment occurred between June 2014 and November 2021. Pre-operative fluoroscopy-guided synovial biopsies were carried out by musculoskeletal radiologists prior to revision surgery. A minimum of five synovial capsular tissue biopsies were obtained from five separate regions in the shoulder. Revision shoulder arthroplasty was performed by fellowship-trained shoulder surgeons. Intraoperative tissue samples were taken from five regions of the joint capsule during revision surgery. Of 98 patients who underwent revision surgery, 71 patients underwent both the synovial biopsy and open biopsy at time of revision surgery. Nineteen percent had positive infection based on PSB, and 22% had confirmed culture positive infections based on intra-operative tissue sampling. The diagnostic accuracy of PSB compared with open biopsy results were as follows: sensitivity 0.37 (95%CI 0.13-0.61), specificity 0.81 (95%CI 0.7-0.91), positive predictive value 0.37 (95%CI 0.13 – 0.61), negative predictive value 0.81 (95%CI 0.70-0.91), positive likelihood ratio 1.98 and negative likelihood ratio 0.77. A patient with a positive pre-operative PSB undergoing revision surgery had an 37% probability of having true positive infection. A patient with a negative pre-operative PSB has an 81% chance of being infection-free. PSB appears to be of value mainly in ruling out the presence of peri-prosthetic infection. However, poor likelihood ratios suggest that other ancillary tests are required in the pre-operative workup of the potentially infected patient

Aim. To assess the clinical characteristics, diagnostic tests and treatment strategies in orthopedic implant-associated infections (OIAI) caused by Cutibacterium spp. Method. We retrospectively included consecutive patients with OIAI caused by Cutibacterium spp. treated at our institution from January 2012 to January 2017. OIAI was diagnosed when: (i) macroscopic purulence, sinus tract or exposed implant was present; (ii) acute inflammation in peri-implant-tissue was documented; (iii) Cutibacterium spp. grew in joint aspirate, ≥2 intraoperative peri-implant tissue samples or in sonication fluid of the removed implant (>50 CFU/ml). Results. Of 67 patients with Cutibacterium OIAI, 42 (63%) had an infected joint prosthesis (21 hip, 12 shoulder, 9 knee) and 25 (37%) an infected fixation device (10 spinal hardware, 11 osteosynthesis, 2 anchorages after rotator cuff reparation, 2 cruciate ligament grafts). 53 (84%) presented with a delayed (3–24 months) or late (>24months) infection. 62 infections were caused by C. acnes and 5 by C. avidum, all being susceptible to levofloxacin and rifampin. Among non-culture-based diagnostic tests, tissue histology had the highest sensitivity (68%), followed by increased synovial fluid leukocyte count/differential (59%). Of culture-based tests, sonication fluid culture showed the highest sensitivity (83%), followed by tissue culture (71%) and synovial fluid culture (61%). Culture positivity rates of synovial fluid, peri-implant tissue and sonication fluid were 20%, 41% and 40%, respectively, after 7 days of incubation and 58%, 74% and 78%, respectively, after 14 days. Most patients were treated with one-stage (24%) or two-stage (55%) implant exchange of the implant. The majority of patients received oral levofloxacin and rifampin for 6–12 weeks. Conclusions. Cutibacterium spp. affected various types of orthopaedic implants in different anatomic locations (lower and upper limbs and spine). Conventional diagnostic tests showed limited sensitivity of Cutibacterium OIAI and can be easily missed when cultures are incubated less than 10–14 days. All Cutibacterium isolates were susceptible to levofloxacin and rifampin

Aim. Diagnosis of periprosthetic joint infection (PJI) is still challenging due to limitations of available diagnostic tests. Many efforts are ongoing to find out novel methods for PJI diagnosis. Recently, several studies have shown a role of the long pentraxin PTX3 as a biomarker in inflammatory diseases and infections. This pilot diagnostic study evaluated the diagnostic ability of synovial fluid and serum PTX3 for the infection of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Method. Consecutive patients undergoing revision surgery for painful THA or TKA were enrolled. Patients with antibiotic therapy suspended for less than 2 weeks prior to surgery and patients eligible for spacer