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Öğe Biomechanical assessment of patellar tendon advancement in patients with cerebral palsy and crouch gait(Elsevier, 2021) Karabulut, Derya; Arslan, Yunus Ziya; Salami, Firooz; Wolf, Sebastian; Götze, MarcoBackground: Patellar height is a valuable measure to evaluate the effect of patellar tendon advancement (PTA) on knee function. In the literature, there is no validated procedure to measure the patellar height. In this study we aimed to (1) determine the patella position through musculoskeletal modeling, (2) investigate the effects of two surgical procedures applied for PTA, and (3) assess the effect of PTA in combination with single-event multilevel surgery (SEMLS) on the knee kinematics of patients with cerebral palsy (CP) and crouch gait. Method: Three-dimensional gait and X-ray data of children with CP and crouch gait were retrospectively analyzed if they had received a SEMLS in combination with PTA (PTA group, n = 18) or without PTA (NoPTA group, n = 18). A computational musculoskeletal model was used to quantify patella position, knee extension moment arm, and knee kinematics pre and postoperatively. Results: Patellar height significantly decreased in the PTA group (P = 0.004), while there was no difference in the NoPTA group (P > 0.05). The bony procedure for PTA provided a better Insall-Salvati ratio than the soft tissue procedure. The peak knee extension moment arm significantly increased in the PTA group (P = 0.008). In terms of postoperative knee joint kinematics, the PTA group was closer to typically developed children than the NoPTA group. Conclusion: Musculoskeletal modeling was found to be an effective tool for the determination of the patellar height. PTA improved the patella position, knee extension moment arm, and knee kinematics and was an effective procedure for the surgical management of crouch gait in patients with CP. (c) 2021 Elsevier B.V. All rights reserved.Öğe Biomechanical comparison of implantation approaches for the treatment of mandibular total edentulism(Proceedings of the institution of mechanical engineers part h-journal of engineering in medicine, 2020) Arslan, Yunus Ziya; Karabulut, Derya; Kahya, Songül; Cansız, ErolApplying four anterior implants placed vertically or tilted in the mandible is considered to provide clinically reasonable results in the treatment of mandibular posterior edentulism. It is also reported that a combination of four anterior and two short posterior implants can be an alternative approach for the rehabilitation of severe atrophy cases. In this study, we aimed to evaluate the biomechanical responses of three different implant placement configurations, which represent the clinical options for the treatment of mandibular edentulism. Three-dimensional models of the mandible, prosthetic bar, dental implant, abutment, and screw were created. Finite element models of the three implant configurations (Protocol 1: Four anterior implants, Protocol 2: Four anterior and two short posterior implants, Protocol 3: Two anterior and two tilted posterior implants: All-on-4™ concept) were generated for 10 patients and analyzed under different loading conditions including chewing, biting, and impact forces. Protocol 2 led to the lowest stress concentrations over the mandible among the three protocols (p < 0.016). Protocol 2 resulted in significantly lower stresses than Protocol 3 and Protocol 1 over prosthetic bars under chewing forces (p < 0.016). None of the implant placement protocols consistently exhibited the lowest stress distribution over abutments. The lowest stresses over dental implants under the chewing, biting, and impact forces were obtained in Protocol 1, Protocol 2, and Protocol 3, respectively (p < 0.016). Protocol 3 was the best option to obtain the lowest stress values over the screws under all types of loading conditions (p < 0.016). In conclusion, Protocol 2 was biomechanically more ideal than Protocol 1 and Protocol 3 to manage the posterior edentulism.Öğe Design of patient-specific maxillofacial implants and guides(Springer, 2021) Arslan, Yunus Ziya; Üzel, Mehmet; Doğru, Suzan Cansel; Yağız, Abdullah; Cansız, Erol; Kocaelli, HümeyraWith the development of three-dimensional (3D) design and manufacturing technologies, it is possible to easily manufacture various computer-aided patient-specific instruments. In the maxillofacial region, treatment of facial defects, asymmetries, and dental disorders can be done efficiently by using custom-made implants. In addition, reconstruction of the jaws even including temporomandibular joints can be performed by today’s 3D technologies. One of the most popular subjects is the use of computer-aided design and manufacturing techniques in orthognathic surgery. Postoperative outcomes of maxillofacial surgeries