Precontoured buttress plate vs reconstruction plate for acetabulum posterior wall fractures: A biomechanical study

Background: The purpose of open reduction and internal fixation of acetabulum posterior wall fractures is to restore anatomical structure and stability of the hip joint, in order to start weight bearing as soon as possible and prevent hip arthrosis; restoration of the anatomy should preserve function of the joint as well. Although "special shaped precontoured plates" have been developed in recent years for surgical treatment of this region, studies comparing the traditional plates with the newly designed precontoured plates are lacking. AIM To evaluate the biomechanical properties of precontoured anatomic buttress and conventional curved reconstruction plates (CCRPs) for posterior wall acetabulum fracture treatment. METHODS Twelve pelvis models were created for testing plate treatment of fracture in the posterior wall of the acetabulum. These 12 pelvis models were used to create 24 hemipelvis models (experimental) by cutting from the sagittal plane and passing over the center of gravity, after which the posterior wall acetabular fractures (of similar type and size) were created. In these experimental models, the right acetabulum was fixed with a 5-hole CCRP, while the left was fixed with a precontoured anatomic buttress plate (PABP). Samples were placed through the test device and were subjected to static load testing, with a constant testing velocity of 2 mm/min until the load reached 2.3 kN or the acetabular fixation failed. Dynamic tests were also performed with sinusoidal wave load, with a maximal load of 2.3 kN and a load ratio of 0.1. RESULTS The average stiffness values were 460.83 +/- 95.47 N/mm for the PABP and 291.99 +/- 118.58 N/mm for the 5-hole CCRP. The precontoured anatomic acetabulum buttress plates had significantly higher rigidity than the CCRPs (P = 0.022). There was a statistically significant difference between the unloaded and 2.3 kN-loaded values of AL (posterosuperior fracture line vertical to the ground surface) and CL (posteroinferior fracture line vertical to the ground surface) parameters for both the PABPs and the 5-hole CCRPs (P = 0.036 and P = 0.045, respectively). According to the static tests, the amount of total displacement was significantly less in the PABPs than in the CCRPs. Comparative analysis of the displacement in the BL (posterior wall fracture line horizontal to the ground) parameter yielded no statistically significant differences between the PABP and the 5-hole CCRPs (P = 0.261). CONCLUSION PABP provides more stable fixation in acetabulum posterior wall fractures than 5-hole CCRP, allowing for proximal or distal fracture line screw application without reshaping

Endemik Bir Balık Türü Olan Aphanıus Vıllwockı' nin Özdere (Sakarya Nehri Havzası ) Populasyonunun Büyüme ve Üreme Özellikleri

Aphanius, which belongs to Cyprinodontidae family, has been accepted as one of the oldest secondary fresh water fish in Anatolia that is represented by 9 different species in Turkey. In the presented study, growth and reproduction properties of Aphanius villwocki population in the Özdere (Polatlı-Ankara) were analyzed. This presented study is the first study on biology of Aphanius villwocki, a species of Aphanius which is endemic in Upper Sakarya River Basin. Under these circumstances, field studies were conducted in monthly basis between June 2012 – July 2013 and in total, 1793 individuals were collected and their sex were determined, 718 of this sample were dissected and their gonads were removed and weighted. The distribution of length, weight, age and sex, length-weight, age- length, age-weight relationships, condition factor of the population and the von Bertalanffy growth parameters of the specimens were examined.Anadolu nun bilinen en eski ikincil tatlısu balıklarından biri olarak kabul edilen, Cyprinodontidae familyasına ait Aphanius cinsi, Türkiye de 9 tür ile temsil edilmektedir. Sunulan çalışmada, bugüne kadar biyolojisi hakkında hiçbir bilgi bulunmayan, Yukarı Sakarya Havzası na endemik bir balık türü olan Aphanius villwocki nin Özdere (Polatlı-Ankara) populasyonunun üreme ve büyüme özellikleri incelenmiştir. Bu kapsamda Haziran 2012-Temmuz 2013 tarihleri arasında aylık periyotlarla arazi çalışmaları yapılmış ve toplam 1793 bireyin eşeyleri saptanmış, bu örneklerin de 718 tanesinin boy ve ağırlık değerleri ölçülerek disekte edilmiş ve gonadları alınmıştır. İncelenen örneklerin boy, ağırlık, yaş ve eşey dağılımları, boy-ağırlık, yaş-ağırlık ve yaş-boy ilişkileri ile kondüsyon faktörü ve Von Bertalanffy büyüme parametreleri ortaya konmuştur.Populasyonda dişi bireylerin 0 ile 5 yaş grubu, erkeklerin ise 0 ile 4 yaş grubu arasında dağılım gösterdiği belirlenmiştir

