Original articles Eur J Orthop Surg Traumatol (2000) 10:159-165 European Journal of Orthopaedic Surgery & Traumatology © Springer-Verlag 2000 Intervertebral disc degeneration - an autopsy study V.L. Fornasier I, G. Garaffo 2, L. Denaro 3 and V. Denaro 4 1 Director, 2 Visiting Fellow, (currently Staff Surgeon, Giarre Hospital, Catania, Sicily) 3 Visiting Fellow, (currently Trainee in Neurosurgery, Rome, Italy), Orthopaedic Pathology, Laboratory of Bone and Joint Pathology, Department of Pathology, Wellesley Central Site, St. Michael's Hospital, University of Toronto 4 Professor and Chair, Department of Orthopaedic Surgery, Campus Bio Medico, Free University of Rome, Italy Abstract: This is an autopsy analysis of 126 thoracolumbar spines. Extensive his- tomorphological examination identified microscopic changes in the nucleus and annulus fibrosus before any gross or radiological changes were evident. His- tomorphological evidence of microavul- sion of the attachment of the annulus fibrosus from its mooring at the margin of the cartilaginous endplate of the ver- tebral body suggests that forces (com- pression, distraction, rotation) applied during movement are contributing fac- tors to the pathogenesis of degenerative disc disease. Key words: Intervertebral disc -- Dege- neration -- Spine Degenerative changes in the interverte- bral disc are a common finding at autopsy in the thoracolumbar spine of adults [1-1o]. In most cases the changes do not necessarily correlate with the cause of death or the primary disease affecting the patient [11, 12]. Biochemi- cal changes have been described in the Code Mdary: 6373.0 Correspondence to: V. Denaro, Department of Orthopaedic Surgery, Campus Bio Medico, Via Emilio Longoni, 83, I-ores5 Roma, Italy mucopolysaccharide composition of the intervertebral disc with aging [13, 14]. Biomechanical stresses have been suspected in the etiology and pathoge- nesis of degenerative disc disease [2, 3, 5, 15-19]. Clinically, evidence of degene- ration is recognized by the presence of narrowing and deformity of the inter- vertebral disc space [20- a3]. This includes ~clefting~ which has been ter- med ~vacuum phenomenom~ [14, 21, 24-28]. This latter feature is proposed to be an accumulation of gas (probably nitrogen) that outlines such ~faults~ within the intervertebral disc [z9, 30]. This is radiologically well demonstra- ted by the injection of contrast mate- rial [16, 28]. Reports in the literature indicate that degenerative changes are more frequent with advancing age [5, 16, 31]. The true significance of these changes has remained undetermined: whether this is the cause or the result of degeneration. In the literature, one finds statements to the effect that this disease is a purely degenerative pro- cess of the intervertebral disc in patients in whom no history of trauma or other precursor disease can be ascertained [3z]. It has been our routine at autopsy to remove the entire thoracolumbar spine in order to examine it for evidence of disease in the bone and paraspinal soft tissues and for the removal of the entire spinal cord. The study was undertaken to exami- ne the spine for evidence of ~damage~ to the intervertebral disc with particular emphasis on the annulus fibrosus. It was postulated that changes at a microscopic level occurred before any recognizable clinical or grossly detectable change could be seen in the intervertebral disc. Material and methods Gross examination was carried out to determine if there was any detectable change in colour, texture, structure of the vertebra and its endplates, the longi- tudinal ligaments and the components of the intervertebral disc (nudeus, annu- lus, endplates). The complete resected thoracolumbar spine was sectioned lon- gitudinally in the sagittal plane. All stu- dy specimens were submitted to fine detail radiography [3@ The fine detail radiograph on single emulsion, high resolution films was assessed both by the naked eye and by magnification with a dissecting microscope. By this method, one was able to visualize trabecular as well as cortical structures; both the osseous components as well as the liga- mentous components could be identi- fied. The integrity, structure, quantity and change in the organization of the elements could be identified. A study based on this technology in the exami- nation of changes in the longitudinal