Biomechanical validation of novel polyurethane-resin synthetic osteoporotic femoral bones in axial compression, four-point bending and torsion.

In addition to human donor bones, bone models made of synthetic materials are the gold standard substitutes for biomechanical testing of osteosyntheses. However, commercially available artificial bone models are not able to adequately reproduce the mechanical properties of human bone, especially not human osteoporotic bone. To overcome this issue, new types of polyurethane-based synthetic osteoporotic bone models have been developed.

Impact of lateral cortical notching on biomechanical performance in cephalomedullary nailing for unstable pertrochanteric fractures.

Purpose: In pertrochanteric femur fractures the risk for fracture healing complications increases with the complexity of the fracture. In addition to dynamization along the lag screw, successful fracture healing may also be facilitated by further dynamization along the shaft axis. The aim of this study was to investigate the mechanical stability of additional axial notch dynamization compared to the standard treatment in an unstable pertrochanteric femur fracture treated with cephalomedullary nailing.

Anatomic variability of the human femur and its implications for the use of artificial bones in biomechanical testing.

Aside from human bones, epoxy-based synthetic bones are regarded as the gold standard for biomechanical testing os osteosyntheses. There is a significant discrepancy in biomechanical testing between the determination of fracture stability due to implant treatment in experimental methods and their ability to predict the outcome of stability and fracture healing in a patient. One possible explanation for this disparity is the absence of population-specific variables such as age, gender, and ethnicity in artificial bone, which may influence the geometry and mechanical properties of bone.

Open the pores - Polydimethylsiloxane influences the porous structure of cancellous bone surrogates for biomechanical testing of osteosyntheses.

Synthetic materials used for valid and reliable implant testing and design should reflect the mechanical and morphometric properties of human bone. Such bone models are already available on the market, but they do not reflect the population variability of human bone, nor are they open-celled porous as human bone is. Biomechanical studies aimed at cementing the fracture or an implant cannot be conducted with them.

Smart Artificial Soft Tissue - Application to a Hybrid Simulator for Training of Laryngeal Pacemaker Implantation.

Surgical simulators are safe and evolving educational tools for developing surgical skills. In particular, virtual and hybrid simulators are preferred due to their detailedness, customization and evaluation capabilities. To accelerate the revolution of a novel class of hybrid simulators, a Smart Artificial Soft Tissue is presented here, that determines the relative position of conductive surgical instruments in artificial soft tissue by inverse resistance mappings without the need for a fixed reference point.

Mechanical and morphometric characterization of custom-made trabecular bone surrogates.

Synthetic bones for biomechanical testing and surgeon training have become more important due to their numerous advantages compared to human bones. Several bone models are already available on the market, but most of them do not reflect the full range of versatile properties that characterize human bone like population-level influences, size, stiffness, bone-implant-interface or morphometry. Thus, the objectives of this study were to develop synthetic trabecular bone surrogates from polyurethane and varying additives and to determine their elastic and plastic mechanical compressive and additionally morphometric properties.

Three internal fixation methods for Danis-Weber-B distal fibular fractures: A biomechanical comparison in an osteoporotic fibula model.

A common agreement for the surgical treatment of osteoporotic ankle fractures has not been defined yet although locking plates are preferred for fractures with poor bone quality. This study aims to evaluate the mechanical stability of locked and conventional plates on osteoporotic Danis-Weber-B-fibula fracture models. Fractured custom-made osteoporotic fibulae were treated with neutralization plate plus lag screw, locking plate plus lag screw, or a standalone locking plate.

Biomechanical models: key considerations in study design.

This manuscript summarizes presentations of a symposium on key considerations in design of biomechanical models at the 2019 Basic Science Focus Forum of the Orthopaedic Trauma Association. The first section outlines the most important characteristics of a high-quality biomechanical study. The second section considers choices associated with designing experiments using finite element modeling versus synthetic bones versus human specimens.

Custom-made polyurethane-based synthetic bones mimic screw cut-through of intramedullary nails in human long bones.

Intramedullary nails are considered the gold standard for the treatment of tibial shaft fractures. Thereby, the screw-bone interface is considered the weakest link. For biomechanical evaluation of osteosyntheses synthetic bones are often used to overcome the disadvantages of human specimens.

The role of mechanical stimulation in the enhancement of bone healing.