can be improved by integrating the patient-specific implants (PSIs) into the treatment protocol. With this novel approach, the contouring that is required to ensure the geometrical compatibility between the patient's anatomical form and the implant is eliminated. Screw positions can be planned during the preoperative simulation so as not to damage any anatomical structure. These preoperative preparations shorten the operating room time. Also, customized osteotomy and drill guides can be used to fixate the implants in the planned position, which minimizes damage possibility over the maxillofacial region and makes surgeries more accurate. The fabrication stages of such implants include (1) obtaining a three-dimensional solid body model of anatomical structures from the patient’s two-dimensional scanning images, (2) simulation of the operation on the anatomical computer model, (3) design of the PSI according to the patient’s model, (4) manufacturing of implants by using proper additive production methods. In this chapter, we described state-of-the-art studies about the development of patient-specific maxillofacial implants and guides, highlighted current insights, and focused on reported clinical outcomes. Besides, we presented the design stages of a PSI and guide for a bimaxillary orthognathic surgery.Öğe Direct validation of model-predicted muscle forces in the cat hindlimb during locomotion(Journal of Biomechanical engineering-transactions of the asme, 2020) Arslan, Yunus Ziya; Karabulut, Derya; Doğru, Suzan Cansel; Herzog, Walter; Pandy, Marcus G.; Lin, Yi-ChungVarious methods are available for simulating the movement patterns of musculoskeletal systems and determining individual muscle forces, but the results obtained from these methods have not been rigorously validated against experiment. The aim of this study was to compare model predictions of muscle force derived for a cat hindlimb during locomotion against direct measurements of muscle force obtained in vivo. The cat hindlimb was represented as a 5-segment, 13-degrees-of-freedom (DOF), articulated linkage actuated by 25 Hill-type muscle-tendon units (MTUs). Individual muscle forces were determined by combining gait data with two widely used computational methods—static optimization and computed muscle control (CMC)—available in opensim, an open-source musculoskeletal modeling and simulation environment. The forces developed by the soleus, medial gastrocnemius (MG), and tibialis anterior muscles during free locomotion were measured using buckle transducers attached to the tendons. Muscle electromyographic activity and MTU length changes were also measured and compared against the corresponding data predicted by the model. Model-predicted muscle forces, activation levels, and MTU length changes were consistent with the corresponding quantities obtained from experiment. The calculated values of muscle force obtained from static optimization agreed more closely with experiment than those derived from CMC.Öğe Effect of a pedicle screw fixation system on lumbar spinal segments: A finite element study(2023) Karabulut, Derya; Doğru, Suzan Cansel; Sürmen, Hasan Kemal; Yaman, Onur; Arslan, Yunus ZiyaSpinal implants have been used to stimulate fusion by surgical adjustment and correct abnormal alignment of the vertebral column. Spinal fusion can cause some spinal disorders and hence describing the changes in biomechanical forces would help to understand these complications. In this study, we used two lumbar models. One of them is used without the fixed pedicle screw system, and the other one was used with that system. Therefore, we aimed to investigate the biomechanical effect of a pedicle screw fixation system on the lumbar functional spinal unit under applied forces. Material and Methods: Computed tomography data of a scoliotic patient was used for the construction of the lumbar models. The second and third vertebrae (L2- L3) of the lumbar spine, two facet joints, an intervertebral disc, and ligaments were constructed. A screw fixation system was employed and Von-Mises stress analysis was carried out for both models. Results: The von Mises stress distribution results showed that the presence of fixed implantation transmitted the compressive forces to the screws and rods in all directions and decreased the stress levels considerably by allowing to stabilize the model. The upper side of the L2 vertebra was the most affected region in flexion and lateral bending. However, the pedicle region had the maximum affected area under applied loads in extension and axial rotation. Conclusion: It was concluded that a fixed implant system preserves the maintenance of the vertebral column and decreases the stress on the adjacent spinal segments, especially for the intervertebral discs.