Minimum Two-Year Follow-Up of Cases with Recurrent Disc Herniation Treated with Microdiscectomy and Posterior Dynamic Transpedicular Stabilisation

Tuncay Kaner*, 1, Mehdi Sasani2, Tunc Oktenoglu2, Ahmet Levent Aydin3, Ali Fahir Ozer2
1 Pendik State Hospital, Neurosurgery Department, Istanbul, Turkey
2 American Hospital, Neurosurgery Department, Istanbul, Turkey
3 Istanbul Physical Therapy and Rehabilitation Training Hospital, Neurosurgery Department, Istanbul, Turkey

Article Metrics

CrossRef Citations:
Total Statistics:

Full-Text HTML Views: 1726
Abstract HTML Views: 420
PDF Downloads: 294
Total Views/Downloads: 2440
Unique Statistics:

Full-Text HTML Views: 1115
Abstract HTML Views: 278
PDF Downloads: 230
Total Views/Downloads: 1623

Creative Commons License
© Kaner et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License ( permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Department of Neurosurgery, Pendik State Hospital, Pendik, Istanbul, Turkey; Tel: (90) 216 4644800; Fax: (90) 216 4644801; E-mail:


The objective of this article is to evaluate two-year clinical and radiological follow-up results for patients who were treated with microdiscectomy and posterior dynamic transpedicular stabilisation (PDTS) due to recurrent disc herniation. This article is a prospective clinical study. We conducted microdiscectomy and PDTS (using a cosmic dynamic screw-rod system) in 40 cases (23 males, 17 females) with a diagnosis of recurrent disc herniation. Mean age of included patients was 48.92 ± 12.18 years (range: 21-73 years). Patients were clinically and radiologically evaluated for follow-up for at least two years. Patients’ postoperative clinical results and radiological outcomes were evaluated during the 3rd, 12th, and 24th months after surgery. Forty patients who underwent microdiscectomy and PDTS were followed for a mean of 41 months (range: 24-63 months). Both the Oswestry and VAS scores showed significant improvements two years postoperatively in comparison to preoperative scores (p<0.01). There were no significant differences between any of the three measured radiological parameters (α, LL, IVS) after two years of follow-up (p > 0.05). New recurrent disc herniations were not observed during follow-up in any of the patients. We observed complications in two patients. Performing microdiscectomy and PDTS after recurrent disc herniation can decrease the risk of postoperative segmental instability. This approach reduces the frequency of failed back syndrome with low back pain and sciatica.

Keywords: Lumbar spine, recurrent disc herniation, decompression, posterior dynamic stabilisation, segmental instability, adjacent level diseases.


Lumbar disc herniation is one of the most common spinal conditions and causes widespread medical problems. Unsatisfactory results are reported in 38% of patients who undergo lumbar disc surgery [1-3]. Recurrent disc herniation is one of the most important reasons for unsatisfactory results and, consequently, failed back syndrome. Reherniation rates have been reported as 5-26% in previously published studies [4-6].

The observed rate of recurrent sciatica after lumbar disc herniation can be as high as 37% [4]. Sciatica due to recurrent disc hernia after lumbar disc surgery, which does not respond to medical treatment and neurological deficit, requires reoperation. In such reoperations wider decompression is typically performed and more disc tissue is excised. It is a well-known fact that aggressive disc tissue removal reduces disc altitude and increases the load on facet joints; therefore segmental instability and spondylosis may develop as a result [7-9]. Such situations are one of the most important causes of failed back syndrome after lumbar discectomy and associated with poor clinical results [9-11].

Our objectives in this prospective clinical study were to prevent segmental instability and to reduce the incidence of poor clinical results with failed back syndrome after reoperation for recurrent disc herniation. In order to prevent failed back syndrome after reoperation in recurrent disc herniation cases we performed PDTS with microdiscectomy. In this paper we present our clinical results after a minimum two-year follow-up period.


