Publications by authors named "Arif Ozkan"

19 Publications

  • Page 1 of 1

Genitalia Preserving Robotic Radical Cystectomy with Intracorporeal Studer Pouch Formation in the Female: Experience in 5 Cases.

Robot Surg 2021 28;8:1-7. Epub 2021 Apr 28.

Koç University, School of Medicine, Department of Urology, Istanbul, Turkey.

We present operative, postoperative, oncologic and functional outcomes of genital tract sparing robot-assisted laparoscopic radical cystectomy, bilateral extended pelvic lymph node (LN) dissection and intracorporeal Studer pouch construction on five female patients with bladder cancer. One of the cases had concomitant nephroureterectomy performed due to a non-functioning kidney. Median patient age, mean operation time, median estimated blood loss and mean duration of hospital stay were 59 (39-78), 462 ± 25, 400 (50-970), 8.8 ± 2.5, respectively. Pathologic stages were pTis (n=1), pT1 (n=1), pT3 (n=1), pT4a (n=1) and pT4b (n=1). Mean LN yield was 32.4 ± 8.9. Positive surgical margins were detected in 2 patients with pT4 diseases. Only minor complications developed that were resolved with medical treatment. Two patients had no, 1 patient had mild, and 2 patients had moderate daytime incontinence. One patient had good, 3 patients had fair, and 1 had poor night-time incontinence. This complex robotic surgery can be performed safely with acceptable short-term surgical, oncological and functional outcomes.
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April 2021

Response to the Letter to the Editor: "Impact of Anterior Kidney Calyx Involvement of Complex Stones on Outcomes for Patients Undergoing Percutaneous Nephrolithotomy".

Urol Int 2021 1;105(1-2):165-166. Epub 2020 Sep 1.

Department of Urology, Newcastle University, Northern Institute For Cancer Research, Newcastle Upon Tyne, United Kingdom.

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September 2020

The effect of plasma melatonin levels in the treatment of lifelong premature ejaculation with selective serotonin reuptake inhibitors.

Andrologia 2020 Dec 20;52(11):e13785. Epub 2020 Aug 20.

Department of Urology, Taksim Education and Research Hospital, Istanbul, Turkey.

The aim of our study was to compare melatonin levels of patients with lifelong premature ejaculation (LPE) (n:60) with healthy controls (n:30) and to investigate the changes of melatonin levels in the treatment with dapoxetine and sertraline. Age, body mass index, duration of marriage, weekly intercourse number, International Index of Erectile Function scores, Intravaginal Ejaculation Latency Time (IELT) and melatonin levels were recorded. LPE patients were divided into two treatment groups. The first group was included 30 patients, who received 60 mg dapoxetine for six weeks, twice a week, an hour before intercourse. The second group received 50 mg of sertraline daily, for six weeks. IELT and melatonin measures were repeated after the treatment. IELT (dapoxetine group: 41.22 ± 21.3 s, sertraline group: 48 ± 23.11 s, control group: 195.54 ± 84.14 s; p < .001) and melatonin levels (dapoxetine group: 5.75 ± 2.04 pg/mL, sertraline group: 5.49 ± 2.88 pg/mL, control group: 13.4 ± 12.09 pg/mL; p < .001) of both LPE groups were significantly lower than control group. Following the six-week sertraline (before: 48 ± 23.11 s, after: 101.01 ± 59.55 s; p < .001) and dapoxetine (before: 41.22 ± 21.3 s, after: 97.39 ± 44.1 s; p < .001) treatments, IELT increased. The melatonin levels increased in the sertraline group (before: 5.49 ± 2.88 pg/mL, after: 10.6 ± 7.37 pg/mL; p < .001). Our results indicate that melatonin levels of LPE patients are lower than levels of healthy volunteers. Furthermore, we found a significant increase in melatonin levels following sertraline treatment.
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December 2020

Can serum procalcitonin levels be useful in predicting spontaneous ureteral stone passage?

BMC Urol 2020 Apr 19;20(1):42. Epub 2020 Apr 19.

Department of Urology, GOP Taksim Education Training and Research Hospital, Karayolları Str. No:621 Gaziosmanpasa, İstanbul, Turkey.

