Biomechanics of dynamic hip screw

OBJECTIVES: Pauwels III fracture is a kind of femoral neck fractures, in which the angle of the fracture line in the coronal plane and the upper edge of the acetabulum is more than 50°. Internal fixation for the treatment of femoral neck fractures is largely performed by cannulated compression screw (CCS), dynamic hip screw, or locking plate. This study aims to compare the biomechanical properties of parallel CCS combined with medial buttress plate fixation and F-type CCS fixation in the treatment of Pauwels III femoral neck fracture by finite element modeling and to determinate the most suitable procedure for such fractures...

BACKGROUND AND OBJECTIVE: The best internal fixation method for the treatment of Pauwels type III femoral neck fractures (FNFs) remains to be demonstrated. Through finite element analysis, this study explored whether dynamic hip screw (DHS) combined with anti rotation screw or medial buttress plate can improve the stability of internal fixation, and the femoral neck system (FNS) with similar structure to DHS and the traditional cannulated screw (CSs) were added for comparison. To evaluate their respective biomechanical advantages and disadvantages in the treatment of Pauwels type III FNFs...

BACKGROUND: Hip fractures in the elderly population are common and the number of patients is rising. For young and geriatric patients with undisplaced fractures osteosynthesis is the primary type of treatment. The dynamic hip screw (DHS) is around for many years and proved its value especially in displaced fractures. Since 2018 the femoral neck system (FNS) is available as an alternative showing promising biomechanical results. The aim of this study is to evaluate clinical results of the FNS and compare it to the DHS...

OBJECTIVES: This study aimed to evaluate the performance of four different fixation techniques for Pauwels type III femoral neck fractures considering the fracture morphology in the sagittal plane. MATERIALS AND METHODS: We constructed three different fracture morphologies in the sagittal plane in Pauwels type III femoral neck fractures: posteriorly angled at 20°, neutral, and anteriorly angled at 20°. We set up four fixation devices, including three cannulated screws (3CS), a dynamic hip screw with an antirotational screw (DHS+CS), a proximal femoral locking plate (PFLP), and three cannulated screws with a medial buttress plate (3CS+MBP)...

Objective: To summarize the characteristics and biomechanical research progress of common internal fixation for femoral neck fractures in recent years, so as to provide reference to clinical treatment of femoral neck fracture. Methods: The domestic and foreign relevant literature on biomechanics of internal fixation of femoral neck fracture in recent years was reviewed, and the biomechanical research progress was summarized. Results: Among the internal fixations currently used in the treatment of femoral neck fractures, three cannulated screws can provide sliding compression at the end of the fracture, but the shear resistance is weak, and the risk of long-term internal fixation failure is high; dynamic hip screw and proximal femoral locking plate have excellent angle stability and overall strength; medial buttress plate can transform vertical shear force into compressive stress to promote fracture healing and produce a certain anti-rotation effect; femoral neck system can support the fracture in multi-axial direction, with excellent anti-rotation and anti-shortening properties; and cephalomedullary nails have high overall strength and failure load...

Background: Dynamic hip screw (DHS) is one of the most widely internal fixations for stabilizing intertrochanteric fracture, however, with a high risk of postoperative complications. The triangle support fixation plate (TSFP) is developed to reduce the postoperative complications. The purpose of study is to evaluate the biomechanical performance of the DHS and TSFP and demonstrate the rationality of triangular internal fixation for stabilizing intertrochanteric fractures. Methods: The CT data of the proximal femur were used to establish finite-element models...

BACKGROUND: Intertrochanteric fracture of femur is one of the commonest fracture seen in elderly, osteoporotic female. The main stay of treatment is fixation with dynamic hip screw or intramedullary device like Proximal Femoral Nail. Intramedullary devices are found to be more biomechanically advantageous. The functional outcome of these fractures depends on the type of fixation, age and stability of fracture. The objective of this study is to assess the functional outcome of Proximal Femoral Nail in intertrochanteric fracture...

The purpose of this study was to compare the fixation stability of proximal fragments and the mechanical characteristics in proximal femur models of basicervical femoral neck fracture fixed by the femoral neck system (FNS) versus the dynamic hip screw. The mean axial stiffness was 234 ± 35 N/mm in the FNS group and 253 ± 42 N/mm in the DHS group, showing no significant difference (p = 0.654). Mean values for x-axis rotation, y-axis rotation, and z-axis rotation after cycle load were 2.2 ± 0...

There has always been a debate between the use of four and two-hole plate for the fixation of stable intertrochanteric fractures. The choice is usually influenced by the general practice of the particular institution and the surgeon's preference. While the dynamic hip screw (DHS) is the implant of choice for stable intertrochanteric fractures of the femur, the length of the side plate to be chosen for optimal results has no clear consensus and previous studies regarding the same have been inconclusive. In our systematic review, we aimed to review the evidence available on the selection of the optimal length of the side plate and bridge the glaring gap that exists in the literature...

