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Objectives Digital annular pulleys (DAPs) are important anatomical structures for finger function. The anatomy, histology and imaging assessment of DAPs, particularly at the level of their entheses, are still not clearly defined. The advent of high-frequency US transducers opened new perspectives in evaluating submillimetre-scale structures, such as pulleys, paving the way for their global assessment. The study aimed to characterize DAPs from an anatomical, histological and US perspective, focusing on the detection and complete description of pulley entheses. Methods US assessment and gross anatomy dissection were conducted on 20 cadaveric hands to study DAP thickness and structure, including enthesis identification. The results of the US and anatomical measurements were correlated. DAP entheses identified by US were characterized via histological analysis. DAPs in 20 healthy controls (HCs) were detected and measured by US. The A1, A2 and A4 DAP entheses were assessed using a new dynamic manoeuvre to better evaluate those structures. Results A total of 1200 DAPs (400 cadaveric, 800 HCs) were analysed. The cadaveric study demonstrated strong correlation between anatomical and US measurement of DAPs (r  = 0.96). At the histological level, DAP entheses at the volar plate, sesamoid bones or phalangeal ridges contained fibrous and fibrocartilaginous tissue. US assessment of A1, A2 and A4 DAPs in HCs allowed the identification of 718/720 (99.73%) entheses. Conclusion US is an effective tool to detect and study DAPs. DAP entheses reveal both fibrous and fibrocartilaginous characteristics. A newly described manoeuvre to optimize DAP enthesis visualization enhances their detection by US. [ABSTRACT FROM AUTHOR]

Objective SpA and PsA represent two frequent inflammatory rheumatic disorders characterized by an increased burden on quality of life due to the association of several comorbidities, especially cardiovascular disease (CVD). The estimated prevalence of CVD ranges from 12 to 19% and differs between the two diseases, however, the incidence of CVD is not completely known. We aimed to systematically review the literature and perform a meta-analysis of controlled observational studies to assess the incidence rate of CVD over time in SpA and PsA. Methods We performed a systematic literature review (SLR) of longitudinal studies with a study period of at least 5 years, including SpA/PsA patients and general population. The main outcome was the occurrence of CVD, including ischaemic heart disease, stroke and death from CV causes. We then performed a random-effects model for meta-analysis. Results The SLR included 34 articles, mainly focused on the association between SpA/PsA and CVD. Twenty-four articles were then selected for the meta-analysis. The overall incidence of CVD was increased in PsA [hazard ratio (HR) 1.28 (95% CI 1.15, 1.43)] and in SpA [HR 1.45 (95% CI 1.22, 1.72)] compared with the general population, with consistency across the different types of CVDs. Interestingly the incidence tended to decrease over time in PsA but not in SpA. Conclusion The SLR and meta-analysis confirmed the increased incidence of CVD in both SpA and PsA patients compared with the general population, although the increase seems to be less prominent in PsA than in SpA. Future studies are needed to confirm our findings. [ABSTRACT FROM AUTHOR]

Objective To evaluate the prevalence of clinical and US (grey-scale and Doppler) abnormalities in joints, periarticular structures and nails of children affected by skin psoriasis (PsO). Methods We conducted a cross-sectional study including consecutive children affected by PsO. A systematic clinical and US evaluation of joints, entheses, tendons and nails were performed by independent examiners blinded to each other's assessment. Results A total of 57 children [26 girls (46%)] with a mean age of 9 years (s. d. 4) were divided into two groups, asymptomatic (Asy, 42 children) and symptomatic (Sy, 15 children), according to musculoskeletal pain. Differences were observed between the two groups in relation to age [9 years (s. d. 3) vs 11 years (s. d. 4), P  < 0.05], PsO duration [2.4 years (s. d. 2.4) vs 5.4 years (s. d. 3.9), P  < 0.001], systemic treatment [23 (54.8%) vs 2 [13.3%], P  < 0.01], tender joint count [0 vs 12 children (80%), P  < 0.001], swollen joint count [0 vs 3 children (20%), P  < 0.01] and entheseal pain [0 vs 10 (66.7%), P  < 0.001] in Asy and Sy children, respectively. US evaluation showed statistically significant differences between the Asy and Sy groups for the presence of US abnormalities [16/42 (38%) vs 12/15 (80%)], synovitis [1/42 (2%) vs 4/15 (25%)] and enthesitis [4/42 (9.5%) vs 5/15 (33%)]. Three children in the Sy group were classified with juvenile PsA (JPsA). Conclusions US abnormalities were higher in the Sy group, with synovitis and enthesitis as the most prevalent findings. Asy patients were more frequently under systemic treatment. US and a systematic clinical evaluation are useful tools for detecting subclinical JPsA in children with PsO and musculoskeletal symptoms. [ABSTRACT FROM AUTHOR]

