Tendon involvement in patients with gout: an ultrasound study of prevalence

Gout and Patellar Tendon Tears: An Uncommon Intersection

Patellar tendon (PT) tears are a rare cause of anterior knee pain and are usually classified as either partial or complete, with various potential etiologies. We present a unique case of a PT tear in a young male patient, precipitated by a history of gout. This case highlights the uncommon intersection of PT tears and gouty arthritis involving the entheses. The patient was a 36-year-old man of Indian origin who presented with a two-week history of atraumatic right knee swelling, with no identifiable precipitating factors aside from a known history of gout flares. Clinical examination revealed swelling and joint line tenderness in the right knee, though the overall assessment was otherwise unremarkable. In this paper, we explore management options for patients presenting with this rare manifestation of gout leading to a PT tear. This case highlights the importance of early assessment through thorough history-taking, physical examination, utilization of appropriate investigation modalities, and expedited treatment to facilitate a favorable outcome. Early intervention enabled a swift recovery and return to sports for the patient. It also serves as a valuable reminder for clinicians to consider PT tears in the differential diagnosis of anterior knee pain and to investigate potential causes of such tears, which may influence subsequent management.

Hyperuricemia May Increase Risk of Achilles Tendon Rupture: A Case Control Study

It has been demonstrated in a number of studies that high levels of uric acid can cause crystal deposition in the tendons of the lower extremities, which in turn can impair the Achilles tendon. This study aimed to interpret whether hyperuricemia is relevant with Achilles tendon rupture. Patients diagnosed with Achilles tendon rupture at the same institution between 2013 and 2022 were included in the case group. Healthy subjects who had physical examinations during the same period were included in the control group. Propensity score matching was used to match in a 1:1 ratio. Demographic and clinical characteristics of patients in both groups were compared. Five hundred and fourteen patients were included in the study (ATR=257; Control group=257). The proportion of individuals with hyperuricemia varied significantly between the 2 groups (Achilles tendon rupture group=43.6%; control group=27.6%; p<0.001). The Achilles tendon rupture and hyperuricemia were linked by conditional logistic regression (p<0.001; OR=2.036; 95CI%=1.400-2.961). Compared with healthy subjects, patients with hyperuricemia have a higher risk of Achilles tendon rupture. Further studies are required to verify the effects of hyperuricemia and monosodium urate crystals on Achilles tendon structure.

Lipidomics and metabolomics investigation into the effect of DAG dietary intervention on hyperuricemia in athletes

The occurrence of hyperuricemia (HUA; elevated serum uric acid) in athletes is relatively high despite that exercise can potentially reduce the risk of developing this condition. Although recent studies have shown the beneficial properties of DAG in improving overall metabolic profiles, a comprehensive understanding of the effect of DAG in modulating HUA in athletes is still lacking. In this study, we leveraged combinatorial lipidomics and metabolomics to investigate the effect of replacing TAG with DAG in the diet of athletes with HUA. A total of 1,074 lipids and metabolites from 94 classes were quantitated in serum from 33 athletes, who were categorized into responders and non-responders based on whether serum uric acid levels returned to healthy levels after the DAG diet intervention. Lipidomics and metabolomics analyses revealed lower levels of xanthine and uric acid in responders, accompanied by elevated plasmalogen phosphatidylcholines and diminished acylcarnitine levels. Our results highlighted the mechanisms behind how the DAG diet circumvented the risk and effects associated with high uric acid via lowered triglycerides at baseline influencing the absorption of DAG resulting in a decline in ROS and uric acid production, increased phospholipid levels associated with reduced p-Cresol metabolism potentially impacting on intestinal excretion of uric acid as well as improved ammonia recycling contributing to decreased serum uric acid levels in responders. These observed alterations might be suggestive that successful implementation of the DAG diet can potentially minimize the likelihood of a potentially vicious cycle occurring in high uric acid, elevated ROS, and impaired mitochondrial metabolism environment.

Updates in Ultrasound in Rheumatology

BACKGROUND

The purpose of the authors' narrative review was to outline the current literature regarding the use of ultrasound in main rheumatic disorders and summarize the updates, specifically about rheumatoid arthritis, psoriatic arthritis, and crystal-induced arthropathies.

METHODS

The authors searched on PubMed for articles discussing the major updates regarding the role of ultrasound in the previously mentioned rheumatic conditions.

RESULTS

The authors have provided the updated definitions, new criteria, and diagnostic scores.

CONCLUSIONS

In rheumatology's dynamic landscape, this review provides valuable insights for researchers and clinicians on ultrasound's role in improving patient care and outcomes in rheumatic diseases.

Ultrasound Features in Gout: An Overview

The accurate diagnosis of gout frequently constitutes a challenge in clinical practice, as it bears a close resemblance to other rheumatologic conditions. An undelayed diagnosis and an early therapeutic intervention using uric acid lowering therapy (ULT) is of the utmost importance for preventing bone destruction, the main point of managing gout patients. Advanced and less invasive imaging techniques are employed to diagnose the pathology and ultrasonography (US) stands out as a non-invasive, widely accessible and easily reproducible method with high patient acceptability, enabling the evaluation of the full clinical spectrum in gout. The 2023 EULAR recommendations for imaging in diagnosis and management of crystal-induced arthropathies in clinical practice state that US is a fundamental imagistic modality. The guidelines underline its effectiveness in detecting crystal deposition, particularly for identifying tophi and the double contour sign (DCS). Its utility also arises in the early stages, consequent to synovitis detection. US measures of monosodium urate (MSU) deposits are valuable indicators, sensitive to change consequent to even short-term administration of ULT treatment, and can be feasibly used both in current daily practice and clinical trials. This paper aimed to provide an overview of the main US features observed in gout patients with reference to standardized imaging guidelines, as well as the clinical applicability both for diagnosis accuracy and treatment follow-up. Our research focused on summarizing the current knowledge on the topic, highlighting key data that emphasize gout as one of the few rheumatological conditions where US is recognized as a fundamental diagnostic and monitoring tool, as reflected in the most recent classification criteria.

