Comparison of stress distribution of adjacent segments after artificial cervical disc replacement versus anterior cervical discectomy and fusion:a finite element analysis / 中国组织工程研究

BACKGROUND:Previous clinical fol ow-up study showed that disc degeneration of adjacent segment after anterior cervical discectomy and fusion was faster than that of artificial cervical disc replacement. Compared with the anterior cervical discectomy and fusion, artificial cervical disc replacement can maintain a good range of motion of replacement segment. Further investigation should be taken to compare the difference between stress and fusion after replacement. OBJECTIVE:To compare the adjacent level discs loads between artificial cervical disc replacement and anterior cervical discectomy and fusion. METHODS:A healthy 30-year-old male volunteer was scanned with CT at the artificial cervical intervertebral disc and anterior cervical plate. Three-dimensional images were reconstructed with Mimics 10.01 and Geomagic Studio.v11 software. Above three-dimensional data were input into the Abaqus6.9 finite element analysis software for meshing, assignment, and stress analysis. Finite element method was used to simulate the stress changes of the adjacent segments after artificial cervical disc replacement and anterior cervical discectomy and fusion. RESULTS AND CONCLUSION:(1) Under the same preload, during anteflexion, posterior extension, and lateroflexion, the disc stress at adjacent segment was significantly larger after anterior cervical discectomy and fusion than normal disc. Compared with normal persons, no significant difference was detected in stress of adjacent segment at anteflexion, posterior extension, and lateroflexion after artificial cervical disc replacement. (2) Compared with artificial cervical disc replacement group, the stress of adjacent segment increased 10.3%-51.6%in the anterior cervical discectomy and fusion group. (3) Finite element analysis showed that the stress was larger in the anterior cervical discectomy and fusion group than in the artificial cervical disc replacement group. With prolonged fol ow-up, compared with the conventional anterior decompression and fusion, artificial cervical disc replacement can better play its protective effect on the adjacent intervertebral disc.

[Adjacent segment degeneration after cervical artificial disc replacement at early mid-term follow-up].

OBJECTIVE: To study the effectiveness of artificial disc replacement for cervical diseases and the adjacent segment degeneration. METHODS: Between January 2008 and October 2010, 39 cases of cervical spondylosis underwent cervical disc replacement. Of them, there were 20 males and 19 females with an average age of 45.7 years (range, 32-60 years) and an average disease duration of 30 months (range, 1 month to 10 years), including 26 cases of cervical myelopathy, 11 cases of nerve root cervical spondylosis, and 2 cases of mixed cervical spondylosis. Single level disc lesion was observed in 27 cases while bi-level lesion in 12 cases. Prestige disc prosthesis was used in 9 patients, Prodisc-C prosthesis in 4 patients, and Discover disc prosthesis in 26 patients. The neurological functional recovery was assessed after operation by Japanese Orthopaedic Association (JOA) score. The range of motion of replaced segment and adjacent segments was measured (Cobb angle), and Kellgren's X-ray assessment was used to evaluate the degree of adjacent segment degeneration. RESULTS: The operation was successfully performed in all cases, with primary healing of all the incisions. All patients were followed up from 12 to 36 months with an average of 23.1 months. JOA score was significantly improved at last follow-up when compared with preoperative score (P < 0.05), and no significant difference was observed in the Cobb angle of replaced segment and adjacent segments between pre- and postoperation (P > 0.05). According to the Kellgren's X-ray assessment, degeneration of the adjacent segments occurred in 5 cases at last follow-up, including 3 cases of degeneration from grade 0 to grade 1 or 2, 1 from grade 1 to grade 2, and 1 from grade 2 to grade 3, with a degeneration rate of 12.8%, but no significant difference was found in degeneration degree when compared with preoperative value (chi2 = 1.793, P = 0.406). No degeneration of adjacent segments occurred in 32 patients at 15 months after operation. CONCLUSION: Artificial disc replacement has a good effectiveness in treating cervical spondylosis, which can maintain the range of motion of the replaced segment and adjacent segments, and may have a protective effect on adjacent segment discs.

Role of Th17 cells and related cytokines in Helicobacter pylori infection / 中华微生物学和免疫学杂志

Objective To investigate the role of Th17 cells and related cytokines in Helicobacter pylori(H.pylori) infection.Methods To establish a mouse model of H.pyloriinfectious gastritis.Meanwhile,a treatment group and control group were set up.The histological changes in the gastric mucosa were observed and scored under light microscopy;The expression of IL-17 and IL-23 mRNAs as well as protein in gastric tissue was detected by RT-PCR and ELISA,respectively;Th17 cells in mice splenocyte were evaluated using the flow cytometry (FCM) method.Results We found significantly higher levels of IL-17 and IL-23 protein and mRNA levels in supernatant of gastric tissue homogenates of infection group as compared to controls and Th17 cells in spleen from mice of H.pylori infection group were all obviously higher than that of control group;IL-17 mRNA,IL-23 mRNA and the ratio of Th17 cells in mice splenocyte of H.pylori infection group mice increased gradually with the time prolonged;The levels of both mRNA and protein levels of IL-17and IL-23 decreased significantly in the treatment group compared with pre-treatment;There was a positive correlation between IL-17 and IL-23 expression levels of mice gastric mucosa and gastric inflammation degree.Conclusion H.pylori infection induced the immune response of Th17 cells;The levels of IL-17 and IL-23 increased in gastric mucosa of mice after H.pyloriinfection;The degree of H.pylori-infected mice gastric inflammation was positive correlation with the levels of IL-17 and IL-23 of gastric mucosa.