Broken screws after interlocking nailing of long bones are commonly seen in Orthopaedic practice. Removal of such screws can be difficult particularly the distal part which is often held within the bone. We describe a simple technique of using Steinman pin to aid removal of broken screws in a case of non-union fracture tibia with broken interlocking nail and screws. Steinman pin being easily av...

In this article, the notions of non-abelian tensor and exterior products of two normal crossed submodules of a given crossed module of groups are introduced and some of their basic properties are established. In particular, we investigate some common properties between normal crossed modules and their tensor products, and present some bounds on the nilpotency class and solvability length of the...

STUDY DESIGN Biomechanical and histologic analysis. OBJECTIVE To compare the strength of the bone-screw interface of standard uncoated pedicle screws with screws treated with hydroxyapatite (HA), titanium plasma spray (TPS), and a composite HA-TPS coating. SUMMARY OF BACKGROUND DATA Transpedicular screw fixation has become the gold standard in the treatment of various thoracolumbar spinal c...

STUDY DESIGN A biomechanical spine model was used to evaluate the impact of screw design on screw-vertebra interface loading during simulated surgical corrections of adult scoliosis. OBJECTIVES To evaluate differences in screw-vertebra interface forces during adult scoliosis correction between favored angle (FA) screws with extension tabs and standard polyaxial screws while varying deformity ...

BACKGROUND Loosening of screws is a common problem in orthopedic and maxillofacial surgery. Modifying the implant surface to improve the mechanical strength of screws has been tried and reported. We developed screws coated with fibroblast growth factor-2 (FGF-2)-apatite composite layers. We then showed, in a percutaneous external fixation model, that this composite layer had the ability to hold...

STUDY DESIGN An in vitro biomechanical comparison of four posterior fixation techniques in the setting of an anterior lumbar interbody fusion (ALIF). OBJECTIVE To compare the initial stability, in terms of range of motion and neutral zone, provided by pedicle screws, facet screws, translaminar facet screws, and H-graft plus interspinous cables in the presence of an anteriorly placed femoral r...

background & aims: thuracolumbar unstable fractures (t, l.u.f) are common after spine truma. posterior pedicular fixation is a technique that is use for fixation of these fractures. this study evaluates the accuracy of pedicular screw placement in t, luf with the assistance of plain radiography in operation rooms. materials & methods: this study is a case-control and analytical study. 35 patien...

Cancellous screws are designed to optimize fixation in metaphyseal bone environments; however, certain clinical situations may require the substitution of cortical screws for use in cancellous bone, such as anatomic constraints, fragment size, or available instrumentation. This study compares the biomechanical properties of commercially available cortical and cancellous screw designs in a synth...

Expansive pedicle screws significantly improve fixation strength in osteoporotic spines. However, the previous literature does not adequately address the effects of the number of lengthwise slits and the extent of screw expansion on the strength of the bone/screw interface when expansive screws are used with or without cement augmentation. Herein, four designs for expansive pedicle screws with ...

BACKGROUND The use of pedicle screws is the gold standard for supplemental posterior fixation in lateral interbody fusion. Information about the performance of transfacet pedicle screws compared to standard pedicle screws and rods in the upper lumbar spine with or without a lateral interbody fusion device in place is limited. METHODS Fifteen fresh frozen human cadaveric lumbar spine segments ...