Impact of Dual-Energy Computed Tomography (DECT) Postprocessing Protocols on Detection of Monosodium Urate (MSU) Deposits in Foot Tendons of Cadavers

OBJECTIVE

To evaluate two different dual-energy computed tomography (DECT) post-processing protocols for the detection of MSU deposits in foot tendons of cadavers with verification by polarizing light microscopy as the gold standard.

MATERIAL AND METHODS

A total of 40 embalmed cadavers (15 male; 25 female; median age, 82 years; mean, 80 years; range, 52-99; SD ± 10.9) underwent DECT to assess MSU deposits in foot tendons. Two postprocessing DECT protocols with different Hounsfield unit (HU) thresholds, 150/500 (=established) versus 120/500 (=modified). HU were applied to dual source acquisition with 80 kV for tube A and 140 kV for tube B. Six fresh cadavers (4 male; 2 female; median age, 78; mean, 78.5; range 61-95) were examined by DECT. Tendon dissection of 2/6 fresh cadavers with positive DECT 120 and negative DECT 150 studies were used to verify MSU deposits by polarizing light microscopy.

RESULTS

The tibialis anterior tendon was found positive in 57.5%/100% (DECT 150/120), the peroneus tendon in 35%/100%, the achilles tendon in 25%/90%, the flexor halluces longus tendon in 10%/100%, and the tibialis posterior tendon in 12.5%/97.5%. DECT 120 resulted in increased tendon MSU deposit detection, when DECT 150 was negative, with an overall agreement between DECT 150 and DECT 120 of 80% (p = 0.013). Polarizing light microscope confirmed MSU deposits detected only by DECT 120 in the tibialis anterior, the achilles, the flexor halluces longus, and the peroneal tendons.

CONCLUSION

The DECT 120 protocol showed a higher sensitivity when compared to DECT 150.

Asymptomatic Hyperuricemia Is Associated with Achilles Tendon Rupture through Disrupting the Normal Functions of Tendon Stem/Progenitor Cells

Hyperuricemia is a metabolic disorder that is essential to the development of inflammatory gout, with increasing prevalence over recent years. Emerging clinical findings has evidenced remarkable tendon damage in individuals with longstanding asymptomatic hyperuricemia, yet the impact of hyperuricemia on tendon homeostasis and associated repercussions is largely unknown. Here, we investigated whether asymptomatic hyperuricemia was associated with spontaneous ruptures in the Achilles tendon and the pathological effect of hyperuricemia on the tendon stem/progenitor cells (TSPCs). Significantly higher serum uric acid (SUA) levels were found in 648 closed Achilles tendon rupture (ATR) patients comparing to those in 12559 healthy volunteers. In vitro study demonstrated that uric acid (UA) dose dependently reduced rat Achilles TSPC viability, decreased the expressions of tendon collagens, and deformed their structural organization while significantly increased the transcript levels of matrix degradative enzymes and proinflammatory factors. Consistently, marked disruptions in Achilles tendon tissue structural and functional integrity were found in a rat model of hyperuricemia, together with enhanced immune cell infiltration. Transcriptome analysis revealed a significant elevation in genes involved in metabolic stress and tissue degeneration in TSPCs challenged by hyperuricemia. Specifically, reduced activity of the AKT-mTOR pathway with enhanced autophagic signaling was confirmed. Our findings indicate that asymptomatic hyperuricemia may be a predisposition of ATR by impeding the normal functions of TSPCs. This information may provide theoretical and experimental basis for exploring the early prevention and care of ATR.

A Tennis Elbow, A First Presentation of Gout Disease

Gout is a common disease, which affects more than 8 million of patients in the US alone. Typically, gout present as articular surfaces are well described in literature. However, the extra articular manifestations are being increasingly reported in the last few years. The extra-articular manifestations of gout disease can present in several ways, including tenosynovitis, and most commonly affecting the lower limb. Here in, the authors are going to present a rare case of recurrent tennis elbow episodes. The only clinical explanation of this novel presentation was presence of high serum uric acid levels.

A glance into the future of gout

Gout is characterized by monosodium urate (MSU) crystal deposits in and within joints. These deposits result from persistent hyperuricaemia and most typically lead to recurrent acute inflammatory episodes (gout flares). Even though some aspects of gout are well characterized, uncertainties remain; this upcoming decade should provide further insights into many of these uncertainties. Synovial fluid analysis allows for the identification of MSU crystals and unequivocal diagnosis. Non-invasive methods for diagnosis are being explored, such as Raman spectroscopy and imaging modalities. Both ultrasound and dual-energy computed tomography (DECT) allow the detection of MSU crystals; this not only provides a mean of diagnosis, but also has furthered gout knowledge defining the presence of a preclinical deposition in asymptomatic hyperuricaemia. Scientific consensus establishes the beginning of gout as the beginning of symptoms (usually the first flare), but the concept is currently under review. For effective long-term gout management, the main goal is to promote crystal dissolution treatment by reducing serum urate below 6 mg/dL (or 5 mg/dL if faster crystal dissolution is required). Current urate-lowering therapies' (ULTs) options are limited, with allopurinol and febuxostat being widely available, and probenecid, benzbromarone, and pegloticase available in some regions. New xanthine oxidase inhibitors and, especially, uricosurics inhibiting urate transporter URAT1 are under development; it is probable that the new decade will see a welcomed increase in the gout therapeutic armamentarium. Cardiovascular and renal comorbidities are common in gout patients. Studies determining whether optimal treatment of gout will positively impact these comorbidities are currently lacking, but will hopefully be forthcoming. Overall, the single change that will most impact gout management is greater uptake of international rheumatology society recommendations. Innovative strategies, such as nurse-led interventions based on these recommendations have recently demonstrated treatment success for people with gout.

