GRAPPA 2023 Debate: Is Psoriatic Disease Really a Primary Enthesitis That Drives Joint Synovitis? The Enthesitis Hypothesis 25 Years On.

The enthesitis hypothesis posits that enthesitis is a primary lesion and that inflammation at the enthesis initiates the musculoskeletal symptoms of psoriatic arthritis (PsA) and spondyloarthropathies (SpA). The hypothesis suggested that inflamed entheseal tissue near the synovium could trigger cytokine-mediated synovitis, that enthesis bone anchorage could explain osteitis, and that the location of entheses at the soft tissue interface could explain dactylitis. Advances in imaging techniques that allow better visualization of enthesitis lesions and the development of animal models have allowed evolution of the concept of enthesitis as a central mechanistic driver of musculoskeletal symptoms in PsA and SpA. A debate between Drs. Dennis McGonagle and Bruce Kirkham at the Group for Research on Psoriasis and Psoriatic Arthritis (GRAPPA) 2023 annual meeting discussed the data supporting and refuting this hypothesis in PsA and SpA, respectively. The major points of this debate are summarized in this article.

A novel nomogram to predict psoriatic arthritis in patients with plaque psoriasis.

OBJECTIVE: To construct a predictive model for Psoriatic Arthritis (PsA) based on clinical and ultrasonic characteristics in patients with plaque psoriasis (PsP). PATIENTS AND METHODS: Demographic, clinical, and ultrasound data were collected from patients with PsP and PsA between May 2019 and December 2022. RESULTS: A total of 212 patients with PsP and 123 with PsA in the training cohort, whereas the validation cohort comprised 91 patients with PsP and 49 with PsA. The multivariate logistic regression identified nail psoriasis (odds ratio [OR] 1.88, 95% CI: 1.07-3.29), synovitis (OR 18.23, 95% CI: 4.04-82.33), enthesitis (OR 3.71, 95% CI: 1.05-13.14), and bone erosion (OR 11.39, 95% CI: 3.05-42.63) as effective predictors for PsA. The area under the curve was 0.750 (95% CI, 0.691-0.806) and 0.804 (95% CI, 0.723-0.886) for the training and validation cohorts, respectively. The Hosmer-Lemeshow goodness-of-fit test showed good consistency for both the training cohort (p  =  0.970) and the validation cohort (p  =  0.967). Calibration curves also indicated good calibration for both cohorts. The DCA revealed that the predictive model had good clinical utility. CONCLUSIONS: We have developed a quantitative, intuitive, and convenient predictive model based on nail psoriasis, synovitis, enthesitis, and bone erosion to assess the risk of PsA in patients with plaque psoriasis.

Subclinical Enthesopathy in Psoriasis-An Ultrasonographic Study.

The present study is aimed at assessing the presence and prevalence of subclinical entheseal changes in Psoriasis (PsO) patients using musculoskeletal ultrasonography (US), conjoined with the analysis of possible differences in terms of demographic, clinical, or biological features. We carried out an observational study on 54 patients with PsO and 40 controls. Subclinical enthesopathy, according to OMERACT definitions, was identified in 20 of the psoriasis patients (37.03%), a significantly difference compared to the controls (5 patients; 10.20%). A comparison between US examinations for psoriasis patients and controls indicates that all the examined areas manifested changes in a significantly higher percentage of patients than the controls. The most common structural changes were represented by thickened tendon (85%), calcification (65%), erosions (35%), power Doppler (PD) signal (20%), and bursitis (5%). The difference in mean MASEI (Madrid Sonographic Enthesitis Index) score between the psoriasis and control groups was statistically significant (10.56 + 2.96 vs. 2.9 + 2.20; p < 0.0001). In conclusion, ultrasound is an easily accessible and vital follow-up method for psoriasis patients to enable an early, subclinical detection of entheseal involvement, i.e., the first red-flag sign for a future transition to psoriatic arthritis (PsA).

Using Ultrasound to Improve Diagnostic Confidence and Management of Psoriatic Disease: Highlights From the GRAPPA 2023 Ultrasound Workshop.

