Investigation on monosodium urate deposition in the first metatarsophalangeal joint and ankle of primary gout patients using dual-energy computed tomography.

BACKGROUND: Gout is caused by deposition of monosodium urate (MSU) crystals. One of the tools of choice to identify MSU crystals is the Dual-Energy Computed Tomography (DECT). This study aims to determine MSU crystal deposition using DECT by comparing its detection in the first metatarsophalangeal joints (MTPJ) with that in the ankles, as well as to analyse the association between the crystal deposition and anthropometrics, clinical characteristics, and serum biochemical levels of a primary gout patient. MATERIALS AND METHODS: This cross-sectional study included patients (n = 94) from the Clinic Hoa Hao Medic Medical Centre in Vietnam, who were diagnosed with primary gout with pain/swelling of at least one ankle or first MTPJ. DECT of both joints was used to identify MSU. Statistical analyses were performed using the Student's t-test, Wilcoxon ranksum, Pearson's chi-square, and Spearman's tests. RESULTS: Approximately 80% had MSU crystal deposition in the ankle and/or first MTPJ with no significant difference in deposition between the two joints. MSU deposition was significantly associated with disease duration (p = 0.003), flare-ups (p = 0.006), and cut-off of 6 weeks' duration (p = 0.006), bone erosion (p = 0.006), and palpable tophi (p = 0.003). There was no association between MSU deposition with age, body mass index (BMI), hypertension, serum levels of uric acid (UA), creatinine, high-sensitive C-reactive protein (hsCRP), total cholesterol (C-total), and triglyceride (TG). CONCLUSIONS: MSU deposition occurred in both ankle and first MTP at the same rate. The deposition was associated with disease duration and flare-ups. Prevention of flare-ups seems helpful to limit MSU crystal deposition.

Articular cartilage of knee and first MTP joint are the preferred sites to find double contour sign as an evidence of urate crystal deposition in asymptomatic hyperuricemic individuals.

BACKGROUND/OBJECTIVE: A cross-sectional study to determine the preferred sites of urate crystal deposition in asymptomatic hyperuricemic individuals by ultrasound. METHODS: In two years period twenty four asymptomatic hyperuricemic individuals (serum uric acid ≥7mg/dl) and fifty controls (serum uric acid <7mg/dl) with age more than 18 years were included in this study. Double contour sign was looked for at three articular cartilage sites (first metatarsophalangeal, tibiotalar and femoral condyle) whereas hyperechoic aggregates were looked for at one joint site (radiocarpal joint) and two tendon sites (patellar tendon and triceps tendon). The Chi-square test was used to compare the categorical variables and discrete variables were compared by one way analysis of variance. The p-value<0.05 was considered significant. RESULTS: Eight out of 24 asymptomatic hyperuricemic individuals had ultrasound evidence of urate crystal deposition in first metatarsophalangeal joint area followed by knee joint area which was detected in 6 patients. The detection rate of ultrasound abnormalities in asymptomatic hyperuricemic individuals was 45.8% with two joint area (knee and first metatarsophalangeal) and 50% with six sites assessment. Amongst controls, 16% were found to have these abnormal ultrasound findings. CONCLUSION: The highest predilection of urate crystal deposition in asymptomatic hyperuricemic individuals is the articular cartilage of Knee and first metatarsophalangeal joints. This explain the frequent clinical presentation of arthritis in these joint areas.

Sensitivity and specificity of ultrasonographic features of gout in intercritical and chronic phase.

AIM: This study aimed to assess the sensitivity and specificity of ultrasonographic features of gout in intercritical and chronic stages and compared ultrasonographic features of gout between patients with persistent high serum uric acid (SUA) and patients with low SUA. METHODS: Adult patients with gout confirmed by demonstration of monosodium urate crystals were recruited, if they were in intercritical or chronic stage clinically. Ultrasonographic examination of the first metatarsophalangeal joints (MTPJs) and the knee joints of both sides were done by a blinded rheumatologist trained in musculoskeletal ultrasound. RESULTS: Sixty-two patients with gout and 30 control subjects were examined. The double contour sign (DCS) was found in 71 (57.3%) first MTPJs and tophi were found in 54 (43.5%) first MTPJs. DCS was present in 43 (69.4%) gout patients but none in the control group (P < 0.001). Sensitivity and specificity (95% CI) of DCS in gout patients were 69.4% (56.4-80.4%) and 100% (88.3-100%), respectively, while of tophi they were 66.1% (53-77.7%) and 100% (88.3-100%), respectively. The sensitivity of DCS increased to 100% in high the SUA subgroup (SUA ≥ 7 mg/dL). The low SUA (SUA < 7 mg/dL) gout subgroup showed significantly higher occurrence of erosions (40%) and tophi (50%) in first MTP joints than the control group. CONCLUSION: MSUS is useful for diagnosis of gout in intercritical or chronic stages, especially in patients with persistently high SUA level.