removal and prosthesis re-implantation were excluded. Quantitative assessment of synovial fluid and serum PTX3 was performed with ELISA method. Musculoskeletal Infection Society (MSIS) criteria were used as reference standard for diagnosis of PJI. Continuous data values were compared for statistical significance with univariate unpaired, 2-tailed Student's t-tests. Receiver operating characteristic (ROC) curve analyses was performed to assess the ability of serum and synovial fluid PTX3 concentration to determine the presence of PJI. Youden's J statistic was used to determine optimum threshold values for the diagnosis of infection. Sensitivity (Se), specificity (Sp), positive (PPV) and negative (NPV) predictive values, positive (LR+) and negative (LR-) likelihood ratio, area under the ROC curve (AUC) were calculated. Results. Sixty-two patients (M:F=28:34) with a mean age of 64 years (40–78) underwent revision of THA (n=52) or TKA (n=10). According with MSIS criteria, 10 cases were categorized as septic and 52 as aseptic revisions. The average synovial fluid concentration of PTX3 was significantly higher in patients with PJI compared to patients undergoing aseptic revision (23,56 ng/mL vs 3,71 ng/mL; P=0.0074). There was no significant difference in terms of serum concentration of PTX3 between the two groups. Synovial fluid PTX3 demonstrated an AUC of 0.93 (95%IC 0.86–0.97) with Se 100%, Sp 85%, PPV 55%, NPV 100%, LR+ 6.6 and LR- <0.01 for a threshold value of 3 ng/mL. Serum PTX3 demonstrated an AUC of 0.59 (95%IC 0.38–0.8) with Se 78%, Sp 50%, PPV 25%, NPV 90%, LR+ 1.56 and LR- 0.44 for a threshold value of 3 ng/mL. Conclusions. Synovial PTX3 demonstrated a strong diagnostic ability for PJI. PTX3 could represent a useful biomarker for detection of PJI in patients undergoing revision surgery for painful THA or TKA. Larger diagnostic studies are required to confirm these preliminary data

Introduction. Several studies have shown that functional outcomes are similar regardless of being discharged directly to home or to a rehabilitation center after total knee arthroplasty (TKA). Therefore, we sought to determine if there is a difference in patient care or patient satisfaction for patients discharged to in-patient rehabilitation or home-based rehabilitation. Materials and Methods. Between February and May of 2015, one hundred and seventy one consecutive patients were prospective identified after undergoing TKA by one of three surgeons. At an average of six-weeks post TKA, all patients were asked a patient administered questionnaire to determine if diagnostic testing (ultrasounds, or x-rays) or blood transfusions were performed during the first-six weeks at either home (n=86) or a rehab (n=85) facility. Results. Patients discharged to in-patient rehabilitation were found to be significantly older and sicker than patients discharged to home-based rehabilitation. Overall a greater number of diagnostic tests were performed on patient discharged to in-patient rehabilitation (23.5%) compared to patients discharged to home-based rehabilitation (8.1%) (p=0.032). Statistical analysis revealed discharge location, rather than age or health status, as the sole independent risk factor for a diagnostic testing being performed. The incidence of radiographs taken prior to the six week postoperative appointment was greater for patients discharged to rehab (10.6%) compared to those discharged home (1.1%) (p=0.008). There was no difference in the frequency of patients feeling like they received adequate physical therapy, adequate care or overall satisfaction. Twenty-nine (34.1%) patients were discharged under the care of the visiting nurse service after leaving the rehabilitation facility. Conclusions. Patients discharged to a rehabilitation facility underwent more testing than patients discharged directly to home. There was no difference in the patient satisfaction or their perception of their overall care. Over a third of patients who go to Rehab are subsequently discharged home under the care of the visiting nurse service. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Aim. Low-grade infections are difficult to diagnose. As the presence of a chronic infection requires extensive surgical debridement and antibiotic treatment, it is important to diagnose a SII prior to surgery, especially when the hardware is revised. We investigated whether serum inflammatory markers or nuclear imaging can accurately diagnose a chronic spinal instrumentation infection (SII) prior to surgery. Method. All patients who underwent revision spinal surgery after a scoliosis correction between 2017 and 2019 were retrospectively evaluated. The diagnostic accuracy of serum C-reactive protein (CRP) and Erythrocyte Sedimentation Rate (ESR), . 18. F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) and Technetium-99m-methylene diphosphonate (99mTc-MDP) 3-phase bone scintigraphy (TPBS) to diagnose infection were studied. Patients with an acute infection or inadequate culture sampling were excluded. SII was diagnosed if ≥ 2 of the same microorganism(s) were isolated from intra-operative tissue cultures. Results. 31 patients were included. The indication for hardware extraction was pseudoarthrosis in the majority of patients (n = 15). 22 patients (71%) were diagnosed with SII. In all infected cases, Cutibacterium acnes was isolated, including 5 cases with a polymicrobial infection. Sensitivity, specificity, PPV and NPV was: 4.5%, 100%, 100% and 30.0% for CRP >10.0 mg/L, 5.5%, 100%, 100% and 29% for ESR > 30 mm/h; 56%, 80%, 83% and 50% for FDG-PET/CT and 50%, 100%, 100% and 20% for TPBS, respectively. Conclusions. The prevalence of SII in patients undergoing revision spinal surgery is high, with Cutibacterium acnes as the main pathogen. No diagnostic tests could be identified that could accurately diagnose or exclude SII prior to surgery. Future studies should aim to find more sensitive diagnostic modalities to detect low-grade inflammation

Aims. The International Consensus Meeting on Musculoskeletal Infection (ICM, Philadelphia 2018) recommended histology as one of the diagnostic tests although this is not routinely used in a number of UK hospitals. This study aims to explore the role of histology in the diagnosis of infection and whether it is of practical use in those cases where the microbiology samples are either diagnostically unclear or do not correspond to the pre-operative diagnosis or the clinical picture. Patients and Methods. We identified 85 patients who underwent revision knee arthroplasty for either septic or aseptic loosening and for whom both microbiology and histology samples were taken. The procedures were performed by the senior experienced surgeons specialised in revision knee arthroplasty in two centres from Liverpool. Each patient had a minimum of five tissue samples taken, using separate knife and forceps and each sample was divided in half and sent for microbiology and histology in different containers. Fifty-four patients (63.5%) underwent a single-staged revision; ten patients (11.8%) underwent the 1. st. stage of a two staged revision; eleven patients (12.9%) underwent the 2. nd. stage of a two staged revision; one patient (1.2%) underwent an additional revision stage; three patients (3.5%) were treated with a DAIR; three patients (3.5%) had a 2-in-1 revision; two patients (2.4%) had a debridement and polyethylene exchange; and one patient (1.2%) had an arthroscopy biopsy of knee replacement. The cost to process five microbiology samples for each patient was £122.45 on average and for the five histology samples was £130. Results. In 63.5% (n=54) the histology and microbiology confirmed an aseptic joint as suspected beforehand. In 8.2% (n=7) the histology result was the same as the microbiology result confirming infection as suspected beforehand. In 15.3% (n=13) where asepsis was suspected beforehand, one of the five microbiology samples unexpectedly grew an organism but all the histological samples showed no evidence of infection. In these cases, the histology result supported the diagnosis of the likelihood of a contaminant. In 5.9% (n=5) we found differences in the microbiology and histology in one sample and in 7.1% (n=6) the histology was different to the microbiology in more than one sample. Conclusions. In cases where the diagnosis of sepsis within a knee replacement is not in doubt due to pre-operative microbiology, we found no benefit in additional histology sampling. In 28.3% of the cases, the histology was of use in the diagnosis of infection in complex cases and a useful tool in the decision process for further management. In over half of the cases where the revision was for aseptic loosening, the histology result did not alter the management but 28.3% of cases that were thought to be aseptic, microbiology revealed at least one positive sample hence the histology was of use in making a final diagnosis, be that of infection, contamination or to rule out infection. Whilst histology is of use in the latter groups but not the aseptic group, these outcomes are not predictable until after the post-operative period hence histology is required in all these cases. Overall, the histology is a cheap test which is of benefit in the diagnosis of complex peri-prosthetic joint infection in one–third of cases and we support the ICM recommendation

