Crystal arthropathies Pearls for MSK Ultrasound practitioners

Dr. Abdallah El-Sayed Allam

MSc of Physical Medicine, Rheumatology and Rehabilitation .

Faculty of Medicine. Tanta University. Egypt

MSK US fellowship. National Taiwan University Hospital. Taiwan

Conclusion

US from bench to bed

Indications

Indications

1. Diagnosis and Differential diagnosis with other

inflammatory arthritis,

2. Detection of the joint effusion (quantity, aspect) and

synovitis (symptomatic or asymptomatic),

3. Detection of Deposits at Hyaline cartilage , fibrocartilage

and Tendons ,

4. Evaluation of Bone contour (erosions, osteophytes),

5. Monitoring of the disease progression and response to

treatment,

6. US-guided aspiration or injection.

Sonography from bench to bed

↑water↓ Acoustic impedance ↓

Reflection Hypoechoic

Monosodium urate crystals

↑Acoustic impedance

↑Reflection

Hyperechoic spots

NTUH

Calcium pyrophosphate dihydrate Crystals

Each unit cell of crystalline CPPD contains one

pyrophosphate (P2O7) for every 2 calciums and

2 waters of hydration, yielding a structural

formula of Ca2P2O7.2H20.

↑ ↑ Reflection

Hyperechoic DEPOSITS

MM

Is the Double Contour Sign Specific for Gout?

Löffler C et al. 2015

225Acute arthritis + DC +PD+SUA

Arthrocentesis

Sensitivity of DC sign for crystalline arthritides was 85% and specificity 80%

Specificity for gout was 64%, for CPPD 52%

Degree 2 and 3 Doppler signals were highly associated with gout and less with CPPD (p < 0.01)

DC + PD+ SUA ↑ specificity for gout to > 90% and resulted in a 7-fold ↑ of the likelihood of diagnosis of gout

but with a loss of sensitivity (42%)

Löffler C et al. 2015

The DC sign alone is suitable for predicting crystal

arthropathies, but it cannot reliably distinguish gout

from CPPD in everyday clinical routine. Combining

PD and SUA levels increases the diagnostic value.

1. 6 examiners ↑ interobserver variability ↑ inaccuracy,

2. Phagocytized urate crystals diagnostic standard for gout.

Authors do not describe whether the presence of

extracellular urate crystals only was also considered

diagnostic for gout

3. Knee Joint + 10 1ST MTP single joint insufficient accuracy

for gout diagnosis,

Systematic bilateral scanning for hyperechoic deposits at the

radiocarpal joint, patellar tendon and triceps tendon, and DC sign

in 3 articular cartilages (1st MTP, talar, and 2nd MCP/femoral) ↑

accuracy sensitivity 85% and specificity 83%. On the other

hand , the sensitivity and specificity for DC sign at the femoral

condyle was 42% and 100%, respectively, and at the 1st MTP J

dorsal cartilage was 62% and 98%, respectively

Naredo E, et al 2014

Basic Calcium Phosphate Crystals

Hydroxyapatite is represented by the formula

Ca10(PO4)6(OH)2 and generally occurs in the

partially carbonate-substituted form. Octacalcium

phosphate (Ca8H2(PO4)6.5H2O) and tricalcium

phosphate (Ca3(PO4)2) also Present.

↑ ↑ ↑ Reflection

Hyperechoic DEPOSITS

Acoustic shadowing

a arc-shaped, with clear posterior acoustic shadow;

b fragmented, withoutshadowing;

c nodular, with no shadow

Conclusion

1. Understanding Chemistry and Histopathology of the

disease as well as Physics of ultrasound understanding

and interpretation of ultrasound images type of the

crystals,

2. Gout hyperechoic spots, DC, Tophi and erosions

3. CPPD Calcifications of middle zone, Punctate pattern,

calcifications are parallel to tendon fascicles.

4. BCC Fragmented and Nodular (no Shadowing) or arc

like with acoustic shadowing,

5. TC Mixed Crystal disease,

6. DC sign can’t differentiate between gout and CPPD,

7. Clinical picture + Lab + US (static & dynamic, PD,>1

joint /tendon) ↑ accuracy of diagnosis,

8. Arthrocentesis is GOLD STANDARD

Thank you