Background: Medical expulsive therapy (MET) is recommended for ureteral stones when there is no indication for interventional treatment. Spontaneous passage (SP) may not always be perceived in patients undergoing MET. We aimed to demonstrate the effects of inflammatory factors on spontaneous ureteral stone passage in patients undergoing MET.

Methods: Our study was conducted between August and November, 2016, in healthy volunteers and patients with a single distal ureteral stone between 5 and 10 mm in diameter and no indications for interventional therapy. Blood and urine samples from all patients and healthy volunteers were tested. The patients were followed up every 2 weeks for 1 month unless emergency situations appeared. Patients with stone-free status at follow-up were concluded to have achieved complete stone passage [SP(+)], and failure [SP(-)] was concluded if the patient had not passed the stone by the end of the study. Blood samples of the patients and the control group were analyzed, recording WBC (white blood cell), CRP (c-reactive protein), SED (sedimentation), MPV (mean platelet volume), NLR (neutrophil-to-lymphocyte ratio), and serum procalcitonin levels. Abnormalities in urine samples were recorded. All patients received diclofenac sodium 75 mg/day, tamsulosin 0.4 mg/day, and at least 3 l/day fluid intake. Patients were followed for a month with kidney, ureter, bladder (KUB) plain films, ultrasonography (USG), and unenhanced abdominal CT scans while undergoing MET. Comparative statistical analyses were performed between the SP(+) and SP(-) groups.

Results: The procalcitonin levels of the SP(-) group were significantly higher (207 ± 145.1 pg/ml) than in the SP(+) group (132.7 ± 28.1 pg/ml) (p = 0.000). The leucocyturia rate of the SP(-) group was significantly higher than in the SP(+) group (p = 0.004). Based on the ROC curve analysis, 160 pg/ml (86.7% sensitivity, 70.8% specificity, p < 0.001; AUC: 0.788 95% CI (0.658-0.917) was identified as the optimal cut-off value for procalcitonin. In logistic regression analysis, a significant efficacy of procalcitonin and leucocyturia was observed in the univariate analysis on spontaneous passage. In the multivariate analysis, significant independent activity was observed with procalcitonin. (p < 0.05).

Conclusion: Our findings suggest that high procalcitonin levels and the presence of leucocyturia have a strong negative effect on SP of ureteral stones between 5 and 10 mm in diameter. This relationship can be explained by stone impaction, possibly caused by increased mucosal inflammation.
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April 2020

Impact of Anterior Kidney Calyx Involvement of Complex Stones on Outcomes for Patients Undergoing Percutaneous Nephrolithotomy.

Urol Int 2020 10;104(5-6):459-464. Epub 2020 Mar 10.

Department of Urology, Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne, United Kingdom.

Introduction: A number of factors that can impact the outcomes of percutaneous nephrolithotomy (PCNL) procedures have previously been investigated. Complex stones that extend to the anterior calyx could affect the success and complication rates of PCNL.

Objective: We analyzed the effect of anterior calyx involvement on the outcomes of patients with complex stones treated with PCNL.

Methods: A total of 132 consecutive patients who underwent PCNL due to complex stones (multiple, partial staghorn, or staghorn stones) between 2015 and 2017 were enrolled in this study. They were stratified into two groups based on whether the stone extended to the anterior calyx (group 1, n = 45) or not (group 2, n = 87). The stratification was achieved through contrast-enhanced computerized tomography (CT). Demographics, laboratory tests, and peri- and postoperative findings (operation and fluoroscopy duration, hospital stay, utilization of flexible instruments, access numbers, total blood count change, stone-free rate [SFR], and complications) were compared between the groups. The SFR was evaluated by plain kidney-ureter-bladder radiography or CT.

Results: The demographics, operation and fluoroscopy duration, access number, and hospital stay were similar between the groups (p < 0.05). A higher drop in the hemoglobin level in group 1 was identified (group 1 [2.14 ± 1.49 g/dL] vs. group 2 [1.43 ± 1.31 g/dL]) (p = 0.006). The SFR among the patients with extension to the anterior calyx was 60%, compared to 77% among the patients with no extension to the anterior calyx (p = 0.041). Flexible instruments were utilized in 60% of the patients of group 1, which was a higher rate than for group 2 (36%) (p = 0.007). Complication rates were similar in the two groups according to the Clavien-Dindo classification (p > 0.05).

