Mahmut Pekedis

Stable fixation of displaced simple transverse olecranon fractures is required to maintain reduction under triceps traction and enable early elbow motion. Although Weber tension band fixation is widely used, the biomechanical influence of tension band material (cable vs cerclage wire) across different pin/anchorage designs remains unclear. This study compared resistance to fracture-line separation among six Weber-based constructs in a standardized synthetic ulna model. Sixty commercially available synthetic ulnae were osteotomized to create a transverse olecranon fracture model (Mayo type IIA) and randomly assigned to six groups (n = 10/group): bicortical pins, eyelet pins, and AA crimp constructs, each combined with either cable or cerclage wire in a figure-of-eight configuration. Specimens underwent monotonic tensile loading simulating triceps traction. Forces corresponding to 2 mm and 3 mm fracture-line separation were recorded. Between-group comparisons were performed within cable and cerclage subgroups, and cable-versus-cerclage comparisons were conducted within matched constructs (α = 0.05). At 2-mm separation, mean forces (N) were 316.1 ± 98.1 (bicortical cable), 277.0 ± 101.7 (eyelet cable), and 249.1 ± 104.2 (AA crimp cable), versus 273.1 ± 34.4 (bicortical cerclage), 283.6 ± 38.4 (eyelet cerclage), and 282.2 ± 36.9 (AA crimp cerclage). At 3-mm separation, mean forces were 340.5 ± 129.6, 336.5 ± 111.0, and 319.4 ± 78.8 for the cable constructs, and 332.9 ± 48.3, 354.7 ± 42.4, and 349.0 ± 37.2 for the cerclage constructs (bicortical, eyelet, and AA crimp, respectively). No significant differences were observed among pin/anchorage designs within the cable or cerclage subgroups at either threshold (all p > 0.05). Similarly, cable versus cerclage comparisons within matched constructs showed no significant differences at 2 mm or 3 mm (all p > 0.05). Under the specific conditions of this synthetic ulna model and monotonic tensile loading protocol, no statistically significant differences were detected between cable- and cerclage wire-based Weber tension-band constructs at either the 2-mm or 3-mm separation threshold. Bicortical, eyelet, and AA-crimp-based configurations also showed no significant differences in early gapping resistance. These findings should be interpreted as controlled monotonic early-separation data and not as evidence of clinical equivalence or fatigue durability.

Anizotropik malzemelerin iki eksende mekanik davranışlarını tespit etmek için mevcut olan endüstriyel çift eksenli makineler oldukça maliyetlidir. Bu çalışmada, evrensel çekme-basma cihazlarıyla uyumlu çalışabilecek basit, ekonomik ve pratik iki eksenli çekme-basma cihazı geliştirilmiştir. Cihaz anizotropik ve doğrusal olmayan davranış sergileyen Aşil tendonu üzerinde test edilmiştir. Cihaz yük taşıyıcı elemanlar, hareketi sağlayan doğrusal ray ve arabalar, numune tutucu çeneler, birim şekil değiştirme rozetleri ve veri alım ünitesinden oluşmaktadır. Öncelikle kasaptan temin edilen dana Aşil tendonlarından, bir yönü fibere paralel, diğer yönü ise fibere dik doğrultuda olacak şekilde “artı (+)” şeklinde örnekler çıkarılmış ve örnekler geliştirilen cihazla test edilmiştir. Elde edilen ölçümler filtrelemeye tabi tutulmuştur. Daha sonra bu ölçümler Ogden malzeme modelinde değerlendirilmiş ve eğri uydurma teknikleriyle numuneye ilişkin parametreler belirlenmiştir. Bu çalışmada geliştirilen portatif ve ekonomik cihaz ile beraberinde uygulanan metodolojik yaklaşım, anizotropik yumuşak doku biyomekaniği alanına önemli katkılar sağlama potansiyeline sahiptir.

