Egyptian Journal of Neurosurgery Volume 30 / No. 3 / July - September

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1 Egyptian Journal of Neurosurgery Volume 30 / No. 3 / July - September Original Article Transforaminal Lumbar Interbody Fusion for the Treatment of Spondylolisthesis and Degenerative Segmental Instability; Surgical and Radiological Outcome Received: 05 August 2015 Accepted: 28 November 2015 Key words: Spondylolisthesis, Transforaminal, Interbody fusion 2015 Egyptian Journal of Neurosurgery. All rights reserved Mohamed Amer* and Ahmad Yousef Department of Neurosurgery, Tanta University ABSTRACT Background: Transforaminal lumbar interbody fusion (TLIF) was originally described by Harms and Rollinger in the early 1980s as a surgical method of treating symptomatic lumbar disk degeneration. Objective: Evaluation of the clinical and radiological results of the instrumented Transforaminal lumber interbody fusion with single cage for the treatment of spondylolisthesis grade1&2 and in degenerative segmental instability. Patients and Methods: This is a prospective study of thirty patients with lumbar spondylolithesis either isthmic or degenerative, admitted and operated by transforaminal lumbar interbody fusion (TLIF) in the Department of Neurosurgery, Tanta University hospital, from January 2010 to July Results: In the thirty patients, 66.7% of them were females. Age of the patients ranged between years with a mean age of 36 years. History of back trauma could be obtained in 40% of patients and incidence of consanguinity was 10% of patients. Low back pain and sciatica were present in all patients. Neurological deficits included sensory deficits in 40%, reflex changes in 40% and motor in 20% of patients. The affected level was L4-5 in 50%, L5-S1 in 40% and was L3-4 in 10% of patients. Grade I was encountered in 60%, and grade II in 40% of patients. All of the patients had good outcome as regard pain relief. The complications occurred in our study including wound infection in two patients, dural tear in two patients and TLIF cage migration with screw malposition in one patient. Clinical and radiological follow up of the patients was done for a period of 3-6 months. Solid fusion was obtained in 86.7%. Conclusion: The instrumented TLIF with single cage is a safe and effective method for the treatment of spondylolisthesis G I & II and degenerative segmental instability. INTRODUCTION Spondylolisthesis is the forward displacement of one vertebra on the vertebra below in the sagittal plane of the spine. There are multiple etiologies of spondylolisthesis including dysplastic, isthmic, degenerative, traumatic, pathologic, and iatrogenic. The degree of forward displacement may be graded according to the Meyerding classification. 1, 2 The intervertebral disc space is an environment that is conducive to fusion because of the advantageous biomechanics of compressive force and the blood supply provided via the endplate after curettage of the cartilage. 3 There are different techniques and technologies available for fusion, and each operative technique has its inherent benefits and disadvantages. 4 Introduced by Cloward more than 50 years ago, posterior lumbar interbody fusion (PLIF) represented a significant evolution in the operative treatment of pathological spinal disorders. Many variations of interbody fusions have since been described including anterior lumbar interbody fusion and transforaminal lumbar interbody fusion (TLIF). 2 * Corresponding Author: Mohamed Amer Ass. Prof. of Neurosurgery, Faculty of Medicine, Tanta University m_amer_2000@yahoo.com; Tel.: Transforaminal lumbar interbody fusion (TLIF) was originally described by Harms and Rollinger in the early 1980s as a surgical method of treating symptomatic lumbar disk degeneration. The procedure allows for the stabilization and support of the anterior column of the spine while allowing for direct nerve root decompression from a posterior approach. The TLIF approach offers a number of potential benefits over conventional posterolateral inter transverse arthrodesis including increased fusion surface area, improved fusion blood supply via subchondral cancellous vertebral body bone, complete access for medial canal and lateral recess decompression, and restoration of intervertebral body height. 5 The ideal indication for a TLIF is a patient with a symptomatic single-level grade I or grade II spondylolisthesis with radicular complaints with or without a neurologic deficit. 3,6 TLIF may also be useful in the surgical management of symptomatic degenerative disc disease with positive discography and minimal intra canal pathology, multiple recurrent symptomatic lumbar disc herniation associated with significant mechanical back pain, post discectomy intervertebral disc space collapse with neuro foraminal stenosis and secondary radiculopathy, symptomatic pseudoarthrosis, post laminectomy kyphosis, and in the treatment of lumbar coronal and/or sagittal deformities. 7 Egyptian Journal of Neurosurgery 213