Conclusions: Our study demonstrated that complicated stones with extension to the anterior calyx are more challenging than cases without extension to the anterior calyx. This was noted by a lower SFR, a more prominent drop in total blood count, and more frequent utilization of flexible scopes.
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March 2021

Noninvasive treatment of intraperitoneal urinary system perforations with percutaneous placement of a peritoneal drainage catheter

Turk J Med Sci 2018 Dec 12;48(6):1141-1146. Epub 2018 Dec 12.

Department of Urology, Gaziosmanpaşa Taksim Education Hospital, İstanbul, Turkey

Background/aim: Intraperitoneal urinary system perforation is a rare but serious complication of endoscopic urologic surgery. Percutaneous placement of a peritoneal drainage catheter is already mainly used for diagnostic purposes. We present our experience with percutaneous drainage catheters for conservative management of intraperitoneal urinary system perforations occurring during endoscopic urologic surgery with close monitorization in selected cases.

Materials And Methods: Urinary system perforations had developed in 21 (0.8%) of 2603 patients undergoing endoscopic urologic surgery at our department in 2014–2016. The perforation was intraperitoneal in only 5 (0.19) of all the patients. A percutaneous peritoneal drainage catheter with the guidance of ultrasonography was placed in four of the patients.

Results: Conservative management by draining excess fluid with a drainage catheter percutaneously placed under close monitorization was successful in four out of five patients with urinary system perforation occurring during endoscopic urologic surgery. The remaining patient was treated successfully with open laparotomy because of fulminant evidence of peritonitis.

Conclusion: Our findings and experience may suggest that conservative management of intraperitoneal urinary system perforations occurring during endoscopic urologic surgery by percutaneous drainage catheter under close monitorization is feasible in carefully selected patients.
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December 2018

Comparison of Single and Prolonged Fluoroquinolone Prophylaxis and Risk Factors for Infectious Complications After Transrectal Prostate Biopsy

Balkan Med J 2018 09 5;35(5):373-377. Epub 2018 Jun 5.

Department of Urology, Northern Institute for Cancer Research Newcastle University, Newcastle, United Kingdom

Background: The ideal prophylaxis duration for transrectal ultrasonography-guided prostate biopsy is incompletely defined.

Aims: To compare the infectious complications of transrectal ultrasonography-guided prostate biopsy with and without extended antibiotic prophylaxis. The secondary aim was to evaluate the risk factors for infectious complications.

Study Design: Prospective observational study.

Methods: Four hundred patients who underwent transrectal ultrasonography-guided prostate biopsy were recruited. Patients orally received either 750 mg ciprofloxacin 60 min before the procedure or 500 mg ciprofloxacin twice a day for a duration of 7 days with the initial dose administered 24 h prior to the procedure. All patients were followed-up for 4 weeks after the transrectal ultrasonography-guided prostate biopsy procedure for infectious complications. Screening of urine was carried out in all patients on the 3 and 7 day after the procedure. Medical histories of all patients were collected prior to biopsy. Information on medical history include the following: hospitalization, urethral catheterization, or urinary tract infections within the past 12 months; antibiotic use within the last 3 months, prior urinary tract interventions, and previous transrectal ultrasonography-guided prostate biopsy and Charlson comorbidity indexes. Ultrasound-guided biopsy was carried out using General Electric’s 7 MHz transrectal ultrasound device in the left decubitus position. Patients received one of the two ciprofloxacin-based prophylaxis regimens. Subsequent transrectal ultrasonography-guided prostate biopsy to all patients were followed-up for 30 days. Further follow-up of patients was carried out on the second and fourth weeks after transrectal ultrasonography-guided prostate biopsy, and symptoms, such as dysuria, rectal bleeding, fever, hematospermia, hematuria, and pollakiuria, were recorded.

