Mechanical performance of porous biomimetic intervertebral body fusion devices: an in vitro biomechanical study.

BACKGROUND: Degenerative disc disease is one of the most common ailments severely affecting the quality of life in elderly population. Cervical intervertebral body fusion devices are utilized to provide stability after surgical intervention for cervical pathology. In this study, we design a biomimetic porous spinal cage, and perform mechanical simulations to study its performances following American Society for Testing and Materials International (ASTM) standards before manufacturing to improve design process and decrease cost and consumption of material. METHODS: The biomimetic porous Ti-6Al-4 V interbody fusion devices were manufactured by selective laser melting (laser powder bed fusion: LPBF in ISO/ASTM 52900 standard) and subsequently post-processed by using hot isostatic pressing (HIP). Chemical composition, microstructure and the surface morphology were studied. Finite element analysis and in vitro biomechanical test were performed. FINDINGS: The post heat treatment can optimize its mechanical properties, as the stiffness of the cage decreases to reduce the stress shielding effect between two instrumented bodies. After the HIP treatment, the ductility and the fatigue performance are substantially improved. The use of HIP post-processing can be a necessity to improve the physical properties of customized additive manufacturing processed implants. INTERPRETATION: In conclusion, we have successfully designed a biomimetic porous intervertebral device. HIP post-treatment can improve the bulk material properties, optimize the device with reduced stiffness, decreased stress shielding effect, while still provide appropriate space for bone growth. CLINICAL SIGNIFICANCE: The biomechanical performance of 3-D printed biomimetic porous intervertebral device can be optimized. The ductility and the fatigue performance were substantially improved, the simultaneously decreased stiffness reduces the stress shielding effect between two instrumented bodies; while the biomimetic porous structures provide appropriate space for bone growth, which is important in the patients with osteoporosis.

Multilayer Electrospun-Aligned Fibroin/Gelatin Implant for Annulus Fibrosus Repair: An In Vitro and In Vivo Evaluation.

Annulus fibrosus (AF) damage is proven to prompt intervertebral disc (IVD) degeneration, and unrepaired AF lesions after surgical discectomy may boost herniation of the nucleus pulposus (NP) which may lead to further compression of neural structures. Moreover, vascular and neural ingrowth may occur within the defect which is known as a possible reason for discogenic pain. Due to a limited healing capacity, an effective strategy to repair and close the AF defect is necessary. In this study, using electrospinning technology, two nature polymers, silk fibroin and gelatin, were linked to imitate the unique lamellae structure of native AF. Our findings revealed that a multilayer electrospun-aligned fibroin/gelatin scaffold with mechanical and morphological properties mimicking those of native AF lamellae have been developed. The average diameter of the nanofiber is 162.9 ± 38.8 nm. The young's modulus is around 6.70 MPa with an ultimate tensile strength of around 1.81 MP along preferred orientation. The in vitro test confirmed its biocompatibility and ability to maintain cell viability and colonization. Using a porcine model, we demonstrated that the multilayer-aligned scaffold offered a crucial microenvironment to induce collagen fibrous tissue production within native AF defect. In the implant-repaired AF, H&E staining showed homogeneous fibroblast-like cell infiltration at the repaired defect with very little vascular ingrowth, which was confirmed by magnetic resonance imaging findings. Picrosirius red staining and immunohistochemical staining against type I collagen revealed positively stained fibrous tissue in an aligned pattern within the implant-integrated site. Relative to the intact control group, the disc height index of the serial X-ray decreased significantly in both the injury control and implant group at 4 weeks and 8 weeks (p < 0.05) which indicated this scaffold may not reverse the degenerative process. However, the results of the discography showed that the effectiveness of annulus repair of the implant group is much superior to that of the untreated group. The scaffold, composed with nature fibroin/gelatin polymers, could potentially enhance AF healing that could prevent IVD recurrent herniation, as well as neural and neovascular ingrowth after discectomy surgeries.

Severity of periodontitis and salivary interleukin-1ß are associated with psoriasis involvement.

BACKGROUND/PURPOSE: Both psoriasis and periodontal diseases are characterized by an exaggerated immune response to the microbiota residing on epithelial surfaces. This study aimed to explore the associations between the severity of psoriasis and periodontal destruction in patients with psoriasis. METHODS: Thirty-three patients diagnosed with psoriasis were referred from the dermatology clinic of National Taiwan University Hospital. Full-mouth periodontal examination was performed and saliva was collected after patients signed informed consent forms. The Psoriasis Area Severity Index (PASI) as well as clinical periodontal parameters including probing depth (PD), plaque index (PI), gingival index (GI), and clinical attachment level (CAL) were evaluated. Salivary cytokines including interleukin (IL)-1ß, IL-12, IL-17, interferon-γ, and tumor necrosis factor (TNF)-α were tested with the Luminex Bio-Plex system. Anti-inflammatory medication, tobacco use, and underlying comorbidities were included in the analysis. RESULTS: Baseline PASI was significantly associated with PI. PASI at follow-up was positively correlated with CAL ≥ 4 mm (%) and saliva IL-1ß levels. Psoriasis patients who used non-steroidal anti-inflammatory drugs or topical steroids had significantly lower GI, PD ≥ 4 mm (%), and saliva IL-1ß and TNF-α levels. Moreover, a history of tobacco use was associated with higher PD ≥ 4 mm (%). CONCLUSION: PI, CAL, and salivary IL-1ß were associated with PASI. Periodontal severity was associated with psoriasis involvement. Periodontal inflammation in psoriasis may be modified by anti-inflammatory medication and tobacco use. Additional large-scale longitudinal and mechanistic studies are needed.