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Biomechanics of dynamic hip screw

Karl Stoffel, Ivan Zderic, Florian Gras, Christoph Sommer, Ursula Eberli, David Mueller, Martin Oswald, Boyko Gueorguiev
OBJECTIVES: To evaluate the biomechanical performance of Femoral Neck System (FNS) in comparison to established methods for fixation of femoral neck fractures in a cadaveric model. METHODS: Twenty pairs of fresh-frozen human cadaveric femora were instrumented either with DHS-Screw, DHS-Blade, 3CS or with FNS in a partially paired design. The specimens were randomized to two paired treatment groups based on the BMD, namely DHS-Screw/DHS-Blade and FNS/3CS. A reduced unstable femoral neck fracture with postero-caudal comminution, AO/OTA 31-B2...
October 13, 2016: Journal of Orthopaedic Trauma
Shabnam Samsami, Sadegh Saberi, Nima Bagheri, Gholamreza Rouhi
BACKGROUND: Vertical femoral neck fractures in the youth could be happened in high-energy accidents, and because of dominant shearing forces, this fracture is considered as a troublesome injury with a controversy regarding selection of the best fixation method. OBJECTIVE: The long term goal of this quasi-experimental study was to find the more stable fixation method among cannulated screws (CSs), proximal femoral locking plate (PFLP), and dynamic hip screw with derotational screw (DHS+DS) for this kind of fracture...
September 28, 2016: Bio-medical Materials and Engineering
Jae Hyuk Yang, Tae Gon Jung, Arjun Rupanagudi Honnurappa, Jae Min Cha, Chang Hwa Ham, Tae Yoon Kim, Seung Woo Suh
Introduction. To compare the biomechanical stability of the femur following the removal of proximal femoral nail antirotation (PFNA-II) and dynamic hip screw (DHS). Material and Methods. 56 paired cadaveric femurs were used as experimental and control groups. In the experimental group, PFNA-II and DHS were randomly inserted into femurs on both sides and then removed. Thereafter, compression load was applied until fracture occurred; biomechanical stability of the femurs and associated fracture patterns were studied...
2016: Applied Bionics and Biomechanics
Radek Bartoska, Vaclav Baca, Zdenek Horak, Maros Hrubina, Jiri Skala-Rosenbaum, Jiri Marvan, David Kachlik, Valer Dzupa
PURPOSE: Proximal femoral fractures are among the most commonly sustained fractures. The current treatment of stable proximal femoral fractures located in trochanteric region primarily involves the use of two systems: extramedullary dynamic hip screws and intramedullary hip nails. Given that these fractures are mainly found in the elderly population, the necessity of a repeat, due to failure of the first, may jeopardize the patient's life. Decisive factors contributing to the healing of a fracture (or the failure thereof) include fracture pattern, technical implementation of the operation (i...
July 2016: Surgical and Radiologic Anatomy: SRA
K Šmejkal, P Lochman, J Trlica, P Novotný, J Šimek, T Dědek
PURPOSE OF THE STUDY: The aim of the study was to analyse causes of impaired bone healing in femoral fractures and to present options of their management. MATERIAL AND METHODS: This is a retrospective study of the data on complications prospectively collected between 2008 and 2013. The patients admitted for primary treatment at the Trauma Centre of the Faculty of Medicine in Hradec Kralove from January 2008 to December 2013 included 1186 patients with injury severity scores (ISS) > 15 and 1340 patients with new injury severity scores (NISS) >15, all older than 16 years...
2015: Acta Chirurgiae Orthopaedicae et Traumatologiae Cechoslovaca
Y Imren, V Gurkan, K Bilsel, E E Desteli, M Tuna, C Gurcan, I Tuncay, C Sen
PURPOSE OF THE STUDY The objective of this study was to establish relative fixation strengths of proximal femoral nail (PFN), dynamic hip screw (DHS), monolateral external fixator (EF), and cannulated screw (CS) in basicervical hip fracture model. MATERIAL AND METHODS The study involved four groups of implanted composite proximal femoral synthetic bones of eight specimens per group; nailing with PFN, DHS, fixation with three cannulated screws, and EF. 70˚ osteotomy was performed to simulate a Pauwels Type 3 basicervical fracture...
2015: Acta Chirurgiae Orthopaedicae et Traumatologiae Cechoslovaca
Bryan G Vopat, Patrick M Kane, P Kaveh Mansuripur, David Paller, Sarath Koruprolu, Emily Abbood, Christopher T Born
OBJECTIVE: Many surgeons currently use long cephomedullary nails for the treatment of intertrochanteric fractures. The optimal indications for deploying distal interlocks are still debatable. This study examined the torsional biomechanical properties of 3-part intertrochanteric femur fractures in a cadaveric bone model using two different distal fixation strategies, an unlocked long cephalomedullary nail versus a dynamically locked nail. Our hypothesis is that a long cephalomedullary nail does not require distal locking fixation when used for treatment of a 3-part intertrochanteric fracture...