Results: Both groups presented similar baseline characteristics and medical history. Infectious complication rates within the 4-week follow-up were similar in both groups (single dose: 3% vs prolonged: 3%) (p>0.05). In both groups, infectious complications significantly increased than that at previous antibiotic usage (single: p=0.028; prolonged: p=0.040). Non-infectious complication ratios showed no significant variation (p>0.05).

Conclusion: Pre-operative single dose of 750 mg oral ciprofloxacin compared with 7 days prolonged treatment resulted in similar infectious complication outcomes in patients undergoing transrectal ultrasonography-guided prostate biopsy. The use of antibiotics within the last 3 months increases the risk for post-transrectal ultrasonography-guided prostate biopsy infectious complications.
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September 2018

Spontaneous rupture of the renal pelvis due to obstruction of pelviureteric junction by renal stone: A case report and review of the literature.

Urol Ann 2017 Jul-Sep;9(3):293-295

Department of Urology, Taksim Training and Research Hospital, Istanbul, Turkey.

Spontaneous rupture of the urinary collecting system with extravasation of the urine is a very rare condition. This situation is commonly associated with an obstructing urinary stone. Herein, we report a case of an 86-year-old patient who has admitted to the emergency service with left flank pain continuing for 7 days and pain has exacerbated in the past 24 h. The patient had nausea, vomiting, and tenderness on the left side of the abdomen and left flank region. The patient was diagnosed with an 8 mm left kidney stone a month ago, and hydration and oral analgesics were recommended to the patient. Spontaneous rupture of the renal pelvis and urinary extravasation were detected by contrast-enhanced computed tomography scan. Double-J ureteral stent was placed to control symptoms and eliminate extravasation. In this paper, diagnosis and treatment options for spontaneous renal pelvis rupture are discussed.
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August 2017

The effect of cement on hip stem fixation: a biomechanical study.

Australas Phys Eng Sci Med 2017 Jun 20;40(2):349-357. Epub 2017 Mar 20.

Department of Biomedical Engineering, Kocaeli University, Umuttepe Campus, 41380, Kocaeli, Turkey.

This study presents the numerical analysis of stem fixation in hip surgery using with/without cement methods since the use of cement is still controversial based on the clinical studies in the literature. Many different factors such as stress shielding, aseptic loosening, material properties of the stem, surgeon experiences etc. play an important role in the failure of the stem fixations. The stem fixation methods, cemented and uncemented, were evaluated in terms of mechanical failure aspects using computerized finite element method. For the modeling processes, three dimensional (3D) femur model was generated from computerized tomography (CT) images taken from a patient using the MIMICS Software. The design of the stem was also generated as 3D CAD model using the design parameters taken from the manufacturer catalogue. These 3D CAD models were generated and combined with/without cement considering the surgical procedure using SolidWorks program and then imported into ANSYS Workbench Software. Two different material properties, CoCrMo and Ti6Al4V, for the stem model and Poly Methyl Methacrylate (PMMA) for the cement were assigned. The material properties of the femur were described according to a density calculated from the CT images. Body weight and muscle forces were applied on the femur and the distal femur was fixed for the boundary conditions. The calculations of the stress distributions of the models including cement and relative movements of the contacts examined to evaluate the effects of the cement and different stem material usage on the failure of stem fixation. According to the results, the use of cement for the stem fixation reduces the stress shielding but increases the aseptic loosening depending on the cement crack formations. Additionally, using the stiffer material for the stem reduces the cement stress but increases the stress shielding. Based on the results obtained in the study, even when taking the disadvantages into account, the cement usage is more suitable for the hip fixations.
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June 2017

A comparison of Amplatz dilators and metal dilators for tract dilatation in mini-percutaneous nephrolithotomy.

Int Urol Nephrol 2017 Apr 23;49(4):581-585. Epub 2017 Jan 23.

Department of Urology, Istanbul Taksim GOP Training and Research Hospital, Karayollari Str, No: 621, Gaziosmanpaşa, Istanbul, Turkey.

Purpose: Our aim was to compare the different characteristics and outcomes of the Amplatz sheaths and single-step metallic dilators which were used for mini-PCNL procedure in a single institution.