The sensitivity of ultrasound (US) to detect, characterize, and monitor the relevant pathologies of psoriatic arthritis (PsA), including synovitis, enthesitis, tenosynovitis, and dactylitis, has made it an attractive tool for informing clinical decisions. The Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) US working group ran 2 sessions during the annual GRAPPA meeting held in July 2023 in Dublin, Ireland. During the first workshop, the group presented 2 topics, followed by a live demonstration and a group discussion. The 2 topics were (1) an overview of the Diagnostic Ultrasound Enthesitis Tool (DUET) enthesitis scoring methodology, and (2) small hand-held probes-will the promise deliver? The live demonstration that followed compared the performance of 2 hand-held US (HHUS) devices vs a console US machine in patients with PsA, and the interactive group discussion considered gaps in the literature and future research suggestions relating to HHUS and its application in psoriatic disease. During the second session, the US working group provided further updates regarding the GRAPPA US studies currently underway or recently completed.

Advances in Psoriatic Disease Research: Insights From GRAPPA Pilot Research Awardees.

Research progress from the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) pilot award program was presented and discussed at the GRAPPA 2023 annual meeting. Topics included identification of protein biomarkers associated with enthesitis in psoriatic arthritis (PsA), the role of HLA-B27 on gut microbial dysbiosis in PsA, single-cell profiling of synovial fluid vs psoriatic skin lesions in PsA, and the role of mechanotransduction in hyperactivation of transforming growth factor-ß via αVß6 integrin in psoriatic epidermis.

Enthesopathies - Mechanical, inflammatory or both?

Entheses have the challenging task of transferring biomechanical forces between tendon and bone, two tissues that differ greatly in composition and mechanical properties. Consequently, entheses are adapted to withstand these forces through continuous repair mechanisms. Locally specialized cells (mechanosensitive tenocytes) are crucial in the repair, physiologically triggering biochemical processes to maintain hemostasis. When repetitive forces cause "material fatigue," or trauma exceeds the entheses' repair capacity, structural changes occur, and patients become symptomatic. Clinical assessment of enthesopathies mainly depends on subjective reports by the patient and lacks specificity, especially in patients with central sensitization syndromes. Ultrasonography has been increasingly used to improve the diagnosis of enthesopathies. In this article, the literature on how biomechanical forces lead to entheseal inflammation, including factors contributing to differentiation into a "clinical enthesitis" state and the value of ultrasound to diagnose enthesopathies will be reviewed, as well as providing clues to overcome the pitfalls of imaging.

The role of GDF5 in regulating enthesopathy development in the Hyp mouse model of XLH.

X-linked hypophosphatemia (XLH) is caused by mutations in PHEX, leading to rickets and osteomalacia. Adults affected with XLH develop a mineralization of the bone-tendon attachment site (enthesis), called enthesopathy, which causes significant pain and impaired movement. Entheses in mice with XLH (Hyp) have enhanced bone morphogenetic protein (BMP) and Indian hedgehog (IHH) signaling. Treatment of Hyp mice with the BMP signaling blocker palovarotene attenuated BMP/IHH signaling in Hyp entheses, thus indicating that BMP signaling plays a pathogenic role in enthesopathy development and that IHH signaling is activated by BMP signaling in entheses. It was previously shown that mRNA expression of growth/differentiation factor 5 (Gdf5) is enhanced in Hyp entheses at P14. Thus, to determine a role for GDF5 in enthesopathy development, Gdf5 was deleted globally in Hyp mice and conditionally in Scx + cells of Hyp mice. In both murine models, BMP/IHH signaling was similarly decreased in Hyp entheses, leading to decreased enthesopathy. BMP/IHH signaling remained unaffected in WT entheses with decreased Gdf5 expression. Moreover, deletion of Gdf5 in Hyp entheses starting at P30, after enthesopathy has developed, partially reversed enthesopathy. Taken together, these results demonstrate that while GDF5 is not essential for modulating BMP/IHH signaling in WT entheses, inappropriate GDF5 activity in Scx + cells contributes to XLH enthesopathy development. As such, inhibition of GDF5 signaling may be beneficial for the treatment of XLH enthesopathy.