The biomechanical environment plays a dominant role in the process of fracture repair. Mechanical signals control biological activities at the fracture site, regulate the formation and proliferation of different cell types, and are responsible for the formation of connective tissues and the consolidation of the fractured bone. The mechanobiology at the fracture site can be easily manipulated by the design and configuration of the fracture fixation construct and by the loading of the extremity (weight-bearing prescription).

Characterization of tissue properties in epidural needle insertion on human specimen and synthetic materials.

The force experienced while inserting an 18-gauge Tuohy needle into the epidural space or dura is one of only two feedback components perceived by an anaesthesiologist to deduce the needle tip position in a patient's spine. To the best of the authors knowledge, no x-ray validated measurements of these forces are currently available to the public. A needle insertion force recording during an automated insertion of an 18-gauge Tuohy needle into human vertebral segments of four female donors was conducted.

Biomechanics of Osteoporotic Fracture Fixation.

Purpose Of Review: Fractures of osteoporotic bone in elderly individuals need special attention. This manuscript reviews the current strategies to provide sufficient fracture fixation stability with a particular focus on fractures that frequently occur in elderly individuals with osteoporosis and require full load-bearing capacity, i.e.

Development of open-cell polyurethane-based bone surrogates for biomechanical testing of pedicle screws.

Artificial bones made of polyurethane are frequently used as an alternative to human bone for biomechanical testing. However, the biomechanical characteristics of these materials are often not validated against those of human bones. Thus, synthetic bone surrogates reflecting procedure-specific biomechanical properties of human bones are necessary for reliable implant design and testing.

Bone surrogates provide authentic onlay graft fixation torques.

Onlay graft bone augmentation is a standard practice to restore the loss of height of the alveolar ridge following loss of a tooth. Cranial grafts, lifted from the parietal bone, are sandwiched and used to bridge the bony defect in the jaw by means of small screws. During the elevation of the covering gum and subsequent screw placement, care has to be taken in order to preserve underlying nerves.

Characterization of polyurethane-based synthetic vertebrae for spinal cement augmentation training.

Vertebral augmentation techniques are used to stabilize impacted vertebrae. To minimize intraoperative risks, a solid education of surgeons is desirable. Thus, to improve education of surgeons as well as patient safety, the development of a high-fidelity simulator for the surgical training of cement augmentation techniques was initiated.

Characterization of an artificial skull cap for cranio-maxillofacial surgery training.

Cranial grafts are favored to reconstruct skeletal defects because of their reduced resorption and their histocompatibility. Training possibilities for novice surgeons include the "learning by doing" on the patient, specimens or simulators. Although the acceptance of simulators is growing, the major drawback is the lack of validated bone models.

Procedure-Specific Validation of Artificial Vertebrae.

Objective: The development of a novel hybrid patient simulator was initiated to provide a safe training possibility for novice surgeons. Integrated artificial vertebrae should be able to realistically mimic the haptics of transpedicular vertebroplasty instrument insertion and pedicle screw placement. Therefore, new open-celled material compositions were developed, tested, and validated with reference to elderly human vertebrae.

Validation of a simulator for cranial graft lift training: Face, content, and construct validity.

Purpose: Surgical skills can be improved through practical exercise. The use of specimens, human as well as animal, or live animals for surgical training is limited due to ethical concerns. Drawbacks of simulators are costs, fidelity and creditibility.

Novel synthetic vertebrae provide realistic haptics for pedicle screw placement.

During vertebral surgery, misplaced pedicle screws can harm vital neural and vascular structures. Haptic distinction between cortical and cancellous bone structures is therefore essential for correct screw placement. This tactile experience during pedicle screw placement can be obtained by training on human or animal specimens even if expensive or ethically questionable.

Characterization of synthetic foam structures used to manufacture artificial vertebral trabecular bone.

Artificial materials reflecting the mechanical properties of human bone are essential for valid and reliable implant testing and design. They also are of great benefit for realistic simulation of surgical procedures. The objective of this study was therefore to characterize two groups of self-developed synthetic foam structures by static compressive testing and by microcomputed tomography.

Novel bone surrogates for cranial surgery training.

Parietal graft lifts are trained on human or animal specimens or are directly performed on patients without extensive training. In order to prevent harm to the patient resulting from fast rotating machinery tools, the surgeon needs to apply appropriate forces. Realistic haptics are essential to identify the varying parietal bone layers and to avoid a penetration of the brain.