Aim. One of the most accurate and inexpensive tests in detection of prosthetic joint infection (PJI) is synovial fluid white blood cell (WBC) count and differential. Since leukocytes produce many different interleukins (IL) in situation of PJI, we hypothesized that ILs could be even more accurate in detection of PJI. The aim of the study was to test, if the synovial fluid IL-6 level is superior to WBC count and differential in detection of PJI. Methods. Unselected patients undergoing total hip or knee revision surgery were prospectively included. In perioperative assessment phase, WBC count, differential and IL-6 levels of synovial fluid were measured. Patients were labelled as positive or negative according to the predefined cut-off values for IL-6 (230pg/ml) and WBC count with differential (1,7 × 10. 9. WBC/ml with ≥65% of granulocytes). During the surgery, at least 4 intraoperative samples for microbiological and one for histopathological analysis were obtained. PJI was defined as presence of sinus tract, inflammation in histopathological samples, and growth of the same microorganism in at least two or more samples of periprosthetic tissue or synovial fluid. Binary diagnostic test was performed to check the diagnostic strength of both methods in detection of PJI. Results. 49 joints of 48 patients (mean age, 71 years; 53% females) undergoing artificial hip (n = 24) or knee (n = 25) revision surgery were included. 11 joints (22%) were infected. Sensitivity of synovial fluid WBC count with differential was 82%, specificity 97%, accuracy 94%, positive and negative predictive values were 90% and 95%, respectively. Sensitivity of IL-6 level was 73%, specificity 95%, accuracy 90%, positive and negative predictive values were 80% and 92%, respectively. There was a strong statistical agreement between both tests (Kappa value=0.749) and consequently there was no significant difference in detection of PJI comparing both tests (P=0.171). Conclusion. Our study revealed that synovial fluid IL-6 level is not superior to synovial fluid WBC count with differential in detecting PJI

This study addresses a crucial gap in the knowledge of normative spinal growth in children. The objective of this study is to provide detailed and accurate 3D reference values for global and segmental spinal dimensions in healthy children under the age of 11. Radiographic spine examinations of healthy children conducted to rule out scoliosis were reviewed in four scoliosis referral centers in North America. All consecutive children aged three to eleven years old with EOS biplanar good quality x-rays, but without diagnosed growth-affecting pathologies, were included. Postero-Anterior and Lateral calibrated x-rays were used for spine 3D reconstruction and computation of vertebral body height and spine length. Median and interquartile range were calculated from cross-sectional data. Smooth centiles growth curves for 3D True Spinal Length (3DTSL) between T1 and S1, as well as for mid-vertebral heights of T5, T12 and L3, where fit and calibrated from data using the Lambda-Mu-Sigma method (GAMLSS package for R). This method automatically selects the best performing distribution from a familly of choices. Tables of centiles were then predicted from the computed models for selected ages. A total of 638 full spine examinations from asymptomatic patients were reconstructed in 3D, 397 in girls and 241 in boys. Medians and interquartile ranges were calculated for 3DTSL (T1-S1): 285 (24) mm, 314 (26) mm and 349 (31) mm, and for selected vertebral heights T5: 10 (1) mm, 11 (1) mm and 12 (1) mm, T12: 13 (2) mm, 14 (1) mm and 16 (2) mm, and L3: 14 (1) mm, 16 (2) mm and 18 (2) mm, respectively for the 3–6, 6–8 and 8–11 age groups. Centile curves ready for clinical use of the 3DTSL (T1-S1) and of the vertebral heights of