A total of 40 recurrent disc herniation cases performed between 2004 and 2007 were selected for this study. Criteria for inclusion in the study were (a) previous operation due to lumbar disc herniation (b) recurrent disc herniation on the operated side and (c) lack of a response to medical treatment at six weeks. Cases with different spinal pathology, spondylolisthesis, traumatic vertebral fracture, scoliosis, infection and serious systemic disease were excluded from the study.

All patients had leg and/or low back pain. All patients were diagnosed by performing preoperative contrast and non-contrast lumbar MRI. All patients were examined with lumbar antero-posterior and lateral X-Rays, as well as lumbar hyperflexion and hyperextension dynamic radiographies.

Cosmic (Ulrich GmbH & Co. KG, Ulm, Germany) dynamic pedicle screws and rigid rod system were used together with the microdiscectomy procedure in all patients (Figs. 1, 2).

Fig. (1).

Cosmic (Ulrich GmbH & Co. KG, Ulm, Germany) dynamic transpedicular screw.

Fig. (2).

A 34-year-old male patient with microdiscectomy was operated upon two years previously due to an L4-L5 herniated lumbar disc. Fifteen days after the first operation, the patient was operated upon again due to recurrent disc herniation; only microdiscectomy was performed. Three months after the second operation, the patient was operated on again due to a second recurrent herniated lumbar disc. PDTS (Cosmic dynamic screw/ rod system) and microdiscectomy were performed. All microdiscectomies were performed at the same level and side. A) Sagittal T2-weighted MR imaging of the patient after second recurrent disc herniation. B) Axial T2-weighted MR imaging of the patient after second recurrent disc herniation. C) Lateral radiographic view after the third operation. D) Antero-posterior radiographic view after the third operation.

Clinical results were evaluated by VAS and Oswestry disability index. Measurements of the segmental lordosis angle (α), lumbar lordosis angle (LL) and intervertebral space (IVS) were used in the evaluation of patients’ radiological results. Both clinical results and radiological outcomes were recorded at 3, 6, 12, and 24 months postoperatively.

Operative Technique

All patients were taken into the operating room under general anaesthesia in the prone position. Prophylactic antibiotics were given to all patients before the operation. All operations were performed using operational microscopy and standard surgical technique. The level of operation was determined via intraoperative fluoroscopy. When the interlaminar level with recurrent disc herniation was approached from the medial aspect, existing laminotomy was widened with the help of a high-speed drill and the facet joints’ medial portions were removed. After identifying the correct nerve root, free disc fragments under the nerve root and passageway were removed. Decompression was finished by performing the required for laminotomy. After carrying out the microdecompression procedure, we also executed posterior dynamic transpedicular stabilisation from the same incision, with the help of lateral intraoperative fluoroscopy by Wiltse approach via inside lateral paravertebral muscle. The dynamic pedicle hinged screws used in our cases were Cosmic (Ulrich Gmbh & Co. KG, Ulm, Germany). Dynamic pedicle screws were used in combination with rigid rods.

Statistical Methods

The NCSS 2007 & PASS 2008 Statistical Software (Utah, USA) program was used to analyse data. Aside from descriptive statistics (average, standard deviation), repeated measures analysis of variance (repeated measures test) was used for the quantitative comparison of data showing a normal distribution. Additionally, the Bonferroni test was used in post-hoc evaluations. The Friedman test was used for the comparison of VAS parameters, which did not show a normal distribution. The Wilcoxon Signed-Rank test was used for post-hoc evaluation. The significance level was p < 0.05 in all evaluations.


The mean follow-up period for all 40 patients was 41 months (range: 24-63 months). The VAS and Oswestry scores showed significant improvements at 3, 12 and 24 months postoperatively as compared to preoperative scores (p < 0.01). Variation in Oswestry measurements was found to be highly significant (p < 0.01) during the follow-up period. Post-hoc Bonferroni test evaluations revealed highly significant decreases in post-operative 3rd-, 12th- and 24th-month measurements (p < 0.01) (Table 1). Variation in VAS scores during the follow-up period was also found to be highly significant (p < 0.01). According to post-hoc Wilcoxon signed-rank test, decreases in the 3rd, 12th and 24th post-operative months were highly significant (p < 0.01) (Table 1).

