Fernstrom spherical endoprostheses, utilized in the 1960s, may have been the first artificial discs implanted in humans. These were non-articulating, ball-bearinglike devices that replaced discs and preserved motion. In 1966, Fernstrom reported the use of these devices in the cervical, as well as the lumbar spine [1] (Fig 1). Modern cervical artificial disc replacement (C-ADR) first made its de...

Technological advances have made more options available for surgical intervention in spinal disorders. From spinal fusion to artificial disc implantation, these advancements have brought great benefits, allowing preservation of spinal motion and flexibility after intervertebral discectomy. Yet the use of artificial discs as a treatment for congenital spinal disorders has been documented in only...

We have performed Smoothed Particle Hydrodynamics (SPH) simulations to study the time evolution of one and two protoplanets embedded in a protoplanetary accretion disc. We investigate accretion and migration rates of a single protoplanet depending on several parameters of the protoplanetary disc, mainly viscosity and scale height. Additionally, we consider the influence of a second protoplanet ...

Background: Degenerative primary osteoarthritis is one of the commonest causes of pain in peripheral joints. This is commonly seen in the knee and hip joints. Replacement of these worn out joints is now the established treatment, which gives stable pain free mobile joints. Arthrodesis or fusion of worn out joints is now rarely performed. Degeneration of the intervertebral disc is a common cause...

The artificial disc is a mobile implant for degenerative disc replacement that attempts to lessen the degeneration of the adjacent elements. However, inconsistent biomechanical results for the neighboring elements have been reported in a number of studies. The present study used finite element (FE) analysis to explore the biomechanical differences at the surgical and both adjacent levels follow...

INTRODUCTION Artificial disc arthroplasty, as a promising treatment for disc degenerative diseases, has been reported to restore normal disc height, preserve segmental motion and decrease adjacent level degeneration. Despite its encouraging short term outcomes, complications related to device and surgical procedure such as subsidence, dislocation and instability due to misalignment warrant furt...

We investigate the evolution of angular momentum in Smoothed Particle Hydrodynamic (SPH) simulations of galaxy formation, paying particular attention to artificial numerical effects. We find that a cold gas disc forming in an ambient hot gas halo receives a strong hydrodynamic torque from the hot gas. By splitting the hydrodynamic force into artificial viscosity and pressure gradients, we find ...