Hakan Oflaz

Development of a 2-dof uterine manipulator with LED illumination system as a new transvaginal uterus amputation device for gynecological surgeries

Abstract Background: Hysterectomy, the most common major gynecological operation worldwide, consists of removal of the uterus and can be performed abdominally, vaginally, or laparoscopically. A uterine manipulator is a key device used for uterine manipulation and cannulation in hysterectomies. The challenges of conventional manipulators are to move the uterus in two distinct planes and to identify cervical landmarks during circular cut and coagulation. Material and methods: In this study, a structural synthesis of the two degrees of freedom parallel manipulator was performed considering the constraints noted by surgeons. Computer-aided design and assembly of the manipulator, the cervicovaginal cap with LEDs, and the external parts were performed before rapid prototyping. The final design of the uterine manipulator was then manufactured from stainless steel and tested on an artificial uterus model using a test chamber. Results: This article presents the design, production and testing processes of an innovative manipulator with a motion capability up to 80° workspace both in the sagittal and coronal planes and an illumination system, easily detectable by the laparoscope, was successfully implemented on the manipulator’s cervical cap in order to overcome the drawbacks of conventional uterine manipulators. Conclusions: Despite all the current studies and uterine manipulators on the market, no research has incorporated all the features mentioned above.

Designing and prototyping a new uterine manipulator with two plane motion mechanism and LED marker illumination system

Hysterectomy, that is removal of uterus, is one of the most common major operations in gynecologic surgeries. Laparoscopy technique is preferred in hysterectomy because of its advantages such as lower intra-operative blood loss, decreased surrounding tissue/organ damage, less operation time, lower post-operative infection and frequency of fever, shorter duration of hospitalization and post-operative returning time to normal activity.

Observation Of stress distribution On a 3D wrist model after scaphoid fracture

Scaphoid bone fractures are very often among carpus fractures. However, sacphoid fractures are diagnozed tardily. So, this lateness changes the treatment prognosis. Kirschner wires are mostly preffered because of its easiness of use as scaphoid fracture detection materials. Aim of this study is analyzing the stress distrubution of wrist and the change of total deformation before and after scaphoid fractures and also after the application of Kirschner wire. Segmentation process was done on CT images of wrist and 3D “stl” model was obtained and converted to solid model and finite element analysis were performed to realise this study. Metacarpal, carpaş, radius and ulna bones were linked as linear arc before the analysis. Afterwards, total stress distrubution and deformation were analyzed according to applied forces on metacarpal bones of fixed radius and ulna bones. By regarding the finite element analysis results, von-Misses stress distrubution were found 240,62 MPa before scaphoid fracture, 338,27 MPa after scaphoid fracture and 2678,1 MPa with after Kirschner wire application. Consequently, stress accumulation were observed on both scaphoid bone and Kirschner wire after scaphoid fracture. After this study, different fixation methods should be compared under same boundry conditions and then the most suitable fixation method may be determined. Moreover, it is encouraging that the most suitable personel implant designs may be done by using engineering approaches mentioned in this study.

Biomechanical comparison of stability of resorbable plate-screw fixation systems in different configurations after sagittal split ramus osteotomy

Sagittal split ramus osteotomy (SSRO) has been successfully and widely applied in the treatment of specific dentofacial deformities. Many techniques and materials have been used by surgeons like wire osteosynthesis miniplates and screws used for fixation and stabilization after SSRO. While most post surgical complications related to titanium mini plates and/or screws requring second surgery to remove and disadvantages of metalic fixations have been developed and employed in studies focusing on evaluation of resorbable metarials in mandibular sagittal split osteotomy fixation and stabilization. Recently more surgeons have prefered to use resorbable materials in upregulation, stil the reliability of resorbable materials at different jaw sites after osteotomies or fractures remains a matter of concern for surgeons which limits to use resorbable materials systems by such surgeons. In literature, number of studies about analysis and comparison of clinical results of sagittal split ramus osteotomy performed with the use of resorbable plate/screw systems have not been satisfactory enough yet. In this study, 8 polyurethane synthetic mandibular replicas (Synbone 8598, Switzerland) were used and totally 2 groups were comprised. Afer employed SSRO on samples, fixations of bone segments were achieved using resorbable plate/screw systems (Inion CPS sistem, Tampere, Finland) in different configurations. Next, stabilities of fixation conducted by different systems were compared with together applying biomechanical loading tests. Then, stabilities of fixations which were applied with various systems were compared by applying biomechanical load tests. For this aim, 20N, 60N, 120N, 140N and 200N compressive loads were performed to each tooth on models by using of servohydrolic universal axial test machine. Experiments were carried out in biological test cabin which was full with continuously circulating physiological saline solution (PBS) at constant 37°C to mimic in vivo successfully. Compressive load behaviors of madibles which were in posterior and anterior region were recorded by using of non-contact video extensometer. According to the results, mandible group fixed by using screw was found more stabile than the group fixed by plate. Moreover, less strain accumulation was observed in neighborhood of the cut zone in posterior part of osteotomy applied mandible in comparison with further areas. In conclusion resorbable screw-plate systems provide sufficient stability in the fixation process. Only the fixation with screws is safer than plate+screw fixation.