X-linked hypophosphatemia (XLH) is a rare bone disorder that leads to short stature and poorly mineralized bones. As adults, patients with XLH often develop a mineralization of the bone-tendon attachment site, called enthesopathy, which results in significant pain. We previously showed that Achilles bone-tendon attachment sites (entheses) in mice with XLH (Hyp) have an enthesopathy characterized by increased bone morphogenetic protein (BMP) signaling. In the current studies, we show that treating Hyp mice with the BMP signaling inhibitor palovarotene prevents enthesopathy, demonstrating that the increased BMP signaling in Hyp entheses leads to enthesopathy development. We also reported that gene expression of Gdf5, which activates BMP signaling, is enhanced in Hyp entheses. Therefore, to determine if the enhanced Gdf5 expression leads to the increased BMP signaling seen Hyp entheses, Gdf5 was deleted from Hyp mice and also deleted specifically in the entheses of Hyp mice. In both mouse models, enthesopathy development was attenuated, demonstrating that the increased Gdf5 expression in Hyp entheses plays a role in enthesopathy development. These data indicate that blocking GDF5 and BMP signaling may prevent enthesopathy in patients with XLH.

Ultrasound Changes in the Enthesis and Peri-enthesis Area of the Patellar and Achilles Tendons in Response to Physical Exercise: Comparison Between Healthy Subjects and Patients with Spondyloarthritis in Clinical Remission.

RATIONALE AND OBJECTIVES: The goal of achieving clinical remission in patients with spondyloarthritis does not necessarily include the resolution of entheseal inflammation from a histological perspective. However, enthesis not clinically inflamed, under mechanical stress, may behave differently from healthy subjects considering the physiopathology of SpA. Our goal was to determine whether ultrasound changes in entheses differ between SpA patients in clinical remission and healthy subjects. METHODS: SpA patients in clinical remission and matched healthy controls were recruited. At baseline, the following variables were measured on the dominant side by ultrasound: thickness of the distal patellar enthesis (hDP), the deep infrapatellar bursa (hDIB), the Achilles enthesis (hA), the preachilleal bursa (hPAB), effusion in the preachileal bursa (hePAB), and the presence of power Doppler signal in both enthesis. All measurements except hDP and hA were collected again after exercise (post-stress ultrasound). RESULTS: 30 patients and 30 controls were enrolled. In all subjects, hDIB, hPAB, and the preachileal bursa occupancy index increased significantly after the exercise. The increase was significantly greater in patients for all variables. At baseline, in patients, hyperemia was detected in one patellar tendon (3.3%) and in two Achilles tendons (6.7%). After exercise, the number of tendons with hyperemia increased to 11/30 (36.7%) and 12/30 (40%), respectively. Among controls, there was no detectable basal hyperemia, but after exercise, it was detected in 1/30 patellar tendons (3.3%) and 2/30 Achilles tendons (6.7%). CONCLUSION: Exercise triggers a greater effusive and hyperemic synovial response in patients in remission than in healthy controls. These findings suggest that the definition of remission should also include an assessment of the synovial response to mechanical stress.

Unveiling Metabolic Similarities of Entheses in Patients with Psoriasis and Psoriatic Arthritis Using Noninvasive In Vivo Molecular Imaging: Results From a Cross-sectional Exploratory Study.

OBJECTIVE: We assessed and compared molecular tissue changes at the entheses in patients with psoriasis (PsO) and psoriatic arthritis (PsA) and in healthy controls (HCs) in vivo using multispectral optoacoustic tomography (MSOT) and described their relationship with clinical and ultrasound findings of enthesitis. METHODS: A cross-sectional study (MSOT and Arthrosonography in PsA) in biologic disease-modifying antirheumatic drug-naïve patients with PsA and PsO and HCs was performed. Participants underwent clinical, ultrasonographic, and MSOT examination of six entheses (lateral humeral epicondyle, distal patellar tendon attachment, and Achilles tendon attachment). MSOT-measured hemoglobin (Hb), oxygen saturation (SO2), collagen, and lipid levels were quantified, and mean differences between groups were calculated using linear mixed effects models. MSOT-measured analytes were compared between entheses with and without clinical and ultrasound anomalies. RESULTS: Ninety participants were included (30 PsO, 30 PsA, and 30 HCs), 540 entheses were clinically assessed, and 540 ultrasound and 830 MSOT scans were obtained. Patients with PsA and PsO showed increased oxygenated Hb (PsA: P = 0.003; PsO: P = 0.054) and SO2 (PsA: P < 0.001; PsO: P = 0.001) levels and decreased collagen signals (PsA: P < 0.001; PsO: P < 0.001) compared with HCs, with more pronounced changes in PsA. Significantly lower collagen levels (P = 0.01) and increased lipids (P = 0.03) were recorded in tender entheses compared with nontender ones. Erosions and enthesophytes on ultrasound were associated with significant differences in SO2 (P = 0.014) and lipid signals (P = 0.020), respectively. CONCLUSION: Patients with PsA and PsO exhibit an analogous metabolic pattern at the entheses that is exacerbated in the presence of inflammation. These findings support the notion of a psoriatic disease spectrum characterized by common immunometabolic tissue changes.