The article responds to comments on the article on the prevalence of findings suggestive of inflammatory arthritis in children with skin psoriasis (PsO). Topics discussed include the possible use of ultrasound (US) abnormalities in early detection of juvenile skin psoriasis in adults (PsA), and the importance of musculoskeletal examination of children with PsO in early PsA detection. Also noted are the findings of less US abnormalities among children under systemic treatment.

Objectives To delineate the impact of peripheral musculoskeletal manifestations on stratification of disease phenotype and outcome in new-onset spondyloarthritis (SpA), using a prospective observational nationwide inception cohort, the BelGian Inflammatory Arthritis and spoNdylitis cohorT (Be-Giant). Methods Newly diagnosed adult SpA patients, fulfilling the Assessment of SpondyloArthritis International Society (ASAS) criteria for axial or peripheral SpA, were included in Be-Giant and prospectively followed every six months. Peripheral involvement (defined as arthritis, enthesitis and/or dactylitis) was determined in relation to clinically similar patient subsets at baseline and disease activity patterns during two-year follow-up, identified through K-means cluster analysis and latent class growth analysis. Results From November 2010 to March 2020, 367 patients were enrolled in Be-Giant, of whom 162 (44%) had peripheral manifestations. Two patient clusters [A, axial predominant (n  = 248) and B, peripheral predominant (n  = 119)] were identified at diagnosis. Longitudinal analysis (n  = 115) revealed two trajectories of disease activity in each cluster: one with persistently high disease activity over time ('High'), the other rapidly evolving to low disease activity ('Low'). In cluster A patients, peripheral manifestations predisposed to the 'High' trajectory [odds ratio (OR) = 2.0, 95% CI: 1.3, 3.1, P  = 0.001], despite more rapid initiation of biologics compared with patients without peripheral manifestations (hazard ratio (HR)  = 2.1, 95% CI: 1.0, 4.4, P  = 0.04 – Cox proportional-hazards model). Conclusion Peripheral musculoskeletal manifestations are major determinants of phenotypical diversity in new-onset SpA. Intriguingly, stratification of axial SpA according to concomitant peripheral involvement identified an endotype with an unfavorable outcome despite more prompt therapeutic intensification with biologics. These observations justify an endotype-tailored approach beyond current ASAS/EULAR management recommendations. [ABSTRACT FROM AUTHOR]

Objectives To assess whether two cluster analysis-based axial SpA (axSpA) endotypes (A for purely axial; B for both axial and peripheral) are stable over time and are associated with different long-term disease outcomes. Methods K-means cluster analysis was performed at each visit (until 5 years) on 584 patients from the DESIR cohort, who completed all planned visits, and validated in 232 consecutive axSpA patients from the BeGiant cohort. Cluster stability overtime was assessed by kappa statistics. A generalized linear mixed-effect analysis was applied to compare outcomes between clusters. Classification and regression tree (CART) analysis was performed to determine a decision rule able to assign a given patient to a definite cluster at onset. Results Both endotypes remained remarkably stable over time. In the DESIR cohort, patients in cluster B showed higher disease activity, worse functional outcome and higher need for anti-rheumatic drugs than patients in cluster A. CART analysis yielded three main clinical features (arthritis, enthesitis and dactylitis) that accurately determined cluster assignment. These results could be replicated in the Be-GIANT cohort. Conclusion Cluster-based axSpA endotypes were reproducible in two different cohorts, stable over time and associated with different long-term outcome. The axSpA endotype with additional peripheral disease manifestations is associated with more severe disease and requires more intensive drug therapy Clinical trial registration clinicaltrials.gov, https://clinicaltrials.gov , NCT01648907. [ABSTRACT FROM AUTHOR]

