Radiological Evaluation of the Lumbar Disc Height Changes in Pre and Post- Operatives of degenerative lumber disorders underwent Computer navigated Mis- TlifAbstract:Objective: This retrospective study to assessment the disc height changes pre and post-operation for the patients with degenerative lumber disease whether the disc height improved by discectomy and cage implantation by MIS-Tlif procedure.Methods: Between the period of January 2015 to October 2018 a retrospective study of 40 patients (21 Female, 19 Male) selected randomly with mean age 52.6 years old who underwent MIS-Tlif were compared pre and postoperation of MIS-Tlif through calculating disc height by digital tool using X-ray image.Results: This study includes 56 segments of lumbar vertebra. The X-Ray post-operatively showed significant physiological changes in disc height with the disc height average 14.38mm compared with the disc height pre-operatively with the average disc height 9.83mm in addition the T-test result was 2.050. The disc height improve significantly P0>.001 after MIS-Tlif, There was no serious complication found after performing the operation.Conclusion: The Mis-Tlif procedure elevates the disc gap. Supported with cage and bone graft can restore the disc height to keep the normal lumber function that may play an important role in relive the symptoms of degenerative lumber disorder.Keywords: MIS-TLIF,Disc height  , computer navigation system, Disc degeneration disease.Introduction:Intervertebral disc consists of three main parts, the cartilaginous end plates, annulus fibrosus, and nucleus pulposus. It controls the movement of the spine and bares a lot of the pressure. It absorbs pressure and it changes if the spine is compressed. Spine Intervertebral discs are characterized by their abundant extracellular matrix and low cell density, coupled with an absence of blood vessels, lymphatics, and nerves in all but the most peripheral annulus layers. In many respects, the absence of this leaves the disc prone to degeneration, because the cells have a large extracellular matrix to maintain without nociceptive feedback to limit and detect damage, and no source of repair through the vasculature. Intervertebral discs are not the same in composition, but consist of two distinctly different regions. The outer annulus fibrosus is a fibrocartilage and contains concentric lamellae which is rich in collagen, whereas the inner nucleus pulposus is less structured and contains a gelatinous substance rich in proteoglycans.Disc degeneration disorders are the most common reason for low back pain. Many cases require operation if the conservative treatment doesn’t improve the symptoms, dynamic stabilization implant systems to fuse the vertebral bodies with or without supplementary devices, and dynamic stabilization devices are employed with the assumption that they will decrease the intervertebral disc loading at the treated level thereby decreasing pain and restrict more degeneration while reducing the degenerative influence on the adjacent levels. Various design concepts ranging from loaded springs to articulating type devices to the nucleus and annular repair devices have been proposed recently. The prevalence of spine surgery has steadily been on the rise over the last two decennium and this direction in prospect to spread over the next twenty-five years. In addition, the number of implanted medical devices that have been developed and the clinical indications for their use have been expanding over the last ten yearsDisc height is racial for the patient with the lumbar degenerative disease. Restore the disc height is important in keeping the normal structure of the lumbar spine.  Mis-TLIF assisted by computer navigation system could accurately play the role in restores the disc height with the satisfied clinical outcome, This method has some obvious advantages over traditional surgeries but few kinds of literature report the disc changes after operation so we aim in this study to declare that disc height restored and the patients symptoms disappear after MIS-Tlif.Methods:Patient’s characteristics:This retrospective study between the period of January 2015 – October 2018 included 40 patients ( 21 F, 19 M) with mean age 52.6 years .56 segments of lumbar vertebra were treated by MIS-Tlif divided as (12 segments L3-L4, 32 segments L4-L5, 12 segments L5-S1).40 patients were with a clear history ,no previous spinal operation, no hypertension or diabetes, none of the patients was having a disease prevent the MIS-Tlif to be performed.Operative technique:Minimally invasive  transforaminal lumbar interbody fusion, is a procedures used to treat disc degenerative disorders that lead to affect disc height, spinal compression and instability MIS ( minimally invasive procedure ) provide substantial advantages over other surgeries, and can show significant results for patients in terms of pain release and form of life after the operation.Minimally invasive transforaminal lumbar interbody fusion depends on the use of micro-tools and graduated dilators to approaches the spine, and then