Methods: Retrospective medical records of 236 patients who underwent mini-PCNL were reviewed and divided into Amplatz (n = 151) and metal (n = 85) groups. Perioperative and postoperative data including operative time, fluoroscopy time, hemoglobin decrease, blood transfusion, hospital stay, stone-free rate and any postoperative complication were recorded.

Results: The groups were statistically similar in terms of operation time, nephrostomy stay, puncture location and hemoglobin decrease. Compared to the metal sheath group, the fluoroscopy time (3.7 vs 5.9 m, p < 0.001) and the hospital stay (53.5 vs 67 h, p = 0.007) were significantly higher in the Amplatz group. Although final stone-free rate was higher for metal group than Amplatz group, no statistical difference was established (82.1 vs 79.5%, p = 0.285). The rates of complications such as fever, blood transfusion, postoperative DJ insertion were similar in two groups with no significant difference.

Conclusion: Although different treatment outcomes of various institutions have been published for mini-PCNL procedure, this is the first study that compares Amplatz and metallic sheaths. This study shows that there is no difference between the two groups in terms of final stone-free rate and complication rate. Even though the indications of each dilatation technique were similar, metal sheaths are most cost-effective (6.1 vs 63 Euro per case; p < 0.001).
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April 2017

Comparison of the Lag Screw Placements for the Treatment of Stable and Unstable Intertrochanteric Femoral Fractures regarding Trabecular Bone Failure.

J Med Eng 2016 22;2016:5470798. Epub 2016 Nov 22.

Department of Biomedical Engineering, Kocaeli University, Umuttepe Campus, 41380 Kocaeli, Turkey.

In this study, the cut-out risk of Dynamic Hip Screw (DHS) was investigated in nine different positions of the lag screw for two fracture types by using Finite Element Analysis (FEA). Two types of fractures (31-A1.1 and A2.1 in AO classification) were generated in the femur model obtained from Computerized Tomography images. The DHS model was placed into the fractured femur model in nine different positions. Tip-Apex Distances were measured using SolidWorks. In FEA, the force applied to the femoral head was determined according to the maximum value being observed during walking. The highest volume percentage exceeding the yield strength of trabecular bone was obtained in posterior-inferior region in both fracture types. The best placement region for the lag screw was found in the middle of both fracture types. There are compatible results between Tip-Apex Distances and the cut-out risk except for posterior-superior and superior region of 31-A2.1 fracture type. The position of the lag screw affects the risk of cut-out significantly. Also, Tip-Apex Distance is a good predictor of the cut-out risk. All in all, we can supposedly say that the density distribution of the trabecular bone is a more efficient factor compared to the positions of lag screw in the cut-out risk.
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November 2016

The relationship between medial meniscal subluxation and stress distribution pattern of the knee joint: Finite element analysis.

J Orthop Sci 2016 Jan 14;21(1):32-7. Epub 2015 Nov 14.

Antalya Memorial Hospital, Department of Orthopaedics and Traumatology, Antalya, Turkey. Electronic address:

Background: Degenerative changes of the knee joint and clinical follow-up after meniscal subluxation are well documented. In the current study three-dimensional (3D) finite element analysis (FEA) of human lower limb was used to investigate the effect medial meniscal subluxation on the loadings of the knee structures.

Methods: Apart from the reference model, a total of ten 3D models were created, according to amount of medial meniscal subluxation. ANSYS® 14 was used to analyze the stress/load distribution, that is to say the maximum equivalent stress (MES) (von Mises stress) on bones, cartilages, ligaments and menisci. MES was expressed as Newton/mm(2) = Megapascal (MPa).

Results: In a static and standing upright position the MES on all knee structures were evaluated in the reference model. Although MES increased in all structures with the increase of medial meniscal subluxation degree, tibia cartilage was found to be the most affected structure with an increase of 22.73-fold in the 10 mm subluxation model when compared with references values.

Conclusion: This study showed that medial meniscus subluxation is associated with increased loadings on all knee structures especially the tibia cartilage. Also the degree of the medial meniscal subluxation correlates with distribution and the amount of loadings on tibia cartilage which may be a prominent feature of knee osteoarthritis.
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January 2016

Changes in the loadings on the shoulder girdle in the case of scapulothoracic fusion.

