Biomechanics external fixator

BACKGROUND: There has been no scientific mechanical assessment demonstrating the optimal fixation technique in multifragmentary fractures of the distal humeral shaft. The purpose of the present study was to compare the biomechanical performance of 5 fixation constructs as used in minimally invasive plating osteosynthesis (MIPO) for distal humeral shaft fractures. METHODS: Three-dimensional (3D) humerus model with 20 mm distal humeral shaft fracture gap simulating multifragmentary fracture was created from computed tomography data and virtually fixed by 5 fixation techniques as MIPO, i...

Background and Objectives : The surgical treatment of proximal humeral shaft fractures usually considers application of either long straight plates or intramedullary nails. By being able to spare the rotator cuff and avoid the radial nerve distally, the implementation of helical plates might overcome the downsides of common fixation methods. The aims of the current study were (1) to explore the biomechanical competence of different plate designs and (2) to compare their performance versus the alternative treatment option of using intramedullary nails...

INTRODUCTION AND IMPORTANCE: Ankle fractures result from a wide variety of mechanisms the biomechanics of this articulation make any fracture altering the contact of the articulation surface lead to increased stresses and an inevitable evolution to tibiotalar arthritis. CASE PRESENTATION: We report the case of a 56-year-old patient admitted for open fracture dislocation of the ankle with a missing medial malleolus. He was treated by external fixation k-wiring and periosteal repair of the deltoid ligament...

Circular external fixators (CEFs) are successfully used in orthopedics owing to their highly favorable stiffness characteristics which promote distraction osteogenesis. Although there are different designs of external fixators, how these features produce optimal biomechanics through structural and component designs is not well known. Therefore, the aim of this study was to conduct a review on CEFs following the PRISMA statement. A search for relevant research articles was performed on Scopus and PubMed databases providing the related keywords...

INTRODUCTION: Distal humerus fractures are a challenge to treat, and the current standard of care, open reduction internal fixation with a double-plate, has a high rate of complications. We proposed a novel internal fixation configuration, lateral intramedullary nail and medial plate (LINMP) and verified its rigidity through biomechanical tests and finite element analysis. METHOD: The study involved biomechanical testing of 30 synthetic humerus models to compare two different fixation systems for an AO 13C-2...

BACKGROUND: Hinge fractures are considered risk factors for delayed or nonunion of the osteotomy gap in distal femoral osteotomies (DFOs). Limited evidence exists regarding the treatment of hinge fractures after DFO, which could improve stability and thus bone healing. PURPOSE: To (1) examine the effect of hinge fractures on the biomechanical properties of the bone-implant construct, (2) evaluate the biomechanical advantages of an additional fixation of a hinge fracture, and (3) test the biomechanical properties of different types of varisation DFOs...

OBJECTIVE: The aim of this study is to investigate stiffness and the maximum load to failure values of single- and double-screw fixation of oblique medial malleolus fractures using partially threaded cancellous screws. Our hypothesis is that single-screw fixation of medial malleolus fractures after SER injuries provides similar stiffness when compared with double-screw fixation. DESIGN: Biomechanical study. METHODS: Twelve composite polyurethane synthetic right distal tibiae were used in the experiment...

BACKGROUND: At present, not all Type AO/OTA 42A2 open fractures can be treated by external fixation brackets, not to mention the inconvenience of this technique in clinical practice. External titanium alloy locking plates, which are lightweight and easy-to-operate, can be used as an alternative treatment option for such patients. However, there are few reports of finite element biomechanical analysis on the titanium alloy locking plates and fixation brackets being placed on the medial side of the tibial fracture...

In low-income countries (LIC), the management of bone infections is a huge challenge. A high number of patients are in the pediatric age group. Children and adolescents exhibit good bone healing potential offering treatment options that mainly rely on the biological response of the infected bone. The purpose of this article is to highlight treatment options for these patients in LIC, which is based on clinical cases that illustrate the principles of the treatment, focusing on bone reaction and healing potential...

Aim - In order to fulfill the purpose of biomechanical substantiation for extrafocal pelvic osteosynthesis in osteoporosis we studied the stress-strain state (SSS) of LEG under conditions of external fixation by apparatuses with cylindrical and conical rods. Studies of the stress-strain state of the lower extremity belt by the finite element method were carried out under conditions of external fixation by devices with cylindrical and conical rods. In the finite element method, the approximate solution is constructed as a superposition of approximating functions...

BACKGROUND: The aim of this study is to investigate mechanical properties of minimally invasive plate osteosynthesis (MIPO), supracutaneousplating (SP), and unilateral external fixators (UEF) which can be performed for open tibial fractures. METHODS: An unstable diaphysial tibia fracture was created in 60 fresh sheep tibia specimens by performing an osteotomy at the middle of bones. Specimens were divided into 3 groups. Specimens underwent fracture fixation with a standard MIPO technique, im-planting the plate 15 mm from the bone for SP group...