Enthesitis as an initial presentation of vascular Behçet's syndrome: a case-based review.

Enthesitis is a characteristic manifestation of spondyloarthropathy (SpA). Historically, Behçet's syndrome (BS) was classified within SpA. Although they are now classified separately, the association between BS and SpA remains controversial. The concept of MHC-I (major histocompatibility complex class I)-opathy has been proposed based on the overlap in immunopathological mechanisms among diseases associated with human leukocyte antigen (HLA) class I. Enthesitis is a frequent complication in patients with BS who also have acne and arthritis. However, information regarding enthesitis in patients with BS without arthritis (BS-WA) is limited. Herein, we report a case of vascular BS complicated by enthesitis. In this case, heel pain was the dominant symptom at presentation. Laboratory tests revealed chlamydia antibody positivity, leading to a tentative diagnosis of reactive arthritis. Despite treatment, C-reactive protein (CRP) levels remained elevated. Imaging revealed numerous aneurysmal lesions in the large vessels. Based on these findings and other symptoms, patient was diagnosed with vascular BS. He tested positive for HLA-B15 and HLA-B46, which are associated with peripheral SpA. Subsequent remission induction therapy for BS was effective and the patient was discharged without complications. Our case and a literature review suggest that there exists a subgroup of BS-WA with a complication of enthesitis, possibly belonging to the spectrum of MHC-I-opathies. It is important to consider BS as a differential diagnosis in patients presenting with enthesitis and to conduct a precise medical history review regarding the symptoms of BS.

Extraarticular manifestations of juvenile idiopathic arthritis and their impact on health-related quality of life.

OBJECTIVES: The objective of this study is to investigate extraarticular manifestations (EAMs) in patients with juvenile idiopathic arthritis (JIA) and assess their impact on health-related quality of life (HRQoL) among these patients. METHODS: This cross-sectional analytic study was carried out on 117 patients with JIA. EAMs were identified clinically by history and examination. Sicca symptoms, peripheral neuropathy, enthesitis, and skin lesions were picked up during clinical examination. Pulmonary involvement was evaluated by high-resolution CT chest. Patients were assessed by abdominal ultrasonography to assess the size of liver and spleen. Atlantoaxial subluxation was evaluated by cervical spine x-rays. Patients were evaluated by Pediatric Quality of Life Inventory-4 (PedsQL-4) and PedsQL-3 arthritis module. RESULTS: The median age of patients was 14 years with a median disease duration 4 years, 82.9% were females. Of the studied 117 JIA patients, 85 patients (72.6%) had at least one EAM. Persistent fatigue (51.3%) was the most prevalent EAM, followed by recurrent skin rash (16.2%), enthesitis (15.4%), recurrent fever (13.7%), and uveitis (12%). Patients with EAMs scored significantly lower in physical functioning (p = 0.001), emotional functioning (p < 0.001), social functioning (p = 0.005), and school functioning (p = 0.001). Regarding PedsQL arthritis module, patients with EAM had also significantly lower scores than did patients without EAM on the domains of pain and hurt (p < 0.001), daily activities (p = 0.008), and worry (p = 0.001). RESULTS: EAMs are prevalent among JIA patients and have a negative impact on their HRQoL. So, early identification and treatment are highly recommended. Key Points • A large percentage of JIA patients experienced at least one extraarticular manifestation (EAM). • Persistent fatigue and recurrent skin rash are the most prevalent EAMs in JIA patients. • JIA patients with EAMs have worse scores in almost all domains of HRQoL.