Smart implant rods for scoliosis treatment

Skolyoz, omurganın frontal düzlemde lateral sapma göstermesiyle oluşan spinal bir deformitedir. Hastalığın gelişimi ve tedavisi yaş aralıklarına göre farklılıklar göstermektedir. Büyüme süreci devam eden hastalarda görülen skolyoz, omurgadaki gelişim nedeniyle zamana bağlı olarak yetişkinlerde görülene kıyasla daha büyük değişiklikler gösterir. Omurgadaki büyüme nedeniyle, sabitlenmiş segmentlerin belirli zaman aralıklarında cerrahi müdahale ile uzatılması gerekmektedir. Pediatrik skolyoz için uzatma işlemini kolaylaştırıcı posterior stabilizasyon sistemleri geliştirilmiş olsa da tedavi süreci, uzama işlemleri için doğru zaman tespit edilemediğinden dolayı olumsuz yönde etkilenmektedir. Tez kapsamında üretilen akıllı implant çubuklar ile tedavi sürecinde sabitlenen iki omurga segmenti arasındaki gerilme ve yükleme takip edilebilecektir. İlk olarak istenilen hassasiyette sensörler üretilmiş ve çubuklara entegre edilmiştir. Akıllı implant çubuklar, ASTM' nin ilgili standartlarına göre önce tekil olarak mekanik testlere tabi tutulmuş sonrasında sistemin mekanik doğrulaması için vertebrektomi modeller kurulmuş ve basma, çekme, yana eğme ve burma yükleri altında test edilerek frekans değerleri ölçülmüştür. Farklı yumuşak doku kalınlıkları ile frekans ölçümleri yapılmış ve etkisi araştırılmıştır. Ayrıca sensörlerin yorulma performanslarının belirlenmesi için çevrimsel yük uygulanmış ve frekans ölçümleri alınmıştır. Sistem, kadavralarda basma ve çekme yükleri altında teste tabi tulumuştur. Mekanik modellemeden sonra canlı hayvan deneyleri gerçekleştirilmiştir. Canlı hayvan deneylerinde 15 koyuna bilateral transpediküler vida yerleştirilmiş ve iki adet rodla birleştirilerek tespit edilmiştir. Koyunlar ameliyat sonrası 6 ay süreyle gözlem altında tutulmuş ve ayda bir kez çubuklarda yer alan algılayıcılardan frekans ölçümleri alınmıştır. Vertebrektomi modellerde ve kadavrada yapılan testler sonucunda, basma ve yana eğme kuvvetleri altında yükün artması dielektrik katsayısı ve kapasitansı etkileyerek frekasın da artmasına sebep olduğu tespit edilmiştir. Çekme testlerinde kuvvet arttıkça frekansta düşme belirlenmiştir. Yapılan testlerle yumuşak doku kalınlığının ölçümleri etkilediği ortaya konmuştur. Çevrimsel yüklemelerin ardından yapılan ölçümler sonucunda ise sistemin dinamik yüklenme koşullarından etkilenmediği ortaya konmuştur. Canlı hayvan deneylerinde alınan frekans ölçümleri sonucunda, füzyonun gerçekleşmesiyle frekans değerleri arasındaki değişimin giderek azaldığı belirlenmiştir. Sonuç olarak, geliştirilen bu sistem ile füzyonun gerçekleşip gerçekleşmediği ve olası komplikasyonlar sonucu çubukların gerilip gerilmediği durumlar, güvenilir bir şekilde ayırt edilip değerlendirilebilecektir. Böylece pediatrik vakalarda düzenli olarak ve hastanın gelişiminden bağımsız olarak yapılan yenileme (revizyon) ameliyatları gerektiği kadar ve gereken zamanda yapılabilecektir. Ayrıca bu akıllı implant çubukların kullanımı ile vida gevşemesi, ayar vidası (nut) çözülmesi gibi hastanın filminden kolayca anlaşılamayan sorunlar vakitlice fark edilebilecek ve gerekli müdahalenin yapılması mümkün olacaktır. Yapılan deneyler sonucunda, skolyoz cerrahisinde sıkça kullanılan vida-çubuk sistemlerinde tedavi sürecini doğrudan ilgilendiren, posterior sabitleme elemanları (akıllı implant çubuk) üzerinden alınmış ölçüm bilgileri ilk kez literatüre kazandırılmıştır.Scoliosis is a spinal deformity caused by lateral curve on the frontal plane of the spine. Development and the treatment of the deformity varies with respect to the age. Scoliosis in patients with on going growth show rather more alteration compared to the adults. Because of the growth of the spine, the fixed segments need to be prolonged by surgical operation at periodic time intervals. Although posterior stabilization systems have been developed to facilitate lengthening for pediatric scoliosis, the treatment process is adversely affected because the correct time for elongation procedures can not be determined. With the smart implant rods produced within the scope of the thesis, stress and load between the two fixed vertebral segments in the treatment process can be tracked. First, sensors with the desired precision are produced and integrated into the bars. Smart implant rods were first subjected to mechanical tests individually according to the relevant standards of ASTM, and then vertebralctomy models were established for mechanical verification of the system and frequency values were measured by testing compression, tension, lateral bending and torsion tests. Frequency measurements were conducted under varying soft tissue thickness and effects were evaluated. Moreover, in order to determine the fatigue performances of the sensors, cyclic loads were applied and frequency measurements were recorded. System was tested on cadaviers under compression and tension tests. After mechanical modelling, animal model experiements were conducted. During the animal model experiments, transpedicular screws were inserted and attached with two rods on 15 sheeps. Sheeps were observed for a period of 6 months after the operation and frequency measurements were held once in a month from the sensors placed on the rods. In vertebrctomy models and cadaver tests, it was found that the increase in load under compression and lateral bending tests, increased the dielectric constant and capacitance, leading to an increase in frequency. Decrease in frequency was determined as the load was increased in tension tests. It has been shown that soft tissue thickness effects the measurements by the tests conducted. As a result of the measurements made after the cyclic loads, it has been revealed that the system is not affected by dynamic loading conditions. As a result of frequency measurements taken in living animal experiments, it was determined that the change between frequency values gradually decreased with the realization of fusion. Consequently, the developed system can reliably determine, whether the fusion has ben realised and prospective complications were seen caused by the increased stress on the rods. Thereof, revision surgeries, which are performed regularly in pediatric cases and independently of the development of the patient, can be performed as many and when needed. In addition, the use of these smart implant rods will make it possible to spot problems that can not be easily understood from the patient's x-ray, such as screw loosening, adjusting screw (nut) dissolving, and enable necessary intervention. As a result of the experiments, the measurements obtained through posterior fixation elements (smart implant rod), which deals with the treatment process in screw-rod systems commonly used in scoliosis surgeon, is introduced to the literatüre for the first time

