Biomedical subjects

F Korkusuz

Publications and source records attributed to F Korkusuz.

27 records · Page 2Linked to original sources

PubMed1997

Biomechanical analysis of the effects of single high-dose vitamin D3 on fracture healing in a healthy rabbit model.

In a previous ultrastructural study, the benefit of a single high dose of vitamin D3 on fracture healing in a healthy animal model was demonstrated. This study examined the biomechanical consequences of applying a single high dose of vitamin D3 in a healthy rabbit model subsequent to femoral fracture. The fracture load, the values of energy absorbed until fracture and the flexural rigidity values of the vitamin D group were significantly higher than the corresponding ones of the control group in the case of fracture. On the other hand, for intact bones, those values did not differ significantly between the two groups. It was concluded that single high-dose vitamin D3 application had positive effects on fracture healing in a healthy animal model, as far as the parameters related to mechanical strength are concerned.

Animals↗

PubMed1997

Prevention of postoperative late kyphosis in Pott's disease by anterior decompression and intervertebral grafting.

A total of 185 patients with Pott's disease were operated on between 1973 and 1992. Anterior decompression by preserving the pleura (extrapleural approach) was the preferred method in the thoracic spine. In the lumbar spine the approach was retroperitoneal, and interbody fusion was performed in both for the thoracic and the lumbar regions. Anterior decompression and intervertebral grafting comprised the treatment. In five patients, internal fixation accompanied anterior decompression and intervertebral grafting. The aim of instrumentation was to enhance anterior spinal stability, and Alici spinal instrumentation was the preferred device. Graft destruction and a late increase in kyphosis was prevented by this means. The mean follow-up period was 7.5 years. Thirty-two of the cases were admitted to the clinic because of Pott's paraplegia: 19 of the cases recovered completely following anterior decompression; partial recovery was observed in 5 cases; but 3 cases did not recover. Various complications, including seven deaths, were observed in 42 of the cases.

Adolescent↗

PubMed1997

An investigation of the chemical synthesis and high-temperature sintering behaviour of calcium hydroxyapatite (HA) and tricalcium phosphate (TCP) bioceramics.

The experimental conditions for the synthesis of sub-micrometre, spherical particles of calcium hydroxyapatite [Ca10(PO4)6(OH)2] (HA) and tricalcium phosphate [Ca3(PO4)2] (TCP) are investigated through chemical coprecipitation from the aqueous solutions of calcium nitrate and di-ammonium hydrogen phosphate salts. The precipitation process employed was also found to be suitable for the production of sub-micrometre HA/TCP composite powders in situ. The synthesized pure HA and TCP powders were found to be stable even at 1300 degrees C in air for prolonged heating times. Bioceramic sample characterization was achieved by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and density and surface area measurements. Crystallographic analyses of HA powders were performed by the Rietveld method on the powder XRD data.

Journal Article↗

PubMed1997

Biomechanics of the Gazi type pelvis external skeletal fixator.

External skeletal fixation is an alternative method of treatment to conventional therapy and open surgical procedures in pelvis fractures. The appropriate type of frame and the configuration of the connecting bars of these fixators are under investigation. In the Gazi type pelvis external fixator (GPEF) which has been developed, a 70 degree angulation is applied to the connecting bars of the anterior quadrangular frame. This configuration, which is expected to improve the stability of the posterior column of the pelvis, was evaluated biomechanically on a phantom with various types of pelvic fractures and separations. The results suggest that the GPEF effectively controls anterior column pelvis fractures such as unilateral pubic ramus fractures, unilateral ischium pubis rami fractures and symphysis pubis separations under vertical loads. The fixator is partially capable of stabilizing the posterior column; however, loads above 700 N cause separation at the fracture site. Further studies and clinical trials are essential to determine the GPEF's effectiveness in reducing blood loss and in providing stability at the posterior column.

Adult↗

PubMed1995

Do porous calcium hydroxyapatite ceramics cause porosis in bone? A bone densitometry and biomechanical study on cortical bones of rabbits.