Table 1.

The Evaluation of Oswestry Disability Index and VAS Measurements

Oswestry+ VAS++
Means ± SD Means ± SD
Pre-op 67,30 ± 9,04 7,22 ± 0,89 (7)
Post-op mo 3 26,35 ± 9,26 3,0 ± 1,28 (3)
Post-op mo 12 12,40 ± 6,50 1,47 ± 0,93 (2)
Post-op mo 24 7,70 ± 3,55 0,97 ± 0,73 (1)
P-values 0,001** 0,001**
Post-hoc Pre-op > Post-op mo 3 (0,001**)
Pre-op > Post-op mo 12 (0,001**)
Pre-op > Post-op mo 24(0,001**)
Pre-op > Post-op mo 3 (0,001**)
Pre-op > Post-op mo 12 (0,001**)
Pre-op > Post-op mo 24(0,001**)

Repeated measures test; Post-hoc Bonferroni test was used.

++ Friedman test; Post-hoc Wilcoxon signed-rank test was used.

SD: Standard deviation; p: Significance level

** p < 0,01.

Variation in Lumbar Lordosis (LL) measurements taken during pre-operative, early post-operative, and post-operative months 3, 12, and 24 were not statistically significant (p > 0.05) (Table 2).

Table 2.

The Evaluation of LL, α and IVS Measurements

Lumbar Lordosis (LL) Segmental Lordosis Angle (α ) Intervertebral Space (IVS)
Means ± SD Means ± SD Means ± SD
Pre-op 43,52 ± 12,99 8,67 ± 4,98 0,27 ± 0,06
Early post-op 42,92 ± 12,65 8,42 ± 4,91 0,28 ± 0,06
Post-op mo 3 42,72 ± 12,15 8,47 ± 4,10 0,27 ± 0,06
Post-op mo 12 42,70 ± 10,94 8,50 ± 3,38 0,27 ± 0,06
Post-op mo 24 42,95 ± 11,08 8,60 ± 3,67 0,26 ± 0,06
+p 0,969 0,970 0,640
Post-hoc N.S. N.S. N.S.

Repeated measures test.

Post-hoc Bonferroni test was used. SD: Standard deviation.

NS: Non-significant (p > 0.05); p: Significance level

** p<0,01.

Changes in segmental lordosis angle (α) measurements taken during pre-operative, early post-operative, and post-operative months 3, 12, and 24 were not statistically significant (p > 0.05) (Table 2).

Changes in intervertebral space (IVS) measurements in pre-operative, early post-operative, and post-operative months 3, 12, and 24 were also not statistically significant (p > 0.05) (Table 2).

Data averages are summarised in Table 3.

Table 3.

Averages of Preoperative and Postoperative Data Points

Preoperative 7.23 67.30 43.53 8.68 0.272
Early postoperative (3rd day) - - 42.93 8.43 0.279
3 Month follow-up 3.00 26.35 42.73 8.48 0.270
12 Month follow-up 1.48 12.40 42.70 8.50 0.270
24 Month follow-up 0.98 7.70 42.95 8.60 0.275

VAS: Visual Analog Scale, ODI: Oswestry Disability Index, LL: Lumbar Lordosis Angle

α Segmental Lordosis Angle, IVS: Intervertebral Space.

No novel recurrent disc herniation was observed during the follow-up period.

We observed complications in two patients. Foreign body reaction was observed in the first patient. The patient was reoperated upon and the dynamic stabilisation system was removed. In the other patient low back pain and sciatica due to PDTS continued. Therefore, the dynamic system was removed and fusion with rigid stabilisation was performed.