Entheseal Involvement in Spondyloarthritis (SpA) and Gout: An Ultrasound Comparative Study

Objective

To compare the assessment of entheses in subjects with spondyloarthritis (SpA) with patients with gout by the Madrid Sonographic Enthesis Index (MASEI).

Method

This cross-sectional study includes videos of entheses evaluated by ultrasound (US) of 30 patients with SpA diagnosed according to the ASAS criteria and 30 patients with gout established by the presence of monosodium urate crystals. Entheses were evaluated for MASEI in 2 Institutes located in two different countries. Demographic and clinical data were registered. Total MASEI score, MASEI-inflammatory, and MASEI-chronic damage were analyzed. Comparisons between groups were obtained by chi-square test and Student's t-test. An inter-reading US reliability was realized.

Results

Patients with gout were older and had significantly more comorbidities than those with SpA. The total MASEI score was not significantly different among diseases (p = 0.07). MASEI-inflammatory was significantly more prevalent at the Achilles tendon in SpA, while the proximal patellar tendon was in gout. Power Doppler was higher in SpA compared to gout (p = 0.005). MASEI-chronic damage related to calcification/enthesophytes predominated in gout (p = 0.043), while calcaneal erosions did in SpA (p = 0.008). The inter-reader concordance was excellent (0.93, CI 95% 0.87–0.96, p = 0.001).

Conclusions

SpA and gout similarly involve entheses according to MASE, however, some inflammatory and chronic lesions differ significantly depending on the underlying disease and tendon scanned.

Update of the current role of ultrasound in asymptomatic hyperuricemia. A systematic literature review

Ultrasound (US) is a recognized imaging modality for the assessment of gout. Recently it is being explored for its potential role in the evaluation of subjects with asymptomatic hyperuricemia (AH). Preliminary reports demonstrated the presence of monosodium urate (MSU)-crystal deposits including aggregates, double contour sign and/or tophi in both intra-articular and periarticular tissues of AH individuals. Although these results are exciting, the value and potential application of US in AH remain to be clearly delineated. In this systematic literature review, we aim to summarise the recent publications regarding the role of US in the assessment of AH. We analyzed possible application of US in the daily clinical practice and its future clinical and research potential in the evaluation of AH individuals.

Reliability of knee joint sonography in the evaluation of gouty arthritis

Objective: To determine the reliability of knee joint sonography in the evaluation of gouty arthritis. Methodology: A search of Google Scholar, PubMed, NCBI, MEDLINE, and Medscape databases, from 1988 up to 2020. The key search terms used were knee joint; knee joint ultrasound; gout; gouty arthritis, knee joint pain; sensitivity; specificity. The reviewer independently screened the titles and abstracts of the relevant articles and full-text downloads to determine whether the inclusion or exclusion criteria were met. Results: In total, 103 articles were identified through the database search. In addition, 11 articles were identified through other sources. Then, screening was performed, and 9 articles were removed due to duplication. Further screening was done for 105 articles, and 27 articles were excluded due to insufficient information. Seventy-eight full-text articles were assessed for eligibility. A total of 13 full-text articles were excluded due to research performed on animals, as the study had been designed as a review of only human studies. Sixty-three studies were included that had a qualitative synthesis. Conclusion: The knee is a weight-bearing joint and may be affected by a myriad of different pathological conditions, therefore a proper diagnosis is of prime importance for a proper management plan. Ultrasound is a non-invasive, radiation-free, and readily available modality that has high sensitivity and specificity in the evaluation of gouty arthritis.

Entheseal involvement of the lower extremities in gout: an ultrasonographic descriptive observational study

OBJECTIVE

The aim of this study was to explore the prevalence and distribution of lower extremity entheseal abnormities by musculoskeletal ultrasound (US) in a cohort of gout patients, taking spondyloarthritis (SpA) patients and asymptomatic hyperuricemia (HUA) patients as controls.

METHOD

One hundred participants with gout, fifty patients with SpA, and twenty-nine patients with asymptomatic HUA were recruited. US was used to assess the bilateral quadriceps, patellar and Achilles tendons, and plantar fascia entheses according to the Outcome Measures in Rheumatology (OMERACT) definitions.

RESULTS

The US examination revealed the presence of one or more abnormalities in at least one enthesis in 45 out of 100 subjects (45.0%) and 152 out of 1000 entheses (15.2%) in the gout patients. Among the affected entheses, the patellar insertion of the quadriceps tendon was the most commonly involved area (38.0% in the gout patients versus 48.0% in the SpA patients with at least one pathological US finding, p = 0.241). There were no significant group differences in entheseal power Doppler (PD) signals, bone erosion, or enthesophytes. The patients with lower limb entheseal involvement in the gout group had an older age, longer disease duration, higher percentage of chronic tophaceous gout, and higher levels of inflammatory biomarkers of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Multivariate logistic regression analysis revealed that age (OR = 1.052, p = 0.001) and the ESR (OR = 1.023, p = 0.028) were correlated with lower limb enthesopathy in gout patients. In the subgroup analysis of gout patients without active inflammation, age (OR = 1.119, p = 0.001) and serum uric acid (UA, OR = 1.012, p = 0.002) were correlated with lower limb enthesopathy in gout.

