Mahmut Pekedis

Erratum to “Does Urinary Bladder Shape Affect Urinary Flow Rate in Men with Lower Urinary Tract Symptoms?”

In the paper titled “Does Urinary Bladder Shape Affect Urinary Flow Rate in Men with Lower Urinary Tract Symptoms?” we should add an author who has contributed to our study for the images: Murat Cinar, Department of Biomedical Engineering, Faculty of Engineering and Architecture, Izmir Katip Celebi University, 35620 Izmir, Turkey. In addition we should here correct the affiliation of one of the authors named Omer Karal and the postal code in the affiliation of the author Mahmut Pekedis.

Effect of hyperbaric oxygen treatment on tendon healing after Achilles tendon repair: an experimental study on rats.

OBJECTIVE The aim of this study was to investigate the effects of hyperbaric oxygen treatment on early tendon healing in the treatment of Achilles tendon ruptures. METHODS Fifty-six male Wistar albino rats were randomized and divided into two groups. Intratendinous betamethasone was administered preoperatively for degeneration in 28 rats and isotonic saline injection was administered to the remaining 28 rats. The Achilles tendons of all rats were sutured following tenotomy. Fourteen rats from each group were then selected and received hyperbaric oxygen therapy. The Achilles tendons were removed, biomechanically evaluated and histopathologically studied on the 11th postoperative day. The biomechanical properties and amount of fibrosis, inflammation and vascularization were compared between the groups receiving hyperbaric oxygen therapy and those not. RESULTS Histopathological study showed the amount of fibrosis was significantly higher in the hyperbaric oxygen therapy group than in the control group without the hyperbaric oxygen therapy. The amount of inflammation and vascularization were significantly higher in the steroid administration group than in the no-steroid group. There was a significant difference in the biomechanical properties of the groups in terms of maximum force, stiffness, elastic modulus and maximum allowable stress. CONCLUSION Hyperbaric oxygen therapy creates a positive histological and biomechanical effect on tendon healing after Achilles tendon repair.

Effect of taurine on rat Achilles tendon healing

Abstract Taurine has anti-inflammatory and antioxidant characteristics. We have introduced taurine into a tendon-healing model to evaluate its effects on tendon healing and adhesion formation. Two groups of 16 rats underwent diversion and repair of the Achilles tendon. One group received a taurine injection (200 mg/ml) at the repair site, while the other group received 1 ml of saline. Specimens were harvested at 6 weeks and underwent biomechanical and histological evaluation. No tendon ruptured. Average maximum load was significantly greater in the taurine-applied group compared with the control group (p < 0.05). Similarly, average energy uptake was significantly higher in the taurine-applied group compared with the control group (p < 0.05). We observed no significant differences in stiffness in both groups (p > 0.05). After histological assessment, we found that fibroblast proliferation, edema, and inflammation statistically decreased in the treatment group (p < 0.05). These findings could indicate greater tendon strength with less adhesion formation, and taurine may have an effect on adhesion formation.

The effect of head trauma on fracture healing: biomechanical testing and finite element analysis

OBJECTIVES We aimed to evaluate the effect of head trauma on fracture healing with biomechanical testing, to compare the results obtained from a femur model created by finite element analysis with experimental data, and to develop a finite element model that can be employed in femoral fractures. METHODS Twenty-two Wistar albino rats were randomized into two groups. The control group was subjected to femoral fracture followed by intramedullary fixation, whereas the head trauma group was subjected to femoral fracture followed by intramedullary fixation along with closed blunt head trauma. Bone sections obtained with computed tomography from rat femurs were transferred into a computer and a 3D mathematical model of femur was created. At the end of week 4, femurs were examined by biomechanical testing and finite element analysis. RESULTS The mean maximum fracture load was significantly higher in the head trauma group than in control group (p<0.05). Maximum strain values were also significantly high in the head trauma group (p<0.05). There was no significant difference between the groups with regard to maximum deformation (p>0.05). The head trauma group had significantly higher mean bending rigidity than the control group (p<0.05). The head trauma group showed no significant difference from the control group in terms of strain energy and elasticity module (p>0.05). There was no significant difference between experimental biomechanical test and finite element analysis (p>0.05). CONCLUSION Noninvasive methods such as finite element analysis are useful in examination of the mechanical structure of bones. Experimental biomechanical test and finite element analysis methods suggest that head trauma contributes to fracture healing.

