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Light and electron microscopy of hydroxyapatite depositions in the ligamentum flavum
A Hijioka1, K Suzuki, T Nakamura
1Department of Orthopedic Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
Study Design:
Ligamenta flava obtained from 24 patients who had undergone surgery for degenerative spinal diseases were investigated regarding the histopathology of hydroxyapatite crystal depositions.
Objectives:
Light and electron microscopy and energy dispersive x-ray microanalysis were done to clarify the cause and process of hydroxyapatite crystal depositions in the ligament.
Summary Of Background Data:
No reports have been made regarding the cause of calcification in the ligamenta flava induced by hydroxyapatite crystal depositions.
Methods:
Samples were fixed in 10% formalin and 2.5% glutaraldehyde for light and electron microscopy. Energy dispersive x-ray microanalysis was done to detect calcium and phosphate hydroxyapatite crystal deposition areas.
Results:
Hydroxyapatite crystals, which occasionally formed clusters, existed in the connective tissue of the dural side around abundant profiles of growing capillaries. Hydroxyapatite crystals showed needle shaped figures, and the x-ray microanalysis revealed that the ratio of calcium to phosphate was about 1.66:1. A decrease or loss of collagenous and elastic fibers was prominent in these hydroxyapatite deposition areas.
Conclusions:
Hydroxyapatite crystal depositions occur around the growing capillaries in the dural side of the ligamenta flava.