BACKGROUND: Posterior internal fixation and fusion system is a main method for chronic back pain caused by intervertebral disc degeneration, but more postoperative adverse reactions occur. Dynamic stabilization system can reduce adjacent-segment degeneration, and theoretically, repair intervertebral disc degeneration.OBJECTIVE: To investigate the efficacy and safety of K-rod dynamic stabilization system in the repair of lumbar degenerative diseases.METHODS/DESIGN: We conducted a prospective, single-center, self-controlled, clinical trial at the Orthopedic Hospital of Shenyang, China. Sixty-seven patients with lumbar degenerative diseases were enrolled, and treated with K-rod dynamic stabilization system. All patients were followed for 2 years. The primary outcome was the changes in the Oswestry dysfunction index scores at baseline, 3, 6, 12 and 24 months postoperatively. The secondary outcomes were the ratio of height vertebral space to body and lumbar lordotic angle at baseline, 3, 12 and 24 hours postoperatively; the visual analogue scale scores for back pain and morphological changes in the lumbar vertebrae on x-ray preoperatively and 3, 6, 12 and 24 months after surgery; the incidence of adverse reactions at 3, 6, 12 and 24 months postoperatively.This trial has been registered at ClinicalTrials.gov (identifier: NCT03214042). The study protocol has been approved by the Ethics Committee of Orthopedic Hospital of Shenyang. All protocols will be performed in accordance with the Ethical Principles for Medical Research Involving Human Subjects in the Declaration of Helsinki. Written informed consent was provided by each patient after they indicated that they fully understood the treatment plan.DISCUSSION: This trial was designed to investigate the efficacy and safety of K-rod dynamic stabilization system for lumbar degenerative diseases, thus providing reference for its clinical application. Partial results demonstrated that the Oswestry Dysfunction Index and Visual Analogue Scale scores at 24 months postoperatively were significantly improved (P < 0.01), but the ratio of height vertebral space to body and lumbar lordotic angle did not differ significantly at different time points (P > 0.01). These results suggest that K-rod dynamic stabilization system can alleviate pain and improve lumbar function in the patients with lumbar degenerative diseases.

OBJECTIVE: From biomechanics, to summarize the application advances of metal screw implantation intemal fixation in cervical diseases. METHODS: A total of 22 articles of biomechanical analysis and clinical application of cervical screw implantation published between 2000 and 2008 were collected to analyze the anatomic basis, biomechanics, clinical application and advantages and disadvantage of cervical screw implantation. RESULTS: Lateral mass screw, pedicle screw internal fixation, and transarticular screw fixation can enhance biomechanical stability of cervical diseases. CONCLUSION: Screw implantation is an effective lower cervical intemal fixation technique and can be used in lower cervical instability and defects caused by various factors, in particular posterior column partial defect.

Objective:To provide a theoretical basis for the clinical application of the posterior route through atlas occipital articular slope screw internal fixation system through the biomechanical study.Methods:Eight cadavers of healthy adults aged 35-60 years and 155-180 cm in height were selected. The specimens with complete anatomical structure and without surgical operation were established as normal models. The model of occipito-atlantoaxial complex was established by breaking the articular capsule, ligament and other connecting structures and cutting the dentate process. The device was established as an internal fixation model through the specimen of atlantooccipital joint slope screw internal fixation system. Given normal model and internal fixation of 1.5 N·m in the moment of flexion, lateral bending and axial rotation and to measure the specimen C 0-C 1 and C 0-C 2 segment of the range (range of motion, ROM), comparative analysis of pillow neck area within the normal model and fixed model changes the range of movement, after the evaluation through the slope between atlas and the occipital screw internal fixation system of mechanical properties. Results:In the normal model, the flexion, flexion and extension, lateral bend and axial rotation ranges of C 0-C 1 segments were 23.85°±2.43°, 4.74°±0.55°, 5.77°±0.75°, respectively; the corresponding activity ranges of C 0-C 2 segments were 30.66°±3.05°, 9.09°±1.37°, 70.97°±9.48°, respectively; in the internal fixation model, the flexion and extension, lateral bend and axial rotation ranges of C 0-C 1 segments were 0.71°±0.24°, 0.24°±0.06°, 0.34°±0.09°, respectively. The corresponding activity range of C 0-C 2 segment was 3.09°±0.82°, 0.74°±0.07°, 1.22°±0.10°, respectively. Compared with the normal model, the range of activity of the internal fixation model in all directions was significantly reduced (<3°), and the reduction ratio of activity was more than 90%. Conclusion:The posterior route through pillow slope screw internal fixation system can effectively reduce the range of motion of the occipital neck in flexion, extension, lateral bending and rotation, and has safe and reliable biomechanical stability.