Structural health monitoring for bolt loosening via a non-invasive vibro-haptics human–machine cooperative interface

For the last two decades, developments in damage detection algorithms have greatly increased the potential for autonomous decisions about structural health. However, we are still struggling to build autonomous tools that can match the ability of a human to detect and localize the quantity of damage in structures. Therefore, there is a growing interest in merging the computational and cognitive concepts to improve the solution of structural health monitoring (SHM). The main object of this research is to apply the human–machine cooperative approach on a tower structure to detect damage. The cooperation approach includes haptic tools to create an appropriate collaboration between SHM sensor networks, statistical compression techniques and humans. Damage simulation in the structure is conducted by releasing some of the bolt loads. Accelerometers are bonded to various locations of the tower members to acquire the dynamic response of the structure. The obtained accelerometer results are encoded in three different ways to represent them as a haptic stimulus for the human subjects. Then, the participants are subjected to each of these stimuli to detect the bolt loosened damage in the tower. Results obtained from the human–machine cooperation demonstrate that the human subjects were able to recognize the damage with an accuracy of 88 ± 20.21% and response time of 5.87 ± 2.33 s. As a result, it is concluded that the currently developed human–machine cooperation SHM may provide a useful framework to interact with abstract entities such as data from a sensor network.

Biomechanical evaluation of sagittal maxillary internal distraction osteogenesis in unilateral cleft lip and palate patient and noncleft patients: A three-dimensional finite element analysis

OBJECTIVE To compare the pattern and amount of stress and displacement during maxillary sagittal distraction osteogenesis (DO) between a patient with unilateral cleft lip and palate (UCLP) and a noncleft patient. MATERIALS AND METHODS Three-dimensional finite element models for both skulls were constructed. Displacements of the surface landmarks and stress distributions in the circummaxillary sutures were analyzed after an anterior displacement of 6 mm was loaded to the elements where the inferior plates of the distractor were assumed to be fixed and were below the Le Fort I osteotomy line. RESULTS In sagittal plane, more forward movement was found on the noncleft side in the UCLP model (-6.401 mm on cleft side and -6.651 mm on noncleft side for the central incisor region). However, similar amounts of forward movement were seen in the control model. In the vertical plane, a clockwise rotation occurred in the UCLP model, whereas a counterclockwise rotation was seen in the control model. The mathematical UCLP model also showed higher stress values on the sutura nasomaxillaris, frontonasalis, and zygomatiomaxillaris on the cleft side than on the normal side. CONCLUSIONS Not only did the sagittal distraction forces produce advancement forces at the intermaxillary sutures, but more stress was also present on the sutura nasomaxillaris, sutura frontonasalis, and sutura zygomaticomaxillaris on the cleft side than on the noncleft side.

NUMERICAL ANALYSIS OF A PROJECTILE PENETRATION INTO THE HUMAN HEAD VIA MESHLESS METHOD

In recent years, physicists, engineers and medical scientists have tried to demonstrate the biomechanics of gunshot wounds with numerical methods and experimental observations. Currently, the finite element method (FEM) is the most widely used numerical method among the studies related to ballistic wound injuries. However, when the FEM is used for the penetration analysis, the path of the projectile in the skull is subjected to extremely large deformations which will introduce errors due to distortion of elements. To overcome this error, the meshfree technique was established to simulate the gunshot wound as a preliminary study in which the skull was modeled by smoothed particle hydrodynamics (SPH) and the projectile was modeled by nondeformable rigid elements. In order to simulate a realistic penetration phenomenon, orthotropic material properties were defined for different regions (forehead, zygomatic and mandible) with material principal axis along the surface of the bones. Human response to the ballistics impacts were determined in terms of force occurring along the pathway of the bullet in the skull, residual velocity of the projectile and penetration depth. The obtained results were compared with the data reported in literature. As a result, mechanical behavior of the head under ballistic impacts simulated by the SPH, compared well with the results determined by the data given in literature, which indicates the applicability of the SPH method as a powerful technique in simulating different gunshot wound mechanisms.

