Researcher:
Yaman, Onur

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Doctor

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Onur

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Yaman

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Yaman, Onur

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2015 - 201932

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    Can right-handed surgeons insert upper thoracic pedicle screws in much comfortable position? Right-handedness problem on the left side
    (Korean Neurosurgical Soc, 2018) Ozdemir, Nail; Acaroglu, Emre; Akyoldaş, Göktuğ; Şentürk, Salim; Yaman, Onur; Faculty Member; Doctor; Doctor; School of Medicine; N/A; N/A; Koç University Hospital; 203677; N/A; 219524
    Objective : Thoracic pedicles have special and specific properties. In particular, upper thoracic pedicles are positioned in cranio-caudal plane. Therefore, manipulation of thoracic pedicle screws on the left side is difficult for right-handed surgeons. We recommend a new position to insert thoracic pedicle screw that will be much comfortable for spine surgeons. Methods : We retrospectively reviewed 33 patients who underwent upper thoracic pedicle screw instrumentation. In 15 patients, a total of 110 thoracic pedicle screws were inserted to the upper thoracic spine (T1-6) with classical position (anesthesiologist and monitor were placed near to patient's head. Surgeons were standing classically near to patient's body while patients were lying in prone position). In 18 patients, a total of 88 thoracic pedicle screws were inserted to the upper thoracic spine with the new standing position-surgeons stand by the head of the patient and the anesthesia monitor laterally and under patient's belt level. All the operations performed by the same senior spine surgeons with the help of C-arm. Postoperative computed tomography scans were obtained to assess the screw placement. The screw malposition and pedicle wall violations were divided and evaluated separately. Cortical penetration were measured and graded at either : 1-2 mm penetration, 2-4 mm penetration and > 4 mm penetration. Results : Total 198 screws were inserted with two different standing positions. Of 198 screws 110 were in the classical positioning group and 88 were in the new positioning group. Incorrect screw placement was found in 33 screws (16.6%). The difference between total screw malposition by both standing positions were found to be statistically significant (p=0.011). The difference between total pedicle wall violations by both standing positions were found to be statistically significant (p=0.003). Conclusion : Right-handedness is a problem during the upper thoracic pedicle screw placement on the left side. Changing the surgeon's position standing near to patient's head could provide a much comfortable position to orient the craniocaudal plane of the thoracic pedicles.
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    Complications of 2-level dynamic stabilization: a correlative clinical and radiological analysis at two-year follow-up on 103 patients
    (2018) Yılmaz, Atilla; Erbulut, Deniz Ufuk; N/A; Çıplak, Necati Mert; Süzer, Süleyman Tuncer; Şentürk, Salim; Yaman, Onur; Sasani, Mehdi; Öktenoğlu, Bekir Tunç; Özer, Ali Fahir; Doctor; Doctor; Doctor; Doctor; Faculty Member; Faculty Member; Faculty Member; N/A; N/A; N/A; N/A; School of Medicine; School of Medicine; School of Medicine; Koc University Hospital; N/A; 221691; N/A; 219524; 219451; 220898; 1022
    AIM: To investigate the postoperative complications, such as screw loosening, screw breakage and adjacent segment disease (ASD), in patients who underwent surgery with 2-level dynamic stabilization systems. MATERIAL and METHODS: Postoperative complications, clinical improvements and radiological parameters in patients who underwent surgery using a dynamic system for 2-level lumbar stabilization were retrospectively reviewed. A total of 103 patients with lumbar degenerative spinal instability underwent 2-level dynamic stabilization. Clinical findings were reviewed at 2-year follow-up. Screw breakage and loosening were evaluated during this duration together with clinical findings. ESULTS: Visual analog scale (VAS) and Oswestry Disability Index (ODI) scores were significantly decreased at the four-month evaluation, and they were also decreased at the 1-year follow up and at the 24th postoperative month. ASD was diagnosed in twelve (8 females, 4 males) of the 103 patients in the follow-up radiological and clinical controls. There were 9 screw breakages and 4 screw loosening cases. The complication rate of 2-level dynamic stabilization was high in this study. CONCLUSION: Our results showed that complications (screw loosening or breakage and adjacent segment disease) are not rare after 2-level dynamic stabilization, unlike the acceptable results with the single-level dynamic system. The most probable explanation is that the instrument system behaves more rigidly with every additional segment.