Biomechanical comparison of supraacetabular external fixation and anterior pelvic bridge plating

Unstable pelvic ring injuries are complex and risky injuries due to high morbidity and mortality. Although anterior pelvic external fixator is a suitable method for rapid stabilization of an injured pelvic ring, due to some disadvantages such as high complication rate, nerve damage, and difficulties of patient's mobility and comfort, there has recently been increased searching for alternative methods for stabilization of the pelvic ring. Pubic symphysis zone freely moves in pelvic models. This study aims to evaluate the biomechanical stability of anterior pelvic bridge plating and compare it with supraacetabular external fixators in an untreated unstable pelvic fracture model. Samples were loaded statically with 2-mm/min loading rate in single leg standing position. Maximum load was 2.3 kN. When loading the samples, photographs were taken continuously. Stiffness values were calculated from the load displacement curves. Some reference parameters were described and were measured from unloaded and 2.3-kN-loaded photographs of the test. The mean stiffness values were 491.14 +/- 52.22, 478.55 +/- 41.44, and 470.25 +/- 44.51 N/mm for anterior pelvic bridge plating group, supraacetabular external fixator group, and Control group, respectively. According to the measured parameters from photographs, the mean displacement at the pubic symphysis was 4.7 +/- 0.32, 15.8 +/- 2.01, and 18.2 +/- 0.47mm for anterior pelvic bridge plating, supraacetabular external fixator, and Control group, respectively. The highest displacement in the pubic symphysis was found in Control group, and minimum displacement was observed in anterior pelvic bridge plating group. When the perpendicular distance between the right and left lower end of ischium was examined, it was observed that displacement was minimum in anterior pelvic bridge plating group compared to other two groups, regarding to the high stability of pubic symphysis. In conclusion, this study revealed superiority of anterior subcutaneous plate fixation with biomechanical results

Effect of cortical bone thickness and density on pullout strength of mini-implants: An experimental study