Int J Med Robot 2016 Sep 17;12(3):538-46. Epub 2015 Jul 17.

Düzce University, Engineering Faculty, Department of Mechanical Engineering, Düzce, Turkey.

Background: Scapulothoracic fusion (STF) may be an alternative and salvage procedure in the treatment of scapular winging. The biomechanical effects of this procedure on the shoulder girdle have not been previously considered. The purpose of this study is to demonstrate the relationship between STF and the stress distribution pattern of the shoulder girdle.

Methods: Three-dimensional solid modeling of the shoulder girdle was carried out using virtual finite element modeling. STF was applied to the reference model obtained in a computer environment. Dynamic and nonlinear analysis was performed.

Results: Stress distributions in joints and ligaments were calculated. With respect to loading on the joints, maximum equivalent stresses increased on acromioclavicular (AC) and GH joints in the case of STF during abduction and flexion respectively.

Conclusion: Results revealed that STF is a non-physiological, static procedure leading to load increase on GH and AC joint cartilages, which may be a cause of potential joint osteoarthritis. Copyright © 2015 John Wiley & Sons, Ltd.
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September 2016

Stress distribution comparisons of foot bones in patient with tibia vara: a finite element study.

Acta Bioeng Biomech 2013 ;15(4):67-72

Department of Mechanical Education, Technical Education Faculty Kocaeli University, Umuttepe Campus, Kocaeli, Turkey.

Blount's disease, or tibia vara, is the most common cause of pathologic genu varum in children and adolescents. Changes in the loading of knee structures such as tibial articular cartilage, menisci and subcondral bone are well documented in case of genu varum. But the mechanical effects of this condition on foot bones are still questionable. In this study, the authors hypothesized that stress distributions on foot bones might increase in patients with tibia vara when compared with patients who had normal lower extremity mechanical axis. Three-dimensional (3D) finite element analyses of human lower limb were used to investigate and compare the loading on foot bones in normal population and patient with tibia vara. The segmentation software, MIMICS was used to generate the 3D images of the bony structures of normal and varus malalignment lower extremity. Except the spaces between the adjacent surface of the phalanges fused, metatarsals, cuneiforms, cuboid, navicular, talus and calcaneus bones were independently developed to form foot and ankle complex. Also femur, tibia and fibula were modeled utilizing mechanical axis. ANSYS version 14 was used for mechanical tests and maximum equivalent stresses (MES) were examined. As a result of the loading conditions, in varus model MES on talus, calcaneus and cuboid were found higher than in normal model. And stress distributions changed through laterally on middle and fore foot in varus deformity model.
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September 2014

Using a Combination of Intralaminar and Pedicular Screw Constructs for Enhancement of Spinal Stability and Maintenance of Correction in Patients With Sagittal Imbalance: Clinical Applications and Finite Element Analysis.

Clin Spine Surg 2016 10;29(8):E421-7

*Department of Orthopedics and Traumatology, Sakarya University Faculty of Medicine†Department of Orthopedics and Traumatology, Akdeniz University Faculty of Medicine, Antalya‡Department of Biomedical Engineering, Duzce University Faculty of Engineering, Duzce§Department of Orthopedics and Traumatology, Bolu Izzet Baysal University Faculty of Medicine, Bolu, Turkey.

Study Design: Case series and finite element analysis.

Objective: To report the clinical results of using intralaminar screw-rod (ILS) constructs as supplements to regular pedicle screw (PS) constructs in "high risk for implant failure" patients and to report the results of a finite element analysis (FEA) of this new instrumentation technique.

Summary Of Background Data: Despite advances in surgery and implantation techniques, osteoporosis, obesity, revision surgeries, and neuromuscular conditions (such as the Parkinson disease) are challenges against achieving solid arthrodesis and maintaining correction. Additional fixation strategies must be considered in these patients. There is only one study in the literature suggesting that ILS can be used as alternative anchor points and/or to increase fixation strength in conjunction with the PSs.

