Clinical device modelling in the measurement of a tissue hardness

Bu çalışmada, doku sertliğini belirlemek için yeni bir sertlik ölçüm cihazının tasarlanması ve üretilmesi amaçlanmıştır. Günümüzde sayısal biyomedikal ve biyomekanik aygıtların yeterince var olmaması nedeni ile sayısal doku sertlik değerlendirmeleri yapılamamaktadır. Serviks, prostat ve benzer yumuşak dokuların sertlik tayini palpasyon metodu ile yapılmaktadır. Palpasyon metodu, uygulayan kişilere göre farklı sonuçlar verdiğinden daha özel ve kolay uygulanabilir klinik cihazlara ihtiyaç duyulmaktadır. Bu ihtiyaç göz önünde bulundurularak doku sertliğini objektif ölçebilecek bir cihaz tasarlanmış ve üretilmiştir. Deneyler dokuya benzer Agoroz jel ve Slikon zarlar üzerinde durometre ve üretilen prototip ile yapılmıştır. Bu ölçüm değerleri arasında karşılaştırma yapılarak kuvvet-sertlik grafiği oluşturulmuştur. Ölçüm sonuçlarından elde edilen kuvvet-sertlik grafiği lineer bulunmuştur. Ayrıca bu üretilen prototip ile yapılan ölçümler sonucu standart sapma değeri ile ortalama değeri arasındaki oran %2,66‘dır. Bu oran durometre için %2,22'dır. Bu sonuçlar, prototipin durometre kadar hassas ölçüler alabildiğini göstermektedir, ve prototip gerekli modifikasyonlar ile çok daha hassas bir hale getirilebilir. Sonuç olarakæ etik kuruldan gerekli izinler alındıktan sonra hayvan ve insan deneyleri planlanıp yapılmalıdır. Elde edilecek olumlu sonuçlar doğrultusunda bu protip, yumuşak doku sertlikleri ve rahatsızlıkları ile ilgili tanılarda ilgili kliniklerde kullanılmaya başlanabilir. Bu sayede subjektif uygulamalar aradan çıkararak yumuşak doku sertlik tanımlamalarında palpasyon yöntemi yerine nesnel değerlendirme yapılmış olacaktır. The aim of this study is to design a new hardness measurement device for soft tissue hardness diagnosing. Presently, quantitative measurement of tissue hardnesses can't be accomplished, because of the lack of biomedical and biomechanical devices. The hardness diagnosis of the servix, prostate or soft tissues is performed by palpation. This method gives results that differ from operator to operator, so special, easy applicable clincal devices need to be developed. At this study, a design of this necessary device was done. Experiments were done on the Agorose gel and silicon membrane which were taken as soft tissues. The Force - Hardness relation graph, that was obtained after the results, was found to be lineer. Furthermore, the range between the standart deviation and the avarage value, that were obtained from the results, was %2,66 for the prototype. This range was %2,22 for the durometer. These results show that the prototype is sensitive as the durometer, even the prototype can be more sensitive by modifications. Consequently, after the ethic committee permissions, studies on animals and humans should be done. After the positive results, this prototype can be started to be used at the concerned clinics. By this way, the subjective factors can be removed in the diagnose of soft tissue hardnesses, so a quantitative evaluation can be done instead of the palpation method

Observation Of Stress Distribution On a 3D Wrist Model After Scaphoid Fracture

19th National Biomedical Engineering Meeting (BIYOMUT) -- NOV 05-06, 2015 -- Istanbul, TURKEYWOS: 000380507300016Scaphoid 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, carpas, 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

The Effect of Heat Treatment on Physical, Chemical and Structural Properties of Calcium Sulfate Based Scaffolds

3D printed calcium sulfate (CS) is a promising material for on custom bone substitutes. Since it dissolves easily in body fluids, manufactured samples require to being improved to reduce solubility.  The main aim of this study was reducing the dissolubility of CS based samples by using sintering and investigating the effect of heat treatment on their physical, chemical and structural properties. To observe the effect of heat treatment on samples, contact angles were measured, X-Ray diffraction analysis (XRD) was performed, and scanning electron microscope (SEM) micrographs were captured before and after the sintering process, and the results were compared. Furthermore, sintered and non-sintered samples were soaked in phosphate buffered saline (PBS) to observe the impact of sintering on the solubility of the material. Also, three different pore sized scaffolds were manufactured to test the limits of the 3D printer for manufacturing of scaffolds with open pores. Sintering process results in a volume reduction and according to SEM results, CS grains were fused together after heat treatment. Although non-sintered CS sample starts to dissolve in high rate and nearly 1/3 of the sample was at the bottom of the glass in a matter of minutes, sintering creates more rigid structure and there were not visible dissolution in PBS at the end of a week. The contact angle of samples cannot be measured, so it can be concluded that 3D printed material showed a super-hydrophilic property. XRD diagram suggested that there is not any new phase created in the printing and sintering processes except related hydrates of CS. As a result of the 3D printing, 500 µm, 750 µm and 1000 µm pore sized scaffolds were manufactured, successfully. However, it was seen that 500 µm pores could not be open by using depowdering after the printing process

Comparative study of biomechanical stability of resorbable and titanium fixation systems after sagittal split ramus osteotomy with a novel designed in-vitro testing unit

Introduction: Sagittal split ramus osteotomy (SSRO) is one of the most popular surgical procedures for correction of mandibular deformities. Several clinical and biomechanical studies exist in the literature which, comparing the stability of different osteosynthesis materials and techniques, were performed using two or three-point biomechanical test models. The aim of this study was to compare the stability of biodegradable and titanium materials for SSRO on one-piece polyurethane mandible samples which were fixed in a novel designed 6-point testing unit

A biomechanical study on preloaded compression effect on headless screws

WOS: 000271538400003PubMed ID: 19911480Commonly used headless design screws such as Acutrak and Herbert screws have limited compressive effect on short fragment fixation. Therefore, we investigated whether preloaded compression techniques could be helpful in improving the compression effect. A prototype of interfragmentary compression screw was designed with a constant pitch to avoid self-compressive effect. Preloaded compression was achieved with a sleeve device before the insertion of the trailer side (the leading side was inserted). Prototype screw test results were compared with those of Acutrak and Herbert screws. Eight pullout and eight compression tests were performed for each of the three screws using homogenous synthetic bone blocks. The mean pullout forces of the Acutrak, Herbert and prototype screws were 67.21, 45.90 and 61.88 N, respectively. Preloaded compression (18.15 N) was higher than the compression produced by Acutrak (15.27 N) and Herbert (15.11 N) screws (p < 0.05). However, at the end of full insertion, half of the power obtained by preloaded compression was lost. Preloaded compression technique was successful in attaining maximum compression rate. During trailing-side insertion, constant pitch design failed to keep compression rate. Variable pitches can be useful to preserve or increase compression rate. In addition, sleeve usage may be more advantageous in thin fragment fixation

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

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