T5, T12 and L3 as a function of age were derived for the 5, 10, 25, 50, 75, 90 and 95th centiles. In general, boys presented linear relationships between spinal dimensions and age, and girls presented more diverging trends with increased variance for older ages. Accordingly curves for boys follow the Normal distribution whereas those for girls follow the original Box-Cox-Cole-Green distribution. Model diagnostic tests (normally distributed residuals, adequate wormplots and |Z statistics| < 2) confirmed adequacy of the models and the absence of significant misfit. Accurate reference values were derived for spinal dimensions in healthy children. Spinal dimension charts showed that the spinal lengths and vertebral heights changed relatively constantly across the age groups closely resembling WHO total body height charts. The reference values will help physicians better assess their patients' growth potential. It could also be used to predict expected spinal dimensions at maturity or changes in pathologic conditions as well as to assess the impact of growth friendly interventions in the correction of spinal deformities

Aims. Tuberculosis (TB) infection of bones and joints accounts for 6.7% of TB cases in England, and is associated with significant morbidity and disability. Public Health England reports that patients with TB experience delays in diagnosis and treatment. Our aims were to determine the demographics, presentation and investigation of patients with a TB infection of bones and joints, to help doctors assessing potential cases and to identify avoidable delays. Patients and Methods. This was a retrospective observational study of all adults with positive TB cultures on specimens taken at a tertiary orthopaedic centre between June 2012 and May 2014. A laboratory information system search identified the patients. The demographics, clinical presentation, radiology, histopathology and key clinical dates were obtained from medical records. Results. A total of 31 adult patients were identified. Their median age was 37 years (interquartile range (IQR): 29 to 53); 21 (68%) were male; 89% were migrants. The main sites affected were joints (10, 32%), the spine (8, 26%) and long bones (6, 19%); 8 (26%) had multifocal disease. The most common presenting symptoms were pain (29/31, 94%) and swelling (26/28, 93%). ‘Typical’ symptoms of TB, such as fever, sweats and weight loss, were uncommon. Patients waited a median of seven months (IQR 3 to 13.5) between the onset of symptoms and referral to the tertiary centre and 2.3 months (IQR 1.6 to 3.4.)) between referral and starting treatment. Radiology suggested TB in 26 (84%), but in seven patients (23%) the initial biopsy specimens were not sent for mycobacterial culture, necessitating a second biopsy. Rapid Polymerase Chain Reaction-based testing for TB using Xpert MTB/RIF was performed in five patients; 4 (80%) tested positive for TB. These patients had a reduced time between the diagnostic biopsy and starting treatment than those whose samples were not tested (median eight days versus 36 days, p = 0.016). Conclusion. Patients with bone and joint TB experience delays in diagnosis and treatment, some of which are avoidable. Maintaining a high index of clinical suspicion and sending specimens for mycobacterial culture are crucial to avoid missing cases. Rapid diagnostic tests reduce delays and should be performed on patients with radiological features of TB. Cite this article: Bone Joint J 2018;100-B:119–24

Aim. Diagnosing periprosthetic joint infection after total joint arthroplasty is often challenging. The alpha defensin test has been recently reported as a promising diagnostic test for periprosthetic joint infection. The goal of this study was to determine the diagnostic accuracy of alpha defensin testing. Method. One hundred and eighty-three synovial alpha defensin and synovial fluid C-reactive protein (CRP) tests performed in 183 patients undergoing evaluation for periprosthetic joint infection were reviewed. Results were compared with the Musculoskeletal Infection Society (MSIS) criteria for periprosthetic joint infection. Results. Alpha defensin tests were performed prior to surgical treatment for infection, and 37 of these patients who had these tests were diagnosed by MSIS criteria as having infections. Among this group, the alpha defensin test had a sensitivity of 81.1% (95% confidence