2015: SpringerPlus
Anderson Freitas, Gustavo Melo Torres, André Cezar de Andrade de Mello E Souza, Rafael Almeida Maciel, Diogo Ranier de Macedo Souto, George Neri de Barros Ferreira
OBJECTIVE: To statistically analyze the results obtained from biomechanical tests on fixation of femoral neck fractures of Pauwels III type, in synthetic bone, using the dynamic hip system with an anti-rotation screw, versus a control group. METHODS: Ten synthetic bones from a Brazilian manufacturer (model C1010) were used and divided into two groups: test and control. In the test group, fixation of an osteotomy was performed with 70° of inclination at the level of the femoral neck, using DHS with an anti-rotation screw...
November 2014: Revista Brasileira de Ortopedia
D Vermesan, R Prejbeanu, D V Poenaru, H Petrescu, E Apostol, F Inchingolo, G Dipalma, A Abbinante, M Caprio, M A Potenza, R Cagiano, G Malcangi, A D Inchingolo, H Haragus
BACKGROUND AND HYPOTHESIS: There is currently no consensus regarding superiority of the intramedullary fixation over the sliding hip screw. Regional variation remains high and not backed up by solid evidence. Given these premises we aimed to analyze weather implant preference can influence the postoperative survival. Secondary objectives were determining the trend for implant choice and confounding factors associated with intramedullary nails compared to sliding hip screws. PATIENTS AND METHODS: Retrospective data was obtained from patient charts with the main diagnosis of extracapsular/ trochanteric fractures, corresponding to ICD S72...
2015: La Clinica Terapeutica
Lukas Weiser, Andreas A Ruppel, Jakob V Nüchtern, Kay Sellenschloh, Johannes Zeichen, Klaus Püschel, Michael M Morlock, Wolfgang Lehmann
INTRODUCTION: Due to the demographic trend, pertrochanteric fractures of the femur will gain increasing importance in the future. Both extra- and intramedullary implants are used with good results in the treatment of these fractures. New, angular stable extramedullary implants promise increased postoperative stability even with unstable fractures. Additional trochanteric plates are intended to prevent secondary impaction, varisation and shortening of the fracture, as well as medialisation of the femoral shaft...
August 2015: Archives of Orthopaedic and Trauma Surgery
Korhan Ozkan, İsmail Türkmen, Adem Sahin, Yavuz Yildiz, Selim Erturk, Mehmet Salih Soylemez
BACKGROUND: The incidence of fractures in the trochanteric area has risen with the increasing numbers of elderly people with osteoporosis. Although dynamic hip screw fixation is the gold standard for the treatment of stable intertrochanteric femur fractures, treatment of unstable intertrochanteric femur fractures still remains controversial. Intramedullary devices such as Gamma nail or proximal femoral nail and proximal anatomic femur plates are in use for the treatment of intertrochanteric femur fractures...
May 2015: Indian Journal of Orthopaedics
C Fang, T W Lau, T M Wong, H L Lee, F Leung
The spiral blade modification of the Dynamic Hip Screw (DHS) was designed for superior biomechanical fixation in the osteoporotic femoral head. Our objective was to compare clinical outcomes and in particular the incidence of loss of fixation. In a series of 197 consecutive patients over the age of 50 years treated with DHS-blades (blades) and 242 patients treated with conventional DHS (screw) for AO/OTA 31.A1 or A2 intertrochanteric fractures were identified from a prospectively compiled database in a level 1 trauma centre...
March 2015: Bone & Joint Journal
Sarat C Kunapuli, Matthew J Schramski, Angela S Lee, John M Popovich, Jacek Cholewicki, N Peter Reeves, Renn J Crichlow
OBJECTIVES: To compare the strength of augmented versus nonaugmented fixation techniques for stabilizing vertical shear femoral neck fractures. METHODS: Two surgical screw constructs were tested with and without augmentation using 40 composite femurs: (1) 7.3-mm cannulated screws placed in an inverted triangular configuration and (2) 135-degree dynamic hip screw (DHS). The augmentation consisted of a 2.7-mm locking plate placed on the anterior-inferior femoral neck...
