Effects of facet joint degeneration on stress alterations in cervical spine C5-C6: A finite element analysis

It has been demonstrated that articular facet degeneration can cause local strain alterations and induce neck pain. This study aims to quantify the biomechanical effects of normal and degenerated C5-C6 articular facets, and evaluate the correlation of mechanical strain between healthy and degenerated spine. A 3-dimensional finite element (FE) model of the C5-C6 cervical spine was developed [Model 0 (M0)]. The asymmetric models of C5-C6 bilateral articular facet joint were established separately to mimic articular facet joint degeneration. The capsule ligament stiffness of C5-C6 unilateral facet joint was altered with minimum and maximum threshold to simulate capsule ligaments' lesion and calcification [Model 1 (M1) and Model 2 (M2), respectively]. Besides, the cervical C5-C6 unilateral articular facet joint direction was changed by 5° and 10° forward to imitate the moderate joint hyperplasia and severe osteophyte (Model 3 and Model 4 respectively). M1 increased the rotation range of ipsilateral side (left), while M2 reduced, and both had limited effect on the contralateral side (right). The angle increased in Model 3 (M3) (61°) and Model 4 (M4) (55°) comparing to M0 during the axial rotation, and the angle of M4 was larger. M3 and M4 increased the nucleus pulposus pressure with and without controlled angular displacement during axial rotation. The pressure of nucleus pulpous increased during M1 rotating to the abnormal side but decreased when rotating to the other side, but the results of M2 were opposite. The capsule ligament stiffness made an impact on segmental mobility and vertebral spatial position, and the sagittal angle of articular facet joint exerted an influence on disc pressure distribution.

Predictive value of CK20 in evaluating the efficacy of treatment and prognosis after surgery for colorectal cancer

Herein, correlations between expression levels of CK20 and efficacy of treatment and postoperative prognosis of colorectal cancer were evaluated to elucidate the clinical value of CK20. Postoperative follow-up was performed on 62 patients who underwent surgery for colorectal cancer between January 2010 and December 2010. Samples of tumor tissues and intraperitoneal drainage fluids were collected. Blood samples were obtained during the 2-year follow-up period. The expression of CK20 in surgical specimen, intraperitoneal drainage fluids, and postoperative serum samples was quantified by enzyme-linked immunosorbent assay, RT-PCR, and western blotting. Correlation between the levels of CK20 and postoperative outcomes was investigated by Spearman correlation analysis. In both tumor specimens and intraperitoneal drainage fluids, CK20 levels were lower in patients with earlier cancer stages than in those at later stages. During postoperative follow-up, serum negative CK20 patients had significantly higher 3-year survival rates than serum positive CK20 patients. All differences were statistically significant (P < 0.05). CK20 levels can provide clinically valuable information on the postoperative prognosis of patients with colorectal cancer.