Porous calcium hydroxyapatite (CHA) ceramics are biocompatible and present osteoconductive properties. These ceramics are widely used in orthopaedic surgery; however, it is not yet known whether they have some adverse effects on bone and bone marrow healing. Our previous radiological study revealed possible local porosis at the adjacent sites of the CHA ceramic. Histological findings of the same study revealed bone marrow swelling and depletion at the implantation site. Osteoclasts removed particles of the implant that may be the cause of local porosis. In the present study, possible local osteoporosis was evaluated by bone densitometry analyses, and compression and three-point bending tests. CHA particles were implanted into the left limbs and a sham operation was utilized on the right limbs of 75 white rabbits. The animals were followed up for 23 weeks for bone mineral density and for 6 months for biomechanical analyses. The CHA implanted area and its distal or proximal adjacent areas were evaluated with a Hologic QDR-2000 bone densitometer. Three-point bending and compression tests were performed with an M-30 K material testing device. The results revealed a time-dependent bone density increase at the CHA implantation site and no significant porosis at adjacent areas of the implant. The stiffness of CHA-implanted bones in three-point bending is larger than that of the control group. CHA-implanted rabbit bones presented a different fracture pattern from the control group. The stiffness of the control and CHA-implanted bones generally increased with time indicating no adverse effects of porous CHA ceramics in bone and bone marrow healing. The clinical relevance of this work is that porous CHA ceramics do not cause local porosis at adjacent areas when implanted into osseous sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Experimental implant-related osteomyelitis treated by antibiotic-calcium hydroxyapatite ceramic composites.

The efficacy of locally implanted antibiotic-calcium hydroxyapatite ceramic composites was investigated for the treatment of experimentally produced, implant-related osteomyelitis in rats. High concentrations of antibiotics were detected at the site of infection and bacteria were eradicated without removal of the metal implants. Parenteral antibiotics and surgical debridement, alone or in combination with antibiotic-impregnated acrylic bone cement, all failed to eradicate the infections.

Animals↗

PubMed1992

Calcium hydroxyapatite ceramic used as a delivery system for antibiotics.

Porous blocks of calcium hydroxyapatite ceramic were evaluated as delivery systems for the sustained release of antibiotics. We tested gentamicin sulphate, cefoperazone sodium, and flomoxef sodium in powder form placed in a cylindrical cavity in calcium hydroxyapatite blocks, using in vitro studies of elution and in vivo studies in rats. Gentamicin sulphate gave a maximum concentration within the first week, which gradually decreased but was still effective at 12 weeks, when 70% of the antibiotic had been released. Even at this stage the antibiotic concentration from a 75 mg dose was five times the minimum inhibitory concentration for staphylococci. In the in vivo studies the release of gentamicin sulphate into the normal bone of rats was at similar rates and levels. The bacteriocidal activity of the drugs was not affected by packing into calcium hydroxyapatite ceramic and the blocks were completely biocompatible on histology. This new system overcomes the disadvantages of other drug delivery systems, avoiding thermal damage to the antibiotics and a second operation for the removal of the carrier. Some mechanical strength is provided by the ceramic and healing may be accelerated by bone ingrowth into its micropores.

Animals↗

PubMed1990

Lateral rhachotomy for thoracic spinal lesions.

Capener's "Lateral Rhachotomy" was modified by additional excision of the pedicle, articular facets, part of the lamina, and a posterior half of the vertebral bodies on one side through a transpleural approach to the thoracic spine, and a retroperitoneal approach to the lumbar spine. The aim was to excise a space-occupying lesion, which exists in front of the thoracic or lumbar spinal cord, safely. This modification enable the authors to expose more than 50% of the spinal canal, and decompress it from its anterior, lateral, and posterior compressing mass. The utmost important point of this procedure is the excision of the lesion under the direct visualization of the dura. In ossification of the posterior longitudinal ligament (OPLL), the dura is usually indented by the thick bony mass, and the lesion extends over a few segment with adhesion. Using "Modified Lateral Rhachotomy," it was possible to explore three or four vertebral levels in continuity through the same skin incision. In the present report, the authors described their "Modified Lateral Rhachotomy" procedure, and reviewed the case material.

Female↗

PubMedDate not supplied

In vitro antibiotic release from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) rods.

Provision and maintenance of adequate concentrations of antibiotics at infection sites is very important in treating highly resistant infections. For diseases like implant related osteomyelitis (IRO) it is best to provide this locally via implanted drug formulations, as systemic administration of the antibiotic may not be effective due to damaged vasculature. In this study, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) rods containing 7, 14 and 22% (mol) 3-hydroxyvalerate were loaded with sulbactam:cefoperazone or gentamicin, and their antibiotic release behaviours were studied under in vitro conditions in physiological phosphate buffer at room temperature. The release patterns were representative of release from monolithic devices where a rapid early release phase is followed by a slower and prolonged release. With PHBV 22 rods, the latter phase continued for approximately 2 months. This duration is critical because a proper antibiotic therapy of IRO requires the minimal effective concentration for at least 6 weeks. After in vitro release, voids with sharp edges were detected on the rods, indicating that the drug crystals dissolved but the polymer did not undergo erosion within this test period. Changing the polymer:drug ratio from 2:1 to 20:1 substantially decreased the drug release rate. A change of polymer type, however, did not lead to any detectable changes in the release patterns. Gentamicin release also followed a similar pattern, except that the concentration of the drug in the release medium exhibited a decrease after long release periods, indicating degradation (or decomposition) of the antibiotic in the release medium.

Absorbable Implants↗