Introduction: Anchorage, which is defined as resistance against undesired tooth movements, is one of the most important factors in success of orthodontic treatment. In recent years, mini-implants have been used instead of uncomfortable headgears and Nance appliances. The pullout test is the most common method for measuring the anchorage capacity of mini-implants. The aim of this study was to investigate the effects of cortical bone thickness and cortical layer bone density on pullout strength of mini-implants. Methods: Mini-implants were placed in polyurethane foam blocks representing 3 different cortical thicknesses (1 mm, 2 mm, and 3 mm) and 3 different cortical bone densities (grade 40, grade 45, and grade 50). Pullout tests were performed with 5 mm/min loading rate. Load vs displacement values were recorded during the tests. Results: Comparing cortical thicknesses on the same bone densities, statistically significant differences were found between 1 mm, 2 mm, and 3 mm thicknesses. Likewise, comparing bone densities on the same cortical thicknesses, statistically significant differences were found among all groups. Spearman rank tests showed that both cortical thickness and cortical bone density are correlated with pullout strength (rs, 0.548; P<0.001 and rs, 0.691; P<0.001, respectively). Conclusions: Although both factors are positively correlated with pullout strength, the effect of cortical bone density was the dominant factor affecting primary stability

Femoral neck fracture: A biomechanical comparison of cannulated screws and the recommended implant with holes

Forty-five third-generation human right femur models (Synbone) were used. The results of fixing the new H beam implant and cannulated screws were compared by using biomechanical test with various stabilizes loads. 3 types of fractures were created in the femur models according to the standard Pauwels classification. In 2 different implants after linear fixation of the fracture to assess the hardness and stability of the bone models, the femoral bone models were subjected by mechanical tests based on static and dynamic pressure and torsional tests. As a result of tests, no significant difference was found (respectively, p = 0.046, p = 0.127) in tests of static pressing and torsional between the sizes of the rigidity of the two methods of fixation. Under dynamic load conditions, the sizes of BL and the new implant system, compared with the cannulated screw significantly decreased (p = 0.041), and when comparing the change in the location of the sizes of CL-, significant differences were found (p = 0.018). As a result, if there is no significant difference under static and dynamic load, instability of the new system with respect to the classical system is established. The fact that the early load on the surface surrounding the operating area is not allowed in practice, the reliability of the new implant is shown from a clinical point of view. We consider using the new H beam implant as an alternative of cannula screws of osteosynthesis in the surgical treatment of femoral neck fractures. © 2019 Ministry of Health. All rights reserved

Yumurtacı tavuk embriyolarında genotipin kemik biyomekanik özellikleri ve bileşimine etkileri

Bone problems are highly prevalent in laying hens. These problems affect the welfare, production and economic losses. Bone development begins in the embryonic period, and if the skeletal system develops well at that time, the subsequent production period can be affected positively. The present experiment aimed to investigate the effect of genotype on biomechanical parameters and composition of bone in the laying hen embryos. For this purpose, 360 fertilized eggs were obtained from two brown (Atak-S and Brown Nick) and two white (Atabey and Nick) layer breeders and incubated. Metatarsus, tibia and femur properties were examined on the embryonic d 19 and 21. Results showed that genotype played an important role in determining the biomechanical properties and mineral composition of the metatarsus, tibia and femur in the embryonic period. Examined bone characteristics improved with embryonic age. The least mineralization was observed in the metatarsus bone. In conclusion, bone properties were influenced from the genotype. However these differences were not related with laying hens being white or brown. The effect of the interaction between genotype and embryonic age on the bone properties should be considered.Yumurtacı tavuklarda kemik sorunları oldukça yaygındır. Bu sorunlar refahı, üretimi ve ekonomik kayıpları etkiler. Kemik gelişimi embriyonik dönemde başladığından bu dönemde iskelet sistemi iyi gelişirse, sonraki üretim periyodu olumlu yönde etkilenebilir. Bu çalışmada genotipin yumurtacı tavuk embriyolarında kemiğin biyomekanik özellikleri ve bileşimine etkisini incelemek amaçlanmıştır. Bu amaçla iki kahverengi (Atak-S ve Kahverengi Nick) ve iki beyaz (Atabey ve Nick) yumurtacı damızlıklardan elde edilen 360 adet döllü yumurta toplanmış ve inkübe edilmiştir. Embiyonik dönemin 19 ve 21. günlerinde metatarsus, tibia ve femur özellikleri incelenmiştir. Sonuçlar, embriyonik dönemde genotipin metatarsus, tibia ve femurun biyomekanik özellikleri ve mineral bileşiminde önemli bir rol oynadığını göstermiştir. Embriyonik yaşın artmasıyla incelenen kemik özellikleri iyileşmiştir. En az minerilizasyon metatarsus kemiğinde gözlenmiştir. Sonuç olarak, kemik özellikleri genotipten etkilenmiştir. Fakat bu farklılıklar beyaz veya kahverengi yumurtacı tavuk olmasıyla ilişkili değildir. Genotip ve embriyonik yaş arasındaki etkileşimin kemik özellikleri üzerindeki etkisi dikkate alınmalıdır

Could isthmic approach to far lateral disc hernias cause instability?