Development of a novel human-machine interface exploiting sensor substitution for structural health monitoring

For the last 20 years the goal of the structural health monitoring community has been to endow man-made structures with a biologically-inspired nervous system in order to detect, localize, and quantify damage in structures. The effort has focused on collecting a wide array of measurements from sensor networks, extracting features from the data, comparing the data to models, and trying to use this information to determine the presence, extent and type of damage. Typically the Structural Health Monitoring community tries to make predictions of the remaining service life of the structure. It is generally assumed that there will be as little human intervention in this process as possible unless a high-consequence decision must be made. A number of advances have been made in structural health monitoring using this approach over the course of the last decade, but we are still struggling to build autonomous machines that can match the ability of a human to detect, localize and quantify damage in structures. This work aims to explore a new paradigm - cooperative human-machine structural health monitoring. The premise of this paradigm is the idea that a human cooperating with a machine will always significantly outperform a machine or human acting independently. There is no reason to not make full use of human resources that are available to us today. Furthermore, the regulatory and litigious environments that exist today for safety-critical structures are going to make it difficult to adopt health monitoring systems that effectively eliminate humans. Why not instead enhance the natural sensing and perception of human inspectors? During the course of this research effort a vibro-tactile haptic interface is under development that will in some sense allow a human to “feel” the pain of a structure when it is damaged. A number of different studies from the neuroscience community [1], [2], have indicated that it is possible to use “sensory substitution” to provide some restoration for lost senses such as sight. In this work we consider the possibility of extending the introception of a human to an external structure. This type of capability will help enable a wide variety of cyber-physical systems that must maintain reliability as well as interact with humans. For instance it may be possible to outfit a single human inspector with a haptic interface so they can single-handedly monitor a whole wind farm as if it were a natural extension of their own body. Alternatively, a single person with a haptic interface may be able to sense the state-of-health of a large ocean linear or an entire swarm of flying robots. These ideas will lead to creating a new class of high-performance, cyber-physical systems.

Does Urinary Bladder Shape Affect Urinary Flow Rate in Men with Lower Urinary Tract Symptoms

We aimed to investigate the role of urinary bladder shape which may potentially change with advancing age, increased waist circumference, pelvic ischemia, and loosening of the urachus on bladder emptying and UFR. We retrospectively investigated the medical records of 76 men. The patients were divided into two groups according to bladder shapes in MRI scan (cone and spheric shapes). There was a significant difference between the two groups in terms of IPSS, Qmax, Qave, and waist circumference. A positive correlation has been demonstrated between mean peak urinary flow rate measured with UFM and mean flow rate calculated using the CP. There was a significant difference between mean urinary flow rates calculated with CP of cone and sphere bladder shapes. The change in the bladder shape might be a possible factor for LUTS in men and LUTS may be improved if modifiable factors including increased waist circumference and loosening of the urachus are corrected.

Greater trochanteric fixation using a cable system for partial hip arthroplasty: a clinical and finite element analysis.

The aim of the study was to investigate the efficacy of greater trochanteric fixation using a multifilament cable to ensure abductor lever arm continuity in patients with a proximal femoral fracture undergoing partial hip arthroplasty. Mean age of the patients (12 men, 20 women) was 84.12 years. Mean follow-up was 13.06 months. Fixation of the dislocated greater trochanter with or without a cable following load application was assessed by finite element analysis (FEA). Radiological evaluation was based on the distance between the fracture and the union site. Harris hip score was used to evaluate final results: outcomes were excellent in 7 patients (21.8%), good in 17 patients (53.1%), average in 5 patients (15.6%), and poor in 1 patient (9.3%). Mean abduction angle was 20.21°. Union was achieved in 14 patients (43.7%), fibrous union in 12 (37.5%), and no union in 6 (18.7%). FEA showed that the maximum total displacement of the greater trochanter decreased when the fractured bone was fixed with a cable. As the force applied to the cable increased, the displacement of the fractured trochanter decreased. This technique ensures continuity of the abductor lever arm in patients with a proximal femoral fracture who are undergoing partial hip arthroplasty surgery.