Materials And Methods: Five patients (3 male and 2 female) with mechanical comorbidities underwent PS+ILS to treat sagittal imbalance. In radiologic analysis, thoracic kyphosis, lumbar lordosis, and sagittal vertical axis were analyzed. FEA of ILS augmentation technique were carried out.Four different models were created: (1) the full-construct model with ILS+PS 2 levels above and below the osteotomy of T10; (2) only PS 2 levels above and below T10; (3) ILS+PS 1 level above and below the osteotomy; and (4) short-segment PS with only PSs 1 level above and below the osteotomy. The stress/load distributions on the implants in vertebrae were analyzed.

Results: The mean age of the patients included in this study was 41 years and the mean follow-up was 28.2 months. A total of 87 PSs and 39 ILSs were used. Both sagittal vertical axis and kyphosis angles showed significant improvements maintained at the latest follow-up. No pseudarthrosis or instrumentation failures were observed. FEA indicated that addition of ILS construct to a PS construct enabled decreased load bearing and increased implant life.

Conclusions: Addition of an ILS construct to PS construct decreases osteotomy line deformation and reduces stress on pedicle fixation points, and the combination improves fixation stability over the conventional PS-rod technique.
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October 2016

The effect of proximal tibial corrective osteotomy on menisci, tibia and tarsal bones: a finite element model study of tibia vara.

Int J Med Robot 2014 Mar 26;10(1):93-7. Epub 2013 Aug 26.

Department of Orthopaedics and Traumatology, Akdeniz University, Antalya, Turkey.

Background: Proximal tibial open wedge osteotomy (PTO) is a corrective operation used in the surgery of lower extremities and is applied to patients with varus deformities for sufficient correction. The aim of the study was to evaluate whether the PTO can achieve decreased stress-bearing on the tibia and tarsal bones in addition to correcting the mechanical axis of the lower limb in patients with tibia vara.

Methods: Three-dimensional (3D) solid modelling of the lower extremity was carried out using computed tomography (CT) and magnetic resonance (MR)-containing images of all of the bony elements and non-bony structures. PTO was applied to the obtained deformed model in the computer environment and the correction was carried out.

Results: Stress distributions in menisci, tibia and tarsal bones were calculated. With respect to loading on the tarsal bones, the maximum equivalent stresses on all bones decreased except for the navicula in the PTO-simulated model in the current study.

Conclusion: These results clearly indicate that PTO can achieve decreased stresses on the tarsal bones in patients with tibia vara.
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March 2014

Changes in the loading of tibial articular cartilage following medial meniscectomy: a finite element analysis study.

Knee Surg Sports Traumatol Arthrosc 2013 Dec 30;21(12):2667-73. Epub 2012 Nov 30.

Department of Orthopaedics and Traumatology, Midyat State Hospital, Mardin, Turkey,

Purpose: Depending on the location and extent of the meniscectomy, loading on the tibial articular cartilage alters. The main purpose of the present study was to analyze the loading on the tibial articular cartilage following medial meniscectomy performed in various location and extent, as well as in the healthy knee, via finite element analyses on the solid models.

Methods: Totally, 11 finite element solid models, including the reference model, were created to investigate the effect of location (anterior, posterior, longitudinal) and extent of meniscectomy (25, 50, 75, and 100 %) on loading of tibial articular cartilage.

Results: Maximum equivalent stress of the tibial cartilage was measured 0.86 Megapascal in the reference model and increased approximately by 78 % in 25 % meniscectomy group, 177.9 % in 50 %, 473.8 % in 75 % meniscectomy group, and 752.6 % in total meniscectomy. When only the amount of meniscal tissue removed was considered ignoring the location of meniscectomy, no significant difference was found in the amount of tissue excised between 25 % meniscectomy and 50 % meniscectomy, as well as between 75 % meniscectomy and total meniscectomy.

Conclusion: In all meniscectomy models, the loadings on tibial articular cartilage increased. Except total meniscectomy, the highest impact was observed in longitudinal 75 % meniscectomy. During the surgical treatment, the contributions of menisci on load absorption by increasing the tibiofemoral contact area must be considered. In fact, the increase in the rate of loading on tibial articular cartilage depends on according to type and amount of meniscectomy.
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December 2013