A New Anatomical Plate for Extra-Articular Distal Humeral Fractures: Biomechanical Study

Introduction: We compared the mechanical properties of two fixation techniques for the treatment of extra-articular distal third humeral fractures. Materials and Methods: Two groups were created from twenty-four humeri. Group 1 was instrumented using a new, precontoured, 8-hole (3.5-mm-diameter) locking compression plate (LCP) placed anterolaterally. Group 2 was instrumented using an 8-hole (3.5-mm-diameter) precontoured posterolateral LCP plate placed on the distal humerus. Four-point bending tests and torsion tests were performed until the specimens broke. Results: The four-point bending stiffness test showed that the stiffness of anterolaterally fixed humeri was significantly higher than that of posterolaterally fixed humeri (p0.05). Conclusions: The anterolateral plate exhibited higher bending stiffness and torsional yield strength than the posterolateral plate. Anterolateral plate fixation can thus be used to manage extra-articular distal humeral fractures. Multiaxial locking screws ensure rigid fixation, allow early elbow motion without olecranon fossa impingement, and prevent iatrogenic injury of the triceps muscle. Level of Evidence I, Therapeutic Studies Investigating the Results of Treatment

A non-linear elastic-plastic stress analysis in a ductile double-lap joint

In this study, an elastic-plastic stress analysis was proposed in order to obtain shear stress distribution in a double-lap joint, analytically. The solution was carried out using incremental theory. The obtained shear stress was then used for determining the peel stress in the adhesive. The elastic peel stress distribution in the adhesive was determined using Newton-Raphson method. In this study, FM73 (Cytec Industries Inc., New Jersey, USA) ductile adhesive was selected as it represents plastic hardening. The analytical results were compared with the finite element solution. For that, ANSYS 10 Software (Figes Engineering A.S., Turkey) was used so as to compare with the analytical results. A good agreement was obtained between the two methods

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

Possible usage of cannulated pedicle screws without cement augmentation

BACKGROUND: The use of pedicle screws is becoming increasingly popular for spinal surgery practice as the technology advances. Screw pullout due to bone quality and loading conditions is one of the most common problems observed after pedicle screw fixation. Several solutions were studied to prevent screw pullout. These can be investigated under three main categories: screw design, expandable screws and cement augmentation. OBJECTIVE: This study aimed to investigate the pullout performance of cannulated screws without cement augmentation on synthetic foams. METHODS: Artificial fusion process for PU is described and validated in our previous studies. For this study six newly designed cannulated pedicle screws were artificially fused to PU foam and pullout test were conducted according to ASTM F543 standard testing protocols. RESULTS: According to the results of post-fusion pullout tests, worst performed cannulated screw design was S3H on healthy bone simulating PU foam. However, pullout strength of unilaterally three holes including (S3H) design was purchased with two times higher loads when compared to control group. Solid cored screws were purchased with 671 N where this value was 1450 N for S3H design. CONCLUSIONS: This study provided that using cannulated pedicle screws without cement augmentation for the cases with healthy bone can be a reliable alternative to classical screws. To the knowledge of the authors this is the first post-fusion study investigating cannulated pedicle screws without cement augmentation.The author would like to acknowledge Turkish Science Foundation (TUBITAK) with the project #111M583 and #113S101 for the financial support for the study. Author also would like to acknowledge to the Osimplant (Bone implant) Ltd. Sti. for preparing the designed implants. Special thanks to Prof. Dr. Adem Sahin for his valuable comments on the study

Evaluation of the success and complication rates of endoscopic retrograde cholangiography according to the difficulty of the procedure

Abstract Endoscopic retrograde cholangiopancreatography (ERCP), is an invasive procedure with a high complication rate used in the diagnosis and treatment of pancreaticobiliary system diseases. A system that grading the difficulty and complexity of the ERCP procedure has been developed by the American Society of Gastrointestinal Endoscopy (ASGE). The aim of the study is to evaluate the degree of difficulty of ERCP procedures according to the ASGE grading system and its effectiveness in predicting the success and complications of the procedure. A total of 600 patients who underwent ERCP were evaluated retrospectively. Of all ERCP procedures, 5.5% were classified as ASGE 1, 46.8% as ASGE 2, 39% as ASGE 3, and 8.6% as ASGE 4. In all procedures, the successful cannulation rate was 96.3%, the technical success rate was 96%, and the clinical success rate was 94.8%. The procedure's success decreased linearly and the need for repetition increased linearly as the ASGE grade increased (p > .05). In terms of complications, there was no statistical difference between ASGE 1–3 and 4. We believe that the ASGE grading system will be useful in clinical practice, particularly for less experienced endoscopists in ERCP procedures

