Biomechanical design of a new proximal humerus fracture plate using alternative materials.

Comminuted proximal humerus fractures are often repaired by metal plates, but potentially still experience bone refracture, bone "stress shielding," screw perforation, delayed healing, and so forth. This "proof of principle" investigation is the initial step towards the design of a new plate using alternative materials to address some of these problems. Finite element modeling was used to create design graphs for bone stress, plate stress, screw stress, and interfragmentary motion via three different fixations (no, 1, or 2 "kickstand" [KS] screws across the fracture) using a wide range of plate elastic moduli (E = 5-200 GPa).

Material Properties and Engineering Performance of Bone Fracture Plates Made from Plant Fiber Reinforced Composites: A Review.

Bone fracture plates are usually made from titanium alloy or stainless steel, which are much stiffer than bone. However, overly stiff plates can restrict axial interfragmentary motion at the fracture leading to delayed callus formation and healing, as well as causing bone "stress shielding" under the plate leading to bone atrophy, bone resorption, and plate loosening. Consequently, there have been many prior efforts to develop nonmetallic bone fracture plates with customized material properties using synthetic fibers (e.

Biomechanical Design Optimization of Distal Humerus Fracture Plates: A Review.

The goal of this article was to review studies on distal humerus fracture plates (DHFPs) to understand the biomechanical influence of systematically changing the plate or screw variables. The problem is that DHFPs are commonly used surgically, although complications can still occur, and it is unclear if implant configurations are always optimized using biomechanical criteria. A systematic search of the PubMed database was conducted to identify English-language biomechanical optimization studies of DHFPs that parametrically altered plate and/or screw variables to analyze their influence on engineering performance.

Biomechanical testing of a computationally optimized far cortical locking plate versus traditional implants for distal femur fracture repair.

Background: This study experimentally validated a computationally optimized screw number and screw distribution far cortical locking distal femur fracture plate and compared the results to traditional implants.

Methods: 24 artificial femurs were osteotomized with a 10 mm fracture gap 60 mm proximal to the intercondylar notch. Three fixation constructs were used.

Topping-Off a Long Thoracic Stabilization With Semi-Rigid Constructs May Have Favorable Biomechanical Effects to Prevent Proximal Junctional Kyphosis: A Biomechanical Comparison.

Study Design: In-vitro cadaveric biomechanical study.

Objectives: Long posterior spinal fusion is a standard treatment for adult spinal deformity. However, these rigid constructs are known to alter motion and stress to the adjacent non-instrumented vertebrae, increasing the risk of proximal junctional kyphosis (PJK).

Cytotoxicity of novel hybrid composite materials for making bone fracture plates.

Bone fracture plates are usually made from steel or titanium, which are much stiffer than cortical bone. This may cause bone 'stress shielding' (i.e.

Biomechanical effects of different loads and constraints on finite element modeling of the humerus.

Currently, there is no established finite element (FE) method to apply physiologically realistic loads and constraints to the humerus. This FE study showed that 2 'simple' methods involving direct head loads, no head constraints, and rigid elbow or mid-length constraints created excessive stresses and bending. However, 2 'intermediate' methods involving direct head loads, but flexible head and elbow constraints, produced lower stresses and bending.

Biomechanical design optimization of proximal humerus locked plates: A review.

Background: Proximal humerus locked plates (PHLPs) are widely used for fracture surgery. Yet, non-union, malunion, infection, avascular necrosis, screw cut-out (i.e.

Biomechanical stress analysis using thermography: A review.

Biomechanics investigators are interested in experimentally measuring stresses experienced by dental structures, whole bones, joint replacements, soft tissues, normal limbs, etc. To do so, various experimental methods have been used that are based on acoustic, optical, piezo-resistive, or other principles, like digital image correlation, fiber optic sensors, photo-elasticity, strain gages, ultrasound, etc. Several biomechanical review papers have surveyed these research technologies, but they do not mention thermography.

Experimental Methods for Studying the Contact Mechanics of Joints.