Recurrent disc herniation accounts for the most common problematic situations after lumbar disc surgery. Recurrent disc herniations are radiologically visualised lumbar disc herniations, which are non-responsive to medical treatments other than surgery [12-16]. The rate of reoperation due to recurrent disc herniation after lumbar disc surgery is approximately 5-15% [3]. The ethyopathogenesis of recurrent disc herniation is a controversial issue. The rate of recurrent disc herniation is significantly higher in preoperative MRI analyses of patients with modic changes in end-plates of the vertebra corpus [17, 18]. Cinotti reported that recurrent disc herniation patients’ pre-operative MRI analyses revealed higher degrees of disc degeneration than were observed in the control group [12]. Cinotti also reported that mechanic loading causes sciatica in 42% of recurrent disc herniation patients [12]. Some experimental studies showed that the frequency of recurrent disc herniation after lumbar disc surgery is higher due to insufficient recovery in the annuli of discs with a high degree of degeneration [15, 19].

A recent study by Barth et al. compared clinical and radiological results of lumbar microdiscectomy and microscopic sequestrectomy after a two-year follow-up period. The microdiscectomy patient group presented deteriorative functional results, whereas the sequestrectomy group presented stable results. There was not any difference in reherniation rate between the two groups [20]. Radiological evaluation of the same study and correlation with clinical results showed that diagnoses of post-operative disc degenerations such as decreases in disc altitude and end-plate degeneration were much less frequent among patients who underwent sequestrectomy as compared to microdiscectomy. Furthermore, modic-type end-plate changes were associated with negative clinical results [21]. Recently, Carragee described a lumbar disc herniation classification system based upon continuity of the annulus and the presence of extruding/free disc fragments [4]. In his study, the reherniation rate after limited discectomy in the fragment-defect (wide annular defect) patient group was as high as 27.3%. Similarly, the reoperation rate in this group was significantly high at 21.2% in comparison to the fragment-fissure (small annular defect) patient group, for which the reherniation and reoperation rate was 1.1%. Moreover, when patients in fragment-defect group, with more than 6 mm annular defect in Carragee classification, were questioned in the postoperative period with 27.3% the complaint rate of persistent/recurrent sciatica after microdiscectomy was much higher than expected [4]. We think that in these patients both clinical and radiological recurrence of lumbar disc herniation would be higher regardless of the surgical treatment is performed or not. On this account, considering reherniation rate of 27.3% and reoperation rate of 21.2% in cases with wide annular defect in Carragee classification, in fragment-defect group; in order to decrease the rates of both reherniation and failed back syndrome we do not think that is it wrong or unnecessary to propose performing PDTS even in the first surgery. Carragee et al. then performed aggressive discectomy in patients with wide annular defects in order to decrease the rate of reherniation [22]. However, after a one-year follow-up period these patients reported persistent low back pain problems. Recurrent disc herniation is one of the most important reasons for unsatisfactory results after lumbar disc surgery and, consequently, failed back syndrome. In contrast, successful results are reported when recurrent disc herniation is treated with another microdiscectomy [23]. However, the risk of developing new recurrences after the first recurrence is 15-20% [24]. The patient’s chances for successful recovery gradually decrease after each simple discectomy and the risk of other spinal operations increases accordingly [24]. Re-performed discectomies do not stop continuous segmental degeneration; moreover, they may aggravate the degeneration process [15, 25-27]. Declines in intra-disc pressure and disc elevation increase loading on facet joints; as a result segmental instability may develop due to laxity in articular capsules and ligaments [7, 8, 19, 28]. Low back pain and/or segmental instability with sciatica significantly contribute to the development of failed back syndrome after lumbar disc surgery. According to the relevant literature, the incidence of spinal instability in patients with low back pain is around 20-30% [29, 30]. Segmental instability is diagnosed in 20% of patients with lumbar disc herniation [31, 32]. Instability after lumbar disc surgery is secondary segmental instability, described as ‘status-post discectomy’ by Frymoyer [33]. In fact this situation is not an overt instability; as described by Benzel, it is a chronic instability [34]. Studies have shown that when performed on segmental degeneration cases, discectomy may cause segmental instability and accounts for 38% of unsatisfactory results [2, 35].