March 2015: Journal of Orthopaedic Trauma
Luc P Cloutier, G Yves Laflamme, Jeremie Menard, Yvan Petit
BACKGROUND: Greater trochanter fractures or osteotomies fixed with lateral plates still present high rates of complications. Unblocked greater trochanter anterior movement during hip extension might be a possible cause of failure. This study aimed to determine, under stair climbing conditions, the biomechanical behaviour of a greater trochanter fragment and the impact of an anterior locking plate on its migration. METHODS: Eighteen femurs paired from nine fresh frozen cadaveric specimens were tested on a quasi-dynamic stair climbing cycling test bench...
September 2014: Clinical Biomechanics
Patrick Kane, Bryan Vopat, David Paller, Sarath Koruprolu, Alan H Daniels, Christopher Born
OBJECTIVES: This study compared the torsional properties of stable intertrochanteric femur fractures in a cadaveric bone model using 2 different distal fixation strategies: unlocked long cephalomedullary nailing versus dynamically locked nailing. METHODS: Fourteen matched pairs of cadaveric femora were randomly assigned to 1 of 2 distal fixation treatment groups: a single distal interlock screw placed in the dynamic orientation or no distal screw fixation. A stable 2-part intertrochanteric fracture was produced...
December 2014: Journal of Orthopaedic Trauma
Jie Wang, Xin-long Ma, Jian-xiong Ma, Dan Xing, Yang Yang, Shao-wen Zhu, Bao-yi Ma, Yang Chen, Rui Feng, Hao-bo Jia, Jing-tao Yu
OBJECTIVE: To compare the biomechanical properties of four types of internal fixation (proximal femoral nail [PFN], dynamic hip screw [DHS], dynamic condylar screw [DCS], and proximal femoral locking plate [PFLP]) for different types of subtrochanteric fractures. METHODS: Thirty-two antiseptic femurs were randomly divided into four groups. After internal fixation had been implanted, different types of subtrochanteric fracture models were produced and each tested under vertical, torsional and vertical damage loads...
May 2014: Orthopaedic Surgery
Sermet Inal, Ferruh Taspinar, Eyyup Gulbandilar, Kadir Gok
BACKGROUND: This study was conducted to examine and compare the pertrochanteric fixator (PTF) and dynamic hip screw (DHS). METHODS: AnsysWorkbench, a commercial finite element based program, was used to investigate the biomechanical parameters of femoral fractures and implants. The human femoral model was scanned and a femoral intertrochanteric fracture was created. Von Mises stress, von Mises strain, and shear and deformation forces on the upper and lower parts of the fracture line; and the von Mises stress, von Mises strain parameters of the screws and implant bodies during axial loading were calculated and compared...
March 2015: International Journal of Medical Robotics + Computer Assisted Surgery: MRCAS
Patrick Kane, Bryan Vopat, Wendell Heard, Nikhil Thakur, David Paller, Sarath Koruprolu, Christopher Born
BACKGROUND: Intertrochanteric hip fractures pose a significant challenge for the orthopaedic community as optimal surgical treatment continues to be debated. Currently, varus collapse with lag screw cutout is the most common mode of failure. Multiple factors contribute to cutout. From a surgical technique perspective, a tip apex distance less than 25 mm has been suggested to decrease the risk of cutout. We hypothesized that a low-center lag screw position in the femoral head, with a tip apex distance greater than 25 mm will provide equal, if not superior, biomechanical stability compared with a center-center position with a tip apex distance less than 25 mm in an unstable intertrochanteric hip fracture stabilized with a long cephalomedullary nail...
August 2014: Clinical Orthopaedics and related Research
Karlmeinrad Giesinger, Lukas Ebneter, Robert E Day, Karl K Stoffel, Piers J Yates, Markus S Kuster
Periprosthetic femoral fractures (PFF) are a serious complication after total hip arthroplasty. Plate fixation with screws perforating the cement mantle is a common treatment option. The study objective was to investigate hip stem stability and cement mantle integrity under dynamic loading. A cemented hip stem was implanted in 17 composite femur models. Nine bone models were osteotomised just distal to the stem and fixed with a polyaxial locking plate the other eight constructs served as the control group. All specimens were tested in a bi-axial material testing machine (100000 cycles)...
June 2014: Journal of Arthroplasty
Milan M Mitković, Miodrag T Manić, Dusan Lj Petković, Sasa S Milenković, Milorad B Mitković
Dynamic trochanteric fractures implants allow fracture fragments to be compressed. Dynamisation can be realized if the axial pin force overcome friction force between pin and body of the implant. Examination of sliding iniciation forces in Mitkovic Selfdinamysible Trochanteric Internal Fixator (SIF). SIF was attached for angle block in the position with vertical orientation of pins. The transversal load of 5 kg was connected to pins by a rope. A dynamometer was used to measure force during the movement of angle block in up direction...
2013: Acta Chirurgica Iugoslavica
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