interval [CI], 64.8% to 92.0%) and a specificity of 95.9% (95% CI, 91.3% to 98.5%). There were 6 false-positive results, 4 of which were associated with metallosis. There were 7 false negatives, all of which were associated with either draining sinuses (n = 3) or low-virulence organisms (n = 4). A combined analysis of alpha defensin and synovial fluid CRP tests was performed in which a positive result was represented by a positive alpha defensin test and a positive synovial fluid CRP test (n = 28). Among this group, the sensitivity was calculated to be 73.0% (95% CI, 55.9% to 86.2%) and the specificity was calculated to be 99.3% (95% CI, 96.2% to 99.9%). An additional combined analysis was performed where a positive result was represented by a positive alpha defensin test or positive synovial fluid CRP test (n = 64). Among this group, the sensitivity was calculated tobe91.9%(95%CI, 78.1%to98.3%) andthe specificitywas calculated tobe79.5%(95%CI, 72.0%to85.7%). Conclusions. Alpha defensin in combination with synovial fluid CRP demonstrates very high sensitivity for diagnosing periprosthetic joint infection, but may yield false-positive results in the presence of metallosis or false-negative results in the presence of low-virulence organisms. When both alpha defensin and synovial fluid CRP tests are positive, there is a very high specificity for diagnosing periprosthetic joint infection

Background. In October 2008, CMS instituted a new “No payment for preventable complications“ programme and has released a list of conditions for which it intends to expand the programme in 2009. Although not reimbursing for preventable complications is justifiable, some of the proposed target conditions are lacking in both adequate diagnostic testing accuracy and preventability. Aims. This study examines the effects of imperfect sensitivity and specificity of diagnostic testing, the prevalence of condition, and the rate of surveillance on the ratio of numbers of DVT/PE diagnosed and those that actually occur. Methods. Given that proximal DVT following orthopaedic surgery are not preventable (incidence 4-10% despite prophylaxis), and that the accepted screening test (duplex ultrasonongraphy) has a sensitivity of 96.5% and specificity of 94%, up to 2.5 times as many DVT will be diagnosed as actually occur. Since the new CMS policy would withhold payment when a complication is identified, hospitals would be encouraged to decrease screening for DVT, which would save them lost reimbursement but would result in an increase in incidence of unrecognised – and therefore untreated – DVT after major orthopaedic surgical procedures. The study examines the likely CMS savings in the United States for implementation of this proposed policy (estimated $300M annually), as well as the potential increase in undiagnosed DVT likely to result from implementation of the policy. The overall goal of this study is to provide information to better enable the reader to draw their own conclusions on whether non-payment for DVT after an orthopaedic procedure is a fiscal policy that makes sense and improves the health and healthcare of Americans

Introduction. While prosthesis survival in Total Knee Arthroplasty (TKA) exceeds 90% at 10 year, failures do occur. One area of concern has been the potential for metal allergy or metal sensitivity causing persistent pain, swelling or early failure of the implant in some patients. Definitive tests for diagnosing metal allergy and metal sensitivity have not been developed and this field remains controversial. In most cases where metal sensitivity is a concern, metals such as Chromium and Nickel are implicated. Despite the lack of good diagnostic tests for identifying these patients, several orthopedic prosthesis manufacturers have developed implants made of Titanium or ceramic designed for use in patients where concerns exist regarding metal allergy. In the absence of good diagnostic tests, use of these devices in patients that self identify is one option. To date, little information has been presented about the incidence of self reported metal sensitivity in patients undergoing joint replacement. This study was undertaken to determine the incidence of self reported metal allergy or sensitivity in patients undergoing total knee arthroplasty. Methods. An IRB approved, retrospective chart review was performed in a consecutive series of 194 patients who had undergone TKA at one institution, with one surgeon. Self reported metal sensitivity and allergy had been routinely elicited from each individual who had not undergone implantation of a previous metallic device, during pre-operative consultation. Results. 