Objectives To investigate the dynamics of response of synovitis to IL-17A inhibition with secukinumab in patients with active PsA using Power Doppler ultrasound. Methods The randomized, placebo-controlled, Phase III ULTIMATE study enrolled PsA patients with active ultrasound synovitis and clinical synovitis and enthesitis having an inadequate response to conventional DMARDs and naïve to biologic DMARDs. Patients were randomly assigned to receive either weekly subcutaneous secukinumab (300 or 150 mg according to the severity of psoriasis) or placebo followed by 4-weekly dosing thereafter. The primary outcome was the mean change in the ultrasound Global EULAR and OMERACT Synovitis Score (GLOESS) from baseline to week 12. Key secondary endpoints included ACR 20 and 50 responses. Results Of the 166 patients enrolled, 97% completed 12 weeks of treatment (secukinumab, 99%; placebo, 95%). The primary end point was met, and the adjusted mean change in GLOESS was higher with secukinumab than placebo [−9 (0.9) vs −6 (0.9), difference (95% CI): −3 (−6, −1); one-sided P= 0.004] at week 12. The difference in GLOESS between secukinumab and placebo was significant as early as one week after initiation of treatment. All key secondary endpoints were met. No new or unexpected safety findings were reported. Conclusion This unique ultrasound study shows that apart from improving the signs and symptoms of PsA, IL-17A inhibition with secukinumab leads to a rapid and significant reduction of synovitis in PsA patients. Trial registration ClinicalTrials.gov; NCT02662985. [ABSTRACT FROM AUTHOR]

Background To assess the reliability of the consensually agreed US definitions of major salivary gland lesions and the US scoring system for salivary gland assessment in patients with SS. Methods Nine experienced sonographers scanned and read the US images of both parotid glands (PGs) and submandibular glands (SMGs) in eight patients with primary and secondary SS in two rounds. A consensually agreed four-grade semi-quantitative scoring was applied in B-mode for morphological lesions: grade 0, normal; grade 1, mild inhomogeneity without anechoic or hypoechoic areas; grade 2, moderate inhomogeneity with focal anechoic or hypoechoic areas; grade 3, severe inhomogeneity with diffuse an- or hypoechoic areas occupying the entire gland or fibrous gland. The presence or absence of typical SS lesions, i.e. the Sjögren's signature, was scored binary. Intra- and interreader reliabilities were computed using weighted and unweighted Cohen's and Light's κ coefficients. Results The mean prevalence of grades 0–3 in PG were 43, 17, 23 and 31% and 28, 14, 33 and 32% for the SMGs, respectively. The weighted κ for intrareader reliability ranged from 0.44 to 1 for grading and 0.64 to 1 for the Sjögren's signature of PG and 0.59 to 1 and −0.09 to 0.6 for SMGs, respectively. The interreader reliability κ for grading in PG was 0.62 (95% CI 0.47, 0.74) and for Sjögren's signature it was 0.36 (95% CI 0, 0.43); in SMG it was 0.62 (95% CI 0.47, 0.72) and 0.03 (95% CI 0, 0.07) respectively. Conclusions The consensually agreed novel US scoring system for major salivary gland lesions showed substantial intra- and interreader reliability in patients with SS. The reliability of the Sjögren's signature was moderate. [ABSTRACT FROM AUTHOR]

Objectives Ultrasound (US) can detect cortical bone lesions in RA. However, not all cortical bone lesions are erosions. Herein, we aimed to define whether US can differentiate between physiological bone channels and pathological erosions in RA and to provide topographic description of their differential localization. Methods RA patients and healthy controls (HC) received US examination of the metacarpophalangeal (MCPJ) and proximal inter-phalangeal (PIPJ) joints adjudicating cortical bone lesions as physiological bone channels or pathological erosions. In a subset of RA patients and HC, high-resolution peripheral quantitative computed tomography (HR-pQCT) of the hand was performed to validate the classification of lesions. Results A total of 40 RA patients and 43 HC were enrolled and totally 771 MCPJ and 638 PIPJ were examined by US, and 94 and 51, respectively, by HR-pQCT. US-defined cortical bone lesions clustered in the lateral part of the MCP (50%) and the dorsal part of the PIPJ (66.7%) in RA. US-defined physiological bone channels clustered in the palmar parts of the MCPJ and PIPJ in both RA (78.8% and 100%, respectively) and HC (51.8% and 80%, respectively). HR-pQCT data confirmed US data with respect to adjudication of physiological bone channels and pathological erosions. Erosions were significantly (all P  <0.000001) larger than physiological channels and preferentially localized at radial and ulnar sites, while physiological channels were clustered at palmar sites. Specificity of US was excellent for erosions in RA and for physiological bone channels in HC and RA. Conclusion US allows differentiation between physiological channels and bone erosions in RA. [ABSTRACT FROM AUTHOR]