Segmental fusion operations are performed frequently as treatment for recurrent disc herniation. Nevertheless, fusion also carries various risks such as adjacent segment degeneration, bone graft donor place pain, and pseudoarthrosis [26,27,35,36]. Today, dysfunctional segmental movement and chronic instability due to recurrent disc herniation are usually treated with posterior dynamic stabilisation. In chronic instability cases it is very important to make sure that the stabilisation surgery is suitable for every age group and certain to yield satisfactory results. Recently, several clinical studies reported that posterior dynamic transpedicular stabilisation yielded good clinical results and represents a safe and effective alternative technique to spine arthrodesis in selected cases of degenerative lumbar spine instability [37-39]. In fact, posterior dynamic stabilisation appears to be essential in order to achieve the desired outcomes. Dynamic stabilisation controls abnormal movements in an unstable, painful segment and facilitates healthy load transfer, in order to prevent degeneration of the adjacent segment [40]. Thus spinal stabilisation is achieved while alleviating unnecessary pain. Some studies reported that posterior dynamic transpedicular stabilisation biomechanically provides stabilisation that is similar to that provided by rigid systems [41-43]. Moreover, dynamic stabilisation systems appear to have advantages over rigid spinal implants. Putzier et al. reported that after 34 months of follow-up, disc degenerations showed far less progression in patients who had nucleotomy with posterior dynamic system applications as compared to patients who did not have dynamic stabilisation [35]. Schaeren et al. reported very successful clinical and radiological results after performing dynamic stabilisation for cases of degenerative spondylolisthesis. However, they also reported that adjacent segment degeneration remained problematic [44]. In another new systematic review study, Barrey et al. reported that there is not a large difference between the effects of rigid stabilisation systems and dynamic systems on adjacent spinal segments [45]. Several studies in the literature reported that recurrent disc herniation with the probability of developing instability and isolated spinal canal stenosis are new indications for dynamic stabilisation systems during the postoperative period [35, 46, 47]. Nevertheless, in recent years dynamic stabilisation devices are being inserted to treat the segmental instability due to iatrogenic decompression or segmental degeneration [48,49].

In this study we detected satisfactory improvements in VAS and Oswestry scores after a minimum of two years’ follow-up. We achieved encouraging clinical and radiological results after performing microdiscectomy together with PDTS in our recurrent disc herniation patients. Furthermore, no novel recurrent disc herniation was seen during the follow-up period (mean: 41 months) in any of the patients included. Consequently, we can recommend performing PDTS along with microdiscectomy in cases of recurrent disc herniation with risk of segmental instability and failed back syndrome. We think that posterior dynamic stabilisation is an effective alternative to fusion in the treatment of chronic instability and degenerative diseases of the lumbar spine.