Enthesitis in a European registry-based cohort of patients with psoriatic arthritis treated with tumour necrosis factor inhibitors: clinical burden, patient-reported outcomes, and treatment response.

OBJECTIVE: To explore the registration of enthesitis among biologic-naïve patients with psoriatic arthritis (PsA) initiating tumour necrosis factor inhibitor (TNFi) treatment across 12 European registries, compare the disease burden and patient-reported outcomes (PROs) between patients with and without enthesitis, and assess the enthesitis treatment response. METHOD: Demographics, clinical characteristics, and PROs at first TNFi (TNFi-1) initiation (baseline) were assessed in patients with PsA, diagnosed by a rheumatologist, with versus without assessment of entheses and between those with versus without enthesitis. Enthesitis scores and resolution frequency were identified at follow-up. RESULTS: Of 10 547 patients in the European Spondyloarthritis (EuroSpA) Research Collaboration Network initiating TNFi, 1357 underwent evaluation for enthesitis. Eight registries included a validated scoring system for enthesitis. At baseline, 874 patients underwent entheses assessment [Maastricht Ankylosing Spondylitis Enthesitis Score (MASES) 485 patients, Spondyloarthritis Research Consortium of Canada (SPARCC) 389 patients]. Enthesitis was detected by MASES in 170/485 (35%, mean score ± sd 3.1 ± 2.4) and by SPARCC in 236/389 (61%, 4 ± 3.4). Achilles enthesitis was most frequent, by both MASES (unilateral/bilateral 28%/9%) and SPARCC (48%/18%). MASES/SPARCC baseline and follow-up scores for TNFi-1 were available for 100/105 patients. Of these, 63 patients (63%) (MASES) and 46 (43.8%) (SPARCC) achieved resolution of enthesitis. The site-specific enthesitis resolution was overall lower at SPARCC sites (peripheral; 63-80%) than at MASES sites (mainly axial; 82-100%) following TNFi-1. Disease activity and PROs were worse in patients with versus without enthesitis. CONCLUSION: Entheseal assessments are only registered in a minority of patients with PsA in routine care. When assessed, enthesitis was common, and a substantial proportion demonstrated resolution following treatment with TNFi-1.

Presentation of enthesitis-related arthritis and juvenile-onset spondyloarthritis: a cross-sectional study in a pediatric and adult clinic.

BACKGROUND: Juvenile idiopathic arthritis (JIA) comprises a whole spectrum of chronic arthritis starting before 16 years of age. The study aims to explore the clinical and demographic descriptors, treatment, and disease progression of enthesitis-related arthritis (ERA) in comparison with juvenile-onset spondyloarthritis (SpA). METHODS: Cross-sectional analysis of consecutive patients in two dedicated clinics, with a single visit and retrospective case-notes review. Arthritis, enthesitis and sacroiliitis were evaluated by scoring disease activity and damage. Continuous variables were reported by median, interquartile range; categorical variables were reported by the frequency comparison of the two groups. RESULTS: Thirty-three cases were included, being 23 (69.7%) with ERA. The median age at diagnosis was 12.5 y (SpA) vs. 9 y (ERA) (p < 0.01); the time from symptom onset to diagnosis was 5.5 y (SpA) vs. 1.5 y (ERA) (p < 0.03). In both groups, the predominant presentation was a single joint or < 5 lower limb joints and asymmetric involvement, with a high frequency of enthesitis. There was a higher frequency of mid-tarsal and ankle synovitis in the ERA group and hip involvement in those with SpA. The comparison of the frequency of spine symptoms at presentation, 30% SpA vs. 21.7% ERA (p = 0.7), was not significant, and radiographic progression to spinal involvement occurred in 43.5% of ERA patients. The median time for spinal progression and age at onset was 2.2 and 12 y for ERA, and 4 and 16.5 y for SpA, respectively. Activity and damage scores were not significantly different between the groups. Treatment comparison resulted in 91.3% of ERA and 100% SpA being treated, predominantly with NSAIDs in both groups, followed by DMARDs and biologics, with a higher frequency of biologics in SpA. CONCLUSION: The main differences were the late diagnoses of SpA, and the hip and spine involvement, with higher frequency of biologic treatment in juvenile-onset SpA compared to ERA.