An exploratory ultrasound study of early gout.

OBJECTIVES: We aimed to determine by ultrasonography (US) the prevalence of articular monosodium urate deposits in patients with gout who do not require urate lowering therapy (ULT) according to international recommendations. METHODS: In this prospective study, we enrolled patients with proven gout demonstrated by crystals in synovial fluid but who did not require ULT. Two trained ultrasonographers assessed 10 joints per patient (metatarsophalangeal [MTP] joints 1-2, knees, metacarpophalangeal [MCP] joints 2-3) to determine the prevalence of the double-contour (DC) sign and tophi in each site. RESULTS: We studied 150 joints from 15 patients (median age 56.9 years [interquartile range 31.7] years; 14 males). The median number of acute attacks per patient was 2.0 [0.7]. Interobserver agreement was good to excellent for all articular sites. The prevalence of the DC sign in the knees and MTP joints was 46.7% and 40% respectively, whereas that of tophi was 26.7% for both sites. No urate deposits were found in MCP joints. The DC sign and tophi were found in at least one articular site in 60% and 46.7% of patients, respectively. All patients with urate levels > 600 µM (10 mg/dl) had a DC sign in at least 1 assessed joint. Urate levels were positively correlated with presence of the DC sign in knees (p=0.005) and MTP joints (p=0.03) but not presence of tophi. CONCLUSIONS: In this study, ultrasonography allowed for detecting articular urate deposits in 60% of gouty patients not requiring ULT by international recommendations.

Reproducibility of musculoskeletal ultrasound for determining monosodium urate deposition: concordance between readers.

OBJECTIVE: Criteria for sonographic diagnosis of monosodium urate (MSU) crystal deposition have been developed, but the interreader reproducibility of this modality is not well established. We therefore assessed agreement using a systematic approach. METHODS: Fifty male subjects ages 55-85 years were recruited during primary care visits to an urban Veterans Affairs hospital, and were assessed by musculoskeletal ultrasound (US) of the knees and first metatarsophalangeal (MTP) joints to evaluate for the double contour sign and tophi as evidence of MSU crystal deposition. Images were read by 2 blinded rheumatologists trained in musculoskeletal US, and the degree of concordance was determined for individual subjects, total joints, femoral articular cartilage (FAC), and first MTP joints. Subjects were further categorized into 3 diagnostic groups: gout, asymptomatic hyperuricemia (no gout, serum uric acid [UA] ≥6.9 mg/dl), and controls (no gout, serum UA ≤6.8 mg/dl), and reader concordance within these 3 groups was assessed. RESULTS: We observed almost perfect agreement between readers for 1) individual subjects (yes/no; n = 50, 100% agreement, κ = 1.000), 2) total joints (n = 200, 99% agreement, κ = 0.942), 3) FAC (n = 100, 99% agreement, κ = 0.942), and 4) first MTP joints (n = 100, 99% agreement, κ = 0.942). Furthermore, findings by side (right/left) and diagnostic group (gout, asymptomatic hyperuricemia, control) showed substantial to almost perfect concordance for all measures. MSU deposition was seen most commonly in gout patients, and deposition was also seen in some subjects with asymptomatic hyperuricemia, but in only 1 control. CONCLUSION: Musculoskeletal US is reliable for detecting MSU deposition in FAC and first MTP joints in gout and asymptomatic hyperuricemia.

Arthroscopic elimination of monosodium urate deposition of the first metatarsophalangeal joint reduces the recurrence of gout.

PURPOSE: To determine if the arthroscopic removal of gouty crystal deposits from the first metatarsophalangeal (MTP) joint will reduce the recurrence rate and improve foot function compared to medical treatment alone. METHODS: Twenty-eight male patients with hyperuricemia (>7.0 mg/dL) and repeated attacks of gouty arthritis of the first MTP joint were included in this study. Arthroscopic intervention of the first MTP joint was performed on 15 patients (group 1), while the other 13 patients were treated with medication alone (group 2). The follow-up period (mean +/- standard deviation) was 3.9 +/- 1.1 years in group 1 and 2.4 +/- 0.3 years in group 2. RESULTS: After treatment, both groups showed a significant improvement in the number of acute attacks of gouty arthritis and in their functional scores on the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale. On both measures, the results for group 1 were significantly better than those for group 2. CONCLUSIONS: Arthroscopic removal of gouty crystals from the first MTP joint can reduce the rate of acute repeated attacks of gouty arthritis and increase foot and ankle function.

