Degenerative Disease Of The Cervical Spine

Fig. 31.11. The DOC plate (Johnson and Johnson/Depuy-Acromed Incorporated, Cleveland, Ohio, USA). Anterior views of two DOC plates. The DOC plate is a dynamic device which compensates for subsidence across the fusion segment. The plate on the left demonstrates the upper crosslink device, which attaches to the vertebral bodies in the upright position. On the right, the upper crosslink has migrated inferiorly to the limiting crosslink, which is the amount of the subsidence allowed by this plate. The inferior crosslink is attached to the inferior vertebral body along the segment of fixation and the middle two crosslinks, seen on the right-hand side of the plate, are used to attach intervening vertebral bodies or the bone graft.

Fig. 31.11. The DOC plate (Johnson and Johnson/Depuy-Acromed Incorporated, Cleveland, Ohio, USA). Anterior views of two DOC plates. The DOC plate is a dynamic device which compensates for subsidence across the fusion segment. The plate on the left demonstrates the upper crosslink device, which attaches to the vertebral bodies in the upright position. On the right, the upper crosslink has migrated inferiorly to the limiting crosslink, which is the amount of the subsidence allowed by this plate. The inferior crosslink is attached to the inferior vertebral body along the segment of fixation and the middle two crosslinks, seen on the right-hand side of the plate, are used to attach intervening vertebral bodies or the bone graft.

extent of fusion required, the presence or absence of a deformity and the extent of its correction and patient factors. In the presence of a cervical kyphosis, attempt at reduction of the kyphosis is optimal. As discussed earlier, correction of the kyphosis would reduce the likelihood of mechanical pain and reduce the amount of translational and compressive force on the fixation device. Both anterior and posterior fixation devices have a limited capacity to resist translational movement. In the setting of cervical spondylitic disease, spinal deformity typically takes the form of kyphosis, due to loss of disk space or vertebral body height. It is very difficult to correct and maintain correction of kyphosis by a posterior approach. Therefore, a component of the fixation/fusion for kyphosis usually involves anterior surgery, utilizing either interbody grafts or a vertebrectomy strut. Adequate immobilization is required following implantation of the interbody grafts. Many would consider an anterior plating procedure to supplement the interbody graft. The plate stabilizes the involved motion segment and the bone graft. It also acts as a load-sharing structure, where some of the axial force placed upon the fused segment is transmitted through the screws and the vertical member of the fixation device, and not solely through the bone graft. This reduces the likelihood of graft subsidence and subsequently the loss of kyphosis correction.

Posterior fixation and fusion for degenerative disease is considered to prevent subsequent kyphosis following laminectomy or to correct and stabilize an unstable motion segment. Utilization of a posterior fixation/fusion technique alone for the correction of a mobile kyphosis has a significant likelihood of fixation failure. Anterior instrumentation can be used to supplement the posterior fixation and fusion to augment the stabilization and likelihood of achieving fusion in such a circumstance.

Laminoplasty is another technique utilized to effect spinal stenosis decompression. The technique involves mobilizing the posterior elements without completely detaching the lamina from the lateral masses. Complete transsection of the lateral aspect of the lamina, combined with a partial scoring of the lamina of the contralateral side, will enable the lamina to be cracked back across the partially transected lamina to expand the canal size. Another technique involves splitting the posterior elements in half down the spinous process. The two halves of the spinous process or the laminae are then spread apart. In both techniques, a bone graft is interposed between the cracked fragments of bone to maintain the patency of the canal following the decompression.

The advantages of laminoplasty are in diminishing the accumulation of epidural scar tissue and maintaining some of the extensive compartment function, by enabling the paraspinal musculature to reinsert upon the posterior elements. Some preliminary studies indicate that the likelihood of inducing kyphosis is lower with a laminoplasty when compared to laminectomy alone or laminectomy combined with segmental fusion. Also, patients who have undergone laminoplasty remain mobile and unfused, which is a more physiological state. Biomechanical studies have not clearly determined if the hypothetical goals of lamino-plasty are realized.

Ossification of the posterior longitudinal ligament is a variation of degenerative disease in the neck, involving significant hypertrophy and calcification of the posterior longitudinal ligament. It typically manifests with symptoms and/or signs of myelopathy. It is more frequently seen and reported in the Japanese literature. There also appears to be some predisposition in the African-American population. Spinal canal decompression is a primary goal in the treatment of such patients. Ideally, a resection of the ossified ligament which is encroaching upon the canal is the goal of surgery. However, the site and the vertical extent of the calcified ligament can make it difficult to adequately decompress the canal without significant morbidity. It is not uncommon to see that the calcified posterior ligament is fused to the dura, which can result in a dural perforation during the decompression, which increases the likelihood of spinal cord injury. In more severe cases, which extend over multiple motion segments, laminectomy with or without fusion can be utilized as a less optimal form of treatment.

Cure Your Yeast Infection For Good

Cure Your Yeast Infection For Good

The term vaginitis is one that is applied to any inflammation or infection of the vagina, and there are many different conditions that are categorized together under this ‘broad’ heading, including bacterial vaginosis, trichomoniasis and non-infectious vaginitis.

Get My Free Ebook


Post a comment