Effectiveness of risankizumab for the treatment of psoriatic arthritis: a multicenter, real-world study.

BACKGROUND: IL-23 inhibitors were recently approved for the treatment of skin psoriasis and psoriatic arthritis (PsA). Risankizumab, a humanized monoclonal antibody that specifically binds the p19 subunit of IL-23, has proven effective on PsA in two randomized controlled trials. To date, only a few real-world data are available on this topic. METHODS: Our study aimed to prospectively evaluate the effectiveness of risankizumab in patients with PsA in a real-world setting. For this purpose, both rheumatologic and dermatologic assessments were performed at baseline and after 28-40 weeks of continuous risankizumab administration. Moreover, joint and entheses ultrasound assessment was performed at the mentioned time points. The rheumatologic assessment was carried out by means of the following scores: (i) clinical Disease Activity Index for Psoriatic Arthritis (cDAPSA); (ii) Leeds Enthesitis Index (LEI); (iii) Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and (iii) Bath Ankylosing Spondylitis Functional Index (BASFI). The degree of skin involvement was measured by both the Psoriasis Area and Severity Index (PASI) and Physician Global Assessment (PGA). Quality of life was assessed by the Health Assessment Questionnaire (HAQ) and Dermatology Life Quality Index (DLQI). Ultrasound assessment of joints and entheses was performed on the basis of the EULAR-OMERACT score. RESULTS: After treatment, cDAPSA decreased from a mean value of 12.9 ± 7.6 to 7.0 ± 6.1 (P < 0.001), and the median PD score significantly decreased from baseline (3; range 1-8) to TP1 (1; range 0-7) (P < 0.001). PASI score also decreased from 8.4 ± 4.9 to 0.3 ± 0.5 (P < 0.001), and PGA from 3.1 ± 1.0 to 0.4 ± 0.5 (P < 0.001). CONCLUSION: We can conclude that risankizumab led to substantial improvement in both skin and joint involvement.

Hematological indices in psoriatic enthesopathy: relation to clinical and ultrasound evaluation.

BACKGROUND: Enthesopathy is considered a crucial aspect of assessment and outcome in psoriatic arthritis (PsA). Musculoskeletal ultrasound (MSUS) is a critical tool for accurately detecting enthesitis. Recent research focuses on identifying simple biomarkers for detecting and monitoring psoriatic enthesopathy. Red cell distribution width (RDW), mean platelet volume (MPV), and neutrophil/lymphocyte ratio (NLR) are components of a complete blood count (CBC) and are reliable bio-inflammatory markers in various rheumatic diseases. AIM OF WORK: To measure MPV, RDW, and NLR in psoriatic enthesopathy and determine their relationship to disease activity and MSUS findings. PATIENTS AND METHODS: This study focused on 30 people with psoriatic arthritis (PsA) as per CASPAR criteria, along with 20 control subjects. Enthesopathy was evaluated clinically using the Leeds Enthesitis Index (LEI). The modified Disease Activity Index of Psoriatic Arthritis (DAPSA28) was calculated, and RDW, MPV, NLR, CRP, and ESR were measured. Each enthesis in LEI was radiologically assessed using plain radiography and MSUS according to OMERACT definitions. RESULTS: There was a significant relationship between clinical tenderness, the presence of enthesophytes on plain radiography, and MSUS findings at entheses sites (p < 0.001 for each). Psoriatic patients had higher levels of RDW and MPV (p < 0.001 and 0.01, respectively) than controls, with no significant differences in NLR (p = 0.189) between the two groups. RDW and MPV levels were positively correlated with the DAPSA28 score. CONCLUSION: Monitoring PsA disease activity can be improved by considering RDW and MPV as reliable indicators and using them to screen for psoriatic enthesopathy with MSUS indices. Key points • Clinically identifying enthesitis in patients with PsA can be challenging. Imaging MSUS indices hold promise for objective analysis, but there is no consensus on which indices to use in clinical trials and daily practice. • Patients with psoriatic enthesopathy have higher RDW and MPV levels, which are positively correlated with DAPSA28 score. • RDW and MPV can be considered in the turn of improved screening of psoriatic enthesopathy with MSUS scores.