Measurement of articular cartilage stiffness of the femoropatellar, tarsocrural, and metatarsophalangeal joints in horses and comparison with biochemical data.

OBJECTIVE: To determine normal cartilage stiffness values in different weight-bearing and non-weight-bearing areas of 3 different equine joints, and to evaluate the relationship between cartilage stiffness and glycosaminoglycan (GAG) and collagen content. STUDY DESIGN: Compressive stiffness of the articular cartilage was measured in 8 horse cadaver femoropatellar (FP), tarsocrural (TC), and metatarsophalangeal (MT) joints. Gross evaluation, collagen content, GAG content, and histologic appearance were assessed for each measurement location. ANIMALS: Eight equine cadavers (4 intact females, 4 castrated males; 7 Quarter Horse or Quarter Horse type, 1 Arabian; aged 4-12 years, weighing 400-550 kg). METHODS: The articular surfaces of 8 equine cadaver FP, TC, and MT joints were grossly evaluated for signs of articular cartilage pathology. Stiffness at preselected sites (FP joint-6 sites; TC joint-3 sites; MT joint-4 sites) was determined using an arthroscopic indentation instrument. Biochemical composition (collagen, GAG content) and histologic evaluation (modified Mankin score) were assessed for each measurement site. RESULTS: All cartilage from all sites evaluated was determined to be normal based on macroscopic and histologic assessments. No significant correlation between Mankin scores and cartilage stiffness values was observed. Site differences in cartilage stiffness were measured in all 3 joints (P<.001). GAG or collagen content had a significant positive correlation with stiffness values in 6 of 13 sites (P<.05, r>0.622, r2>0.387). CONCLUSION: Relative cartilage stiffness values measured in healthy equine joints are site dependent and can be measured using an indentation device intended for arthroscopic application. CLINICAL RELEVANCE: An indentation instrument provided an objective means of determining relative compressive stiffness of articular cartilage. Further research needs to be performed to confirm the site and joint differences observed in this study in clinically normal horses and to determine if the tester can be used clinically to predict articular cartilage pathology.

Fibrocartilages in the extensor tendons of the interphalangeal joints of human toes.

The extensor tendons of the fingers and toes form part of the capsule of the interphalangeal joint and press against the proximal phalanx during flexion. Previous work on the fingers has shown that there is a "sesamoid" fibrocartilage on the deep surface of each tendon that labels immunohistochemically for a variety of glycosaminoglycans and collagens. However, we know little about the molecular composition of the tendon in the toes. This question is of special interest, because the mechanics of the interphalangeal joints differ in the upper and lower limbs-the toes balance the forefoot, distribute load during the gait cycle, and transmit the pull of larger muscles. This means that their extensor tendons are more often under higher tension than those in the fingers. Here, we report the presence of an equivalent fibrocartilage and compare its immunolabelling characteristics in all the toes. Six forefeet were removed from elderly cadavers, and the interphalangeal (IP) joints were fixed in 90% methanol. The extensor tendon and its enthesis were dissected out from the IP joint of the big toe and from the proximal interphalangeal (PIP) joint of all lesser toes, decalcified, cryosectioned, and immunolabelled with a panel of monoclonal and polyclonal antibodies for type I, II, III, and VI collagens; chondroitin 4 and 6 sulphates; and dermatan and keratan sulphate. Antibody binding was detected with the Vectastain ABC Elite avidin-biotin-peroxidase kit (Vector Laboratories, Burlingame, CA). The extensor tendon in all the toes had a metachromatic, sesamoid fibrocartilage on its deep surface that immunolabelled for all glycosaminoglycans and for type I, III, and VI collagens. Labelling for type II collagen was seen in the sesamoid fibrocartilage of all toes but was particularly characteristic of the 2nd through 5th toes. The immunolabelling patterns of the enthesis fibrocartilage were similar in all toes and to results reported previously for fingers. The normal occurrence of type II collagen in the sesamoid fibrocartilage of the 2nd through 5th toes is in contrast to our published data on the fingers. The finding can be related to the more constant loading of the tendon in the toes. The greater prominence of type II collagen in the sesamoid fibrocartilage of the 2nd through 5th toes could be related to a difference in joint position during walking between the 1st toe and the 2nd through 5th toes--the PIP joints of the latter are usually more flexed than the IP joint of the former.