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    POLY 382-New directions in silicone-urea copolymers
    (Turkish Neurosurgical Soc, 2019) Öğrenci, Ahmet; Koban, Orkun; Yılmaz, Mesut; Yaman, Onur; Dalbayrak, Sedat; N/A; Yaman, Onur; Doctor; N/A; Koç University Hospital; 219524
    Aim: To evaluate the satisfaction of patients operated due to degenerative lumbar spinal diseases with dynamic stabilization placing polyetheretherketone (PEEK) rods and to share their radiological and clinical results (mid-term) with visual analogue scale (VAS) and Oswestry disability index (ODI) scores. Material and Methods: The preoperative and postoperative low back pain, leg pain VAS and ODI scores of 172 patients who were operated for degenerative spinal diseases, were evaluated. Preoperative and postoperative lumbar lordosis were compared. The patients included to the study were evaluated postoperatively around the 2nd year with lumbar MRI by means of adjacent segment disease (ASD) and additional problems. Results: A statistically but not radiologically-by means of sagittal profile reconstruction-significant increase in lumbar lordosis angle was achieved. Significant improvement was observed in the comparison of preoperative and postoperative period in the analysis of patients' preoperative low back pain (p<0.0001), and decompression-related leg pain VAS scores (p<0.0001). Significant improvement was also observed in the ODI scores of the patients (p<0.0001). Among 172 patients with dynamic stabilization, there were 10 patients who underwent reoperation (5.8%). Conclusion: Although it is statistically significant, it can be seen that the lumbar lordosis can not be corrected at significant degrees radiographically in the operations performed with the PEEK rod. Dynamic stabilization with PEEK rod is insufficient for sagittal correction, but the mid-term results reached satisfactory reoperation rates clinically outcomes. Rate of ASD is quite low in stabilization with PEEK rod.
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    Biomechanical comparison of transdiscal fixation and posterior fixation with and without transforaminal lumbar interbody fusion in the treatment of l5-s1 lumbosacral joint
    (Sage Publications Ltd, 2018) Ozalp, Hakan; Ozkaya, Mustafa; Demir, Teyfik; N/A; Yaman, Onur; Doctor; N/A; Koç University Hospital; 219524
    Transdiscal screw fixation is generally performed in the treatment of high-grade L5-S1 spondylolisthesis. The main thought of the study is that the biomechanical performances of the transdiscal pedicle screw fixation can be identical to standard posterior pedicle screw fixations with or without transforaminal lumbar interbody fusion cage insertion. Lumbosacral portions and pelvises of 45 healthy lambs' vertebrae were dissected. Animal cadavers were randomly and equally divided into three groups for instrumentation. Three fixation systems, L5-S1 posterior pedicle screw fixation, L5-S1 posterior pedicle screw fixation with transforaminal lumbar interbody fusion cage insertion, and L5-S1 transdiscal pedicle screw fixation, were generated. Axial compression, flexion, and torsion tests were conducted on test samples of each system. In axial compression, L5-S1 transdiscal fixation was less stiff than L5-S1 posterior pedicle screw fixation with transforaminal lumbar interbody fusion cage insertion. There were no significant differences between groups in flexion. Furthermore, L5-S1 posterior fixation was stiffest under torsional loads. When axial compression and flexion loads are taken into consideration, transdiscal fixation can be alternatively used instead of posterior pedicle screw fixation in the treatment of L5-S1 spondylolisthesis because it satisfies enough stability. However, in torsion, posterior fixation is shown as a better option due to its higher stiffness.
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    Clinical comparison between patients operated for unilateral radiculopathy via a contralateral (facet-sparing) and ipsilateral side approach
    (Turkish Neurosurgical Soc, 2018) Öğrenci, Ahmet; Koban, Orkun; Yılmaz, Mesut; Yaman, Onur; Dalbayrak, Sedat; N/A; Yaman, Onur; Doctor; N/A; Koç University Hospital; 219524
    Aim: To compare clinical outcomes of the patients operated from the contralateral or ipsilateral side for unilateral radiculopathy in spinal stenosis. Material and Methods: This was a retrospective study. Twenty patients were listed as Group 1 (Contralateral) with unilateral radiculopathy and spinal stenosis with/without lateral recess syndrome or foraminal stenosis. Decompression from opposite side of radiculopathy was performed to Group 1 patients. Decompression from the radiculopathy side was performed to the patients in Group 2 (Ipsilateral). Twenty eight patients were listed as Group 2. Back pain visual analogue scale (VAS) score and leg pain VAS score were assessed at preoperative, postoperative 1st month and postoperative 12th month. The results were compared statistically. Results: Two patients were excluded because of reoperation at the 2nd month from the Group 2 to assessment 12th month VAS score. There was no significant difference between two groups at 1st month back pain VAS and leg pain VAS scores. There was no significant difference between two groups at 12th month back pain VAS and leg pain VAS scores. Dynamic stabilization was performed at 2nd month to two patients after the first operations for instability. So, there was no difference in clinical outcomes between the patients treated by contralateral approach and ipsilateral approach when instability did not occur. However, there is a risk of instability of the same side approach and surgery owing to shaving of the facet joint. Conclusion: In the contralateral approach, the recess of the contralateral side and foramen can be better seen than in the ipsilateral approach. So, this is a facet-sparing approach to spinal stenosis with/without lateral recess syndrome or foraminal stenosis with unilateral radiculopathy. The contralateral approach to unilateral radicular complaints is quite effective. With this approach, facet joints are protected from possible instability.