2 Contraindications to a TLIF include: cases of severe anterior disc space collapse with circumferential osteophyte formation in which disc space distraction would be technically challenging and subject to potential implant subsidence. Relative contraindications for TLIF have also evolved and currently include multilevel (3 levels) disc disease, single-level disc disease causing radicular pain without symptoms of mechanical low back pain, and severe osteoporosis (with attendant risk of implant subsidence through the endplates). The TLIF cage is available in the traditional kidney shape or banana shape. 4,8 214 PATIENTS AND METHODS This prospective study was conducted upon thirty adult patients with lumbar spondylolisthesis grade I & II and degenerative segmental instability subjected to transforaminal lumbar interbody fusion, between January 2010 and July The patients were subjected to full history, general and neurological examination and laboratory investigation. The radiographic studies were obtained and could serve to evaluate the extent of decompression needed. It included plain radiograph with kinetic films, CT lumbosacral spine and MRI spine. Axial CT images were necessary to ascertain the suitability of the pedicles to be instrumented for the placement of screws. In general, the diameter of the pedicles should be at least 5 mm in the lumbar region for the placement of screws. A rule of thirds is used for preoperative planning: the diameter of the pedicle screw should be no greater than two-thirds the width of the pedicles to be instrumented, and the pedicle screw length should extend no further than two thirds the length of the body. The Inclusion criteria include Grade I or II spondylolisthesis, Degenerative segmental instability and patients with previous unsuccessful posterior fusion. While the Exclusion criteria include patients with significant osteoporosis (with attendant risk of implant subsidence through the endplates), Infection and Spondylolisthesis of higher than grade II (Relative contraindication). Surgical Procedure: The TLIF procedure is composed of several steps firstly exposure of the posterior spinal elements with placement of pedicle screw instrumentation. Then unilateral or bilateral facetectomy were done with exposure of the posterior lateral disc, placement of an interbody device, and posterolateral fusion. A general anesthetic was administered and the patient was positioned in the prone position on the operating room table. The patient was placed on chest rolls with the knees slightly bent. Pressure points were padded appropriately. The C-arm was brought into position for intraoperative fluoroscopy. The patient is prepared and draped, and the C-arm was used to obtain a lateral fluoroscopic image to confirm the location of the pathology and to plan the incision. A midline incision was used. The dissection was carried down to the facial level using electro cauterization or sharp dissection. Removal of the spinous processes of the level to be decompressed was done, and then laminectomy and foraminotomy were performed. The first step in placement of the pedicle screws is to identify important pedicle landmarks. Once an entry point has been chosen, the bone is decorticated under fluoroscopic guidance; a T-handled awl is advanced manually through the cancellous center of the pedicle into the vertebral body. The mediolateral orientation in the axial plane depends upon the level. After decompression is complete and the contralateral pedicle screws are in position, a discectomy was performed. The pedicle screws contralateral to the exposure connected to a rod, allowing for sequential distraction of the intervertebral space, distraction may also be performed with a laminar spreader contacting the intact spinous processes. After a complete interbody discectomy, a structural interbody spacer filled with an osteo inductive graft material is then inserted unilaterally. The spacers used in our study include carbon and peak cage. After placement of the cages, the tightening connection between the screw and rod is loosened and the interspace is then compressed. If the table or frame is in a flexed position, it is important to extend the table to create lordosis before tightening the implants. The cages are checked again for position and tightness within the disc space. A posterior or posterolateral fusion may be added to increase the likelihood of fusion. Follow up: All patients were evaluated in the outpatient clinic on regular period. Oswestry Disability Index (ODI) was used for pre and post operative disability assessment