Purpose To characterize in vivo the transpedicular approach (TA) as an alternative route to study intervertebral disc (IVD) regeneration strategies in a sheep model. Methods 48 IVD of 12 sheep were used. TA was performed under fluoroscopy, followed by nucleotomy (2-mm shaver resector). A polyurethane scaffold was used to repair the end-plate. X-ray and MRI images were acquired pre-, intra-and post-operatively (1, 3, 6 months). Complications were recorded. Results TA was feasible in all animals; nucleus pulposus (NP) from L1 to L5 was accessible. Nucleotomy followed by end-plate repair was achieved. Loss of NP signal intensity was shown in MRI images of the nucleotomy group. Conclusions TA is feasible in vivo, repeatable after only a short learning period and safely performed without significant morbidity. This animal model allows the study of IVD degeneration physiopathology and investigation of IVD regeneration techniques in vivo.
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.
A 1-year-old sexually intact male Korat cat was referred for ophthalmological consultation due to anisocoria. Mydriasis with external ophthalmoplegia and absence of pupillary light responses in the right eye and nasofacial hypalgesia were seen. Cavernous sinus syndrome (CSS) was suspected. Bilateral deformities of the jaw and phalangeal bones, severe spinal pain and abnormal conformation of the lumbar spine were also present. Radiographic examination revealed several mineralised masses in the appendicular and axial skeleton, indicative of multiple cartilaginous exostoses. For further investigation of the CSS-related neurological deficits, the cat underwent computed tomography (CT) examination of the skull. CT images revealed a non-vascularised, calcified, amorphous mass originating from the right lateral skull base and superimposing on the sella turcica. Based on the severity of diffuse lesions and owing to the clinical signs of extreme pain, the cat was euthanased. A diffuse skeletal and intracranial osteochondromatosis was diagnosed histologically.
Introduction To study the efficacy of novel regenerative strategies is necessary to develop new models that do not implement annulus fibrosus (AF) damage. We hypothesize an ideal preclinical model to study novel biological therapies for nucleus pulpous (NP) regeneration can be achieved by approaching the NP via the endplate (EP) route through a minimal invasive transpedicular approach.1 The aim of the study is to characterize a preclinical ovine model triggering EP damage and repair with or without mechanical nucleotomy, while keeping the AF intact. Material and Methods Sheep (n = 12, 3 years old), were used. Throughout the transpedicular approach, a 2mm tunnel was drilled to the NP. Nucleotomy was performed using a shaver resector. The tunnel was sealed using a press-fit porous polyurethane (PU) cylinder. Five lumbar discs were assigned to different groups: EP tunnel (A); EP tunnel + nucleotomy (B); EP tunnel + repair with PU scaffold (C); EP tunnel + nucleotomy + repair (D); no treatment (E). X-ray and MRI was performed at 0, 1, 3 and 6 mths after. Disc height and MRI indexes were calculated and disc macro- and micro-morphology were analyzed. MRI images and gross anatomy photographs were graded using both Pfirrmann2 and Thompson3 grading systems. Results MRI analysis showed a progressive decrease of NP signal intensity with different degrees of degeneration. According to Pfirrmann degenerative grade, the C group showed a grade II, group A appeared as grade III, group D looked as grade IV and group B appeared as grade V. Morphologically, all stages of the degenerative process from Thompson grade I to grade V were also observed with the same association. Histological analysis revealed progressive disc narrowing, fragmentation of the NP matrix in D and B group. The scaffold in the tunnel of C and D groups appeared colonized by cells without sign of bone formation at all time point. NP tissue was in the tunnel with infiltration of inflammatory cells in A and B groups. Conclusion A new preclinical model to study tissue-engineering strategies for NP regeneration has been developed and characterized by approaching the NP via the EP route through a minimal invasive transpedicular approach [1]. Keeping the AF intact, the different degrees of IDD have been observed according to Pfirrmann and Thompson grading system. The sealing of the tunnel prevents the NP to leak out of the disc space. This represents a significant contribution toward the translation of new regenerative strategies for biological restoration of early and mild IVD degenerative. Acknowledgment The support of the Italian Ministry of Instruction, University and Research Grant (PRIN-200938NT8Z), the Young Investigator Research Grant of the Italian Ministry of Health (GR-2010–2318448) and the BIOSPINA Award of the Italian Society of Spine Surgery (SICV&GIS) are gratefully acknowledged. References Vadalà G, Russo F, Pattappa G, et al. The transpedicular approach as an alternative route for intervertebral disc regeneration. Spine 2013;38(6):E319–E324 P...
Case summaryA 16-year-old neutered female domestic shorthair cat was referred for chronic history of reluctance to jump, stiffness of the tail and lower back pain. Mild pelvic limb ataxia, reduced perianal reflex and lumbosacral discomfort were present on neurological examination. On magnetic resonance imaging, a well-defined rounded structure of 3 mm in diameter was identified on the right dorsal aspect of the epidural space at L7–S1, causing displacement of the cauda equina. The lesion was hyperintense to spinal cord parenchyma on T2-weighted images and hypointense on T1-weighted images, consistent with a fluid-filled structure. A Lumbosacral dorsal laminectomy was performed. A clear fluid-containing structure was identified between the right L7 nerve root and the cauda equina. Following surgical excision, histopathology confirmed the cystic nature of the lesion and revealed thick disorganised sheaths of fibrocollagenous tissue and flattened mesenchymal cells lining the luminal part of the cyst wall. A diagnosis of intraspinal ganglion cyst was made. The cat recovered uneventfully. Seven months after surgery euthanasia was performed for unrelated reasons; no neurological deficits were present.Relevance and novel informationThis is the first reported case of intraspinal ganglion cyst in a cat. Intraspinal extradural cysts should be considered among other differential diagnoses for cats with lumbosacral myelopathy/radiculopathy.
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