cut through the muscle tissue to gateway the influenced vertebras. With MIS technique, the incision is made to side the spine with minimal incision size about 4-5cm. Graduated dilators are used to aside the vertebral muscle in the stand of cutting them. Tlif needs a part of the vertebral bone to be removed. This is the lamina of the vertebra-the bony dome that coating the back side of the spinal canal. Through this opening can do the discectomy so the fusion can take place. Minimally invasive Tlif usually depend on using the pedicle screws and rods to fuse the vertebral bodies. Wires and hooks are not as a rule in this type of procedures.The disc height improved by discectomy and cage implantation by MIS-Tlif procedure.A discectomy is the surgical removal of abnormal disc material that presses on a nerve root or the spinal cord. The procedure involves removing a portion of an intervertebral disc, which causes pain, weakness or numbness by stressing the spinal cord or radiating nerves. A cage is placed in the inter-body space and packed with bone graft to help stimulate bone growth. It restores the height of the spine and stabilizes the vertebrae as they fuse together. In a successful fusion, the bone grows around and through the cage over time, making it the only place in the body where a material is implanted and active in the reparative process which elevates the disc height after the MIS-Tlif procedure. In other words, the cage and the material it is made out of play an active role in the growth of the bone that forms the fusion.Bone graft material come in many kinds often, the patient’s bone is taken from the hip bone, and sometimes the surgeon will use the allograft to reduce the recovery time for the patient. Bone morphogenetic protein can also be used.Recovery time:Minimally invasive technique minimize recovery time compared to other procedures, and most of the patients can be back home directly after the operation with some exceptions which need more time for examination, many patients will show improvement on their symptoms directly after the operation. Patients will need to start the exercise and physical therapy; this is less what the open surgery must afford. Minimally invasive Tlif is a beneficial procedure that can provide an improvement in spinal stability and decrease pain.Radiological assessment:Radiographic examinations were performed pre and postoperative, Radiographic data were collected and evaluated by the same observer. In all patients, X-Ray performed in our radiology department in order to calculate the intervertebral height index (DHI) preoperatively and postoperative using digital tools. The intervertebral disc height is expressed as an average of the sum of the measurements at the anterior and posterior regions of the disc (anterior line +  posterior line/2). The disc space height normalized with the anteroposterior diameter (d) of the upper vertebral body to correct the magnification differences of the radiographs.Fig 1: disc height (Anterior line+ posterior line)/ 2This X-Ray  showing the disc height pre and post MIS-Tlif :Secondary spinal stenosis due to lumbar disc herniation L5-S1Disc height pre=(5.6+11.1)/2=8.35mmDisc height post=(7.4+22.2)/2=14.8mm                  MIS-Tlif operation of 2 segments (L3-L4, L4-L5(                  Disc height is calculated by using digital tool (Anterior line + posterior line)/2Statistical analysis:For comparing the differences between the preoperative and post operatives disc height we use the T-test. Statistical significance was set at a P value < 0.001. The statistical analysis was performed using SPSS software.RESULTS:56 segments of 40 patients were selected randomly between the period 2015-2018 using the X-Ray to measure the disc height according to Dabbas method. No patient has a history of any spinal operations. 19 patient male, 21 female, with a mean age of 52.6 years. All the cases showed improvement on the disc height postoperatively. though the average of the posterior line pre-post(6.76mm – 10.61mm), and  the anterior disc line average was pre-post (12.9mm – 18.16mm ), and the mean of  disc height pre MIS-Tlif was 9.83mm compared with the disc height post MIS-Tlif with average 14.38 the patient’s complaints improved  after MIS-Tlif  with no complication .the postoperative X-ray showed no subsidence or collapse of the cage or bars, and  none of the pedicle screws show a sign of loosening position?.Discussion:Intervertebral discs undergo age-related degenerative changes that contribute to some of the most common causes of impairment and disability for middle aged and older persons: spine stiffness, neck pain, and back pain. Potential causes of the age-related degeneration of intervertebral discs.Disc aging lead to overall loss of water content and conversion to fibrocartilage especially there is a decrease in the water content, nutritional support, proteoglycans and PH. Many ligaments and muscle attack to the back of the spine to provide power movement which will help the disc tissue to stand longer any disorder will affect the anatomical structure will lead