Abstract

Background: The lumbar spine and cervical spine are vulnerable with degeneration, which is related to idiosyncratic problem, aging or improper stress of the spine. Biochemical and structural changes of disc, narrowing of intervertebral disc space, acute or chronic disc protrusion related to disc degeneration with/without neural symptoms are well documented. We are interested in the morphologic changes of the excised herniated or degenerative discs from the spinal surgeries for herniated intervertebral disc (HIVD), spondylolisthesis or spinal stenosis.

Methods: The specimens are collected under the permission of institutional review board (IRB), and are divided into three main groups, including 9 specimens (9 cases) of HIVD, 12 specimens (10 cases) of spondylolisthesis, and 10 specimens (10 cases) of spinal stenosis. Five disc specimens of 3 cadavers (3 from lumbar L4-5 disc and 2 from thoracic T9-10 disc) with no mentioned disc disease are obtained for control group. Histochemical stains of hematoxylin and eosin (H and E) stain and safranin-O-fast green stain are performed to evaluate the content of glycosaminoglycans and chondrocytic proliferation. The photos of disc lesions are taken with consistent LED light of Niko n Coolscope II to analyze the discoloration within the H and E and safranin-O stained sections. Kruskal-Wallis test (one-way ANOVA) was performed for significance check.

Results: HIVD cases have younger age (p=0.036). The excised disc specimens of HIVD group show mild loss of glycosaminoglycans over nucleus pulposus, and even less eosinophilic change in the nucleus pulposus. The discs of spondylolisthesis and spinal stenosis groups may display uneven loss of glycosaminoglycans with occasionally massive loss, and more eosinophilic change than that of HIVD group (p=0.014). Clonal proliferation of chondrocytes over the areas other than endplate and outer rim of annulus fibrosus is a consistent phenomenon in all three groups of degenerative discs, and displaying lesser degree of chondrocytic proliferation among the HIVD cases without significant difference.

Conclusion: We notice that focal eosinophilic change or even necrosis of extracellular matrix is probable an important pathologic picture of degenerative disc and clonal proliferation of chondrocytes is present in all 3 groups of degenerative intervertebral discs. The chondrocytic proliferation in the disc fibrocartilage might be similar to the chondrocytic proliferation within the articular cartilage of grade 3-4/6 knee osteoarthritis.

Keywords: Chondrocytic proliferation; Colorimetry analysis; Degenerative intervertebral disc; Safranin-O-fast green stain