Öğe Effect of model parameters on the biomechanical behavior of the finite Element cervical spine model(Hindawi Publishing Corporation, 2021) Doğru, Suzan Cansel; Arslan, Yunus ZiyaFinite element (FE) models have frequently been used to analyze spine biomechanics. Material parameters assigned to FE spine models are generally uncertain, and their effect on the characterization of the spinal components is not clear. In this study, we aimed to analyze the effect of model parameters on the range of motion, stress, and strain responses of a FE cervical spine model. To do so, we created a computed tomography-based FE model that consisted of C2-C3 vertebrae, intervertebral disc, facet joints, and ligaments. A total of 32 FE analyses were carried out for two different elastic modulus equations and four different bone layer numbers under four different loading conditions. We evaluated the effects of elastic modulus equations and layer number on the biomechanical behavior of the FE spine model by taking the range of angular motion, stress, and strain responses into account. We found that the angular motions of the one- and two-layer models had a greater variation than those in the models with four and eight layers. The angular motions obtained for the four- and eight-layer models were almost the same, indicating that the use of a four-layer model would be sufficient to achieve a stress value converging to a certain level as the number of layers increases. We also observed that the equation proposed by Gupta and Dan (2004) agreed well with the experimental angular motion data. The outcomes of this study are expected to contribute to the determination of the model parameters used in FE spine models.Öğe Esnek Kıyafetli Giyilebilir Alt Gövde Dış İskelet Sistemi(2023) Bebek, Özkan; İnal, Habibe Serap; Arslan, Yunus Ziya; Ünal, Ramazan; Uğurlu, Regaip BarkanDış iskelet robotlar, paraplejik kullanıcılara yürüme kazanımı sağlamakta etkin olarak kullanılabilmektedir. Ancak bu sistemlerde de geliştirilmesi gereken alanlar bulunmaktadır. Bu proje, dış iskelet robotlarının geliştirilmesinde özellikle şunlara odaklanmıştır: (i) İnsan-makina etkileşiminin konforlu ve sürdürülür hale getirilmesi (ii) İnsanın fiziksel durumunun ölçülebilirliğinin arttırılması (iii) Uyarlanabilir hiyerarşik kontrolcüler ile üst seviyede karar alma mekanizmalarının sağlanması. Dış iskelet kontrolünde karşılaşılan en önemli sorunlardan biri insanın fiziksel durumunun gözlemlenememesidir. Bu durum, insan-makina bütünleşik sisteminin kararlılığının belirlenmesinde sorun teşkil etmektedir. Bu projede, rijit bir dış iskelet sistemi ve dış iskelete entegre veri toplayabilen esnek algılayıcılarla donatılmış bir kıyafet geliştirilmiştir. İnsan-robot-çevre etkileşiminin gözlemlenmesi hiyerarşik kontrolcülerin uygulanmasına olanak vermiştir. Proje kapsamında geliştirilen prototip, klinik çalışma kapsamı dışında yapılan testler ile değerlendirilmiştir. Dış iskelet sisteminin üst düzey yörünge öğrenimi için öncelikle sağlıklı bireylerde yürüme verileri toplanmış, gösterimden öğrenme yaklaşımı izlenerek antropomorfik özelliklere göre yörünge üretimi öğrenilmiştir. Dış iskelet sistemine entegre edilen koltuk değneğine uygulanan kuvvetleri minimize eden son teknoloji pekiştirmeli öğrenme algoritmaları uygulanmıştır. Çevresel etkenleri algılama metotları geliştirilmiş ve çevresel etkenler, öğrenme sırasında aksiyona parametre olarak verilmiştir. Geliştirilen dış iskeletin kontrol algoritması öncelikle benzetim ortamında değerlendirilmiş daha sonra bir alt gövde dış iskeletinde gerçek-zamanlı olarak değerlendirilmiştir. Ek olarak dış iskelet sisteminin güvenli bir şekilde hareket etmesini sağlamak için kontrol sed fonksiyonları kullanılmış, simülasyonda oluşturulan engellerin, kontrol sed fonksiyonuyla çalışan robot modeli tarafından güvenli bir şekilde aşıldığı gözlemlenmiştir. Ayrıca pekiştirmeli öğrenme temelli bir kontrolcü daha geliştirilmiş ve iki bacaklı robotlarda simülasyon ortamında denge bozucu momentum testleriyle doğrulanmıştır.Öğe Estimating ground reaction forces from gait kinematics in cerebral palsy : A convolutional neural network approach(Springer, 2024) Arslan, Yunus Ziya; Özateş, Mustafa Erkam; Salami, Firooz; Wolf, Sebastian ImmanuelPurpose While gait analysis is essential for assessing neuromotor disorders like cerebral palsy (CP), capturing accurate ground reaction force (GRF) measurements during natural walking presents challenges, particularly due to variations in gait patterns. Previous studies have explored GRF prediction using machine learning, but specifc focus on patients with CP is lacking. This research aims to address this gap by predicting GRF using joint angles derived from marker data during gait in patients with CP, thereby suggesting a protocol for gait analysis without the need for force plates. Methods The study