Purpose: This study aims to characterize the mechanical properties of implant‐supported full arch fixed complete dentures manufactured by milling and injection techniques.Materials and Methods: Twenty‐two samples with milling and injection manufacturing techniques were fabricated. Twenty‐two titanium samples were manufactured to be used as the control group. Additionally, eight PEEK samples from both the injection and milling groups were manufactured and tested using a uniaxial tensile test, and the obtained results were used as input data for finite element analysis (FEA). All‐on‐four PEEK hybrid prostheses supported with 2 implants on the mandible were used for the simulations. The FEA computations were performed for a bilateral 150 N force applied in both vertical and oblique directions.Results: A significant difference was observed between the injection and milled PEEK groups in terms of modulus of elasticity (Injection PEEK group: 3.1 ± 0.6 GPa, Milling PEEK: 4.6 ± 0.9 GPa) and flexural rigidity (Injection PEEK group: 28.0 ± 5.8 kNmm², Milling PEEK: 41.2 ± 8.4 kNmm²) (p < 0.05), while no significant differences were observed between the injection and milled PEEK groups in terms of other parameters (p > 0.05). The finite element results showed that the highest stresses were observed in the Injection PEEK group, while the lowest were observed in the Milling Titanium group. Both injection and milled PEEK frameworks exceeded the yield stress limit during vertical and oblique loading.Conclusion: It was concluded that the forces implemented on rigid framework material such as titanium were better distributed to the implants supporting the all‐on‐four prosthesis.

Although diabetes is associated with alterations in the structural and functional properties of soft tissue, the response of the human Achilles tendon to location-dependent variations in both quasi-static and dynamic loading is unclear. This study aimed to characterize the elastic, viscoelastic, hysteresis, and failure properties of the distal, midsubstance, and proximal Achilles tendons in diabetic and nondiabetic patients and to investigate the relationship between biomechanical and clinical observations. Tendons were obtained from patients who underwent above- or below-knee amputation. Dumbbell-shaped specimens were harvested from the three sites. Relaxation tests were performed to determine viscoelastic characteristics. Cyclic loading tests at various frequencies were deployed to determine the dynamic modulus and phase angles. Incremental cyclic loading tests were carried out to investigate the backbone curve and energy dissipation due to hysteresis. Additionally, monotonic loading tests were performed to determine the elastic and failure properties. The results show that biomechanical parameters are not significantly different among the three sites. However, the midsubstance site exhibits significantly higher energy dissipation compared to other sites. Additionally, an increase in cyclic frequency enhances the phase angle, indicating that higher energy dissipation may protect the tendon from high loading rates. Furthermore, an increase in body mass index (BMI) and hemoglobin A1c (HbA1c) is significantly and negatively correlated with stiffness and viscoelasticity, suggesting that improving metabolic health may prevent tendon impairment. These findings may assist in creating more effective therapeutic strategies for tendon repair.

This study introduces a novel anchor-type proximal femoral nail (AT-PFN) to improve the bone-fixation integrity over the standard screw-type nail (SST-PFN). Quasi-static incremental cyclic load test was performed to investigate load-displacement, cumulative deformation energy, time-strain, and backbone curves. The finite element analysis (FEA) was implemented to identify the stress and strain distributions. Additionally, non-destructive dynamic tests were conducted, and the measurements were processed using statistical pattern recognition, based on vector autoregression and principal component analysis to investigate the nonlinearity due to bone-fixation interface. The results demonstrate that the AT-PFN significantly improves the bone-fixation integrity compared to SST-PFN.

The main aim of this study is to develop an approach that detects and classifies objects in indoor areas by applying Hector Simultaneous Localization and Mapping (SLAM) and "You Only Look Once" (YOLO) algorithms to an autonomous, custom-made mobile robot. The approach is based on the Robot Operating System (ROS) and computer vision. The mobile robot's motion, path, and communication are controlled by the ROS navigation package. This paper provides a detailed description of the approach implemented to create a new map with objects, as well as information about the hardware and software configuration of the mobile robot. The object identification process and map creation are performed using a low-budget Laser Imaging Detection and Ranging (LIDAR) sensor and non-encoder DC motors. The results show that the proposed technique can detect objects with an accuracy of 97.8% and 94.86% for the x and y cartesian axes, respectively..