to more pressure on the disc tissue and end with disc degeneration. Degenerative disc disease can occur in any place in the spinal cord but mainly its happen in the low back and it’s a condition more than disease cause the disc will lose their flexibility of courser age related to disc tissue include the disc dry and shrink small tears occur in the annulus, bone spurs appear and the disc became thinner in addition to spinal cord stenosis.Degenerative disc disease develops as a result of the effects of aging on your spine and specifically on your intervertebral discs. It can also be associated with an injury to the back, but even in that scenario, your discs have usually become weak because, with age, discs lose water content, may become thinner; both of which can alter the strength and shape of one or more discs. Before you can feel the result of Degenerative disc disease pain and other symptoms your discs and other spine structures are changing. This is simply the natural result of the stress and strain each of us puts our backs through every day. In this prospective study used 40 patients pre and post MIS-Tlif and after calculating the disc height its clear that MIS-Tlif is a success procedure to treat the patients complain of low back  pain and the disc height showed significant improvable Some of the spine degenerative disorders that require surgical intervention such as degenerated discs. The surgical process providing a solution to remove the problem of lower-back pain only more than fix it. The perfect treatment technique would include returning the physical and mechanical functionality of the disc. However, current research has been able to identify only MIS-Tlif to solve this complaint.  MIS-TLIF is also an effective method to treat lumbar spine deformity and avoid complications compare with Tlif, provide pleasant clinical outcomes. This method has some clear advantages over convention surgeries. It is a technique with more advantages than other procedure treats spinal disorders. In the treatment of patients with spinal disorders the cage can be placed between the vertebral bodies which prevent the pressure on the nerve root. After inducing the supplementary instrumentation, it can result in convenient postoperative stability. For surgical procedures in lumbar spine disorders, MIS-Tlif has the advantages over other surgeries with minimum blood loss and short time surgical procedure and early discharge from the hospital. MIS-TLIF is important surgery in reconstructing spinal stenosis to attain a considerable surgical outcome. The MIS-Tlif can achieve significant post-operation results, most of the authors support the use of MIS-TLIF in the treatment of the lumbar spinal disorders results in significant improvement of disc height.Disc degenerative diseases are one of the main problems which can be treated by MIS-Tlif and the disc height will show improvement, and the symptoms will decrease.MIS-Tlif is a surgical procedure to treat condition such as disc degenerative disorders, and it provide stabilize and immobilize the joint between two vertebra which will alleviate the pain and improve back function the damaged intervertebral disc is replaced with a especially designed cage that maintain proper alignment of the spine and restores proper disc height.In this prospective study we hypothesized not to find any subsidence or collapse, and any worse outcome, any complication during the operation, the patients who performed the MIS-TLIF have shown improvements after the operation and the symptoms disappear and they get back to their normal life after a short hospital stay. The drawback of MIS are prolonged learning period, it demands a specialist with considerable experience, the medical instruments which are used in the operation is very expensive not every hospital can have it ,longer surgery time compare with the open procedure and increase the risk of surgery failure from this all points we can find the MIS-Tlif is more convenient for the patients and that’s what we are looking for improving it. There is a criteria before the operation room.If the patients will not improve with the conservative treatments, there was no improvement of the patient’s symptoms and need surgical intervention, the surgical procedures for all the patients were transforaminal lumbar interbody fusion. Conclusion:The Mis-Tlif procedure evaluate the disc gap sported with cage and bone graft can restore the disc height to keep the normal lumber function .MIS-Tlif operation is highly safe procedure in treating the disc degenerative d conditions, and improve the patients symptoms with less blood loss during the operation, less pain, short healing time, and the patient can get back to his normal life after short period, MIS-Tlif is a  successful procedure for primary cases as well as for revision cases with expressive increase in disc height and reduce  in patients complaints.                     References:Does minimally invasive fusion technique influence surgical outcomes in isthmic spondylolisthesis? 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