employed an extensive dataset comprising both typically developed (TD) subjects (n=132) and patients with CP (n=622), captured using motion capture systems and force plates. Kinematic data included lower limb angles in three planes of motion, while GRF data encompassed three axes. A one-dimensional convolutional neural network model was designed to extract features from kinematic time series, followed by densely connected layers for GRF prediction. Evaluation metrics included normalized root mean squared error (nRMSE) and Pearson correlation coefcient (PCC). Results GRFs of patients with CP were predicted with nRMSE values consistently below 20.13% and PCC scores surpassing 0.84. In the TD group, all GRFs were predicted with higher accuracy, showing nRMSE values lower than 12.65% and PCC scores exceeding 0.94. Conclusion The predictions considerably captured the patterns observed in the experimentally obtained GRFs. Despite limitations, including the absence of upper extremity kinematics data and the need for continuous model evolution, the study demonstrates the potential of machine learning in predicting GRFs in patients with CP, albeit with current prediction errors constraining immediate clinical applicability.Öğe Evaluation of mandibular condyle position in Class III patients after bimaxillary orthognathic surgery: A cone-beam computed tomography study(2024) Küçükçakır, Osman; Ersan, Nilüfer; Arslan, Yunus Ziya; Cansız, ErolThis retrospective study evaluated the mandibular condyle position before and after bimaxillary orthognathic surgery performed with the mandibular condyle positioned manually in patients with mandibular prognathism using cone-beam computed tomography. Methods: Overall, 88 mandibular condyles from 44 adult patients (20 female and 24 male) diagnosed with mandibular prognathism due to skeletal Class III malocclusion who underwent bilateral sagittal split ramus osteotomy (BSSRO) and Le Fort I performed using the manual condyle positioning method were included. Conebeam computed tomography images obtained 1–2 weeks before (T0) and approximately 6 months after (T1) surgery were analyzed in three planes using 3D Slicer software. Statistical significance was set at P < 0.05 level. Results: Significant inward rotation of the left mandibular condyle and significant outward rotation of the right mandibular condyle were observed in the axial and coronal planes (P < 0.05). The positions of the right and left condyles in the sagittal plane and the distance between the most medial points of the condyles in the coronal plane did not differ significantly (P > 0.05). Conclusions: While the change in the sagittal plane can be maintained as before surgery with manual positioning during the BSSRO procedure, significant inward and outward rotation was observed in the axial and coronal planes, respectively, even in the absence of concomitant temporomandibular joint disorder before or after the operation. Further long-term studies are needed to correlate these findings with possible clinical consequences.Öğe Evaluation of treatment protocols in surgically assisted rapid maxillary expansion by finite element analysis(2024) Arslan, Yunus Ziya; Cihaner , Duygu; Karabulut, Derya; Dogan Onur, Ozen; Cansiz, ErolBackground and Objectives: Transverse maxillary deficiency is an important maxillary anomaly that is very common in society and remains current in orthodontics. The maxillary expansion has been used in treatment for a long time. While maxillary expansion can be performed with rapid maxillary expansion in young adults, it is performed with surgically assisted rapid maxillary expansion (SARME) in individuals who have reached skeletal maturity. No consensus has been reached on the most successful surgical technique or the ideal appliance for treating transverse maxillary deficiency. Accordingly, we aimed to evaluate various surgical techniques and orthodontic appliances for treating transverse maxillary deficiency using the finite element method (FEM) to identify the treatment protocol that minimizes stress on the maxillary bone and teeth. Materials and Methods: On the virtual models obtained from the cone beam computed tomography of a patient, two different incisions (the pterygomaxillary junction is separated and not separated) were made and combined using three different orthodontic appliances (tooth, bone, and hybrid assisted). Then, stresses over the maxillary bone and maxillary teeth were calculated by FEM. Results: Our results showed that when the pterygomaxillary plates were separated, fewer stresses were observed on the bone and teeth. Although hybrid-supported appliances created less stress on the teeth than tooth-supported appliances and no difference was found between bone-supported appliances, it was found that hybrid-supported appliances created less stress on the bone than the other appliances. Conclusions: The separation of the pterygomaxillary junction in the SARME operation and the use of a bone-supported or hybrid-supported appliance would place less stress on the bone and teeth.