Designing and prototyping of a new uterine manipulator which will overcome drawbacks of conventional uterine manipulators and assist laparoscopic hysterectomies

Hysterectomy, that is removal of uterus, is one of the most common major operations in gynecologic surgeries. Laparoscopy technique is preferred in hysterectomy because of its advantages such as lower intra-operative blood loss, decreased surrounding tissue/organ damage, less operating time, lower post-operative infection and frequency of fever, shorter duration of hospitalization and post-operative returning time to normal activity. During total laparoscopic hysterectomy, first uterine vessels and ligaments are cauterized respectively, and then cervicovaginal connections are cauterized and coagulated to remove uterus completely. Uterine manipulators are used during laparoscopy to maximize the endoscopic vision of surgeons by moving related organs. However, conventional uterine manipulators have important drawbacks particularly to move uterus in three dimensions and to show cervicovaginal landmark during laparoscopic circular cauterization which is difficult and hand skill required process, and amputation of the uterine cervix. A new transvaginal uterine manipulator may overcome these important drawbacks of these currently available devices. For this reason, a 3 dimensional (3D) scanning technique was used to obtain real world data such as uterine dimensions and computer aided design software is used in designing of the new manipulator and then 3D printer was used in prototyping. Special light emitting diodes (LEDs) were mounted on the cervical cap of the manipulator to guide light beams from inside of cervicovaginal tissue to abdominal cavity to facilitate the visualization of tissue landmarks. In brief, structural synthesis, CAD and rapid prototyping of parallel manipulator with 2-dof and which allows the uterus to be manipulated in both anterior posterior and lateral axis was performed in the scope of this thesis. Furthermore, a circular LED system was designed and implemented on system to ease the determination of cervicovaginal landmark. In the light of the findings acquired from the study, designed manipulator has ability to manipulate uterus in anterior posterior and lateral axis. Moreover, LED illumination system which can be detected easily by the laparoscope is successfully implemented on the manipulators cervical cap.

Development, 3D printing and characterization of calcium sulfate based scaffolds for bone tissue engineering

Clinic applications of bone tissue (BT) transplantation are used widely for treatment of large bone defects. In BT field, development of biomimetic bone tissue scaffolds which have appropriate chemical and mechanical properties for clinic applications is needed. Biomimetic bone tissue scaffolds should be used for bone grafts which are developed with tissue engineering approach to mimic extracellular matrix. Since bone have high percentage of hydroxyapatite, ceramic biomaterials have grand potential to be used as inorganic tissue scaffold. Literature shows that ceramic based scaffolds such as calcium sulphate, β-tricalcium phosphate and hydroxyapatite support cell attachment, can be resorbed by osteoclasts and also degradation rate of the ceramics are in accordance with bone regeneration rate. The most critical step is production of defect matching scaffold in on custom artificial bone applications. Therefore, powder based three dimensional (3D) printing become prominent because of the numerous advantages such as design independency and high controllability of inner and outer structure. Scaffolds were designed by using CAD programs and printed with CaSO4M.5H2O (calcium sulphate hemihydrate) powders by using 3D printing technology. Then mechanical and biological properties of the scaffolds were tested to investigate the usage potential of CaSO4.0.5H2O based 3D printed scaffolds in tissue engineering. Cytotoxicity results showed that 3D printed scaffolds provided a suitable environment for cell culture. As a result, usage of 3D printing technology in production of controllable scaffold production for artificial tissue development has an important potential.