ABSTRACT
Netrin-1 may protect and repair the damage caused by cerebral infarction, in terms of inhibiting apoptosis and inflammatory, and promoting angiogenesis and axon regeneration, etc. Netrin-1 may associate with the pathogenesis and outcome of cerebral infarction. The application of Netrin-1 in clinic needs more researches.
ABSTRACT
Objective To evaluate the influence of dynamic fixation (rotating and sliding pedicle screws) on stability of the atlantoaxial joint. Methods A series of in vitro biomechanical tests were performed using six fresh adult cervical spines (occipital bone-C4 segment) to simulate different conditions in surgery， including the intact state, the injury state, rigid fixation, rotating pedicle screw fixation, sliding pedicle screw fixation. The repeated measurement design was employed, and under intact, injury and different fixation states, the pure moment of 1.5 N·m in flexion-extension, left-right lateral bending, left-right axial rotation directions were applied using the spinal testing machine. The movement of atlantoaxial spine was measured consecutively by three-dimensional （3D） measurement system in order to analyze the range of motion (ROM) and neutral zone (NZ) of atlantoaxial joints. Results Under injury state, ROM of atlantoaxial joints was significantly larger than that under intact state during flexion, extension, lateral bending and rotation, leading to the instability of atlantoaxial joints. ROM of fixation segments was significantly reduced during flexion, extension, lateral bending and rotation after rigid and dynamic fixation. Compared with rigid fixation, dynamic fixation showed a significant ROM increase during lateral bending. NZs of fixation segments after dynamic fixation were significantly reduced. There were no significant ROM differences between rigid fixation and dynamic fixation. Conclusions The stability of atlantoaxial joints by dynamic fixation during flexion, extension and rotation was comparable to that by rigid fixation, but weaker during lateral bending. Dynamic screw fixation can maintain the relative stability of atlantoaxial joints.
ABSTRACT
Objective To investigate the effect of asymmetric lumbar discectomy on facet joint force and stability of lumbar spine. Methods Seven human cadaver specimens (L2-3 segment) were selected to make intact, 1/4 discectomy and 1/2 discectomy status and applied with pure moment of 7.5 N•m. The range of motion (ROM) and facet joint force of L2-3 segment during flexion/extension, lateral bending and axial rotation were recorded, respectively. Results During extension, a significant increase in facet joint force was found under 1/4 discectomy status at the remained side. During lateral bending, the facet joint force at both sides under 1/2 discectomy status increased significantly than that under intact status. During axial rotation, facet joint force increased significantly only at the side without discectomy under 1/2 discectomy status. Except flexion, ROM under 1/4 discectomy and 1/2 discectomy status were larger than that under intact status in all the other motion directions (P<0.05). There was no significant difference in ROM between both sides during lateral bending and axial rotation direction. Conclusions The asymmetric lumbar discectomy can increase the ROM in all motion directions except flexion, and can enlarge the facet joint force asymmetrically, which indicate that instability of lumbar spine and facet joint force increasing resulted from asymmetric degeneration of the disc might lead to backache.