Öğe Evaluation of various design concepts in passive ankle-foot orthoses using finite element analysis(Elsevier, 2021) Sürmen, Hasan Kemal; Arslan, Yunus ZiyaAnkle-foot orthoses (AFOs) are typically prescribed to improve the gait function of ambulatory children with neurological conditions such as cerebral palsy or spina bifida. Due to the excessive and repetitive loading conditions, plastic material deformation can be observed in AFOs, especially over the lateral and medial parts of the ankle, which limits the effect of AFOs in the stabilization of the ankle joint. Trimline design and severity influence the rotational stiffness of an AFO considerably. In this study, we proposed novel trimming approaches for AFOs such that the trimlines were performed on the dorsal side rather than lateral and medial sides to reduce the magnitude of peak stresses and provide a homogenous stress distribution over AFOs. We analyzed eight dorsal trimline designs having different basic geometries by using the finite element method. To objectively evaluate the stress levels, the same boundary and loading conditions were considered for all design alternatives. We found that low peak stress values were observed in the AFO models with trimline geometries of the circle, ellipse, and slot variations. The vertical elliptic trimline on the dorsal side of the AFO was the most effective to decrease the magnitude of the peak stresses. The findings of our study are expected to contribute a complementary solution to orthotists in the fabrication of AFOs with high durability. (C) 2021 Karabuk University. Publishing services by Elsevier B.V.Öğe Finite element spine models and spinal instruments: a review(World Scientific Publishing Company, 2022) Akıncı, Saliha Zeyneb; Arslan, Yunus ZiyaThere is considerable biomechanics literature on finite element modeling and analysis of the spine. To accurately mimic the biomechanical behavior of the vertebral column, a generated computational model has to include anatomical structures that are consistent with physiological reality. In this review article, we focused on the finite element spine models that have been developed by various approaches in the literature. Firstly, the anatomical features of the spine and the spinal components have been briefly explained. We then focused on the modeling stages of vertebrae, ligaments, facet joints, intervertebral discs, and spinal instruments. With this paper, we expect to provide a comprehensive resource regarding the modeling preferences used in spine modeling.Öğe Fundamentals of 3D printing and its applications in biomedical engineering(Springer Natur, 2020) Arslan, Yunus Ziya; Sürmen, Hasan Kemal; Örteş, FarukThree-dimensional (3D) printing is a practical manufacturing method that allows us to transform objects designed in the digital environment into physical objects using layered manufacturing methods. The terms of rapid prototyping and additive manufacturing are also used to express the manufacturing process using 3D printers. Unlike the subtractive manufacturing (machining) approach in which 3D objects are constructed by successively cutting material away from a solid block of material, additive manufacturing processes produce parts by adding material one layer at a time. In 3D printing technology, parts with complex geometries can be manufactured using less material compared to conventional manufacturing techniques. There is no need for molding in 3D printing, and the production of a part with different geometry can be quickly adapted. Objects designed in a digital environment can be directed to the production process immediately. Three-dimensional printing, which is very suitable for the production of objects with free-form surfaces, has been widely used in the medical sector, especially in the production of patient-specific biomedical devices [1]. Three-dimensional printing applications are spreading rapidly in many areas of the medical sector. Nowadays, orthopedic implants, prostheses, orthoses, dental products, anatomical models, customized tablets for personalized medicine, and many surgical instruments can be produced using 3D printers [2–5]. Three-dimensional printing allows significant flexibility for the fabrication of biomedical devices, offering geometric freedom without limitations experienced in traditional manufacturing methods. By using the 3D printing method, we are able to print complex shaped functional parts with detailed internal features and adjust the material density to produce lighter biomedical devices with fewer parts. Since the biomedical