Ca. Scotchford et Sy. Ali, MAGNESIUM WHITLOCKITE DEPOSITION IN ARTICULAR-CARTILAGE - A STUDY OF 80 SPECIMENS FROM 70 PATIENTS, Annals of the Rheumatic Diseases, 54(5), 1995, pp. 339-344
Objective-To examine articular cartilage from a number of joint sites,
using a large sample group, for the presence of magnesium whitlockite
crystal deposition. Methods-Articular cartilage specimens were taken
from a total of 70 patients. The majority of specimens were taken from
femoral heads, with smaller numbers from femoral condyle, tibial plat
eau, radius, ulna, and several small peripheral joints. Normal and ost
eoarthritic articular cartilage specimens were obtained from patients
undergoing prosthesis replacement or amputation. Specimens were resin
embedded and examined using transmission electron microscopy and x ray
microanalysis. Results-Magnesium whitlockite crystals were identified
, on the basis of morphology, size and elemental composition, in artic
ular cartilage from all sites sampled. The distribution of crystals wa
s similar in all samples (restricted to the superficial zone), althoug
h the density of deposition was extremely variable, with the greatest
density observed in femoral head specimens. No magnesium whitlockite c
rystals were observed in osteophytic or epiphysial cartilage. Conclusi
ons-This study demonstrated the widespread extent of magnesium whitloc
kite deposition in human articular cartilage, albeit at much lower den
sity than previously reported in femoral head articular cartilage. In
consideration of possible roles for these crystals in articular cartil
age, it is concluded that an opportunistic mode of formation, possibly
influenced by mechanical stresses, would be most plausible.