CONCLUSION

Lower extremity entheseal involvement might be neglected but should be considered as an important element in the evaluation of gout patients. Enthesopathy most frequently involves in the patellar insertion of the quadriceps tendon and is characterized by entheseal hypoechogenicity and/or thickening. Key Points • Lower extremity enthesopathy might be neglected as an important element in gout. • Enthesopathy is most frequently involved in the patellar insertion of the quadriceps tendon in gout. • Age and ESR are correlated with lower limb enthesopathy in gout patients.

Explaining Variability in the Prevalence of Achilles Tendon Abnormalities: A Systematic Review With Meta-analysis of Imaging Studies in Asymptomatic Individuals

OBJECTIVE

To estimate the prevalence of, and factors associated with, Achilles tendon abnormalities observed on imaging in asymptomatic individuals.

DESIGN

Systematic review with stratified meta-analysis and meta-regression.

LITERATURE SEARCH

Embase, Scopus, MEDLINE, CINAHL, SPORTDiscus, and Web of Science were searched from 1980 to August 2020.

STUDY SELECTION CRITERIA

We included studies that reported the prevalence of Achilles tendon abnormalities, observed with any imaging modality, in an asymptomatic population. We excluded studies if participant mean age was younger than 12 years or if participants had current/previous lower-limb tendon injuries/symptoms or other systemic conditions.

DATA SYNTHESIS

Random-effects proportion meta-analysis was used to estimate prevalence. We used meta-regression for continuous variables (mean age and body mass index [BMI], sample size, proportion of female participants) and stratified categorical variables (imaging modality and participation in physical activity) to explain between-study heterogeneity.

RESULTS

We included 91 studies (10 156 limbs, 5841 participants). The prevalence of Achilles tendon abnormalities on imaging ranged from 0% to 80% per participant. Between-study heterogeneity was high (I²>90%, P<.001), precluding data pooling. Between-study heterogeneity was partly explained by participant mean BMI (slope, 2.8% per 1-unit increase in BMI; 95% confidence interval: 0.57%, 5.03%; P = .015) and participation in physical activity per limb, and mean age of 40 years old or older (P = .022) per participant.

CONCLUSION

There was substantial variability in the prevalence of Achilles tendon abnormalities on imaging in asymptomatic individuals. Higher prevalence of abnormalities was associated with older age (40 years old or older), higher BMI, and participation in physical activity. A large proportion of heterogeneity remains unaccounted for, likely due to variations in abnormality definitions and study design. J Orthop Sports Phys Ther 2021;51(5):232-252. Epub 28 Mar 2021. doi:10.2519/jospt.2021.9970.

Physical Activity and Investigation With Magnetic Resonance Imaging Partly Explain Variability in the Prevalence of Patellar Tendon Abnormalities: A Systematic Review With Meta-analysis of Imaging Studies in Asymptomatic Individuals

OBJECTIVE

To estimate the pooled prevalence of, and factors associated with, the presence of patellar tendon abnormalities observed on imaging in people without symptoms.

DESIGN

Systematic review with stratified meta-analysis and meta-regression.

LITERATURE SEARCH

We searched Embase, Scopus, MEDLINE, CINAHL, SPORTDiscus, and Web of Science from 1980 to August 2020.

STUDY SELECTION CRITERIA

We included studies that reported the prevalence of asymptomatic patellar tendon abnormalities on imaging. We excluded studies of participants with current tendon pain, a history of tendon pain, or other systemic conditions.

DATA SYNTHESIS

Stratification and meta-regression of studies based on study-level descriptive statistics (mean age, body mass index, proportion of female participants, physical activity participation, imaging modality) were performed using a random-effects model to account for between-study heterogeneity. Risk of bias was assessed using the modified Newcastle-Ottawa scale.

RESULTS

Meta-analysis of 64 studies (7125 limbs from 4616 participants) found significant between-study heterogeneity (I²≥90%, P<.01), which precluded a summary prevalence estimate. Heterogeneity was partially explained by studies that included participants who were physically active and studies that assessed tendon abnormalities using magnetic resonance imaging compared to ultrasound (P<.05). Mean age, body mass index, proportion of female participants, and sample size did not explain the remaining heterogeneity.

CONCLUSION

There was substantial variability in the reported prevalence of asymptomatic patellar tendon abnormalities. A clear and valid method is needed to assess and report the presence of patellar tendon abnormalities to increase research capacity and establish the clinical value of imaging the patellar tendon. J Orthop Sports Phys Ther 2021;51(5):216-231. Epub 28 Mar 2021. doi:10.2519/jospt.2021.10054.

Gouty Involvement of Foot and Ankle: Beyond Flares

The foot and ankle are common locations of deposition of monosodium urate (MSU) crystals, as indicated by the clinical manifestations presented by patients with gout, which are not limited to the acute inflammation of the big toe. We present a narrative literature review aimed to update the gout involvement of foot and ankle and how it affects the quality of life. Cumulative reports indicate that gout, even at the non-tophaceous stage, could cause pain, gait impairment and limit the mobility at lower limbs. These patients may present difficulties in some activities of daily living such as choosing footwear, thus leading to an impaired quality of life. Gout is a curable disease by dissolving MSU crystals but remains unclear how this could modify some of these foot and ankle manifestations, especially when structural damage has already occurred. Furthermore, a collaboration between rheumatologists and podiatrists seems helpful to understand, relieve these symptoms and improve the quality of life in gouty patients.

[Risk factors and diagnostic value for ultrasound-detected tendon monosodium urate crystal deposition in patients with gout]

OBJECTIVE

To evaluate frequency and patterns, risk factors of MSU (monosodium urate) crystal deposition at lower extremity tendon by ultrasonography in gout patients, and to explore diagnostic value by ultrasonography.