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    Minimally invasive translaminar endoscopic approach to percutaneous vertebroplasty cement leakage: technical note
    (Elsevier Science Inc, 2018) N/A; N/A; N/A; N/A; N/A; Şentürk, Salim; Akyoldaş, Göktuğ; Ünsal, Ülkün Ünlü; Yaman, Onur; Özer, Ali Fahir; Doctor; Faculty Member; Doctor; Doctor; Faculty Member; N/A; School of Medicine; N/A; N/A; School of Medicine; Koç University Hospital; Koç University Hospital; Koç University Hospital; N/A; 203677; N/A; 219524; 1022
    Background: Percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty are 2 common procedures that could be applied simply in treatment of vertebral compression fractures. Despite simplicity and safe application of these procedures, there are some drawbacks as well. Cement leakage into the spinal canal is the most common complication of PVP and PKV procedures. The aim of this article is to present a minimally invasive alternative technique for removing cement leakage fragment after the PVP. Methods: A 44-year-old female patient began to complain of L4 radiculopathy after L4 PVP. The lumbar computed tomography demonstrated cement fragment closed to upper medial aspect of the left L4 pedicle. A minimally invasive translaminar endoscopic procedure was performed to remove the cement fragment. Results: Following the endoscopic procedure, the patient's complaints resolved completely and she was discharged on postoperative day 1. The minimally invasive intervention provided shorter operation time, minimal blood loss, and reduced complication rate due to its simplicity. In particular, there was no need to undergo general anesthesia. Conclusion: Endoscopic translaminar approach could be safely performed in patients with symptomatic cement leakage after PVP or a percutaneous kyphoplasty procedure.
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    Extraosseous, epidural cavernous hemangioma with back pain
    (Termedia Publishing House Ltd., 2015) Ozdemır, Nail; Yaldiz, Can; Ozkal, Birol; Dalbayrak, Sedat; N/A; Yaman, Onur; Doctor; N/A; Koç University Hospital; N/A
    Background: Cavernous malformations are characterized by enlarged vascular structures located in benign neural tissues within the cerebellum and spinal cord of the central nervous system. Cavernous hemangiomas (CHs) account for 5% to 12% of all spinal vascular malformations. Case Report: We removed a hemorrhagic thoracic mass in a 40-year-old male patient who presented with progressive neurological deficits. Conclusions: We found it appropriate to present this case due to its rarity.
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    Comparison of Wiltse and classical methods in surgery of lumbar spinal stenosis and spondylolisthesis
    (Via Medica, 2015) N/A; Yaman, Onur; Doctor; N/A; Koç University Hospital; N/A
    Aim: Minimally invasive approaches to posterior lumbar surgery are available today that can enhance patient comfort by greatly reducing tissue damage and offer better clinical results. However, such methods have not yet gained widespread popularity despite their significant advantages. This study compares the Wiltse method and the classical method of lumbar surgery based a cohort, clinical study of 57 patients. The patients all had degenerative lumbar spinal stenosis and/or spondylolisthesis and had developed multifidus muscular atrophy. Materials and methods: We enrolled 57 patients admitted to our clinic between April 2012 and September 2013 with a diagnosis of degenerative lumbar spinal stenosis and/or spondylolisthesis. These were treated with the classic posterior approach (n = 26) or the Wiltse method (n = 31). Findings: In the classical method group, the ratio of female to male patients was 20/6 and the mean age was 58.19 +/- 10.17 years. A comparison of preoperative and postoperative multifidus muscle cross-sectional measurements (average of right and left) revealed a 36.09% atrophy level in the classical method group and a 26.34% atrophy level in the Wiltse group (p <0.01). However, atrophy development was 18.82% higher in the classical method group (p < 0.05) relative to the Wiltse group. Conclusion: The Wiltse method is less invasive and causes less tissue damage. It reduces the change of hemorrhage and multifidus muscles and offers a shorter duration of hospitalization with less pain.