devices and implants must be compatible with the patient’s anatomy, the production of such devices by traditional manufacturing methods is a challenging task. In addition, because these devices are supposed to be designed for patient-specific purposes, the design of each item should be independently carried out for each patient [6]. Three-dimensional printing technology does not require additional production stages such as production line installation and mold design, thereby having the advantage of manufacturing the parts immediately, which makes the 3Dprintingmethod very suitable for the production of biomedical devices. Three dimensional printing has been one of the widely preferred approaches in the biomedical sector because of its high geometrical accuracy and resolution. In addition, the ability to print complex body implants by taking into account the magnetic resonance image (MRI) [7] and computed tomography (CT) [8] data further increased the functionality of this technology. Three-dimensional bioprinting is another application area of the 3D printing technology in which the complex 3D living tissues and artificial organs are constructed [9]. It is possible to produce 3D functional and living tissues using 3D bioprinting [10]. These printers generally use materials such as hydrogel, silicon, and protein solutions. The major aim in this field is to produce functional and transplantable human organs in the near future [11]. Some disadvantages of the 3D printing method are (i) it is not economically feasible for mass production, (ii) size of the part to be manufactured is limited to the dimensions of the 3Dprinter, and (iii) production speed is relatively low. Furthermore, the variety of materials used in 3D printing is also limited. On the other hand, new strategies are being developed that allow different types of materials to be used in the 3D printing technology [12–15]. Thanks to these novel technologies, many types of metal [16], plastic [17], composite [18], and organic materials [19] can be used in 3D printing. In biomedical applications, post-processing is of particular importance. For example, stair-stepped surface, which is a result of layer-by-layer manufacturing, may lead to undesirable surface conditions for implants required biocompatibility [20]. In such cases, surface finish operations should be done carefully and precisely. Moreover, clean and sterile manufacturing environments are required in the manufacture of medical products such as implants. In this context, precautions against contamination should be carefully taken for printing platform and other 3D printer equipment [21]. In this chapter, the general working principle of 3D printers, commonly used 3D printing technologies, and types of materials used in 3D printers were addressed. In addition, scientific studies focusing on 3D printing technology in the biomedical field have been discussed.Öğe İskelet kaslarındaki kuvvet üretim mekanizmasının Huxley tipi kas modelleriyle incelenmesi(2021) Arslan, Yunus ZiyaHareketin gerçekleştirilmesinde birincil rol oynayan ve lokomotor sistem bileşenlerinden olan iskelet kasları, kasılma esnasında çeşitli biyokimyasal ve mekanik süreçler sonucunda kuvvet üretirler. Kas kuvvetlerinin çeşitli deneysel veya klinik amaçlar için bilgisayar ortamında benzetiminin (simülasyonunun) yapılabilmesi amacıyla matematiksel kas modelleri kullanılmaktadır. Kas modellerinin, gerçek kas kuvvetlerini yüksek doğrulukla üretebilmeleri modellemede esas alınan varsayımlarla yakından ilişkilidir. Yapısal modeller olarak da bilinen Huxley tipi kas modelleri, kasılma esnasındaki biyokimyasal ve mekanik etkileşimleri esas alarak kuvvetin yanı sıra çeşitli kas karakteristiklerinin de hesaplanmasında kullanılan matematiksel modellerdir. Çapraz köprü teorisine dayanan ve kas yapısındaki filamentlerin etkileşimi üzerine kurulu bu modeller, halen deneysel çalışmaların da etkisiyle, modifiye edilmeye ve geliştirilmeye devam edilmektedir. Kas modellerinin yapısını, kullanılan varsayımları ve bu modellerin kabiliyetlerini anlamak, gerçeğe yakın kas kuvvetlerinin ve kasın dinamik karakteristiklerinin yeniden üretimi açısından önem arz etmektedir. Bu derleme makalede, Huxley tipi matematiksel kas modellerinin yapı ve özellikleri ile ürettikleri kuvvet cevapları, deneysel olarak elde edilen kas karakteristiklerini kestirmedeki performansları açısından incelenmiştir. Bu amaç doğrultusunda, çalışmada bir Huxley modeli kullanılarak farklı kasılma durumları için kas kuvvetleri elde edilmiş ve model performansları değerlendirilmiştir. Ayrıca Huxley tipi modellerde gerçekleştirilen değişimler sunulmuş, modellerin avantaj ve dezavantajlarının yanı sıra hangi tür çalışmalar için elverişli oldukları da ortaya konmuştur.