Pedicle screw pullout testing in osteoporotic and control human cadaveric vertebrae, comparing augmented vertebrae.To compare the strengths of pedicle screws fixed vertebrae using polymethyl methacrylate delivered by 2 augmentation techniques, a standard transpedicular approach kyphoplasty type approach.Pedicle instrumentation spine carries an increased risk loosening, pullout, fixation failure. Osteoporosis is often cited as contraindication for fixation. Augmentation vertebral body may...

A biomechanical study was conducted to assess the stabilization performance of transfacet pedicle screw fixation.To compare effects short-term and long-term cyclic loading on lumbar motion segments instrumented with either a or construct.Facet fixation is an alternative that permits use minimally invasive strategy. It not known whether facet can provide stability equivalent during cyclical loading. Therefore, standard techniques were compared biomechanically.Lumbar tested under conditions....

Object Minimally invasive pedicle screws inserted vertically (that is, dorsoventrally) through the pedicle, as opposed to more common coaxial technique, offer potential advantages by minimizing soft-tissue stripping during screw placement. The are designed for insertion a medial starting point with vertical trajectory and into vertebral body. As such, no lateral dissection beyond is necessary. However, effects of this technique on biomechanical performance over short- long-term unknown....

Cadaveric biomechanical study.To determine fatigue behavior of cortical bone trajectory (CBT) pedicle screws.Cortical screws have been becoming popular in spine surgery; however, the long-term new CBT remains understudied and limitations not well defined.Twelve vertebrae from six cadaveric lumbar spines were obtained. After mineral density (BMD) measurements, each vertebral body was instrumented with group, that is, (4.5 × 25 mm) or standard screw (6.5 55 mm). A load (± 4 Nm sagittal...

This article reports the degradation and biological properties of as-drawn Mg–4Zn–1Sr (designated as ZSr41) pure Mg (P–Mg) wires bioresorbable intramedullary pins for bone repair. Specifically, their cytocompatibility with marrow derived mesenchymal stem cells (BMSCs) in vitro, effects on peri-implant tissues vivo rat tibiae were studied. The ZSr41 showed a significantly faster than P–Mg vitro vivo. average daily rates both greater respective rates, likely because site implantation is highly...

Jefferson's fracture, first described in 1927, represents a bursting fracture of the C1 ring with lateral displacement masses. It has been determined that if total mass (LMD) exceeds 6.9 mm, there is high likelihood transverse atlantal ligament (TAL) rupture, and LMD less than 5.7 mm TAL injury unlikely. Several recent radiographic studies have questioned accuracy validity "rule Spence" it lacks biomechanical support.To determine amount necessary for failure using modern techniques.Using...

Background: Common suture configuration techniques used for ligament and tendon grafts repair are the Krackow locking stitch a nonlocking loop stitch, such as whipstitch. Clinically, preferences of orthopaedic surgeons vary. Hypothesis: The whipstitch, with varying loops, produce different biomechanical physical effects on end. Study Design: Controlled laboratory study. Methods: A total 52 fresh-frozen porcine flexor digitorum tendons were assigned into 10 groups. Two configurations (Krackow...

Cortical bone drilling for preparation of screw placement is common in multiple surgical fields. The heat generated while may reach thresholds high enough to cause osteonecrosis. This can compromise implant stability. Orthopaedic drill bits are several orders more expensive than their similarly sized, publicly available industrial counterparts. We hypothesize that an bit will generate less during drilling, and the not after cortical passes.We compared 4 4.0 mm orthopaedic 1 3.97 bits. Three...

In Brief Study Design. vitro biomechanical comparison of transarticular facet screws to lateral mass plates in two level instrumentations the cervical spine. Objective. Lateral are costly, and screw placement is difficult. Facet have never been tested as an alternative This study compared two-level human cadaveric spines. Summary Background Data. Translaminar shown similar performance pedicle fixation lumbar spine, especially flexion. They proven be fast, safe, effective, with authors...

In Brief Study Design. Investigation on architecture of lumbar pedicle. Objective. To determine morphological properties pedicular cancellous bone. Summary Background Data. Many researchers have been stimulated to study trabecular by improvements in stereological technology. Although the structure vertebral bone has well studied literature, no information is available about Methods. Eight cadaveric L3 vertebrae were harvested. After colleting mineral density (BMD) data vertebrae, pedicle...

The initial fixation strength of pedicle screws is commonly tested using a standard pull-out test with load applied at constant rate. This method overlooks the cyclic nature in situ loading responsible for clinical failure. study was undertaken to determine effects stress relaxation properties bone-screw interface on screw strength. Pedicle were inserted into calf lumbar vertebrae paired testing array. After embedding and mounting custom fixture, axial tests performed rates 1, 5, 25 mm/min....

The goal of this study was to investigate the effect ligament failure on instantaneous center rotation (ICR) in lower lumbar spine.A 3D finite element model L4-5 segment obtained and validated. Ligament simulated by reducing ligaments a stepwise manner from posterior anterior. A pure bending moment 7.5 Nm applied 3 anatomical planes for purpose validation, 6-Nm analyze failure. For each loading case, reduction step, load increment, range motion ICR mobile (L-4) vertebra were calculated...

Cortical screw (CS) fixation has been recently proposed as an alternative to the standard pedicle (PS) technique. Biomechanical studies involving individual pullout and single level motion segment stabilization showed comparable performance of both techniques. However, whether this new technique can be applied multilevel lumbar segments with significant destabilization unclear.To compare stability CS traditional PS in unstable 3 spondylolisthesis model.This is a biomechanical study comparing...

Objectives: The objectives of this study were (1) to compare the axial and torsional stiffness a dynamic hip screw with two- four-hole side-plate in synthetic model healed stable intertrochanteric femur fracture (2) evaluate load failure, as well propensity peri-implant fracture. Methods: Fourth-generation composite models, simulating osteoporotic bone, implanted 135° screws (DHS) either or without Specimens cyclically loaded up nondestructive determine stiffness. Constructs then failure...

Object The center (axis) of rotation (COR) in the lumbar spine has been studied well. However, there is limited information on kinetic and kinematic consequences imposed shift location COR, although this type can be seen after surgeries using motion preservation or dynamic stabilization devices. objective study was to assess changes spinal segment due various CORs. Methods A 3D finite element model L4–5 constructed validated. loaded under a 7.5-Nm bending moment while constrained rotate...

Object Although the gross anatomy of pedicle in human spine has been investigated great detail, knowledge microanatomy trabecular and cortical structures is limited. An understanding mechanical properties structure bone essential for improving quality screw placement. To enhance this understanding, authors examined cadaveric lumbar vertebrae. Methods In study, obtained seven The lateral medial cortices these specimens were sectioned embedded polymethylmethacrylate. Cross-sectional slices...