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    Approach to lumbar degenerative scoliosis
    (Türk Nöroşirurji Derneği, 2018) Malçok, Ümit Ali; Yaman, Onur; Doctor; School of Medicine; Koç University Hospital; N/A
    Lumbar degenerative scoliosis occurs in the adult period after 50 years of age. It develops on a background of asymmetric disc degeneration. The patients should be explained that adult scoliotic deformity is a de novo development and can be progressive. To be able to decide on the treatment method in these patients, the complaints, clinical findings, radiological measurements and systemic diseases should be evaluated together. We need all this information to predict the level of healing after surgery. The use of the SRS-Schwab Classification will provide a better understanding of post-surgical expectations. The Berjano and Lamartina classifications can be used to predict what curvatures should be involved in fusion, and what the fusion levels should be. According to the literature, patients who underwent surgical treatment are more likely to have a higher quality of life than patients who are followed conservatively. / Lomber dejeneratif skolyoz 50 yaş sonrası erişkin dönemde görülür. Asimetrik disk dejenerasyonu zemininde gelişmekte olduğu görülmektedir. Erişkin skolyotik deformitenin bir de novo deformite olduğu ve hastalığın ilerleyici olduğu hastalara anlatılmalıdır. Bu hastalarda tedavi yöntemine karar verebilmek için; şikayetleri, klinik bulguları, radyolojik ölçümleri ve sistemik hastalıkları birlikte yorumlanmalıdır. Cerrahi sonrası iyileşme seviyesini öngörebilmek için tüm bunlara ihtiyacımız var. SRS-Schwab Sınıflaması’nın kullanılması cerrahi sonrası beklentilerin daha iyi anlaşılmasını sağlayacaktır. Hangi eğriliklerin füzyona katılması gerektiği ya da füzyon seviyelerinin ne olması gerektiğini öngörebilmek için Berjano ve Lamartina sınıflamasından yararlanılabilinir. Literatürdeki serilere bakıldığında cerrahi tedavi yapılan hastaların yaşam kalitesi, konservatif takip edilen hastalara göre daha yüksek olduğu izlenmektedir.
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    Comparison of titanium screw with polyester band with clamp (lotus) and rigid titanium transverse binder system using the finite element analysis
    (Turkish Spine Society, 2017) Erkal, Birol; Yaldız, Can; Karatay, Mete; Çelik, Haydar; N/A; Karabulut, Deniz; Zafarparandeh, Iman; Yaman, Onur; Solaroğlu, İhsan; Özer, Ali Fahir; Other; PhD Student; Doctor; Faculty Member; Faculty Member; N/A; Graduate School of Sciences and Engineering; N/A; School of Medicine; School of Medicine; N/A; N/A; Koç University Hospital; N/A; N/A; N/A; N/A; 219524; 102059; 1022
    Objective: There are many studies in the literature for posterior spinal instrumentations. In this study, we compared a titanium screw with a polyester band with a clamp (LOTUS) and a rigid titanium transverse binder system, which are used in the lower lumbar region and to examine the strength and superiority of the systems against each other with the finite element (FE) analysis. Material and Methods: A Ti6Al4V grade 5 titanium biocompatible alloy support for a pediclebased posterior stabilization system and a polyethylene band support for a pedicle-based posterior stabilization system were compared as testing material. Results: Range of motion was decreased by 95.8 % when a pedicle-based stabilization system was used at L4–L5. Range of motion was decreased further, about 1%, when the polymer band was used in conjunction with a posterior stabilization system in axial rotation. Conclusion: Similar results were observed when a titanium transverse connector was used. In light of the results of all finite element analyses, neither the titanium screws with a polyester band with a clamp (LOTUS) nor the rigid titanium transverse binder system has a significant superiority over the other. Equivalent results in the limitation of movement and rigidity allow the use of these systems in short-segment posterior spinal instrumentation with the same indications. / Amaç: Literatürde posterior spinal enstrümantasyon için pek çok çalışma vardır. Biz bu çalışmada lomber bölgede, sonlu eleman (FE) analiziyle, polyester bant sıkılaştırıcı ve rijit titanyum transvers bağlayıcı sistemleriyle bağlanmış titanyum vidanın, birbirlerine üstünlüklerini ve güçlerini değerlendirdik. Materyal – Metot: Test materyali olarak, Ti6Al4V grade 5 biyolojik uyumlu alaşıma sahip pedikül temelli posterior stabilizasyon sistemi ve polietilen bantla desteklenmiş pedikül posterior stabilizasyon sistemi karşılaştırıldı. Bulgular: Sonuç olarak, pedikül temelli stabilizasyon sistemi L4-5’de kullanıldığı zaman hareket oranı % 95.8 azaldı. Posterior stabilizasyon sisteminin bağlantısında polimer bant kullanıldığında, posterior stabilizasyon sistemi aksiyel rotasyonunun hareket oranı yaklaşık % 1 azaldı. Sonuç: Titanyum transvers bağlantı kullanıldığında benzer sonuçlar gözlendi. Tüm sonlu eleman sonuçlarının ışığında ne polyester bant kullanılan titanyum vidalarda ne de rijit titanyum transvers bağlantı sistemi kullanılan sistemde diğerine önemli bir üstünlük gözlenmemiştir. Aynı endikasyon ile rijit alaşımların kullanıldığı kısa segment posterior spinal enstrümantasyon sisteminin hareketin sınırlandırılmasındaki sonuçları eşit bulunmuştur.