METHODS

Patients diagnosed with gout and age matched healthy controls had ultrasound scanning of both feet and knees including joints and tendons (achilles, quadriceps, and patellar tendon). Readers who scored the ultrasound scans for MSU crystal deposition were blinded to the patients' clinical diagnoses. Clinical characteristics were compared between positive and negative crystal deposition groups by US, and risk factors of MSU deposition in tendons were analyzed. Diagnostic values of MSU deposition were evaluated by ultrasonography according with positive MSU crystal in synovial fluid or tophi by polarized microscopy.

RESULTS

Eighty patients and eighty healthy controls were included. Thity-three patients (47.5%) had tophi by physical examination. The achilles tendon was the most commonly involved tendon site 41(51.2%), followed by the quadriceps tendons 22(27.5%), and patella tendon 10(12.5%). There were no MSU deposition in healthy control group at tendon by ultrasonography. Compared with negative MSU deposition at tendon site by ultrasonography, tendon MSU positive patients had longer mean gout duration [(87.3±40.9) months vs. (7.7±2.6) months, P=0.001];higher frequency of gout flare [2(1, 2) /year vs. 1(1, 1) /year, P=0.001]; higher BMI [(26.3±2.5) kg/m²vs. (23.3±2.1) kg/m², P=0.05]. Also, the mean serum uric acid and creatinine levels were higher in tendon MSU positive group [(584.6±87.6) μmol/L vs. (460.4±96.7) μmol/L, P=0.001] and [(90.9±33.3) μmol/L vs. (70.6±40.2) μmol/L, P=0.02] separately. Logistic regression analysis showed gout duration and flare frequency were independent risk factors for MSU deposition at tendon by ultrasonography (P < 0.01). Joint or tophi aspirations were performed in all the eighty gout patients, and positive MSU crystals in synovial fluid analysis by polarized microscopy were defined as the golden standard of gout diagnosis. When compared with the golden standard, the sensitivity and specificity were 94.0% and 78.0% separately for MSU deposition at tendon by ultrasonography.

CONCLUSION

Tendon involvement at the lower extremity tendons in gout is very common. Long gout disease duration and high frequency of gout flare are both independent risk factors of tendon MSU deposition by ultrasonography. Ultrasonography had good sensitivity and specificity for detecting tendinous tophi and aggregates.

An Unusual Presentation of Gout Involving the Ankle Ligaments

Gout is the most common inflammatory arthritis due to deposition of monosodium urate (MSU) crystals in joints and connective tissues. In contrast to joint disease, the majority of extra-articular involvement remains asymptomatic in patients with gout. Achilles tendon is the most common site of involvement and the inflammation elicited by MSU crystals can be falsely attributed to injury or overuse. In addition, tendon or ligament damage secondary to MSU crystal deposition can lead to ligament tear or tendon rupture.

However, the diagnosis of gout in patients with extra-articular involvement is often delayed or even missed because tissue sampling is not feasible in routine clinical practice. Advanced imaging techniques using ultrasound and dual-energy computer tomography (DECT) can detect MSU crystal deposition in a non-invasive manner and confirm the diagnosis of gout in patients with extra-articular involvement.

The following case demonstrates an atypical presentation of gout causing multiple ligament tears in the ankle and highlights the role of DECT in the diagnosis of gout with extra-articular involvement.

Differences in Achilles tendon stiffness in people with gout: a pilot study

Background

Gout has been associated with weaker foot/leg muscles and altered gait patterns. There is also evidence of on-going foot pain and an increased risk of tendinopathy, with the Achilles and patella tendons most frequently affected in gout. Additionally, the inflammation associated with gout may change tissue elasticity. Ultrasound imaging utilising shear wave elastography (SWE) offers a non-invasive method of quantifying changes in tendon stiffness. SWE findings have not previously been reported in individuals with gout. We sought to determine differences in Achilles tendon stiffness in people with gout compared to controls (non-gout).

Methods

A cross sectional study comparing 24 people with gout and 26 age/sex-matched controls. Clinical and demographic data were collated, and US imaging used to determine tendon thickness, presence of gouty tophi and/or aggregates and levels of angiogenesis. Ten shear wave elastography (SWE) measures were taken along the centre of a longitudinal section of the mid-portion of each Achilles tendon. Prior to data collection, intra-observer error was good (>0.69). Data were summarised using descriptive statistics and a repeated measures ANCOVA was used to compare SWE measures between the two groups for the left and right foot separately after accounting for Body Mass Index (BMI).

Results

A small proportion of those with gout presented with intra-tendon aggregates and/or intra-tendon tophi in one or both tendons. There was no statistically significant difference in tendon thickness between groups. Neo-vascularity was present in a third of gout participants. SWE findings demonstrated significantly reduced tendon stiffness in those with gout compared to controls: right Achilles mdiff =1.04 m/s (95% CI (0.38 to 1.7) p = 0.003 and left Achilles mdiff = 0.7 m/s (95% CI 0.09 to 1.32) p = 0.025. No relationship between the presence of tophi and SWE values were detected.

Conclusion

Subjects with chronic gout show significantly reduced Achilles tendon stiffness compared to non-gout controls. From a clinical standpoint, our findings were similar to SWE measurements in subjects with Achilles tendinopathy and who did not have gout.

Ultrasonography and dual-energy computed tomography: impact for the detection of gouty deposits

Ultrasonography (US) and dual-energy computed tomography (DECT) are useful and sensitive diagnostic tools to identify monosodium urate deposits in joints and soft tissues. The purpose of this review is to overview the imaging findings obtained by US and DECT in patients with gout, to understand the strengths and weaknesses of each imaging modality, and to evaluate the added value of using both modalities in combination.