Background: The aim of this study is to investigate the relationship between the degree of instability and the amount of isthmus excised during transpars (isthmic) approach which is accomplished with partial resection of the pars interarticularis used in distal lateral disc herniation. Methods: Thirty-six ovine lumbar spine segments were used in the study. 25% and 50% of the right side isthmus of each spinal segment were excised. Flexion, lateral bending and axial rotation tests were performed in both groups. Findings: There was no statistically significant difference found between the groups for yield moment, stiffness and ultimate load in flexion tests (p = 0.262, p = 0.749 and p = 0.200, respectively). Statistically significant difference was found between the groups for yield moment, stiffness and maximum load in lateral bending tests (p = 0.016, p = 0.010 and p = 0.016, respectively). There was no statistical difference found between the groups for yield torque and stiffness in axial rotation tests (p = 0.855 and p = 0.314). Interpretation: These results show that a significant loss of resistance especially during the lateral bending loading was occurred with increasing resection portion of isthmus. With the load applied during the lateral bending of the pars interarticularis, the vertebra resected by 50% percent fractured significantly easier in comparison to the vertebra resected by 25% percent. Pars interarticularis is an important structure with an important role in stability. It is presumed that the more defect is created during the drill-up of the pars interarticularis, the more instability will be occurred

Perforated H-beam implant can be used in femoral neck fracture

This biomechanical study evaluated comparison osteosynthesis of the femoral neck fracture model by 3 cannulated screw implants and new perforated H beam implants under different loading conditions with 45 third generation right proximal femur bones. A standardized Pauwels Type 3 of the femoral neck fracture was performed in the femur models. For assessing the rigidity and strength of fixation methods, the proximal femur bones after their osteosynthesis were then mechanically tested in axial compression, and torsional and dynamic axial compression loading. To determine the structural advantage of the new implant system, perforated and nonperforated new implant systems were comparing about pull out performance. When loading the samples, photographs were taken continuously. The reference parameters were described and measured from unloaded and loaded photographs of the static and dynamic tests. There was no significant difference between stiffness values of two fixation methods under static and rotational loading. Under dynamic loading, the displacement of the superior point of femoral head at the fracture line showed a significant decrease between the new implant system and cannulated screws. Comparing the relative motion at the mid line of the fracture in femoral neck between groups, a significant increase was found in H Beam implant group. Perforated H beam implants have similar static and torsion properties with golden standard. Although there was significant difference under dynamic loading which simulate movement early after surgery, the patient was not allowed to move early after surgery in the clinical practice. Therefore, the differences due to the perforated "H" beam implant would not cause clinical insecurity. Therefore, it is assumed that the perforated "H" beam implant can be used for internal fixation as an alternative to cannulated screws in the treatment of instable femoral neck fracture

The Prevention Effect Of N-Acetylcysteine On Epidural Fibrosis In The Postlaminectomy Rat Model

Aim: The development of epidural fibrosis after laminectomy lead to postoperative morbidities, persistent radicular pain and failed back syndrome. Various materials or drugs have been used to inhibit formation of epidural fibrosis and reduce the compressive effect on neural structures. Nevertheless, the effects are not satisfied. NAC has mucolytic, antioxidant and anti-inflammatory effect. The aim of this study was to evaluate the effect of NAC on spinal epidural fibrosis in the post-laminectomy rat model. Methods: Twenty-four albino rats were divided randomly into three equal groups: control, spongostan and Local NAC. Each animal underwent a laminectomy. Local NAC group (n=8): 100mg/kg was locally applied with a spongostan soaked with 0,5 ml of the solution and was left on the dura mater. At 4 weeks post surgery, the animals euthanized and their tissue samples at the laminectomy site were assessed histological evaluation for dura thickness, epidural fibrosis grading, inflammatory response grading and presence of arachnoidal involvement. All data were evaluated by statistically. Results: Epidural fibrosis were observed significant lower in the NAC group when compared with control group (p= 0.001) . Inflamattory cell density was significant lower in the NAC group when compared with control and spongostan group(p=0.001 and p=0.015, respectively). Arachnoidal involvement was not observed in NAC group. The differences between all groups weren’t statistically significant for dura thickness and fibloblastic density (p=0.162 and p=0.056, respectively, Kruskal Wallis test) Conclusion: The results of our study suggested that NAC has anti-fibrotic effects on epidural fibrosis in the post-laminectomy rat model