Objective To compare the performance of different spinal radiographic damage scoring methods in patients with early axial spondyloarthritis (axSpA). Methods Five-year spinal radiographs from the DESIR cohort were scored by three readers (averaged) for the calculation of the Stoke AS Spine Score (SASSS), modified Stoke Ankylosing Spondylitis Spine Score (mSASSS), Radiographic AS Spinal Score (RASSS), BASRI-spine and BASRI-total, and following the OMERACT filter, scores were compared according to truth, discrimination (reliability and sensitivity to change) and feasibility. The proportion of patients with a net change > smallest detectable change and >1 was calculated. The proportion of total variance explained by the patient (true variance) was calculated for the change scores as a measure of reliability, using analysis of variance. Results In total 699 patients were included. Five-year net changes > smallest detectable change (>1) were: RASSS 17% (17%), mSASSS 12% (12%), BASRI-spine and BASRI-total 12% (9%), SASSS 11% (11%). The mSASSS and the RASSS performed the best in terms of capturing the signal (positive change) related to noise (negative change). The proportion of variance explained by the patient was highest for the mSASSS and RASSS (85% for both 5-year progression scores vs 50–55% for other methods). The proportion of patient variance in the thoracic segment of the RASSS was unsatisfactory (46% for progression). Conclusion The existing scoring methods to assess spinal radiographic damage performed well in early phases of axSpA. The mSASSS and RASSS captured most change. There was no clear gain in additionally scoring the thoracic spine for the RASSS. The mSASSS remains the most sensitive and valid scoring method in axSpA, including early phases of the disease. [ABSTRACT FROM AUTHOR]

Advances in treatments and treatment strategies for PsA have led to many patients responding well to management of their disease, and targeting remission as a treatment goal is now a possibility. Treat to target is a strategy aimed at maximizing benefit, irrespective of the type of medication used, by monitoring disease activity and using it to guide therapy. The measurement of response to treatment has been the subject of wide discussions among experts for some time, and many instruments exist. Comparisons of the different measures and their different strengths and weaknesses is ongoing. The impact of modern imaging techniques on monitoring disease progression is also evolving, and advanced techniques using both MRI and US have the potential to improve management of PsA through identification of risk factors for poor prognosis as well as accurate assessment of inflammation and damage, including subclinical disease. Increased understanding of the pathways that drive the pathogenesis of PsA will be key to identifying specific biomarkers for the disease and developing effective treatment strategies. Targets for response, considerations for use of a treat to target strategy in PsA, different imaging techniques and serological aspects of remission are all discussed in this review, and areas for further research are identified. [ABSTRACT FROM AUTHOR]

The article presents a case of a 42-year-old female who was presented to a clinic for routine visit for her 15-year long psoriatic disease with skin, nail and joint involvement to discuss silent acro-osteolysis in psoriatic disease and recurrent micro-trauma.

Objectives. The aim of this study was to evaluate the association between two semi-quantitative Doppler US scoring systems (SQS), and the quantitative scoring (QS) of Doppler pixel count. Methods. Adult patients with RA and inadequate clinical response to anti-rheumatic therapy were examined with musculoskeletal US (MSUS). Dorsal MSUS of the wrists, MCP and MTP 2-5 were performed. MSUS images with sign of synovitis were collected and the QS was measured. Five assessors blinded to the QS evaluated the images independently, according to either SQS method. Association between QS and SQS was studied using correlations and multilevel models taking into account the clustering of ratings at the rater, patient and joint levels. Results. Analysis of the 1190 ratings revealed a strong correlation (p = 0.89, P < 0.0001) and significant associations (P < 0.0001) between QS and SQS. Correlations between QS and SQS according to Szkudlarek et al. (p = 0.87, P < 0.0001) or Hammer et al. (p = 0.91, P < 0.0001) were similar. A total of 239 (20.1 %) images were given a SQS grade that did not match that expected based on initial QS, using pre-defined cut-offs. Main explanations for discrepancies were different perceived region of interest (40.7%) and Doppler pixel count near cut-offs between SQS grades (32.3%). Conclusion. We showed that both SQS methods correlated well with QS to assess synovitis, but SQS methods are intrinsically limited when the Doppler pixel count is close to the cut-offs between the SQS grades. Analysis discrepancies between these methods may help further revision of criteria used to assess disease activity with MSUS in RA. [ABSTRACT FROM AUTHOR]