Biomechanics researchers often experimentally measure static or fluctuating dynamic contact forces, areas, and stresses at the interface of natural and artificial joints, including the shoulders, elbows, hips, and knees. This information helps explain joint contact mechanics, as well as mechanisms that may contribute to disease, damage, and degradation. Currently, the most common in vitro experimental technique involves a thin pressure-sensitive film inserted into the joint space; but, the film's finite thickness disturbs the joint's ordinary articulation.

Mechanical Properties of Synthetic Bones Made by Synbone: A Review.

Biomechanical engineers and physicists commonly employ biological bone for biomechanics studies, since they are good representations of living bone. Yet, there are challenges to using biological bone, such as cost, degradation, disease, ethics, shipping, sourcing, storage, variability, etc. Therefore, the Synbone® company has developed a series of synthetic bones that have been used by biomechanical investigators to offset some drawbacks of biological bone.

Biomechanical properties of artificial bones made by Sawbones: A review.

Biomedical engineers and physicists frequently use human or animal bone for orthopaedic biomechanics research because they are excellent approximations of living bone. But, there are drawbacks to biological bone, like degradation over time, ethical concerns, high financial costs, inter-specimen variability, storage requirements, supplier sourcing, transportation rules, etc. Consequently, since the late 1980s, the Sawbones® company has been one of the world's largest suppliers of artificial bones for biomechanical testing that counteract many disadvantages of biological bone.

Biomechanics of plate fixation following traditional olecranon osteotomy versus novel proximal ulna osteotomy for visualizing a distal humerus injury.

After a distal humeral injury, olecranon osteotomy (OO) is a traditional way to visualize the distal humerus for performing fracture fixation. In contrast, the current authors previously showed that novel proximal ulna osteotomy (PUO) allows better access to the distal humerus without ligamentous compromise. Therefore, this study biomechanically compared plating repair following OO versus PUO.

Biomechanical design optimization of distal femur locked plates: A review.

Clinical findings, manufacturer instructions, and surgeon's preferences often dictate the implantation of distal femur locked plates (DFLPs), but healing problems and implant failures still persist. Also, most biomechanical researchers compare a particular DFLP configuration to implants like plates and nails. However, this begs the question: Is this specific DFLP configuration biomechanically optimal to encourage early callus formation, reduce bone and implant failure, and minimize bone "stress shielding"? Consequently, it is crucial to optimize, or characterize, the biomechanical performance (stiffness, strength, fracture micro-motion, bone stress, plate stress) of DFLPs influenced by plate variables (geometry, position, material) and screw variables (distribution, size, number, angle, material).

Biomechanical Comparison of Subsidence Between Patient-Specific and Non-Patient-Specific Lumbar Interbody Fusion Cages.

Study Design: Biomechanical study.

Objectives: Several strategies to improve the surface of contact between an interbody device and the endplate have been employed to attenuate the risk of cage subsidence. 3D-printed patient-specific cages have been presented as a promising alternative to help mitigate that risk, but there is a lack of biomechanical evidence supporting their use.

A 20-Year Review of Biomechanical Experimental Studies on Spine Implants Used for Percutaneous Surgical Repair of Vertebral Compression Fractures.

A vertebral compression fracture (VCF) is an injury to a vertebra of the spine affecting the cortical walls and/or middle cancellous section. The most common risk factor for a VCF is osteoporosis, thus predisposing the elderly and postmenopausal women to this injury. Clinical consequences include loss of vertebral height, kyphotic deformity, altered stance, back pain, reduced mobility, reduced abdominal space, and reduced thoracic space, as well as early mortality.

Evaluation of the contact surface between vertebral endplate and 3D printed patient-specific cage vs commercial cage.

Biomechanical study. To evaluate the performance of the contact surface for 3D printed patient-specific cages using CT-scan 3D endplate reconstructions in comparison to the contact surface of commercial cages. Previous strategies to improve the surface of contact between the device and the endplate have been employed to attenuate the risk of cage subsidence.

Biomechanical design of a new percutaneous locked plate for comminuted proximal tibia fractures.

