title: The application of atomic force microscopy for the detection of microcrystals in synovial fluid from patients with recurrent synovitis.
abstract: Synovial fluid from 33 patients with inflammatory arthritis was examined with a polarized light microscope (PLM) and an atomic force microscope (AFM). Two samples were imaged with a transmission electron microscope (TEM) to determine calcium/phosphate ratios and identify microcrystals of calcium pyrophosphate dihydrate and octacalcium phosphate. Additional correlative x-ray diffraction studies were performed on several samples including purified hydroxyapatite and sodium chloride crystals. Monosodium urate, calcium pyrophosphate dihydrate, hydroxyapatite, octacalcium phosphate, and cholesterol crystals were identified with AFM. AFM images of these microcrystals revealed detailed surface topology, including lattice parameters and structural irregularities at the crystals' surface. These features were consistent with those obtained by TEM and x-ray diffraction studies. In addition, AFM images revealed that some specimens contained microcrystals that were undetected by PLM and/or TEM. These results suggest that AFM may provide a simple yet powerful technique for the detection of microcrystals in synovial fluid taken from patients with crystal-induced arthritis.
authors.affiliation: Department of Medicine, University of Chicago, IL, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Blair
authors.forename: L B
authors.initials: LB
authors.lastname: Sorensen
authors.forename: M F
authors.initials: MF
authors.lastname: Arnsdorf
authors.forename: R
authors.initials: R
authors.lastname: Lal
mesh_terms: D001168:Arthritis / Q000503:physiopathology; D002130:Calcium Phosphates / Q000032:analysis*; D002131:Calcium Pyrophosphate / Q000032:analysis; D003460:Crystallization; D017886:Durapatite / Q000032:analysis; D006801:Humans; D018625:Microscopy, Atomic Force / Q000379:methods; D008859:Microscopy, Polarization / Q000379:methods; D012008:Recurrence; D013582:Synovial Fluid / Q000737:chemistry*; D013585:Synovitis / Q000209:etiology / Q000378:metabolism*; D014527:Uric Acid / Q000032:analysis
chemical_list: D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C022045:octacalcium phosphate; D014527:Uric Acid; C485838:calcium phosphate, monobasic, anhydrous; D017886:Durapatite; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous; D002131:Calcium Pyrophosphate