The following paper talks about the dynamic modeling and control of robot manipulators using Hamilton’s equations in screw theory framework. difference between proposed work with diverse methods literature is ease obtaining laws directly screws co-screws, which considered modern robotics by authors. In addition, geometric algebra (GA) introduced as a simple iterative tool to obtain co-screws. O...

BACKGROUND The pullout strength of pedicle screws is influenced by many factors, including diameter of the screws, implant design, and augmentation with bone cement such as PMMA. In the present study, the pullout strength of an innovative fenestrated screw augmented with PMMA was investigated and was compared to unaugmented fenestrated, standard and dual outer diameter screw. METHODS Twenty f...

The ability of various screw types to stabilize depressed tibial plateau fractures was determined in a biomechanical study using a Sawbones model. Two sizes of both cancellous and cortical screws were evaluated for both supportfrom below and through the depressed fragment. As a general trend, cancellous bone screws provided a greater resistance to fragment displacement than cortical bone screws...

OBJECTIVE To present the clinical benefits of an instrument designed to facilitate removal of polyaxial screws during revision surgery. METHODS All polyaxial screws can be removed without additional materials or a large amount of debridement using our newly designed instrument. Forty-two screws were removed from five patients without any complications using this instrument. RESULTS We remov...

OBJECT Intraoperative imaging often does not provide adequate visualization to ensure safe placement of screws. Therefore, the authors investigated the accuracy of a freehand technique for placement of pars, pedicle, and intralaminar screws in C-2. METHODS Sixteen cadaveric specimens were instrumented freehand by 2 experienced cervical spine surgeons with either a pars or pedicle screw, and b...

STUDY DESIGN Six different techniques for atlantoaxial fixation were biomechanically compared in vitro by nondestructive testing. OBJECTIVE To evaluate the immediate three-dimensional stability of a new atlas claw combined with transarticular screws and alternative techniques for transarticular screw fixation in comparison with established techniques. SUMMARY OF BACKGROUND DATA Posterior tr...

Crossed Uncrossed Differentials (CUDs) have long been used as surrogate for the interhemispheric transfer time (IHTT). Evidence is presented that macular vision is the province of the major hemisphere, wherein all commands are initiated regardless of the laterality of the effectors of such commands. Using clinical and time-resolved data it is shown also that the above arrangement (i.e. neural h...

Current surgical treatment of idiopathic scoliosis involves the use of various segmental instrumentation. Various pedicle screws have allowed for improved correction. Although monoaxial screws have improved rotational control compared with polyaxial screws, their use may increase screw-bone interface or vertebral endplate forces if not inserted in an exactly straight trajectory. Uniaxial screws...

We investigated the effects of hydroxyapatite (HA) coating on the purchase of pedicle screws. A total of 23 consecutive patients undergoing lumbar fusion was randomly assigned to one of three treatment groups. The first received uncoated stainless-steel screws, the second screws which were partly coated with HA, and the third screws which were fully coated. The insertion torque was recorded. Af...

The effects of baking on the mechanical properties and fracture characteristics of low-carbon boron (10B21) steel screws were investigated. Fracture torque tests and hydrogen content analysis were performed on baked screws to evaluate hydrogen embrittlement (HE) susceptibility. The diffusible hydrogen content within 10B21 steel dominated the fracture behavior of the screws. The fracture torque ...