Novel stepwise model of intervertebral disc degeneration with intact annulus fibrosus to test regeneration strategies |
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| Authors: | Gianluca Vadalà Fabrizio Russo Francesca De Strobel Marco Bernardini Giulia Maria De Benedictis Caterina Cattani Luca Denaro Matteo D'Este David Eglin Mauro Alini Vincenzo Denaro |
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| Affiliation: | 1. Department of Orthopaedic and Trauma Surgery, Campus Bio‐Medico University of Rome, Rome, Italy;2. Department of Animal Medicine, Productions and Health, University of Padua, Legnaro, Italy;3. Neurosurgery Division, Department of Neuroscience, University of Padua, Padua, Italy;4. AO Research Institute Davos, Davos, Switzerland |
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| Abstract: | Novel preclinical models that do not damage the annulus fibrosus (AF) of the intervertebral disc are required to study the efficacy of new regenerative strategies for the nucleus pulposus (NP). The aim of the study was to characterize a preclinical ovine model of intervertebral disc degeneration (IDD) induced by endplate (EP) damage and repair via the transpedicular approach, with or without partial nucleotomy, while keeping the AF intact. Twelve adult sheep were used. By the transpedicular approach, a 2 mm tunnel was drilled to the NP through the EP. A partial‐nucleotomy was performed. The tunnel was sealed using a polyurethane scaffold. Lumbar discs were assigned to different groups: L1‐2: nucleotomy; L2‐3: EP tunnel; L3‐4: nucleotomy + EP repair; L4‐5: EP tunnel + repair; L5‐6: control. X‐Ray and MRI were performed at 0, 1, 3, and 6 months after surgery. Disc height and MRI indexes were calculated. Macro‐ and micro‐morphology were analyzed. Pfirrmann and Thompson grades were assigned. The treated discs exhibited a progressive decrease in NP signal intensity and MRI index, displaying specific grades of degeneration based on the surgical treatment. According to Pfirrmann and Thompson grades different procedures were staged as: EP tunnel + repair: grade‐II; EP tunnel: grade‐III, nucleotomy + EP repair: grade‐IV; nucleotomy: grade‐V. A new stepwise model of IDD to study and test safety and efficacy of novel strategies for NP regeneration has been characterized. The different degrees of IDD have been observed similar to Pfirrmann and Thompson grading system. The intact AF allows for loading studies and eliminating the need for AF closure. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2460–2468, 2018. |
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| Keywords: | intervertebral disc degeneration disc regeneration animal models tissue engineering tests endplate |
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