Isolation and characterization of calcium phosphate crystals in the human articular knee cartilages and intervertebral discs: an electron microscopic study

ABSTRACT

The multiple complains of pain resulting from intervertebral disc prolapse or osteoarthritic knee joint is one of the most significant neurosurgical and orthopaedic disorders in industrialized society. The exact relationship between calcium phosphate crystal deposition and these diseases remains obscure, although there is evidence supporting a rapid degenerative arthropathy within a specific set of patients. Several basic calcium phosphate crystals have been reported to be associated with osteoarthritis joint diseases as well as in lumbar disc prolapse patients. To compare the presence and characters of calcium phosphate crystals in normal and osteoarthritic human articular knee cartilages as well as in degenerated disc patients. Five normal articular knee cartilages and intervertebral discs were taken from human cadavers at the dissection room, Faculty of Medicine, Taibah University. Osteoarthritic articular cartilage, and disc prolapse, fifteen specimens each, were obtained from Saudi German, Madinah National Hospitals; and Alexandria University Hospital respectively. Specimens were examined by light and electron microscopy, and electron probe x-ray microanalysis. No crystals could be detected at the light microscopic level. By electron microscopy, crystals were detected in cartilages from all pathological sites sampled. Few or no crystals were observed in normal articular knee cartilages and intervertebral discs. Coexistence of calcium pyrophosphate dihydrate and cuboid calcium phosphate crystals was seen in all cases. Identification was based on the distinctive morphology, size range and XRMA spectrum. The results of this research confirmed the density of calcium phosphate and pyrophosphate dehydrate crystals in osteoarthritic cartilage, and degenerated disc that may provide a useful diagnostic and therapeutic approach to osteoarthritis and disc prolapse patients