Imaging of crystalline arthropathy in 2020

Crystal-related arthropathies are the result of crystal deposition in joint and periarticular soft tissues. Identification of urate crystals is mandatory to distinguish gout from other crystalline arthropathies, including calcium pyrophosphate dihydrate and basic calcium phosphate crystal deposition diseases. ACR/EULAR classification criteria for gout included dual-energy computed tomography and ultrasound with equal impact to the final score. Different diagnostic strengths of these imaging modalities depend on disease duration and scanned anatomic site. While ultrasound has been indicated as the first-choice imaging technique, especially in the early stages of the disease, dual-energy computed tomography has shown to be highly specific, allowing the detection of crystal deposits in anatomic sites not accessible by ultrasound, such as the spine. At the spinal level, MRI findings are usually nonspecific. Finally, there is preliminary evidence that at the knee, dual-energy computed tomography may discriminate calcium pyrophosphate dihydrate from basic calcium phosphate crystal deposits.

[Gout]

Gout is a chronic disease due to the deposition of monosodium urate microcrystals in joints and tissues. Its incidence and prevalence are increasing worldwide in close relation with the epidemic of obesity and metabolic syndrome. Gout is related to chronic hyperuricemia that should be treated to ensure the reduction or even the disappearance of acute attacks ("gout flares") and to reduce the size and number of tophi. If arthritis of the first metatarsophalangeal joint is the most typical form, other joints may be affected, including the spine. Demonstration of urate microcrystals arthritis allows diagnosis of gout but, in the absence of possibility of performing joint puncture, imaging may be useful for providing complementary diagnostic elements. Appropriate care is essential to reduce the number of flares and the evolution towards gouty arthropathy but also in terms of public health in order to reduce costs related to this pathology.

Gout: state of the art after a decade of developments

This review article summarizes the relevant English literature on gout from 2010 through April 2017. It emphasizes that the current epidemiology of gout indicates a rising prevalence worldwide, not only in Western countries but also in Southeast Asia, in close relationship with the obesity and metabolic syndrome epidemics. New pathogenic mechanisms of chronic hyperuricaemia focus on the gut (microbiota, ABCG2 expression) after the kidney. Cardiovascular and renal comorbidities are the key points to consider in terms of management. New imaging tools are available, including US with key features and dual-energy CT rendering it able to reveal deposits of urate crystals. These deposits are now included in new diagnostic and classification criteria. Overall, half of the patients with gout are readily treated with allopurinol, the recommended xanthine oxidase inhibitor (XOI), with prophylaxis for flares with low-dose daily colchicine. The main management issues are related to patient adherence, because gout patients have the lowest rate of medication possession ratio at 1 year, but they also include clinical inertia by physicians, meaning XOI dosage is not titrated according to regular serum uric acid level measurements for targeting serum uric acid levels for uncomplicated (6.0 mg/dl) and complicated gout, or the British Society for Rheumatology recommended target (5.0 mg/dl). Difficult-to-treat gout encompasses polyarticular flares, and mostly patients with comorbidities, renal or heart failure, leading to contraindications or side effects of standard-of-care drugs (colchicine, NSAIDs, oral steroids) for flares; and tophaceous and/or destructive arthropathies, leading to switching between XOIs (febuxostat) or to combining XOI and uricosurics.

Gouty Achilles Tendinopathy: A Case Report

Tendinopathy in the presence of gouty arthropathy is relatively common, yet the clinical suspicion for gout involvement in acute tendon pain remains low. A 49-year-old man presented with an acute, tender, erythematous mass to the right posterior heel. A computed tomographic scan was obtained, which revealed a septated fluid collection superficial to the Achilles tendon. The patient was taken to the operating room for an incision and drainage with debridement, and the abscess was found to be filled with caseous material. The diagnosis of gout was confirmed with pathology. The calcaneus was submitted to biopsy, and the results were negative for osteomyelitis. The patient was returned to the operating room for repair of the Achilles tendon with flexor hallucis longus tendon transfer. Postoperatively, the patient was nonweightbearing for 6 weeks. Oral colchicine was used perioperatively, and a steroid taper was administered. The patient was started on allopurinol and colchicine for chronic treatment. At 14 months, the patient was walking without pain or recurrence of the mass. Although the relationship between hyperuricemia and tendinopathy is not completely understood, it is apparent that tendon involvement may be a sequela in patients with gout. When a patient presents with acute tendon pain, gout should be considered in the differential diagnosis.

Diagnosis and Treatment of Patellar Tendon Gouty Tophus: A Case Report

The main aim of this case report is to thoroughly describe the steps of diagnosis and treatment in the rare incidence of patellar tendon gouty tophus. The case of a 53-year-old man manual worker who was treated with open excision of the lesion, following failure of extended medical treatment with rheumatological input, is presented. Surgical treatment led to full restoration of the patient's knee function. Open or arthroscopic surgery is a viable option for the unusual case of intratendinous patellar gouty deposition if the patient fails medical management. Medical treatment should still be the mainstay.

Recent developments in advanced imaging in gout

The plain radiographic features of gout are well known; however, the sensitivity of plain radiographs alone for the detection of signs of gout is poor in acute disease. Radiographic abnormalities do not manifest until late in the disease process, after significant joint and soft tissue damage has already occurred. The advent of dual-energy computed tomography (DECT) has enabled the non-invasive diagnosis and quantification of gout by accurately confirming the presence and extent of urate crystals in joints and soft tissues, without the need for painful and often unreliable soft tissue biopsy or joint aspiration. Specific ultrasound findings have been identified and may also be used to aid diagnosis. Both ultrasound and magnetic resonance imaging (MRI) may be used for the measurement of disease extent, monitoring of disease activity or treatment response, although MRI findings are nonspecific. In this article we summarize the imaging findings and diagnostic utility of plain radiographs, ultrasound, DECT, MRI and nuclear medicine studies in the assessment as well as the implications and utility these tools have for measuring disease burden and therapeutic response.