Purpose: Osteosynthesis has been recommended for treatment of Pauwels type III femoral neck fractures in young patients. However, no implant of choice has been reported so far. This study was conducted in order to compare the fixation stability of two conventional fixation methods with three different novel fixed angle devices in this type of fracture. Materials and Methods: A total of 25 composite femurs (4th Generation Saw bone; Pacific Research Laboratories, USA) corresponding to human bone were used...

Objective: To examine the clinical results and biomechanical mechanism of the dynamic hip screw (DHS) and derotation screw (DS) in the treatment of displaced femoral neck fractures (FNF) based on different reduction qualities in young patients (≤65 years of age). Methods: All patients with FNF who received closed reduction and internal fixation with DHS+DS from January 2014 to August 2019 were retrospectively analyzed. Data on demographics, surgery, clinical outcomes, and postoperative complications were collected...

BACKGROUND: Femoral neck fractures in young people are usually Pauwels Type III fractures. The common treatment method are multiple parallel cannulated screws or dynamic hip screw sliding compression fixation. Due to the huge shear stress, the rate of complications such as femoral head necrosis and nonunion is still high after treatment. The aim of our study was to compare the stabilities of two fixation methods in fixating pauwels type III femoral neck fractures. METHODS: All biomimetic fracture samples are fixed with three cannulated screws combined with a medial buttress plate...

Most trochanteric fractures of the femur are classified as low-energy fractures as they are seen in people with decreased mechanical properties of bone tissue. The treatment is assumed to provide biomechanical fixation with the possibility of dynamization between bony fragments to stimulate the biological processes of bone union. The aim of the study was to analyze a complication presenting as migration of the cervical screw of an intra-medullary nail towards the hip joint acetabulum and present the therapeutic management of this complication...

BACKGROUND: Patients with a lateral femoral wall (LFW) fracture were reported to have high rates of re-operation and complication. Although the LFW thickness was a reliable predictor of post-operative or intra-operative LFW fracture, there was a paucity of literature evaluating the critical stress distributions on the femur and screws of intertrochanteric fractures treated with dynamic hip screw (DHS). This study aimed to investigate the biomechanical performance of intertrochanteric fractures with different LFW thickness treated with DHS device...

Introduction Most surgeons prefer a single implant for segmental proximal and diaphyseal femur fractures, although results are controversial and still no consensus for proper management is present. This prospective study analyses the functional and radiological outcome of managing 17 patients with ipsilateral shaft and proximal femur fractures by dual implant osteosynthesis at our center. Methods Over a two-year period, we managed 17 patients with a mean age of 35 years, with cancellous cannulated screws or dynamic hip screws for intracapsular femur fractures and improvised proximal femoral nail for extracapsular proximal femur fractures...

BACKGROUND: The optimal internal fixation strategy for vertical femoral neck fractures (VFNFs) in nongeriatric patients remains uncertain. Therefore, the purpose of this study was to compare the clinical prognoses and underlying mechanical characteristics of a novel off-axis screw technique with dynamic hip screws (DHSs) and three traditional parallel screws. METHODS: This study included a clinical investigation and a patient-specific finite element analysis (FEA)...

Background: Hip fractures account for a large proportion of hospitalization among the trauma cases. Low cost, simple technique, easy removal, and high rate of the bone union makes extramedullary (EM) fixation techniques a preferred choice. A close-fit bone and plate are essential for the success of such implantation. Various studies have found femur morphometry being related to regional features and social differences. Most of the available commercial implants are developed based on the data of the Caucasian population...

OBJECTIVE: To evaluate the biomechanical behavior of a metaphyseal stem specifically designed for the fixation of Pauwels type-III femoral neck fractures using finite-element analysis. METHODS: Three different constructions were studied: the dynamic hip screw with a superior anti-rotation screw (DHS + ARS), multiple cannulated screws in an inverted triangle configuration (ASNIS), and the Metaphyseal Nailing System (MNS), a new implant developed by the authors...

In this study, the biomechanical differences among three internal fixation configurations for treatment of Pauwels type II and III femoral neck fractures were analyzed. Using finite element analysis, the femur displacement and stress distributions of the internal fixation device and fracture section were obtained for different patients and movement conditions. The results show that patients with osteoporosis are more prone to femoral varus and femoral neck shortening, and the fracture probability of the device for these patients is higher than that for patients with normal bone...

Objective  The present study aims to identify the energy required for synthetic proximal femoral fracture after removal of three implant types: cannulated screws, dynamic hip screws (DHS), and proximal femoral nail (PFN). Methods  Twenty-five synthetic proximal femur bones were used: 10 were kept intact as the control group (CG), 5 were submitted to the placement and removal of 3 cannulated screws in an inverted triangle configuration (CSG), 5 were submitted to the placement and removal of a dynamic compression screw (DHSG), and 5 were submitted to the placement and removal of a proximal femur nail (PFNG)...