Assessment of enthesopathy in conventional pelvis radiography: Another tool for spondyloarthritis diagnosis beyond sacroiliitis.

INTRODUCTION/OBJECTIVES: Enthesitis is a cardinal feature of spondylarthritis (SpA), and the pelvis is a common site of enthesitis. This study aimed to establish the association between pelvic enthesis involvement on pelvic X-ray and SpA diagnosis through a radiographic enthesis index (REI) and to assess the reliability and accuracy of this REI. MATERIALS AND METHODS: The participants were SpA patients and a control group composed of patients with chronic lumbar pain without SpA. Three blinded observers assessed each pelvic radiography three times. Three zones were used: Zone I (ZI), the iliopubic ramus; Zone II (ZII), the pubic symphysis, and Zone III (ZIII), the ischiopubic ramus. A grading system was created from 0 to 3 [Grade 0, normal; Grade 1, minimal changes (subcortical bone demineralization and/or periosteal wishkering, seen as radiolucency and trabeculation of the cortical bone upon tendon insertion); Grade 2, destructive changes (Grade 1 findings and erosions at the enthesis site); and Grade 3, findings of Grade 2 plus >2 mm whiskering out of the cortical bone) for the REI. The sum of the results of the three zones was called the total REI. For statistical analysis, we used the weighted kappa statistic adjusted for prevalence and bias using Gwet's agreement coefficient. RESULTS: We enrolled 161 patients, 111 of them with SpA (39.6 % with axial SpA and 47.7 % with peripheral SpA) and 50 without SpA. In the SpA group, 36.7 % and 25.7 % had REI Grades 2 and 3 in ZIII, respectively, while only 6 % of the controls had these grades. For ZI, the frequency of Grades 1 to 3 was 42.3 % in the SpA group (8.1 %, 14.4 %, and 19.8 %, respectively), compared to only 2 % in the controls. ZII was unaffected in most of the patients with SpA (82.9 %) and in the controls (98 %). In the control group, Grade 0 was the most common REI grade in all three zones. The agreement was almost perfect for each zone and between the independent readers. The ROC-curve analysis showed that the highest performance areas were the total REI, ZIII, and ZI. Most (75 %) of the SpA patients without sacroiliitis on X-ray were REI-positive. The sensitivity of the REI for SpA diagnosis was 82 %, while the sensitivity of sacroiliitis on X-ray was 38.7 %. CONCLUSIONS: The assessment of pelvic enthesis using the REI on pelvic radiography may be useful for SpA diagnosis. Total REI, ZIII, and ZI had the highest accuracy and almost perfect reliability. The REI is especially helpful in patients without sacroiliitis on imaging.

Axial Spondyloarthritis: an overview of the disease.

Axial Spondyloarthritis (axSpA) is a chronic, inflammatory, immune-mediated rheumatic disease that comprises two subsets, non-radiographic and radiographic axSpA, and belongs to a heterogeneous group of spondyloarthritides (SpA). Over the years, the concept of SpA has evolved significantly, as reflected in the existing classification criteria. Considerable progress has been made in understanding the genetic and immunological basis of axSpA, in studying the processes of chronic inflammation and pathological new bone formation, which are pathognomonic for the disease. As a result, new medication therapies were developed, which bring more effective ways for disease control. This review presents a brief overview of the literature related to these aspects of disease after summarising the available information on the topic that we considered relevant. Specifically, it delves into recent research illuminating the primary pathological processes of enthesitis and associated osteitis in the context of inflammation in axSpA. The exploration extends to discussion of inflammatory pathways, with a particular focus on Th1/Th17-mediated immunity and molecular signaling pathways of syndesmophyte formation. Additionally, the review sheds light on the pivotal role of cytokine dysregulation, highlighting the significance of the IL-23/17 axis and TNF-α in this intricate network of immune responses which is decisive for therapeutic approaches in the disease.