PURPOSE: The mechanical characteristics of leg lengthening over a nail (LON) using an external fixator are not well known; specifically, the number of rings and K-wires required for this method has not been determined. This study aimed to compare the mechanical characteristics of leg LON using the simplest configuration for a domestic frame and those of leg lengthening using the Ilizarov frame alone. METHODS: The mechanical characteristics of cow tibial samples for lengthening over an intramedullary nail in combination with a domestic external fixator (LON samples) and for lengthening with the Ilizarov frame (Ilizarov samples) were evaluated by assessing axial compression, bending load, and torsional load...

BACKGROUND: For severe anterior glenoid bone loss due to recurrent shoulder instability, the Latarjet procedure offers a dynamic sling effect in addition to bone augmentation. Yet, it heavily alters the surrounding anatomy, while fixation and graft union issues are also common. PURPOSE/HYPOTHESIS: The purpose of this study was to compare a novel printed 3-dimensional (3D) partial glenoid arthroplasty (PGA) implant with the classic Latarjet procedure. It was hypothesized that by replicating the original glenoid geometry and preserving soft tissue anatomy, PGA may better reproduce normal joint kinematics...

Anterior pelvic ring fractures are common in geriatric patients. The Supraacetabular External Fixator (SEF) is a relatively simple and effective surgical procedure. On the other hand, there is the option of a Subcutaneous Iliopubic Plate (SIP) osteosynthesis. Only limited comparative biomechanical data of these two devices are available. Therefore, this biomechanical study's objective was to compare the stabilizing effect of the SEF versus the SIP in a model of Fragility Fractures of the Pelvis (FFP) type Ia...

BACKGROUND: This study aimed to analyze quantitative correlation between the posterior malleolus fracture and fixation and the rotational stability of the ankle and to explore supplementary surgical indications for posterior malleolus fracture. METHODS: Twenty fresh frozen cadaver specimens were selected and dissected. Based on the tibial insertion of the ligament complex, the model for the supination external rotation stage 3 ankle fracture with a posterior malleolar fragment and syndesmosis diastasis was created...

BACKGROUND: Stabilization of extra-articular distal radius fractures by wrist joint bridging (WB) dynamic fixation allows for early motion of the wrist, but relies on exact positioning of the device. In fact, physiological movement appeared to be compromised with even distinctly aberrant positioning of such device. To investigate this issue in more detail, we developed an in-vitro testing apparatus suitable for assessing the forces required for flexion and extension of the wrist. METHODS: The experimental set-up enables the transmission of the translational movement of the traverse of a universal testing machine into the main physiological movement (flexion and extension) of the wrist...

PURPOSE: Discrepancies exist between previous biomechanical and clinical studies when determining acceptable metacarpal shortening after metacarpal fractures. This study aimed to determine the amount of acceptable shortening after a metacarpal fracture before finger motion and strength is compromised. METHODS: We defrosted ten fresh-frozen cadaveric hands. A screw-driven external fixator was placed to stabilize the metacarpal, then a 15.0-mm section of the index metacarpal was excised and replaced with a three dimensional-printed, custom-designed polyethylene insert...

OBJECTIVE: The objective of this study was to evaluate the biomechanical properties of different internal fixation methods for Maisonneuve fractures under physiological loading conditions. METHODS: Finite element analysis was used to numerically analyze various fixation methods. The study focused on high fibular fractures and included six groups of internal fixation: high fibular fracture without fixation + distal tibiofibular elastic fixation (group A), high fibular fracture without fixation + distal tibiofibular strong fixation (group B), high fibular fracture with 7-hole plate internal fixation + distal tibiofibular elastic fixation (group C), high fibular fracture with 7-hole plate internal fixation + distal tibiofibular strong fixation (group D), high fibular fracture with 5-hole plate internal fixation + distal tibiofibular elastic fixation (group E), and high fibular fracture with 5-hole plate internal fixation + distal tibiofibular strong fixation (group F)...

We aimed to illustrate kicking leg dynamics during submaximal effort soccer side-foot kicks. Side-foot kicks with three effort levels (50, 75 and 100% effort levels based on maximal effort) of eight male university soccer players were captured (500 Hz) while initial ball velocities were monitored simultaneously. Systematic regulation in joint kinetics (angular impulses) was clearly demonstrated for hip flexion and knee extension moments thereby supporting the interpretation that the final foot velocity is controlled in a context of a planar, sequential segmental system...

BACKGROUND: Lateral meniscal deficiency with valgus malalignment increases the rate of lateral compartment osteoarthritis. Lateral meniscal allograft transplantation (LMAT) with a concomitant varus-producing opening-wedge distal femoral osteotomy (DFO) is an option yet to be evaluated biomechanically. PURPOSE/HYPOTHESIS: The purpose of this study was to clarify the biomechanical effects of the realignment procedure in the setting of LMAT. We hypothesized that (1) given the dependence of the lateral compartment on the lateral meniscus, a DFO and increasing degrees of varus would be insufficient to restore lateral compartment pressures to normal from a lateral meniscus-deficient state, and that (2) LMAT would restore lateral compartment pressures to the intact state while DFO would decrease lateral compartment pressures for any given state of the meniscus...