Objectives. To describe existing techniques of US-guided synovial biopsy (USG-SB) and critically appraise the literature on this technology through the OMERACT filter. Methods. USG-SB techniques are described and compared. A systematic literature search of PubMed and Embase was performed for original research reports including US and SB. The subjects, procedure protocols and reported results were analysed. A future research agenda is proposed. Results. USG-SB can be performed using a portal-and-forceps or a dedicated semi-automatic guillotine-type biopsy needle approach. Of 50 reports identified, 7 were included in the review. Large, intermediate and small joints were all amenable to USG-SB. We found great heterogeneity with regard to indications for and definition of a successful procedure and of synovitis. Adverse events were assessed in most papers with an overall major complication rate of 0.4%. However, there was a lack of construct validity using a histological comparator. Relatively few papers reported details on the technique used, tissue processing, synovitis scoring and blinding for tissue analysis. Conclusion. USG-SB can be regarded as a valuable tool for large-scale synovial tissue sampling. Standardization of the techniques of USG-SB and tissue processing is needed. Future research should focus on the reliability, responsiveness and feasibility of this procedure in prospective studies. [ABSTRACT FROM AUTHOR]

Objective. To produce consensus-based definitions of the US elementary lesions in gout and to test their reliability in a web-based exercise. Methods. The process consisted of two steps. In the first step a written Delphi questionnaire was developed from a systematic literature review and expert international consensus. This collated information resulted in four statements defining US elementary lesions: double contour (DC), tophus, aggregates and erosion. The Delphi questionnaire was sent to 35 rheumatology experts in US, asking them to rate their level of agreement or disagreement with each statement. The second step tested the reliability by a web-exercise. US images of both normal and gouty elementary lesions were collected by the participants. A facilitator then constructed an electronic database of 110 images. The database was sent to the participants, who evaluated the presence/absence of US elementary lesions. A group of 20 images was displayed twice to evaluate intra-reader reliability. Results. A total of 32 participants responded to the questionnaires. Good agreement (>80%) was obtained for US definitions on DC, tophus, aggregates and erosion in the Delphi exercise after three rounds. The reliability on images showed inter-reader values for DC, tophus, aggregates, erosion findings of 0.98, 0.71, 0.54 and 0.85, respectively. The mean intra-reader values were also acceptable: 0.93, 0.78, 0.65 and 0.78, respectively. Conclusion. This, the first consensus-based US definition of elementary lesions in gout, demonstrated good reliability overall. It constitutes an essential step in developing a core outcome measurement that permits a higher degree of homogeneity and comparability between multicentre studies. [ABSTRACT FROM AUTHOR]

Objectives. To investigate the prevalence of knee US findings of inflammation and structural damage in aged individuals (≥60 years) of a long-term population-based cohort and to correlate these findings with demographic, clinical and laboratory parameters. Methods. Cross-sectional clinical and US investigation of both knee joints during the 2010 follow-up of the prospective population-based Bruneck Study. Demographic variables, physical activity, comorbidities, medications, pain, and functional scales related to the knee joints were recorded. US-assessed parameters were synovial hypertrophy, power Doppler signal, joint effusion, cartilage abnormalities, osteophytes, enthesopathy and bursitis. Statistics included univariate and multivariate regression analysis. Results. A total of 488 subjects (mean age 72.5 years; 53.5% females, 46.5% males) were examined by clinical assessment, and 433 of these underwent US examination of both knees. Both inflammatory and structural abnormalities were found in 296 (68.8%) subjects. Inflammatory abnormalities were significantly associated with age in years, male gender, diabetes and the presence of knee joint symptoms. In the multivariate analysis, age, male gender and knee swelling emerged as independent predictors of inflammation [odds ratio (OR) (95% CI) = 1.06 (1.03, 1.09), 2.55 (1.55, 4.21) and 5.92 (1.99, 17.58), respectively]. Conclusion. The present study showed a high prevalence of US inflammatory abnormalities in the knee joints of a normal aged population. These data suggest a substantial contribution of inflammation in progressive impairment of joint function with age. [ABSTRACT FROM AUTHOR]