in all cases. Use of pain medication before and after surgery was compared. Return to work was evaluated as a percent of working capacity (at the latest follow-up evaluation) of the pre morbid occupation as estimated by the patient (100%, 75%, 50%, 25%, 0%). Data collection and analysis of outcome were completed based on the Oswestry Disability Index (ODI) as following: Excellent outcome: This group included cases with no more pain or neurological deficits. Normal daily life activities and patient s satisfaction was more than 80%. Good outcome: When the patient had a significant improvement in the back pain and sciatica, occasional analgesics were required and they experienced less numbness and paraesthesia with a noticeable improvement in weakness. No constraint in daily activities any more. Patient s satisfaction was 60-80%. Fair outcome: Pain had improved up to 50% compared with the pre operative status but still requiring strong analgesics; mild improvement in sensory and motor symptoms was Egyptian Journal of Neurosurgery

3 evident but the patient still had some difficulty with his daily life activities. Patient s satisfaction was around 50-60%. Poor outcome: Patients who experienced same preoperative symptoms or the symptoms had worsened up after surgery and there were a significant restriction of their daily life activities. Radiological follow up: Approximately one day after surgery, antero-posterior and lateral plain radiographs were obtained to ensure that the instrumentation in good position. All patients will undergo plain x-ray and CT scans to assess pedicle screw, cage placement and fusion 3 and 6 months after surgery. Fusion was graded as follow: Grade I (complete fusion): Trabecular bone was seen to bridge the disc space, with accompanying remodeling of the cortical end plates. Grade II (partial fusion): Trabecular bone was seen extending from the end plate into the disc space, but forming an incomplete bridge. Grade III (no fusion): No evidence of Trabecular bone formation was seen extending from the endplates. RESULTS This prospective study involved thirty patients with lumbar spondylolithesis either isthmic or degenerative, admitted and operated in Department of Neurosurgery, from January 2010 to July Female's patients were affected in 66.7% while 33.3% were males. The age of patients ranged between years with a mean age of 36 years. History of back trauma could be obtained in 40% of patients and incidence of consanguinity was in 10% of patients positive. Low back pain and sciatica were present in all patients. Neurological deficits included sensory deficits in 40%, reflex changes in 40% and motor in 20% of patients. The affected level was L4-5 in 50% (Fig. 1), L5-S1 in 40% (Fig. 2) and L3-4 in 10% of patients. Grade I was encountered in 60%, and grade II in 40% of patients. 100% of patients had good outcome as regard pain relief. (Table 1) Plain x-ray has a role in diagnosis of pars fracture, level and degree of slip. CT spine diagnoses pars fracture and associated conditions such as associated disc prolapse or lumbar canal stenosis. MRI may benefit in selected cases. The causes of nerve root compression were fibrocartilaginous mass in all patients, hypertrophied facets in 80% hypertrophied ligaments in 66.7% and disc prolapse in 20% of patients. a b c d Fig. 1 a-d: A case of L4-L5 grade II spondylolithesis. a: A preoperative plain x ray lateral view of the lumbosacral spine. b: MRI lumbosacral spine, sagittal view T2 of the same patient. c: A post operative plain X-ray AP. d: A post operative lateral views show the TLIF with good realignment and maintenance of disc height. Egyptian Journal of Neurosurgery 215

4 a b c d Fig. 2 a-c: A case of L5-S1 spondylolithesis grade I. a: A preoperative MRI lumbosacral spine sagittal view. b: A preoperative plain X-ray lateral view of the same patient. c: A post operative CT lumbo-sacral spine with TLIF. d: A postoperative plain X-ray lumbo-sacral spine, lateral view of the same patient. Table 1: Patients' characteristics Patient characteristic No (%) X 2 P- value Age (in years) (10%) Range (24-52) > (50%) Mean ± SD (43.5±8.4) > (33.3%) > 50 2 (6.7%) Sex Males 10 (33.3%) Females 20 (66.7%) Consanguinity Present 3 (10%) Absent 27 (90%) Associated back trauma Present 12 (40%) Absent 18 (60%) Type of spondylolisthesis Isthmic 18 (60%) Degenerative 12 (40%) Duration of symptoms (in months) > 6 18 (60%) (23.3%) (16.7%) Clinical presentation Low back pain 30 (100%) Leg pain 30 (100%) Neurodeficit 18 (60%) 216 Egyptian Journal of Neurosurgery