The pullout performance of pedicle screws

This brief book systematically discusses all subjects that affect the pullout strength of pedicle screws. These screws are used in spinal surgeries to stabilize the spine. The holding strength of the pedicle screw is vital since loosening of the pedicle screws can cause revision surgeries. Once the pedicle screw is pulled out, it is harder to obtain same stabilization for the fused vertebrae. The book reviews the effect of screw designs, application techniques, cement augmentation, coating of the screw and test conditions on the pullout strength. The studies with finite element analysis were also included

New Pedicle Screw Design With Expandable Shell for Low Bone Quality

[No abstract available]This work was financially supported by The Scientific and Technological Research Council of Turkey with Project # 111M583

Toggling effect on pullout performance of pedicle screws: Review

Screw loosening in spine surgery is a clinical complication in patients with poor bone quality. Pedicle screws are subjected to bending moments and axial loads that may cause toggling during daily movements of spine. The purpose of this study was to assess the previous studies related to toggling effect on pullout performance of pedicle screws by surveying the whole literature and to provide some discussion for new studies about pullout performance of pedicle screws after toggling. The search was performed by combining terms of pedicle screw, toggling, screw loosening, fatigue, cyclic loading, and pullout. The retrieved articles dealing with determined terms and also their references were reviewed. Some of these articles were eliminated after review process. Toggling was determined to be crucial for the stabilization performance of pedicle screw because the loosening mechanism of screws was affected directly by cyclic loading. The toggling or cyclic loading affected the holding capacity of pedicle screws negatively, and the possibility of loosening or failure problem for pedicle screws increased with cyclic loading magnitude. Loading conditions, screw properties, test medium, level of spinal region, and cement usage were determined by many researchers as the most important parameters affecting the toggling performance as well as the pullout strength of pedicle screws. The pullout strength of pedicle screws generally decreased with cyclic loading. The parameters of cyclic loading were fairly important for pullout performance of pedicle screws. Screw properties and cement augmentation had critical effects on the stability of screws under cyclic loading, as well

A new alternative to expandable pedicle screws: Expandable poly-ether-ether-ketone shell

Screw pullout is a very common problem in the fixation of sacrum with pedicle screws. The principal cause of this problem is that the cyclic micro motions in the fixation of sacrum are higher than the other regions of the vertebrae that limit the osteo-integration between bone and screw. In addition to that, the bone quality is very poor at sacrum region. This study investigated a possible solution to the pullout problem without the expandable screws' handicaps. Newly designed poly-ether-ether-ketone expandable shell and classical pedicle screws were biomechanically compared. Torsion test, pullout tests, fatigue tests, flexion/extension moment test, axial gripping capacity tests and torsional gripping capacity tests were conducted in accordance with ASTM F543, F1798 and F1717. Standard polyurethane foam and calf vertebrae were used as embedding medium for pullout tests. Classical pedicle screw pullout load on polyurethane foam was 564.8N compared to the failure load for calf vertebrae's 1264N. Under the same test conditions, expandable poly-ether-ether-ketone shell system's pullout loads from polyurethane foam and calf vertebrae were 1196.3 and 1890N, respectively. The pullout values for expandable poly-ether-ether-ketone shell were 33% and 53% higher than classical pedicle screw on polyurethane foam and calf vertebrae, respectively. The expandable poly-ether-ether-ketone shell exhibited endurance on its 90% of yield load. Contrary to poly-ether-ether-ketone shell, classical pedicle screw exhibited endurance on 70% of its yield load. Expandable poly-ether-ether-ketone shell exhibited much higher pullout performance than classical pedicle screw. Fatigue performance of expandable poly-ether-ether-ketone shell is also higher than classical pedicle screw due to damping the micro motion capacity of the poly-ether-ether-ketone. Expandable poly-ether-ether-ketone shell is a safe alternative to all other expandable pedicle screw systems on mechanical perspective.The author acknowledges Turkish Science Foundation (TUBITAK) for the financial support for the study with project number 111M583

Biomechanical analysis of C5-C6 spinal unit with prosthetic disc by finite element method

Spinal fusion and total disc arthroplasty are used in the surgical treatment of cervical disc degeneration. When mobility is desired in the functional spinal unit, total disc arthroplasty is preferred instead of fusion. In this research, the effects of artificial disc prosthesis on the biomechanical behaviour of the C5-C6 functional spinal unit were investigated via finite element method. Firstly, three-dimensional CAD models of C5 and C6 vertebrae were created by using a computerized tomography images of a healthy human neck via 3D Slicer computer software. The mobility of the healthy model consisting of intervertebral disc, joints, and soft tissues was validated by previously published experimental studies in the field. On the second step, a ball and socket type artificial disc was defined using connector elements between C5-6 functional spinal unit to simulate the total disc arthroplasty method. Finally, to investigate the effect of prosthesis core radius changes on the biomechanical properties of functional spinal unit, healthy and implanted models were analysed via finite element method. © 2019 Polish Academy of Sciences. All rights reserved