Computer-assisted frameless stereotactic image guidance allows precise preoperative planning and intraoperative localisation of the image. It has been developed and tested in the laboratory. We evaluated the efficacy, clinical results and complications of placement of a pedicle screw in the lumbar spine using this technique. A total of 62 patients (28 men, 34 women) had lumbar decompression and...

Vascular injury presented immediately after the penetration, but delayed onset of vascular symptom caused by an embolism or vessel dissection after cervical fusion or traumatic event is extremely rare. We present a case of a 56-year-old woman who underwent an operation for cervical fusion for type II Odontoid process fracture. She presented symptoms of seizure with hemiparesis in 6 days after t...

The aim of this study was to compare the interfragmentary compression generated across a simulated femoral fracture model by a conventional 4.5 mm AO/ASIF cortical lag screw with a differentially pitched cortical compression screw. A 45-degree osteotomy was made in a whole bone composite femoral shaft, this was internally fixed with either a conventional 4.5 mm AO/ASIF cortical lag screw or the...

Proximal humeral fractures are common injuries with increasing incidence, particularly in the aging population. Nondisplaced or minimally displaced fractures can be treated conservatively whereas surgical fixation is usually indicated in the cases of displaced fractures. Various surgical options have been used for treatment of these fractures. Good outcomes have been reported with use of the Pr...

BACKGROUND Efforts to select the appropriate number of implants in adolescent idiopathic scoliosis (AIS) instrumentation are hampered by a lack of biomechanical studies. The objective was to biomechanically evaluate screw density at different regions in the curve for AIS correction to test the hypothesis that alternative screw patterns do not compromise anticipated correction in AIS when using ...

there have been a number of developments in screw design and implantation techniques over recent years, including proposal of an alternative trajectory entitled as cortical bone trajectory (cbt). cortical bone trajectory has been investigated in recent medical treatments as an alternative for screw fixation aimed at increasing purchase of pedicle screws in higher density bone. cbt screw inserti...

STATEMENT OF PROBLEM Clinicians must know if a new screw can predictably increase reverse torque after multiple screw insertion cycles. PURPOSE The purpose of this study was (1) to compare the effect of multiple implant prosthetic screw insertion and removal cycles on reverse torque, (2) to determine whether a new screw, after multiple screw insertion cycles, affects reverse torque, and (3) t...

This paper studies the vectors of cofactors in a screw matrix assembled by n screws and investigates the properties and different arrangements of cofactors. An augmentation screw which is linearly independent of n screws in the screw matrix is proposed and is used to relate the vector of cofactors to a reciprocal screw and subsequently to the reciprocal screw system. The paper proposes a new al...

The recently discovered twist-bend nematic phase of achiral bent-shaped molecules, NTB, has a doubly degenerate ground-state with a periodically modulated heliconical structure and unusual distortion elasticity, the theoretical description of which is still debated. We show that the NTB phase has the same macroscopic symmetry as another periodic mesophase, the chiral smectic-A, SmA*. Based on t...