5 The complications occurred in our study including wound infection in two patients, dural tear in two patients and TLIF cage migration and screw malposition in one patient. (Table 2) Table 2: Surgical complications Complications No. of patients % TLIF cage migration Screw malposition Dural tear Wound infection X P. value Clinical and radiological follow up of patients was done for a period of 3-6 months. Solid fusion was obtained in 86.7%. (Table 3) X Table (3): Clinical outcome based on the Oswestry Disability Index (ODI) Result No. of patients % Excellent (satisfactory) Good (satisfactory) Fair 2 6.7(satisfactory) P. value DISCUSSION Age of the patients were between 24 to 52 years old with a mean age of 36 years. Peek, 1989 found mean age of incidence 24.6 years. 9 Burkus, 1992 had found a mean age of 40 years. The younger age in this study may be attributed to heavy work with increasing incidence of pars fractures. 10 In our study, two thirds of patients were females, while only one third were males. While Peek, 1989 found female to male ratio 3:1. The female predominance may be attributed to repeated birth trauma, tendency to obesity, weak musculature and osteoporosis. 9 The incidence of consanguinity was 10%. This is low in comparison with Wynne-Davis and Scott, 1979 (19%), who concluded that there was a genetic element to isthmic spondylolisthesis that appeared to be etiologically related. The pattern of inheritance could not be identified. 11 The incidence of back trauma in this study was in 40% of patients, while 60% had no definite history of back trauma. Aruna, 2002 reported incidence of back trauma in about 50% of patients in their series. 12 The main clinical presentation in this study was low back pain and sciatica, which were present in all patients. This coincides with Burkus, 1992 and Peek, 1989 reported low back pain in 93% and sciatica in 21% of his patients. 10, 9 Neurological deficits consisted of dermatomal sensory loss in 40%, diminished or absent reflexes in 40%, and weakness in 20% of patients. No patient had incontinence. Peek, 1989 reported sensory loss in 100% and diminished or absent reflexes in 60% of his patients. Burkus, 1992 reported neurological deficits in 10% of his patients. 10, 9 The affected vertebral level in this study was L4-5 in 50%, L5-S1 in 40% and L3-4 in 10% of patients. In contrary to Cheng in 1989 who found the affected level L5-S1 in 85% and L4-5 in 15% of his patients. 13 Steiner and Michelli 1985 attributed this to the frequent presence of congenital anomalies e.g. spina bifida at the lumbosacral junction that weakens the motion segment and predispose for slippage. 14 In this study, 60% of patients were grade I while 40% were grade II spondylolithesis according to Meyerding grading system. Cheng, 1989 found grade I in 60% and grade II in 15% of his patients. 13 In this study, a trial of conservative treatment including bed rest, anti-inflammatory drugs, physiotherapy and bracing was tried in all patients. This was the same with Cheng, 1989; Nachemson, ,15 The Indications of surgery in this study were intractable pain not responding to conservative treatment and this was present in all the studied patients, Neurological deficits including sensory, motor or reflex changes and Slip progression. Burkus, 1992; Cheng, 1989 Lambardi 1985 and Peek, 1989 reported these as indications for surgical interference. 10,13,6,16, 9 Aruna, 2002 reported decompressive surgery in adults with radicular symptoms or neurological deficits by removal of loose posterior elements and fibro 12 cartilaginous tissue. With decompression alone, improvement is obtained in a majority of patients but may lead to a high incidence of progressive slippage. Interestingly, such progression does not always distract significantly from a good clinical outcome. 16 Although good results can be obtained by decompression without coincident bony fusion, when patients without fusion are compared with those who undergo fusion, better results are generally seen in the fusion group. Most authors advocate fusion for spondylolithesis especially following wide decompression. 17 Bony fusion alone may provide relief of pain and neurological deficits in children and adults with isthmic spondylolisthesis. Bony fusion can be achieved by a variety of methods including anterior interbody, posterior interbody, transforaminal lumber inter body fusion, or intertransverse fusion. 12 In this study, the operative technique included decompression by removal of spinous process, bilateral laminectomy, removal of fibro cartilaginous mass, complete facetectomy, foraminotomy and aggressive Egyptian Journal of Neurosurgery 217