Öğe İzokinetik Testlerde Mekanik Terimlerin Atletik Performansla İlişkilendirilmesi: Spor Bilimciler İçin Bir Rehber(İbrahim ERDEMİR, 2024) Kural, Doğa; Arslan, Yunus Ziyaİzokinetik testler, sporcuların atletik performansını mekanik yönleriyle ortaya koyar. Ancak mekanik terimlerin anlamı spor bilimciler tarafından net bir şekilde bilinmemektedir. Bu sebeple testten elde edilen mekanik çıktıların atletik performanstaki karşılığı da anlaşılamamaktadır. Kuvvet, tork, yapılan iş ya da üretilen güç gibi terimler birbiriyle bağlantılıdır; fakat birbirinden farklı atletik performans özelliklerini ifade eder. Bu terimlerin anlamı ve performanstaki yansımalarının bilinmemesi sporcuların performansının yanlış değerlendirilmesine sebep olmaktadır. Ayrıca terimlerin yanlış kullanılması biyomekanik ve spor bilimleri camiası arasında bir iletişim engeli oluşturmaktadır. Bu sebeple bu çalışmada izokinetik testlerde kullanılan temel mekanik parametrelerin hem ölçüm hem de matematiksel hesaplama yöntemleri ile elde edilmeleri amaçlanmıştır. Ayrıca bu parametrelerin atletik performans açısından kullanımları değerlendirilmiştir. Bu çalışmada bir sprinterden pilot ölçüm alınmıştır. İzokinetik test baskın bacakta ve oturur pozisyonda diz ekleminde 60-120-240 der/s hızlarda uygulanmıştır. İzokinetik test ile eklem torkunun zamana, açıya ve hıza bağlı değişim grafikleri elde edilmiş ve bu veriler kullanılarak eklemin hareket boyunca yaptığı iş, ürettiği güç ve tepe torka ulaştığı açı değerleri hesaplanmıştır. Ayrıca birbirinden farklı birçok izokinetik test çıktısının beraber yorumlanarak performansın nasıl değerlendirileceği vurgulanmıştır. Patlayıcı kuvvet, çabukluk ve çabuk kuvvette devamlılık gibi atletik performans ölçümleri ile izokinetik test sonuçları arasındaki korelasyon ve anlamlı ilişkiler farklı spor disiplinleri içerisinde örneklendirilmiştir.Öğe Kinematics, kinetics, and forces of the knee joint during walking(Elsevier, 2024) Karabulut, Derya; Arslan, Yunus ZiyaMotion analysis is a valuable tool to monitor the kinematics and kinetics of body parts quantitatively and the decision-making process in clinical implementations. In gait analysis systems, temporospatial parameters, joint angles, joint moments, and ground reaction forces can be recorded. However, some other biomechanical parameters such as muscle forces, joint reaction forces, and muscle-tendon unit length change cannot be noninvasively recorded in gait analysis systems. Accordingly, musculoskeletal modeling and simulation tools are very widely used to obtain such biomechanical parameters. In this chapter, we presented the details about kinematics and kinetics of the knee joint during a healthy gait. In this context, joint angles, joint moments, muscle forces, and joint reaction forces were provided. Furthermore, some special cases seen in various musculoskeletal disorders that affect the ability of gait are also investigated.Öğe Machine learning-based prediction of joint moments based on kinematics in patients with cerebral palsy(Journal of Biomechanics, 2023) Arslan, Yunus Ziya; Özateş, Mustafa Erkam; Karabulut, Derya; Wolf, Sebastian Immanuel; Salami, FiroozJoint moments during gait provide valuable information for clinical decision-making in patients with cerebral palsy (CP). Joint moments are calculated based on ground reaction forces (GRF) using inverse dynamics models. Obtaining GRF from patients with CP is challenging. Typically developed (TD) individuals’ joint moments were predicted from joint angles using machine learning, but no such study has been conducted on patients with CP. Accordingly, we aimed to predict the dorsi-plantar flexion, knee flexion–extension, hip flexion–extension, and hip adduction-abduction moments based on the trunk, pelvis, hip, knee, and ankle kinematics during gait in patients with CP and TD individuals using one-dimensional convolutional neural networks (CNN). The anonymized retrospective gait data of 329 TD (26 years ± 14, mass: 70 kg ± 15, height: 167 cm ± 89) and 917 CP (17 years ± 9, mass:47 kg ± 19, height:153 cm ± 36) individuals were evaluated and after applying inclusion–exclusion criteria, 132 TD and 622 CP patients with spastic diplegia were selected. We trained specific CNN models and evaluated their performance using isolated test subject groups based on normalized root mean square error (nRMSE) and Pearson correlation coefficient (PCC). Joint moments were predicted with nRMSE between 18.02% and 13.58% for the CP and between 12.55% and 8.58% for the TD groups, whereas with PCC between 0.85 and 0.93 for the CP and between 0.94 and 0.98 for the TD groups. Machine learning-based joint moment prediction from kinematics could replace conventional moment calculation in CP patients in the future, but the current level of prediction errors restricts its use for clinical decision-making today.