BACKGROUND CONTEXT Achieving solid implant fixation to osteoporotic bone presents a clinical challenge. New techniques and devices are being designed to increase screw-bone purchase of pedicle screws in the lumbar spine via a novel cortical bone trajectory that may improve holding screw strength and minimize loosening. Preliminary clinical evidence suggests that this new trajectory provides scr...

PURPOSE Pullout strength of screws is a parameter used to evaluate plate screw fixation strength. However, screw fixation strength may be more closely related to its ability to generate sufficient insertion because stable nonlocked plate-screw fracture fixation requires sufficient compression between plate and bone such that no motion occurs between the plate and bone under physiological loads....

To evaluate the mechanical stress and elastic deformation exercised in the thread/shaft transition of Schanz screws in assemblies with different screw anchorage distances in the entrance to the bone cortex, through the distribution and location of tension in the samples. An analysis of 3D finite elements was performed to evaluate the distribution of the equivalent stress (triple stress state) i...

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...

OBJECTIVES To examine the application of bioabsorbable screws for anterior cervical decompression and bone grafting fixation and to study their clinical effects in the treatment of cervical spondylosis. METHODS From March 2007 to September 2012, 56 patients, 36 males and 20 females (38-79 years old, average 58.3±9.47 years), underwent a novel operation. Grafts were fixed by bioabsorbable scre...

The geometric optimization of orthopedic screws can considerably increase their orthopedic efficiency. Due to the high geometric parameters of orthopedic screws, a finite element simulation is an effective tool for analyzing and forecasting the effect of the parameters on the load-bearing capacity of different types of screws and bones. Thus, in the present study, the tensile strength of a typi...

BACKGROUND Conventional screws used for fracture fixation in orthopedic surgery continue to rely on the historic buttress thread design. While buttress screws generally provide solid resistance against unidirectional axial loading forces, their design suffers from several limitations, as the buttress thread does not adequately resist multiaxial forces. Furthermore, the buttress screw is prone t...

Aims: The present study is to evaluate the effect of internal fixation with cancellous bone screws in the treatment for femoral neck fractures. Methods: A total of 64 patients with femoral neck fractures hospitalized at our hospital from January 2014 to December 2014 were included in the present study. The 64 patients were randomly divided into Con group (internal fixation by thread needles; n ...

Careful treatment planning, space management, augmentation of bone and attention to the details of implant surgical and prosthetic techniques are important factors when treating anterior maxilla specially replacement of missing teeth. This case report addresses a chair-side ridge augmentation procedure using autograft bone harvested with trephine drills and placed without using screws and the f...

Robotic spine surgery systems, used for placing pedicle screws, have been in clinical use since 2004; however, these systems act only as a positioner guide tubes, which the surgeon uses to manually advance tools prepare site and place hardware (e.g., screws). This article presents development, operation, evaluation of new, commercial-robot-based, image-guided system that automates process bone ...