36 of the 194 patients had a previously well functioning implanted metal device. In addition, data was missing in 19 patients. Therefore, data from 139 out of 158 consecutive patients who had no prior implanted metal devices was available. 20 of 139 patients (14%) reported a known metal allergy or sensitivity. This included 19 of 86 females (22%) and 1 of 53 males (2%). This difference was statistically significant (P=0.001). Conclusions. If self reported prior metal sensitivity or allergy is used to guide prosthesis selection in TKA, approximately 14% of patients would be candidates for “hypo-allergenic” prostheses. If only particular sizes of components are offered in these alternative materials, smaller sizes or female gender specific sizes should be considered due to the higher incidence of self reported metal allergies in female patients

The use of peritumoral oedema on magnetic resonance (MR) imaging to predict soft tissue tumour grade is controversial. The clinical significance of oedema visualised on MR scans is poorly defined in the literature. We undertook this study to ascertain a diagnostic relationship between peritumoral oedema surrounding soft tissue sarcomas and the histological grade of the tumour. One hundred and ten consecutive soft tissue tumours were extracted from the New Zealand Bone and Soft Tissue Tumour Registry. Key inclusion criteria were tumours deep to fascia, measuring more than 5cm in any dimension. Both benign and malignant sarcomas were included. MR scans and histology were reviewed, separately and in random order by a single author. Histology was graded as benign, low or high grade (based on the American Joint Committee on Cancer grading system). Peritumoral oedema was defined as the increased signal intensity, on T2 or STIR images, immediately surrounding a discrete lesion. It was measured on two or more planes with the largest value used in diagnostic calculations. Oedema greater than or equal to 20mm was defined as a positive test result. Twenty five random scans were double read to ensure inter-observer reliability. Data was obtained for 83 tumours, 36 benign and 47 malignant (34 high grade and 13 low grade). The tumours in all groups were matched for size. The mean peritumoral oedema was 10.5mm for benign tumours, 20.6mm for low grade sarcomas (p<0.1), 28.1mm for high grade tumours (p<0.01) and 26.1mm if all malignant tumours were included as a single group (p<0.01). Using peritumoral oedema as a diagnostic test for tumour grade resulted in a specificity of 72%. The highest diagnostic ability was found when comparing benign to high grade tumours which yielded sensitivity of 59% and a positive likelihood ratio of 2.1. This data suggests a high false negative rate and that the test adds little to the diagnostic process. To our knowledge this is the first study which assesses the diagnostic accuracy of peritumoral oedema to predict the histological grade of soft tissue sarcomas. Our results show a statistically significant difference, in surrounding peritumoral oedema, exists when comparing benign to high grade sarcomas and to all malignant tumours. This relationship is not apparent for low grade tumours. As a diagnostic test, using only peritumoral oedema to predict histological grade is unreliable

Aim. To determine whether rep-PCR genotyping can improve the diagnosis of coagulase-negative staphylococci(CoNS)bone and joint infection relative to the standard method based on phenotypic identification. Method. Observational study comparing diagnostic tests (January 2011-March 2015), including all orthopaedic surgery patients with clinically suspected infection and ≥2 surgical specimens culture-positive for CoNS. Data collection included epidemiologic and clinical information, current clinical signs of suspected infection, and microbiological information. Each CoNS strain was analyzed by both methods (phenotyping, VITEK and API;and genotyping, rep-PCR). In accordance with current IDSA guidelines, CoNS strains identified as identical in ≥2 samples within the same surgical episode were considered pathogenic. The results of the two techniques were compared and statistically analyzed. Results. 