For patients with rheumatoid arthritis (RA), remission can be achieved with tight control of inflammation and early use of disease modifying agents. The importance of remission as an outcome has been recently highlighted by European League Against Rheumatism recommendations. However, remission when defined by clinical remission criteria (disease activity score, simplified disease activity index, etc) does not always equate to the complete absence of inflammation as measured by new sensitive imaging techniques such as ultrasound (US) . There is evidence that imaging synovitis is frequently found in these patients and associated with adverse clinical and functional outcomes. This article reviews the data regarding remission, ultrasound imaging and outcomes in patients with RA to provide the background to a consensus statement from an international collaboration of ultrasonographers and rheumatologists who have recently formed a research network - the Targeted Ultrasound Initiative (TUI) group. The statement proposes that targeting therapy to PD activity provides superior outcomes compared with treating to clinical targets alone and introduces the rationale for a new randomised trial using targeted ultrasound in RA. [ABSTRACT FROM AUTHOR]

Objective. To present the published data concerning the US assessment of tendon lesions as well as the US metric properties investigated in inflammatory arthritis.Methods. A systematic literature search of PubMed, Embase and the Cochrane Library was performed. Selection criteria were original articles in the English language reporting US, Doppler, tenosynovitis and other tendon lesions in patients with RA and other inflammatory arthritis. Data extraction focused on the definition and quantification of US-detected tenosynovitis and other tendon abnormalities and the metric properties of US according to the OMERACT filter for evaluating the above tendon lesions.Results. Thirty-three of 192 identified articles were included in the review. Most articles were case series (42%) or case–control (33%) studies describing hand and/or foot tenosynovitis in RA patients. The majority of older articles used only B-mode, whereas the most recent studies have incorporated Doppler mode. Definition of tenosynovitis or other tendon lesion was provided in 70% of the evaluated studies. Most of the studies (61%) used a binary score for evaluating tendon abnormalities. Concerning the OMERACT filter, 24 (73%) articles dealt with construct validity. The comparator most commonly used was clinical assessment and MRI. There were few studies assessing criterion validity. Some studies evaluated reliability (36%), responsiveness (21%) and feasibility (12%).Conclusion. US seems a promising tool for evaluating inflammatory tendon lesions. However, further validation is necessary for implementation in clinical practice and trials. [ABSTRACT FROM PUBLISHER]

Objective. To investigate the role of a new hybrid imaging modality, integrated in the US equipment and derived by a real-time MRI and US fusion process, in the hand and wrist joints of a small group of rheumatic patients.Methods. Consecutive patients with OA and RA with hand and wrist involvement were studied. Clinical assessment, physical examination, hand and wrist radiography and laboratory tests were carried out. After performing 0.2T MRI (T1, T2 and short time inversion recovery sequences) of the dominant hand and wrist, images were recorded in a US machine equipped with a virtual navigator system. Ultrasonography was performed in the same joints using an 18 MHz linear probe. Image MRI/US superposition was carried out, with real-time contemporary visualization of the US and related MRI images. Randomly selected stored images of different joints were subsequently re-analysed by a different operator. Concordance between the static and dynamic evaluations was assessed.Results. Nine patients (six with OA and three with RA) were studied. The real-time MRI/US overlap provided fusion images of both tools. A striking concordance in the visualization of the bony profile was found with evidence of pronounced osteophytes in OA and bone erosions in RA. The analysis of stored selected images demonstrated a high concordance between real-time and static assessment.Conclusion. MRI/US fusion imaging gives a composite set of information with accurate anatomical correlations. [ABSTRACT FROM PUBLISHER]

Imaging has always been an integral part of the assessment of SpA. This group of diseases involving the axial skeleton and peripheral joints is a particularly intriguing area for sonographers, because it requires the evaluation of both articular and extra-articular regions. Among extra-articular features enthesitis has recently emerged as an area of special interest for both basic science and clinical researchers as well as for those working in the field of musculoskeletal imaging. This review provides information about research in this area focusing on the current concept and definition of enthesitis by US. [ABSTRACT FROM AUTHOR]