الفهرس 
Anatomy and Biomechanics ofOnly 14 pages are availabe for public view
 |  | from | 138 |  |  |
| | | from | 138 | | |
Abstract
Spondylolisthesis is defined as a displacement of a vertebral body on the one below it. The most common direction of spondylolisthesis, is a forward or anterior displacement of the superior vertebral body. The intact neural arches of the lumbar vertebrae add stability to the spinal motion segments, in part through the function of the inferior and superior articular processes of the facet joints. In the lumbar region, anterior displacement of the superior vertebra of each motion segment is resisted through overlapping of its inferior articular processes with the superior articular processes of the vertebra below . Breakdown of this normal locking mechanism occurs with articular defects and defects in the neural arch. These pathologic defects produce five recognizable clinical groups of spondylolisthesis dysplastic, isthmic, degenerative, traumatic, and pathologic. Congenital spondylolisthesis with forward displacement of a vertebral body at birth. In isthmic spondylolisthesis, the basic lesion is a defect in the pars interarticularis of the neural arch, the etiology of this lesion is unknown. In degenerative listhesis, the primary pathology is degeneration of the disc followed by facet degeneration, but the neural arch is intact, and most commonly it occurs at the L4-L5 interspace. Traumatic spondylolisthesis are really examples of fracture dislocations of the spine. An acute traumatic slip can be openly reduced and maintained in the reduced position with the use of instrumentation and fusion. In pathologic spondylolisthesis on occasion, generalized bone disease such as osteogenesis imperfecta, osteomalacia. Management of the local lesion in this group of cases depends on the management of the cause of the primary disease. Iatrogenic spondylolisthesis secondary to aggressive surgical intervention that destabilizes a spinal segment. Conservative treatment is include short periods of rest, anti-inflammatory medications, and, bracing. An epidural steroid injection sends steroids which are very strong anti-inflammatories right to the nerve root that’s inflamed.Epidural steroid injections have been advocated, seem to be most beneficial in patients with radiculopathy. If epidural steroid injection is successful, physical therapy should be instituted. A physical therapy program is one of the more effective ways to treat spondylolisthesis for two main reasons: it can help strengthen the muscles that support the spine, and it can teach the patient how to keep his spine safe and prevent further and future injury. Epidural block and extended bed rest appear to be of little value and carry a significant risk of morbidity, especially in elderly patients. There are a wide variety of binders, belts braces, and other devices designed to offer relief from back pain. However, long-term wear of back braces may lead to gradual weakening of the supportive muscles owing to the effect of unloading the spine; therefore, this may not be desirable. For patients in whom no perative treatment is unsuccessful, operative intervention should be considered. Most patients with the more common low-grade slips will be managed successfully with non operative treatment. Complete preoperative work-up, detailed planning for intraoperative contingencies, technical execution, and activity restriction are all requirements for success. The consensus about surgical approaches is that anterior interbody fusion in the surgical management of degenerative lumbar spondylolisthesis improves clinical outcomes and achieves solid fusion. However, surgical indications for this procedure should be limited because of the differing stages of degenerative spondylolisthesis. Although there is some consensus for fusion in the surgical treatment of degenerative spondylolisthesis with stenosis, indications for additional instrumentation remain controversial. Generally, presence of significant movement in the listhetic segment indicates instrumentation. Any intention for correction of listhetic segment warrants either interbody fusion or extension of fusion down to the sacrum, with instrumentation. Recurrent stenosis of a previous laminectomy level often indicates instrumented fusion. Instrumentation certainly improves the successful fusion rate but there is no conclusive evidence that it improves clinical outcome.The authors recommend posterior in situ fusion for those symptomatic patients with evidence of disc or facet abnormality. The addition of a posterior decompression in the setting of leg pain without radicular findings does not significantly improve the results and should be avoided. The results in the presence of a true radiculopathy do improve with combined posterior decompression and fusion. The goal of surgery in high-grade spondylolisthesis is to improve pain, neurologic deficits, and avoid further displacement. Restoration of sagittal balance will be a major goal if kyphosis disallows the patient to stand, walk, or look forward. Cosmetic criteria do not appear to be major surgical indications in most subjects.However, surgery for high-grade spondylolisthesis, is reduction techniques, carries a high incidence of major complications, mainly neurologic. In those conditions the risk/benefit ratio for this surgery has to be assessed carefully. Fusion in situ appears indicated for pain and minor walking disturbances in the absence of neurologic symptoms or deficits. Reduction (essentially partial) will be indicated in more severe cases. Complete reduction or vertebrectomy will only be indicated in a few extremely severe cases. Surgery in high-grade spondylolisthesis and spondyloptosis is a high-risk surgery and should be performed only by experienced surgeons in well-equipped centers. Younger adults with high-grade isthmic spondylolisthesis frequently require surgical treatment and there is no one option that is right for all such patients. Advocates of in situ fusion cite numerous advantages, the most widely accepted of which would be a decreased risk of neurologic injury. Instrumented reduction and fusion, while offering a number of potential benefits, clearly is able to restore more normal mechanics to the lumbar spine. Careful analysis of the patient’s pathologic anatomy, signs, and symptoms allows the surgeon to offer the patient the procedure with the most favorable risk/benefit ratio. Minimally invasive lumbar procedures,the goals of these procedures are to reduce the approach-related morbidity associated with traditional lumbar fusion. As well, there are benefits and disadvantages associated with each technique. Therefore, the development of procedures that minimize tissue trauma without compromising effectiveness represents an important advancement in the field of spine surgery. New technologies will allow surgeons to effectively perform more complex spinal procedures using techniques that minimize tissue injury. Instrumented reduction and fusion, while offering a number of potential benefits, clearly it is able to restore more normal mechanics to the lumbar spine, resulting in an improved appearance and posture.For many years, spinal fusion has been the mainstay of treatment for back pain caused by lumbar instability. However, the increase in fusion rates has not been paralleled with an improvement in clinical outcomes. Motion sparing techniques, such as dynamic spacers and spine arthoplasty, have gained widespread popularity as they hold several advantages over spinal fusion, thus increasing the number of techniques available to stabilize the abnormal motion segment.