[1] Andrews DW, Lavyne MH. Retrospective analysis of microsurgical and Standard lumbar discectomy Spine 1990; 15: 329-5.
[2] Caspar W, Campbell B, Barbier DD, Kretschmmer R, Gottfried Y. The Caspar microsurgical discectomy and comparison with a conventional Standard lumbar disc procedure Neurosurgery 1991; 28: 78-87.
[3] Frymoyer JW, Hanley E, Howe J, Kuhlmann D, Matteri R. Disc excition and spine fusion in the management of lumbar disc disease. A minimum ten year follow-up Spine 1978; 3: 1-6.
[4] Carragee EJ, Han MY, Suen PW, et al. Clinical outcomes after lumbar discectomy for sciatica: The effects of fragment type and anular competence J Bone Joint Surg Am 2003; 85: 102-8.
[5] Suk KS, Lee HM, Moon SH, et al. Recurrent lumbar disc herniation: Results of operative management Spine 2001; 26: 672-.
[6] Frymoyer JW. Radiculopathies: lumbar disc herniations and recess stenosis-patient selection, predictors of success and failure, and nonsurgical treatment options In: Frymoyer JW, Ed. The adult spine. New York: Raven Press 1991; pp. 1719-32.
[7] Cinotti C, Postacchini F. Lumbar disc herniation. Wien: Springer-Verlag 1999; pp. 81-93.
[8] Kirkaldy-Willis WH, Wedge JH, Yong-Hing K, Reilly J. Pathology and pathogenesis of lumbar spondylosis and stenosis Spine 1978; 3: 319-28.
[9] Wenger M, Mariani L, Kalbarczyk A, Groger U. Long-term outcome of 104 patients after lumbar sequestrectomy according to Williams Neurosurgery 2001; 49: 329-5.
[10] Faulhauer K, Manicke C. Fragment excision versus conventional disc removel in the microsurgical treatment of herniated lumbar disc Acta Neurochir 1995; 133: 107-1.
[11] Striffeler H, Groger U, Reulen HJ. ‘Standard’ microsurgical lumbar discectomy vs ‘conservative’ microsurgical discectomy. A preliminary study Acta Neurochir 1991; 112: 62-4.
[12] Cinotti G, Roysam GS, Eisenstein SM, Postacchini F. Ipsilateral recurrent lumbar disc herniation. A prospective, controlled study J Bone Joint Surg Br 1998; 80(5): 825-32.
[13] Larson SJ, Maiman DJ. Surgery of the Lumbar Spine. New York: Thieme 1999; pp. 1-132.
[14] Reith C, Lausberg G. Risc factors of recurrent disc herniation Neurosurg Rev 1989; 12: 147-50.
[15] Osti OL, Vernon-Roberts B, Fraser RD. Anulus tears and intervertebral disc degeneration: An experimental study using an animal model Spine 1990; 15: 762-.
[16] Ebeling U, Kalbarcyk H, Reulen HJ. Microsurgical reoperation following lumbar disc surgery. Timing, surgical findings, and outcome in 92 patients J Neurosurg 1989; 70(3): 397-404.
[17] Kim JM, Lee SH, Ahn Y, et al. Recurrence after successful percutaneous endoscopic lumbar discectomy Minim Invasive Neurosurg 2007; 50(2): 52-.
[18] Liphofer JP, Theodoridis T, Becker GT, et al. (Modic) signal alterations of vertebral endplates and their correlation to a minimally invasive treatment of lumbar disc herniation usingepidural injections Rofo 2006; 178(11): 1105-4.
[19] Hampton D, Laros G, McCarron R, Franks D. Healing potential of the anulus fibrosus Spine 1989; 14: 398-401.
[20] Barth M, Weiss C, Thome C. Two-year outcome after lumbar microdiscectomy versus microscopic sequestrectomy. Part 1: Evaluation of clinical outcome Spine 2008; 33(3): 265-72.
[21] Barth M, Diepers M, Weiss C, Thome C. Two-year outcome after lumbar microdiscectomy versus microscopic sequestrectomy. Part 2: Radiographic Evaluation and Correlation with clinical outcome Spine 2008; 33(3): 273-9.
[22] Carragee EJ, Spinnickie AO, Alamin TF, et al. A prospective Controlled study of limited versus subtotal posterior discectomy: Short-Term Outcomes in Patients with herniated lumbar intervertebral discs and large posterior anular defect Spine 2006; 31: 653-7.
[23] Yorimitsu E, Chiba K, Toyama Y, Hirabayashi K. Long-term outcomes of Standard discectomy for lumbar disc herniation: A follow-up study of more than 10 years Spine 2001; 26(6): 652-7.
[24] Weber H. Lumbar disc herniation. A controlled, prospective study with ten years of observation Spine 1983; 8(2): 131-40.
[25] Frei H, Oxland TR, Rathonyi GC, et al. The effect of nucleotomy on lumbar spine mechanics in compression and sheir loading Spine 2001; 26: 2080-9.