Öğe Makine öğrenmesi ile kinematik veriden serebral palsili hastalarınyürüyüş karakteristiğinin analizi(2023) Arslan, Yunus Ziya; Özateş, Mustafa Erkam; Wolf, Sebastian ImmanuelSerebral palsi (SP), nöromotor fonksiyon bozuklarına dayanan bir rahatsızlıktır ve özellikle yürüme kinematiğini etkileyebilir. SP'li hastaların hareket yeteneklerini iyileştirmek için kişiye özgü değerlendirmelere ihtiyaç vardır. Bu değerlendirmeler için laboratuvarlarda kullanılan yer tepki kuvveti (YTK) ölçümleri, SP hastalarının tedavisinde önemli bir rol oynar. Ancak YTK'nin doğal yürüyüş sırasında ölçülmesi zor ve donanım gerektirdiği için maliyetlidir. Bu çalışmada SP'li hastaların YTK'lerini kuvvet platformlarına ihtiyaç duymadan tahmin etmek için makine öğrenimi kullanılarak SP hastalarının yürüyüş analizi için yeni bir yaklaşım sunulmaktadır.Yöntem:Araştırma, 40 sağlıklı birey ve 40 SP hastasının yürüme verisi kullanılmıştır. İlk olarak, bir boyutlu konvolüsyonel sinir ağına (CNN) girdi olarak kullanılan kinematik veriler aracılığıyla sağlıklı ve SP'li bireylerin sınıflandırılabilmesi için bir model geliştirilmiştir. Ardından, SP'li hastaların kinematik verileri ikinci bir CNN modeline beslenerek YTK tahmin edilmiştir. Bulgular:SP hastalarının ve sağlıklı bireylerin yüksek doğruluk oranlarıyla (%98) sınıflandırılabilmesi sağlanmıştır. Ayrıca, SP'li hastalarda YTK, %13.3’lük (± 5.1) normalize edilmiş ortalama karesel hatave 0.88’lik ± (0.07) Pearson korelasyon katsayısı oranları ile kestirilebilmiştir. Bu sonuçlar, laboratuvar ortamında YTK ölçümü yapılamayan hastalar için önemlidir. Sonuç:Bu çalışmada, SP hastalarının tedavisinde kullanışlı ve hızlı bir hareket analizi yöntemi sunulmuş ve SP hastalarının tedavi süreçlerini geliştirmeye yardımcı olacak bir yöntem uygulanmıştır. Bununla birlikte çalışmadan elde edilen sonuçların klinik karar verme süreçleri açısından hataya yer bırakmayacak bir dikkatle ele alınması gerekmektedir.Öğe Patellar tendon advancement for the treatment of crouch gait in patients with cerebral palsy(2023) Karabulut, Derya; Arslan, Yunus Ziya; Salami, Firooz; Wolf, Sebastian Immanuel; Goetze, MarcoCrouch gait is a frequent gait pathology in children with cerebral palsy (CP). Patellar tendon advancement (PTA) is a typical surgery among single-event multilevel surgery (SEMLS) for the treatment of crouch gait and performed to enhance the knee joint kinematics and kinetics Patella position had a considerable effect on the torque-producing capacity of the quadriceps and hence, patellar height is a typical metric to assess the influence of PTA on knee function. Patellar height can be assessed by using several radiographic imaging methods. How ever, in the literature, there is no consensus on objective quantification of the patellar height In our study, we aimed to i) objectively quantify the patella position using X-ray data and musculoskeletal modeling and ii) monitor the effect of PTA in combination with SEMLS on the knee kinematics of patients with CP and crouch gait.Öğe Sensitivity of model-predicted muscle forces of patients with cerebral palsy to variations in muscle-tendon parameters(World Scientific Publishing, 2021) Arslan, Yunus Ziya; Karabulut, DeryaComputational musculoskeletal modeling and simulation platforms are efficient tools to gain insight into the muscular coordination of patients with motor disabilities such as cerebral palsy (CP). Muscle force predictions from simulation programs are influenced by the architectural and contractile properties of muscle-tendon units. In this study, we aimed to evaluate the sensitivity of major lower limb muscle forces in patients with CP to changes in muscle-tendon parameters. Open-access datasets of children with CP (n=8) and healthy children (n=8) were considered. Monte Carlo analysis was executed to specify how sensitive the muscle forces to perturbations between +10% and ?10% of the nominal value of the maximum isometric muscle force, optimal muscle fiber length, muscle pennation angle, tendon slack length, and maximum contraction velocity of muscle. The sensitivity analysis revealed that muscle forces of CP patients and healthy individuals were most sensitive to perturbations in the tendon slack length (p<0.05), while forces of CP patients were more sensitive to tendon slack length when compared to the healthy group (p<0.05). Muscle forces of patients and healthy individuals were insensitive to the other four parameters (p>0.05), except for the gracilis and sartorius muscles in which the proportion of optimal muscle fiber length to tendon slack length is higher than 1; forces of these two muscles were also sensitive to the optimal muscle fiber length. The results of this study are expected to contribute to our understanding of which parameters should be personalized when conducting musculoskeletal modeling and simulation of patients with CP.