6 discectomy, transpedicular screw fixation and TLIF cage insertion. This was followed by posterolateral bony fusion. Hee et al. and Whitecloud et al. compared TLIF with combined anterior and posterior fusion. They found that TLIF patients had a shorter operative time, less blood loss, lower need for blood transfusion, lower need for postoperative intensive care, shorter hospital stay and lower hospital cost compared to single stage anterior and posterior fusion. 18,19 Humphreys et al. compared Posterior Lumbar Interbody Fusion (PLIF) and TLIF. They concluded that TLIF had a much lower complication rate than PLIF. 20 Brislin and Vaccaro have noticed the lower risk of nerve tethering in TLIF compared to the more traditional PLIF. 8 The results of TLIF have been widely described in the literature. Rosenberg and Mummaneni reported on a series of 22 patients, with a good and excellent outcome in 21 and with minimal complications. 21 Moskowitz recommended early mobilization and short hospital stay following the TLIF procedure. 7 By using a unilateral transforaminal access with the insertion of a single cage it was possible to achieve restoration of disc space height, segmental lordosis, and reduction of spondylolisthesis with its biomechanical advantages. These were achieved with less dural retraction and less trauma to the spinal canal. Another advantage of a single cage is to insert more bone grafts into the disc space outside the cage, which may theoretically increase the grafting area resulting in a higher fusion rate. 3,14,22,23 The TLIF procedure has become increasingly popular due to a number of potential benefits over conventional intertransverse arthrodesis, including increased fusion surface area, an improved vascular fusion bed within the anterior interbody space, and restoration of intervertebral body height. Preliminary results appear promising and, in the carefully selected patient, a TLIF may provide excellent results with a relatively low complication rate. 3,14,23 TLIF is a procedure that provides a circumferential fusion while avoiding the morbidity of an anterior lumbar approach. Several clinical studies have demonstrated high fusion rates and successful clinical outcomes after the TLIF procedure. 24 In our study, solid fusion was obtained in 86.7%. In this study, unintended dural tear was the main operative complication and occurred in two patients (6.7%), and was repaired by simple sutures. Malposition of screws occurred in one patient (3.3%) and he was pain free and underwent follow up. TLIF cage migration occurs in only one patient and was revised and we found that the cause of migration was loosening of screws. Wound infection was the main postoperative complication and occurred in two patients (6.7%). The infection was superficial and subsided by using antibiotics and daily dressing. Dickman 1992, & West 25, reported infection rate range from 0-6%. 218 In our study, 100% of patients had good outcome, as regard pain relief according to Parker et al score, this coincided with Peek, 1989 who had good outcome in all of his patients. 2,9 In this study, 86.7% of patients had solid fusion while 13.3% had no fusion. Peek, 1989 had solid fusion in all of his patients. Burkus, 1992 had solid fusion in 80% of his patients. 9,10 Direct instrumented reduction and TLIF is an efficient option to treat high grade isthmic spondylolisthesis. It provided immediate stability and superior clinical and radiological outcomes. 2,27 The establishment of fusion was considered on radiographic confirmation of continuous bone traversing the grafted segments, with no evidence of motion on flexion & extension radiographs. McGuire, 1993 in this study, patients who had solid fusion achieved good outcome as regards pain relief. 28,29 Prospective and retrospective studies done by Kaneda, 1985; and Ricciardi 1995 proved direct relationship between failure to achieve arthrodesis and 30, 31 unsatisfactory pain outcome. Xiao 2009, indicate that TLIF is a safe technique that provides satisfactory shortened medium-term results. He concluded that TLIF with one cage and excised local bone in augmentation with a bilateral pedicle screw seem to be an effective and affordable option. 32 CONCLUSION Using a unilateral transforaminal access with the insertion of a single cage, it was possible to achieve restoration of disc space height, segmental lordosis, reduction of spondylolisthesis and satisfactory fusion rate. The instrumented TLIF with single cage is a safe and effective method for the treatment of spondylolisthesis GI & II and degenerative segmental instability. Disclosure: The authors have no personal, financial or institutional interest in any of the drugs, materials, or devices described in this article. Ethics approval Ethics approval was provided by the Ethical Committees in faculty of Medicine, Tanta University Egypt. REFERENCES 1. Amundson G, Edwards CC, Garfin SR: Spondylolisthesis, in Rothman RH, Simeone FA (eds): Spine (ed 3). Vol. 11, Philadelphia, PA, WB Saunders p , Koptan W, El Miligui Y, El-Sharkawi M, Ramadan M: Unilateral Transforaminal Lumbar Interbody Fusion for High Grade Isthmic Spondylolisthesis. The Egyptian Spine Journal 1:49-56, 2012 Egyptian Journal of Neurosurgery