Amaç: Tendon transferleri, ortopedik cerrahide özellikle pediatrik deformiteler ve sinir hasarı sonrası fonksiyonel kapasiteyi arttırmak amacıyla sık kullanılan tekniklerdir. Tendon transferleri birkaç temel prensip etrafında şekillenmiştir. Bu prensipler transfer sonrası hareket beklenen eklemin esnek olması, transfer yapılacak yumuşak dokunun iyileşmeye elverişli olması, donor tendonun yeterli ekskürsiyona ve kuvvete sahip olması, doğrusal bir çekiş eksenine sahip olması ve aynı zamanda feda edilebilir olmasıdır. Bu prensiplerin çoğu iyi bir preoperatif planlama ile uyulabilecek sınırları ifade ederken intraoperatif değiştirilebilir temel değişken olarak transfer edilecek bölgedeki dokunun mahiyeti ve uygulanacak transfer tekniğinin bu doku ile etkileşimi olarak öne çıkmaktadır. Gereç ve Yöntem: Çalışmamızda osseotendinöz bir iyileşme beklentisi ile tarsal kemiklere transfer edilerek tespit edilen tibialis anterior transferi uygulamalarında 3 farklı tespit yöntemini kıyaslamayı amaçladık. Bu teknikler: 1) Askı düğme sistemi ile tespit 2) Çapa dikiş ile tespit 3) Tünel tekniği ile tespit. Bunun için toplam 9 kadavrada 3 farklı cerrahi teknik 3er farklı kadavrada uygulanmıştır. Sonuç parametresi olarak tespit sonrası transfer edilen tendonun traksiyon kuvveti ile direnebildiği maksimum kuvvet, maksimum kuvvet etki ettiği andaki deplasman değerlendirilmiştir. Biyomekanik testin tamamlanmasının ardından tibialis anterior transfer edilen ayak bileği mediali disseke edilerek median plantar sinirin hasarlanıp hasarlanmadığı araştırılmıştır. Bulgular: Deneylerde elde edilen sonuçlara göre gruplar arasında kopma öncesi maksimum kuvvet değerinde ve maksimum kuvvet uygulandığı andaki deplasman miktarında anlamı bir fark olmadığı ortaya konulmuştur. Dokuz kadavranın hiçbirinde median plantar sinir hasar görmemiştir. Sonuç: Önerilen tekniğin karşılaştırılan teknikler ile benzer biyomekanik dayanım sunması, implant maliyeti olmaması, kalıcı tespit materyali bırakılmasını gerektirmemesi ve nörovasküler hasar yaratma olasılığı açısından risk oluşturmaması sebebiyle etkin ve güvenli bir yöntemdir.

Structural health monitoring (SHM) plays a crucial role in extending the service life of engineering structures. Effective monitoring not only provides insights into the health and functionality of a structure but also serves as an early warning system for potential damages and their propagation. Structural damages may arise from various factors, including natural phenomena and human activities. To address this, diverse applications have been developed to enable timely detection of such damages. Among these, vibration-based methods have received considerable attention in recent years. By leveraging advancements in computer processing capabilities, machine learning and deep learning algorithms have emerged as promising tools for enhancing the efficiency and accuracy of vibration-based SHM. This study focuses on the application of convolutional neural networks (CNNs) for the classification and detection of structural damage within a steel-aluminum building model. An experimental platform was devised and constructed to generate data representative of building damage scenarios induced by bolt loosening. Both the typical placement of sensors on each floor and the utilization of only one accelerometer were employed to understand the effect of scarcity of accelerometers. By subjecting the building model to controlled vibrations and environmental conditions, the response data from both sensor configurations were collected and analyzed to evaluate the effectiveness of the CNN approach in detecting structural damage under varying sensor deployment strategies. The findings demonstrate that the CNNs exhibited high accuracy in both damage classification and detection, even under scenarios with limited sensor coverage. Moreover, the proposed method proved effective in identifying structural damage within building structures.

This study aimed to develop a vibro-haptics feedback based smart corset to stimulate humans to be in ideal posture by monitoring the spline in thoracic vertebrae of T5-T12 levels, and provide a vibro-tactile stimuli to human's skin at lumbar L3 level. A corset contains a microcomputer, sensors and an actuator was implemented on 12 participants for 2 cases to determine its efficiency. In the first case, tactile stimuli was not provided to the participants, while in the second case tactile stimuli was ensured. The results showed once the vibro-tactile stimuli was represented to the participants, their posture regime improved significantly with a value of 53.13±23.14 %. Moreover, it was also observed that their non-ideal postural duration significantly decreased. These results suggest that the corset provides vibro-tactile feedback that encourage humans in seated posture to beneficial postural habits while using computers.