More tendon degeneration in patients with shoulder osteoarthritis

PURPOSE

Tendon disorders are a major problem in the general population. It is known that rotator cuff tendinopathy contributes to osteoarthritis (OA) of the shoulder. The aim of the study was to analyse the presence of tendinopathy in patients with shoulder OA and an intact rotator cuff, using a multimodal approach.

METHODS

Thirteen consecutive patients median age 67 (52-84) years, with OA of the shoulder, and 13 consecutive control patients, with a fracture of the proximal humerus, median age 70 (51-84) years, underwent an open biopsy procedure from the biceps and subscapularis tendon in conjunction with shoulder arthroplasty. In addition to a macroscopic evaluation, the samples underwent histologic, morphologic and ultrastructural analyses in light and transmission electron microscopy.

RESULTS

Macroscopic degeneration was found in 15 of 26 specimen in the OA group but in seven of 25 in the control group (p = 0.048). The histologic analysis revealed a non-significant difference for the total degeneration score (TDS) between the study groups. The morphologic evaluation of the samples revealed that the OA group had significantly more samples with non-homogeneous extracellular matrix (ECM), (p = 0.048). Ultrastructurally, the OA group revealed a significantly larger fibril diameter in the biceps tendon (p < 0.0001) but not in the subscapularis tendon compared with the control group.

CONCLUSION

A significantly worse macroscopic appearance and significantly more morphologically inhomogeneous ECM, indicating more tendon degeneration, were found in the OA group compared with the control group. This indicates that it could be beneficial to treat the tendinosis in an early stage to decrease symptoms from the OA.

STUDY DESIGN

Level of evidence, III.

An Untypical Case of Gouty Infiltration of Both Peroneal Tendons and a Longitudinal Lesion of the Peroneus Brevis Tendon Mimicking Synovial Sarcoma

We present a case of a 70-year-old male patient with an untypical gout infiltration of the peroneal tendons mimicking synovial sarcoma. The patient had a negative history of gout at initial presentation in our department. Magnetic resonance imaging of the region revealed a finding highly suspicious for synovial sarcoma of the peroneal tendons. Open biopsy was performed. Histopathological examination of the tissue samples demonstrated the presence of gout with no signs of malignancy. The gout infiltration was excised in a subsequent surgery. Orthopedic surgeons should be aware of the potential manifestation of gout in tendons and bear this in mind in the differential diagnosis of soft tissue tumors.

Brief Report: Monosodium Urate Monohydrate Crystal Deposits Are Common in Asymptomatic Sons of Patients With Gout: The Sons of Gout Study

OBJECTIVE

To estimate the prevalence and distribution of asymptomatic monosodium urate monohydrate (MSU) crystal deposition in sons of patients with gout.

METHODS

Patients with gout were mailed an explanatory letter with an enclosed postage-paid study packet to mail to their son(s) age ≥20 years old. Sons interested in participating returned a reply form and underwent telephone screening. Subsequently, they attended a study visit at which blood and urine samples were obtained and musculoskeletal ultrasonography was performed, with the sonographer blinded with regard to the subject's serum urate level. Images were assessed for double contour sign, intraarticular or intratendinous aggregates/tophi, effusion, and power Doppler signal. Logistic regression was used to examine associations. Adjusted odds ratios (OR_adj ) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

One hundred thirty-one sons (mean age 43.8 years, mean body mass index 27.1 kg/m² ) completed assessments. The serum urate level was ≥6 mg/dl in 64.1%, and 29.8% had either a double contour sign or intraarticular aggregates/tophi in ≥1 joint. All participants with MSU deposition had involvement of 1 or both first metatarsophalangeal joints. Intratendinous aggregates were present in 21.4% and were associated with intraarticular MSU crystal deposits (OR_adj 2.96 [95% CI 1.17-7.49]). No participant with a serum urate level of ≤5 mg/dl had MSU crystal deposition seen on ultrasonography, and 24.2% of those with serum urate levels between 5 and 6 mg/dl had ultrasonographic MSU deposition. MSU crystal deposition was associated with increasing serum urate levels (OR_adj 1.61 [95% CI 1.10-2.36] for each increase of 1 mg/dl).

CONCLUSION

Asymptomatic sons of patients with gout frequently have hyperuricemia and MSU crystal deposits. In this study MSU crystal deposits were present in participants with serum urate levels of ≥5 mg/dl. Evaluation of subjects without a family history of gout is needed to determine whether the threshold for MSU crystal deposition is also lower in the general population.

The popliteal groove region: A new target for the detection of monosodium urate crystal deposits in patients with gout. An ultrasound study

OBJECTIVES

To determine the prevalence of the ultrasound findings indicating monosodium urate crystal deposits at the popliteal groove region in patients with gout; to evaluate the diagnostic accuracy of ultrasound in detecting monosodium urate crystal deposits at the popliteal groove region, patellar tendon and the knee hyaline cartilage; to investigate the correlation between the ultrasound findings at the popliteal groove region and the clinical features.

METHODS

Bilateral ultrasound assessment of the popliteal groove region, patellar tendon and femoral condyles' hyaline cartilage was performed on 47 consecutive patients with gout and 37 controls. The ultrasound findings indicating monosodium urate crystals (aggregates, tophi and "double-contour" sign) were identified according to the Outcome Measures in Rheumatology definitions.