255 CoNS isolates from 52 surgical episodes with suspected infection in 42 patients (55% male, mean age 61.5±20.6 years) were included. The patients' Charlson comorbidity index was 0.7±1.1. Implanted material was present in 79% of episodes and the surgical site had undergone previous surgery in 93%. CoNS infection was diagnosed by phenotyping in 73% of patients (mean, 2.2±1.3 different strains identified per episode)and 77% by rep-PCR analysis(mean, 1.8±0.6 different strains per episode). The kappa index of concordance was 0.59±0.14 (p<0.01). In patients in whom CoNS was considered not a cause of infection by phenotyping, 37% were considered infective agents by genotyping, accounting for 10%of the total. Conclusions. The two diagnostic methods showed moderate agreement in the diagnosis of postoperative bone and joint infection. Rep-PCR had a somewhat higher capacity for identifying CoNS strains. Rep-PCR could be of value as a complementary technique to phenotyping when the latter technique identifies CoNS strains as being non-pathogenic

The AAOS clinical practice guideline for diagnosis of periprosthetic joint infection (PJI) and the MSIS definition of PJI were both “game changers” in terms of diagnosing PJI and the reporting of outcomes for research. However, the introduction of new diagnostic modalities, including biomarkers, prompted a re-look at the diagnostic criteria for PJI. Further there was a desire to develop an evidence-based, validated algorithm for the diagnosis of PJI. This multi-institutional study led by Dr. Jay Parvizi examined revision total joint arthroplasty patients from three academic institutions. For development of the algorithm, infected and aseptic cohorts were defined. PJI cases were defined using only the major criteria from the Musculoskeletal Infection Society (MSIS) definition (n=684). Aseptic cases underwent revision for a non-infective indication and did not show evidence of PJI or undergo a reoperation for any reason within 2 years (n=820). Risk factors, clinical findings, serum and synovial markers as well as intraoperative findings were assessed. A stepwise approach using random forest analysis and multivariate regression was used to generate relative weights for each of the various variables assessed at each stage to create an algorithm for diagnosing PJI using the 3 most important tests from each step. The algorithm was formally validated on a separate cohort of 422 patients, 222 who were treated with a 2-stage exchange for PJI who subsequently failed secondary to PJI within one year and 200 patients who underwent revision surgery for an aseptic diagnosis and had no evidence of PJI within two years and did not undergo a reoperation for any reason. The first step in evaluating PJI should include a physical examination to identify a sinus tract, followed by serum testing for C-reactive protein (cut-off value 1mg/dl), D-dimer (cut-off value 860ng/mL) and/or erythrocyte sedimentation rate (cut-off value 30mm/hr) in that order of importance. If at least one of these are elevated, or if there is a high clinical suspicion, joint aspiration should be performed, sending the fluid obtained for a synovial fluid white blood-cell (cut-off value 3,000 wbc/uL) or leukocyte esterase strip testing, polymorphonuclear percentage (cut-off value 80%) and culture. Alpha defensin did not show added benefit as a routine diagnostic test. Major diagnostic criteria are the same whereby the presence of a sinus tract or (2) positive cultures showing the same organism defines PJI. Special care should be taken in cases of ALTR (failed metal-on-metal bearing), crystalline deposition disease, inflammatory arthritis flares or slow growing organisms. In the rare cases where no fluid is obtained at the time of an attempted aspiration and revision surgery is not planned, then this is the rare scenario where nuclear imaging (my preference is an indium labeled white blood cell scan) or a biopsy can be performed. The updated definition of PJI demonstrated a higher sensitivity of 97.7% when compared to the MSIS criteria (79.3%) and the ICM definition (86.9%), with a similar specificity of 99.5%. However, just over 2% of patients examined do fall into the “inconclusive” category. The proposed diagnostic algorithm demonstrated a high overall sensitivity (96.9%) and specificity (99.5%)