[26] Rahm MD, Hall MD. Adjacent-segment degeneration after lumbar fusion with instrumentation: A retrospective study J Spinal Disord 1996; 9: 392-400.
[27] Zuchermann J, Hsu K, Picetti G, et al. Clinical efficacy of spinal instrumentation in lumbar degenerative disc disease Spine 1992; 17: 834-7.
[28] Southern EP, Fye MA, Panjabi MM, et al. Disc degeneration: A human cadaveric study correlation magnetic resonance imaging and quantitative discomanometry Spine 2000; 25: 2171-5.
[29] Pope MH, Panjabi M. Biomechanical definitions of spinal instability Spine 1985; 10: 255-6.
[30] Weiler PJ, Eng P, King KJ, Gertbein SD. Analysis of sagittal plane instability of the lumbar spine in vivo Spine 1990; 15: 1300-6.
[31] Frymoyer JW, Selby DK. Segmental Instability. Rationale for treatment Spine 1985; 10: 280-6.
[32] Morgan FB, King T. Primary Instability of lumbar vertebrae as a common cause of low back pain J Bone Joint Surg (Br) 1957; 39: 6-22.
[33] Frymoyer JW. Segmental instability In: Frymoyer JW, Ed. The adult spine. New York: Raven Press 1991; pp. 1873-91.
[34] Benzel EC. Biomechanics of spine stabilization. 2nd. Rolling Meadows, IL: AANS Pers 2001.
[35] Putzier M, Schneider SV, Funk JF, et al. The surgical treatment of the lumbar disc prolapse. Nucleotomy with additional transpedicular dynamic stabilization versus nucleotomy alone Spine 2005; 30(5): E109-14.
[36] Banwart JC, Asher M, Hassanein S. Iliac crest bone graft harvest donor site morbidity. Astatistical evaluation Spine 1995; 20: 1055-60.
[37] Kaner T, Sasani M, Oktenoglu T, Cosar M, Ozer AF. Utilizing dynamic rods with dynamic screws in the surgical treatment of chronic ınstability: A prospective clinical study Turk Neurosurg 2009; 19(4): 319-26.
[38] Sapkas GS, Themistocleous GS, Mavrogenis AF, et al. Stabilization of the lumbar spine using the dynamic neutralization system Orthopedics 2007; 30(10): 859-65.
[39] Ricart O, Serwier JM. Dynamic stabilisation and compression without fusion using Dynesys for the treatment of degenerative lumbar spondylolisthesis: A prospective series of 25 cases Rev Chir Orthop Reparatrice Appar Mot 2008; 94(7): 619-27.
[40] Sengupta DK. Dynamic stabilization devices in the treatment of low back pain Neurol India 2005; 53(4): 466-74.
[41] Aylott C, McKinlay KJ, Freeman BJC, McNally DS. The dynamic neutralisation system for the spine (Dynesys): Acute biomechanical effects on the lumbar spine J Bone Joint Surg (Br) 2005; 87(1): 39.
[42] Bozkuş H, Senoglu M, Ozer AF, Sonntag VK, Crawford NR. Comparative stabilization properties of rigid and hinged-dynamic pedicle screw fixation techniques J Neurosurg Spine 2010. in press
[43] Niosi Ca, Zhu Q, Wilson DC, et al. Biomechanical characterization of three-dimentional kinematic behaviour of the dynesis dynamic stabilization system: An in vitro study Eur Spine J 2006; 15(6): 913-22.
[44] Scharen S, Broger I, Jeanneret B. Minimum four-year follow-up of spinal stenosis with degenerative spondylolisthesis treated with decompression and dynamic stabilization Spine 2008; 33(18): E636-42.
[45] Barrey CY, Ponnappan RK, Song J, Vaccaro AR. Biomechanical evaluation of pedicle screw-based dynamic stabilization devices for the lumbar spine: A systematic review SAS J 2008; 2: 159-70.
[46] Ahn SH, Ahn MW, Byun WM. Effect of the transligamentous extension of lumbar disc herniation on their regression and the clinical outcome of sciatica Spine 2000; 25(4): 475-80.
[47] Atlas SJ, Keller RB, Chang Y, et al. Surgical and nonsurgical management of sciatica secondary to a lumbar disc herniation Spine 2001; 26(10): 1179-87.
[48] Sasani M, Aydin AL, Oktenoglu T, et al. The combined use of a posterior dynamic transpedicular stabilization system and a prosthetic disc nucleus device in treating lumbar degenerative disc disease with disc herniations SAS J 2008; 2(3): 62-8.
[49] Schmoelz W, Onder U, Martin A, Strempel AV. Non-fusion instrumentation of the lumbar spine with a hinged pedicle screw rod system: An in vitro experiment Eur Spine J 2009; 18(10): 1478-85.