Hasan Havitcioglu

Evaluation of bone plate with low-stiffness material in terms of stress distribution

The aim of this study is to evaluate a newly developed bone plate with low-stiffness material in terms of stress distribution. In this numerical study, 3D finite element models of the bone plate with low-stiffness material and traditional bone plates made of stainless steel and Ti alloy have been developed by using the ANSYS software. Stress analyses have been carried out for all three models under the same loading and boundary conditions. Compressive stresses occurring in the intact portion of the bone (tibia) and at the fractured interface at different stages of bone healing have been investigated for all three types of bone-plate systems. The results obtained have been compared and presented in graphs. It has been seen that the bone plate with low-stiffness material offers less stress-shielding to the bone, providing a higher compressive stress at the fractured interface to induce accelerated healing in comparison with Ti alloy and stainless-steel bone plate. In addition, the effects of low-stiffness materials with different Youngs modulus on stress distribution at the fractured interface have been investigated in the newly developed bone-plate system. The results showed that when a certain value of Youngs modulus of low-stiffness material is exceeded, increase in stiffness of the bone plate does not occur to a large extent and stress distributions and micro-motions at the fractured interface do not change considerably.

Primary intramuscular hydatidosis of supraspinatus muscle.

Abstract Hydatid disease of the muscle is very rare and represents approximately 3% of all patients with hydatidosis. Since the infection closely resembles a soft-tissue tumor on clinical examination, the preoperative radiologic diagnosis is very important to avoid biopsy. We report an unusual case of primary intramuscular hydatidosis with its magnetic resonance imaging appearance, clinical and pathological findings.

A new method to measure vertebral rotation from CT scans

Abstract CT measurement methods have good reliability for idiopathic scoliosis transverse plane deformity evaluation. However, because of application difficulties and variations in how these methods are applied, more sensitive methods are needed. This paper presents a new method for measurement of vertebral rotation from tomographic scans. First, the method was subject to clinical, intra-observer and inter-observer analysis. Twenty-three patients with adolescent idiopathic scoliosis were studied to test the clinical reliability of this method. There were no statistical differences between the results of the new method and Ho’s method (P = 0.3380) in the clinical study. Intra-observer and inter-observer analysis showed that this method was reliable. An experimental study was then conducted to show the confidence limits of our new method, which were found to be ± 1.6°, and there was no significant difference between the mean rotation value obtained from CT scans using our new method and that obtained using the mechanical method. These results suggest that our new method is a simple, practical and reliable method for measurement of vertebral rotation from CT scans.

Biomechanical properties of human hair with different parameters

Background/purpose: Investigations on the mechanical properties of human hair are inadequate. This research explores the break force of anagen hair by forming criteria according to the diameter of hair, gender, age, strain, use of drugs and hair dyes and how these criteria affect the mechanical resistance of hair.

The stiffness characteristics of hybrid Ilizarov fixators

The use of hybrid Ilizarov models around femoral area is gaining clinical popularity lately. Hybrid systems show different mechanical properties. The purpose of this report is to examine the stiffness characteristics of the C-arch and half-pins on the hybrid Ilizarov fixators. Eight models that included standard Ilizarov and hybrid models were applied to six femoral sawbones. The distal part of fixation was composed of a two-ring frame applied identically to all bones. The difference of the configuration was at the proximal part, where half-pins with or without C-arches were either added to the proximal two-ring frame or replaced the proximal one- or two-ring frame. Osteotomy was performed in the femoral diaphysis and the bone was distracted 2cm. The stability of the system was tested with the axial compression testing machine. Displacements between the adjacent fracture sides were measured with the video extensometer in three dimensions. We found that proximal half-pin applications alone had less stiffness, but half-pins with C-arch had more stiffness than the model including only half-pins. Additional half-pins onto one- or two-ring frames had more longitudinal stiffness, but this system showed weak resistance against transverse displacement.

Dermal argyria: Cutaneous manifestation of a megaprosthesis for distal femoral osteosarcoma

We present a patient with dermal argyria as a cutaneous manifestation of a silver-coated megaprosthesis used for a distal femoral osteosarcoma. Histological and electron microscopic analyses also showed silver deposition in the dermis.

Effect of Rotation on Frontal Plane Deformity in Idiopathic Scoliosis

To analyze the effect of rotation on frontal plane deformity in idiopathic scoliosis, 44 patients with idiopathic scoliosis aged 11 to 18 years were examined using standing anteroposterior and true AP radiographs. Axial rotation was measured by computed tomography. Patients were divided into two groups according to Cobb angle: patients with angles <30 degrees comprised group 1 and patients with angles >30 degrees comprised group 2. Cobb angle increased with true-AP projection a mean of 21.2% in group 1 and 16.7% in group 2. Rotation degree was significantly correlated with increasing degree of frontal plane deformity (P<.01) in group 1 but not in group 2 (P>.05). These results demonstrate the influence of rotation over frontal plane deformity and is more apparent at curves >30 degrees.

Biocompatibility and biomechanical characteristics of loofah based scaffolds combined with hydroxyapatite, cellulose, poly-l-lactic acid with chondrocyte-like cells

The current study reports the biocompatibility and biomechanical characteristics of loofah-based scaffolds combined with hydroxyapatite (HA), cellulose, poly-l-lactic acid (PLLA) with chondrocytes-like cells. Scanning electron microscope (SEM) micrographs of the scaffolds showed that the addition of PLLA usually resulted in an increase in cells attachment on scaffolds. Mechanical and elemental analyzes were assessed using tensile test and Energy Dispersive X-ray spectrometry (EDS), respectively. In summary, we showed that the loofah+PLLA+HA scaffolds perform significantly better than other loofah-based scaffolds employed in terms of increasing a diversity of mechanical properties including tensile strength and Youngs modulus. Based on the analysis of the differential scanning calorimetry (DSC) thermograms and EDS spectrums that give an idea about the calcium phosphate (CaP) ratios, the improvement in the mechanical properties could principally be recognized to the strong interaction formed between loofah, PLLA and HA. The viability of chondrocytes on loofah-based scaffolds was analyzed by XTT tests. However, none of the scaffolds have proved to be toxic in metabolic activity. The histological evaluation obtained by hematoxylin and eosin (H&E), Masson trichrome, toluidine blue and immunohistochemistry methods showed that cells in all scaffolds produced extracellular matrix that defined proteoglycan and type I-II collagens. The results of this study suggest that the loofah-based scaffold with desirable properties can be considered as an ideal candidate for cartilage tissue engineering applications.

Calcium pyrophosphate dihydrate crystal deposition disease mimicking malignant soft tissue tumor

Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease has multiple clinical features with variable courses creating several pitfalls in clinical diagnosis. There are number of reported cases mimicking malignant skeletal tumors such as chondrosarcoma. However, no case of CPPD disease with radiographic noncalcified soft tissue mass has been reported in the literature. Here we report a case of CPPD disease clinically mimicking soft tissue tumor with its magnetic resonance imaging appearance and histopathology.

Bilateral congenital subluxation of the proximal tibiofibular joint with magnetic resonance imaging findings: a case report.

Abstract. There appear to be no criteria in the differential diagnosis of traumatic and congenital subluxation of the proximal tibiofibular joint in the literature. We report a case with bilateral congenital subluxation of the proximal tibiofibular joint and describe the magnetic resonance imaging features for the differential diagnosis.