RESULTS

One or more ultrasound abnormalities (aggregates and/or tophi) were found in at least one popliteal groove region in 23 out of 47 patients with gout (48.9%) and in 4 out of 37 controls (10.8%) (P < 0.001). Sensitivity, specificity and diagnostic odds ratio of the ultrasound findings at the popliteal groove region, patellar tendon and at the femoral condyles' hyaline cartilage were 0.49/0.89/7.9, 0.62/0.81/6.9 and 0.30/1.0/32.0, respectively. There was a significant correlation between the ultrasound findings at the popliteal groove region and history of knee inflammatory involvement (P < 0.001, V = 0.644) and number of gouty "attacks" in the previous year (P = 0.012, V = 0.434).

CONCLUSIONS

This study provides new insights into the ultrasound assessment of patients with gout, highlighting the clinical relevance of the popliteal groove region as an area of collection of otherwise undetectable monosodium urate crystals.

Gout Can Increase the Risk of Receiving Rotator Cuff Tear Repair Surgery

BACKGROUND

Gout commonly involves joint inflammation, and clinical epidemiological studies on involved tendons are scant. Rotator cuff tears are the most common cause of shoulder disability, and surgery is one of the choices often adopted to regain previous function.

PURPOSE

To investigate the risk of receiving rotator cuff repair surgery among patients with gout and to analyze possible risk factors to design an effective prevention strategy.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The authors studied a 7-year longitudinal follow-up of patients from the Taiwan Longitudinal Health Insurance Database 2005 (LHID2005). This included a cohort of patients who received a diagnosis of gout during 2004-2008 (gout cohort) and a cohort matched by propensity scores (control cohort). A 2-stage approach that used the National Health Interview Survey 2005 was used to obtain missing confounding variables from the LHID2005. The crude hazard ratio (HR) and adjusted HR were estimated between the gout and control cohorts.

RESULTS

The gout and control cohorts comprised 32,723 patients with gout and 65,446 people matched at a ratio of 1:2. The incidence of rotator cuff repair was 31 and 18 per 100,000 person-years in the gout and control cohorts, respectively. The crude HR for rotator cuff repair in the gout cohort was 1.73 (95% confidence interval [CI], 1.23-2.44; P < .01) during the 7-year follow-up period. After adjustment for covariates by use of the 2-stage approach, the propensity score calibration-adjusted HR was 1.60 (95% CI, 1.12-2.29; P < .01) in the gout cohort. Further analysis revealed that the adjusted HR was 1.73 (95% CI, 1.20-2.50; P < .001) among patients with gout who did not take hypouricemic medication and 2.70 (95% CI, 1.31-5.59; P < .01) for patients with gout aged 50 years or younger.

CONCLUSION

Patients with gout, particularly those aged 50 years or younger and without hypouricemic medication control, are at a relatively higher risk of receiving rotator cuff repair surgery. Strict control of uric acid levels with hypouricemic medication may effectively reduce the risk of rotator cuff repair.

Ultrasound Characteristics of the Achilles Tendon in Tophaceous Gout: A Comparison with Age- and Sex-matched Controls

OBJECTIVE

To investigate the frequency and distribution of characteristics of the Achilles tendon (AT) in people with tophaceous gout using musculoskeletal ultrasound (US).

METHODS

Twenty-four participants with tophaceous gout and 24 age- and sex-matched controls without gout or other arthritis were recruited. All participants underwent a greyscale and power Doppler US examination. The AT was divided into 3 anatomical zones (insertion, pre-insertional, and proximal to the mid-section). The following US characteristics were assessed: tophus, tendon echogenicity, tendon vascularity, tendon morphology, entheseal characteristics, bursal morphology, and calcaneal bone profile.

RESULTS

The majority of the participants with tophaceous gout were middle-aged men (n = 22, 92%) predominately of European ethnicity (n = 14, 58%). Tophus deposition was observed in 73% (n = 35) of tendons in those with gout and in none of the controls (p < 0.01). Intratendinous hyperechoic spots (p < 0.01) and intratendinous power Doppler signal (p < 0.01) were more frequent in participants with gout compared to controls. High prevalence of entheseal calcifications, calcaneal bone cortex irregularities, and calcaneal enthesophytes were observed in both gout participants and controls, without differences between groups. Intratendinous structural damage was rare. Hyperechoic spots were significantly more common at the insertion compared to the zone proximal to the mid-section (p < 0.01), but between-zone differences were not observed for other features.

CONCLUSION

US features of urate deposition, tophus, and vascularization are present throughout the AT in patients with tophaceous gout. Despite crystal deposition, intratendinous structural changes are infrequent. Many characteristics observed in the AT in people with tophaceous gout, particularly at the calcaneal enthesis, are not disease-specific.

Imaging of gout: New tools and biomarkers?

While joint aspiration and crystal identification by polarizing microscopy remain the gold standard for diagnosing tophaceous gout, agreement among medical and ancillary health personnel examining synovial fluid using polarizing microscopy for the detection of monosodium urate (MSU) crystals appears to be poor. Imaging modalities, including conventional radiography (CR), ultrasonography (US), magnetic resonance imaging (MRI), and dual-energy computed tomography (DECT), have been found to provide information on the deposition of MSU crystals in tissues, and the consequences of such deposition. CR can demonstrate typical "punched out lesions" with marginal overhangs, but the sensitivity for erosion detection is better for DECT and US. US is inexpensive and can identify tophus deposition in and around joints, erosions, and tissue inflammation if power Doppler US is used. MRI can show tophi, bone marrow edema, and inflammation, but MRI findings of tophi may be nonspecific. DECT can identify and color-code tophaceous material, and provide an overview of the tophus burden of a joint area. Because of the lower number of available studies, the strength of evidence for the newer imaging can be improved through further research.