The present invention relates generally to a spinal plate and, in particular, to a dynamic cervical plate. The human spine is made of 7 cervical, 12 thoracic, 5 lumbar vertebrae and the sacrum. Between each vertebral body is the intervertebral disc that connects the two adjacent vertebrae. The very first and the second vertebrae, C1 and C2 respectively, connect to the skull superiorly and the last lumbar vertebrae, L5, connects to the sacrum inferiorly. The cervical portion of the spine is made of 7 vertebrae C1 through C7. The intervertebral disc can become damaged with age or trauma resulting in degenerative disc disease, disc herniation, loss of disc height which ultimately can lead to nerve or spinal cord impingement causing neurologic symptoms, such as radiating pain, numbness, tingling and motor weakness. Degenerative disc disease can also cause chronic neck pain. Various treatment modalities are used to remedy this problem including a surgical procedure called anterior cervical discectomy and fusion (ACDF). In this procedure the disc is removed, then an interbody spacer consisting of a bone or cage is placed to enhance the fusion process as well as to maintain the disc space height. A cervical plate may then be fixed to the anterior aspect of the spine with screws to maintain the lordotic sagittal alignment. Cervical plates can be static or dynamic. Static plates are rigid, and do not allow settling of the vertebrae. Dynamic plates have some degree of movement in the superior inferior direction such that its length changes to a limited degree. This movement allows the dynamic cervical plate to adjust its height as the vertebral body height decreases over time. This helps to load the interbody graft during normal postures, and avoids overloading the interbody graft in extension positions. Some needs, however, remain. For one, visibility of the spine while placing dynamic plates is difficult because of the increased width of these types of plates. Therefore, intermediate screw fixation of the plate becomes a challenge. Often, the intermediate points on the plate cannot be easily moved to accommodate a screw position directly over the vertebra. Finally, because of the lack of visualization, it often becomes difficult to assess whether the vertebrae have been properly aligned with the plate.
USPTO Backgrounds
USPTO Backgrounds