7 3. Mummaneni PV, Haid RW, Rodts GE: Lumbar interbody fusion: state of- the-art technical advances. Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March J Neurosurg Spine 1:24-30, Stonecipher T, Wright S: Posterior lumbar interbody fusion with facet screw fixation. Spine 14: , Harms J, Rolinger H: A one-stage procedure in operative treatment of spondylolisthesis: dorsal traction-reposition and anterior fusion. Z Orthop 120: , La Rosa G, Conti A, Cacciola F, Cardali S, La Torre D, Gambadauro NM, Tomasello F: Pedicle screw fixation for isthmic spondylolisthesis: does posterior lumbar interbody fusion improve outcome over posterolateral fusion? J Neurosurg 99:143 50, Moskowitz A: Transforaminal lumbar interbody fusion. Orthop Clin North Am 33: , Brislin B, Vaccaro AR: Advances in posterior lumbar interbody fusion. Orthop Clin North Am 33: , Peek RD1, Wiltse LL, Reynolds JB, Thomas JC, Guyer DW, Widell EH: In situ arthrodesis without decompression for Grade-III or IV isthmic spondylolisthesis in adults who have severe sciatica. J Bone Joint Surg Am 71:62-8, Burkus JK, Lonstein JE, Winter RB, Denis F: Long-term evaluation of adolescents treated operatively for spondylolisthesis. A comparison of in situ arthrodesis only with in situ arthrodesis and reduction followed by immobilization in a cast. J Bone Joint Surg Am, 74: , Wynne-Davies R, Scott JH: Inheritance and spondylolisthesis: a radiographic family survey. J Bone Joint Surg Br 61: , Aruna G. Isthmic spondylolisthesis. Neurosurg. Focus 13 (1): Article 1, Cheng CL, Fang D, Lee PC, Leong JC: Anterior spinal fusion for spondylolysis and isthmic spondylolisthesis. Long term results in adults. J Bone Joint Surg Br Mar 71:264-7, Steiner ME, Micheil LJ: Treatment of symptomatic spondylolysis and spondylolisthesis with the modified Boston brace. Spine 10: , Nachemson AL: Newest knowledge of low back pain, critical look: Clin Orthop 279:8-20, Lombardi JS, Wiltse LL, Reynolds J, Widell EH, Spencer C: Treatment of degenerative spondylolisthesis. Spine (Phila Pa 1976). 10:821-7, Herkowitz HN, Sidhu KS: Lumbar spine fusion in the treatment of degenerative conditions: current indications and recommendations. J Am Acad Orthop Surg 3: , Hee HT, Castro FP Jr, Majd ME, Holt RT, Myers L: Anterior/posterior lumbar fusion versus transforaminal lumbar interbody fusion: analysis of complications and predictive factors. J Spinal Disord; 14: , Whitecloud TS and Bulter JC: Anterior lumbar fusion utilizing transvertebral fibular graft. Spine 13: , Humphreys SC, Hodges SD, Patwardhan AG, Eck JC, Murphy RB, Covington LA: Comparison of posterior and transforaminal approaches to lumbar interbody fusion. Spine 26: , Rosenberg WS, Mummaneni PV: Transforaminal lumbar interbody fusion: technique, complications, and early results. Neurosurgery 48: , La Rosa G, Conti A, Cacciola F, Cardali S, La Torre D, Gambadauro NM, Tomasello F: Pedicle screw fixation for isthmic spondylolisthesis: does posterior lumbar interbody fusion improve outcome over posterolateral fusion? J Neurosurg 99:143 50, Salehi SA, Tawk R, Ganju A, LaMarca F, Liu JC, Ondra SL: Transforaminal lumbar interbody fusion: surgical technique and results in 24 patients. Neurosurgery 54: , discussion 374, Lowe TG, Tahernia AD, O Brien MF, Smith DA: Unilateral transforaminal posterior lumbar interbody fusion (TLIF): indications, technique, and 2-year results. J Spinal Disord Tech 15:31 8, Dickman CA1, Fessler RG, MacMillan M, Haid RW: Transpedicular screw-rod fixation of the lumbar spine: operative technique and outcome in 104 cases. J Neurosurg 77:860-70, West JL 3rd, Bradford DS, Ogilvie JW: Results of spinal arthrodesis with pedicle screw-plate fixation. J Bone Joint Surg Am 73: , Park Y1, Ha JW, Lee YT, Oh HC, Yoo JH, Kim HB: Surgical outcomes of minimally invasive transforaminal lumbar interbody fusion for he treatment of spondylolisthesis and degenerative segmental instability. Asian Spine J 5:228-36, Ekman P, Möller H, Hedlund R: The long-term effect of posterolateral fusion in adult isthmic spondylolisthesis: a randomized controlled study. Spine J 5: 36 44, McGuire, R, Amundson, G: The use of primary internal fixation in spondylolisthesis. Spine 18: , Kaneda K, Satoh S, Nohara Y, Oguma T: Distraction rod instrumentation with posterolateral fusion in isthmic spondylolisthesis. 53 cases followed for months. Spine 10:383-9, 1985 Egyptian Journal of Neurosurgery 219

8 31. Ricciardi JE, Pflueger PC, Isaza JE, Whitecloud TS: Transpedicular fixation for the treatment of isthmic spondylolisthesis in adults. Spine 20: , Xiao Y-X, Chen Q-X, Li F-C: Unilateral Transforaminal Lumbar Interbody Fusion: a Review of the Technique, Indications and Graft Materials. The Journal of International Medical Research 37: , Egyptian Journal of Neurosurgery