Comminuted proximal tibia fractures are an ongoing surgical challenge. This "proof of concept" study is the first step in designing a new percutaneous plate for this injury under toe-touch weight-bearing as prescribed after surgery. Finite element simulations generated design curves for overall stiffness, bone and implant stress, and interfragmentary motion using 3 fixations (no, 1, or 2 "kickstand" (KS) screws across the fracture gap) over a range of plate elastic moduli (E = 5 to 200 GPa).

Proximal Ulna Osteotomy for Complex Fractures of the Distal Humerus: A 3-Dimensional Laser Analysis and Comparison With Olecranon Osteotomy.

Purpose: The current methods of distal humerus (DH) articular surface visualization only allow a limited view of the joint. This study describes an osteotomy procedure that increases the visualization of and access to the DH articular surface for fixation without compromising ligaments.

Methods: Eighteen fresh-frozen human elbows (9 matched pairs) underwent proximal ulna osteotomy (PUO) or transverse olecranon osteotomy (OO) contralaterally.

Effect of head size and rotation on taper corrosion in a hip simulator.

Aims: This study investigates head-neck taper corrosion with varying head size in a novel hip simulator instrumented to measure corrosion related electrical activity under torsional loads.

Methods: In all, six 28 mm and six 36 mm titanium stem-cobalt chrome head pairs with polyethylene sockets were tested in a novel instrumented hip simulator. Samples were tested using simulated gait data with incremental increasing loads to determine corrosion onset load and electrochemical activity.

Biomechanical comparison of 3 types of transdiscal fixation implants for fixing high-grade L5/S1 spine spondylolisthesis.

Background Context: There are several options for the stabilization of high-grade lumbosacral spondylolisthesis including transdiscal screws, the Bohlman technique (transdiscal fibular strut) and the modified Bohlman technique (transdiscal titanium mesh cage). The choice of an optimum construct remains controversial; therefore, we endeavoured to study and compare the biomechanical performance of these 3 techniques.

Purpose: The aim of this study was to compare 3 types of transdiscal fixation biomechanically in an in vitro porcine lumbar-sacral spine model.

Biomechanical optimization of the far cortical locking technique for early healing of distal femur fractures.

This finite element study optimized far cortical locking (FCL) technology for early callus formation in distal femur fracture fixation with a 9-hole plate using FCL screws proximal to, and standard locking screws distal to, the fracture. Analyses were done for 120 possible FCL screw configurations by varying FCL screw distribution and number. A hip joint force of 700 N (i.

Biomechanical analysis of fixation methods for acetabular fractures: A review.

Acetabular fractures are known as one of the most frequent types of pelvic fractures with growing frequency among elderly people. Because of this, it is important to establish the methods of repair that will produce optimal outcomes for fracture healing and joint remobilization. Open reduction and internal fixation are considered as the "gold standard" of acetabular fracture repair; however, to the best of authors' knowledge, there is no systematic review comparing different repair methods from biomechanical point of view.

Prognostic factors for predicting health-related quality of life after intramedullary nailing of tibial fractures: a randomized controlled trial.

Aims: Using tibial shaft fracture participants from a large, multicentre randomized controlled trial, we investigated if patient and surgical factors were associated with health-related quality of life (HRQoL) at one year post-surgery.

Methods: The Study to Prospectively Evaluate Reamed Intramedullary Nails in Patients with Tibial Fractures (SPRINT) trial examined adults with an open or closed tibial shaft fracture who were treated with either reamed or unreamed intramedullary nails. HRQoL was assessed at hospital discharge (for pre-injury level) and at 12 months post-fracture using the Short Musculoskeletal Functional Assessment (SMFA) Dysfunction, SMFA Bother, 36-Item Short Form 36 (SF-36) Physical, and SF-36 Mental Component scores.

Biomechanical design using in-vitro finite element modeling of distal femur fracture plates made from semi-rigid materials versus traditional metals for post-operative toe-touch weight-bearing.

This proof-of-concept study designs distal femur fracture plates from semi-rigid materials vs. traditional metals for toe-touch weight-bearing recommended to patients immediately after surgery. The two-fold goal was to (a) reduce stress shielding (SS) by increasing cortical bone stress thereby reducing the risk of bone absorption and plate loosening, and (b) reduce delayed healing (DH) via early callus formation by optimizing axial interfragmentary motion (AIM).