Ca. Scotchford et al., THE ISOLATION AND CHARACTERIZATION OF MAGNESIUM WHITLOCKITE CRYSTALS FROM HUMAN ARTICULAR-CARTILAGE, Osteoarthritis and cartilage, 3(2), 1995, pp. 79-94
A number of basic calcium phosphate crystals have been demonstrated in
human articular tissues. The exact relationship between crystal depos
ition and disease remains obscure, although there is evidence supporti
ng a rapid degenerative arthropathy within a specific set of patients.
Limited reports of 'cuboid' calcium phosphate microcrystals in articu
lar cartilage have been made over the last 10 years. In this study the
occurrence of such crystals, not apparent by light microscopy, in hum
an articular cartilage has been confirmed by transmission electron mic
roscopy and X-ray microanalysis of tissue prepared by aqueous and anhy
drous processing techniques. A crystal isolation technique involving c
ollagenase digestion, centrifugation and sodium hypochlorite treatment
was developed enabling crystal characterization by electron and X-ray
diffraction. Crystals were identified as magnesium whitlockite; the f
irst report of this mineral in articular cartilage. The presence of th
is mineral phase in normal and osteoarthritic articular cartilage is d
iscussed with consideration given to physical conditions known to favo
r whitlockite formation and those extant in articular cartilage.