Robotics in Neurosurgery: Evolution, Current Challenges, and Compromises.

Background: Advances in technology have pushed the boundaries of neurosurgery. Surgeons play a major role in the neurosurgical field, but robotic systems challenge the current status quo. Robotic-assisted surgery has revolutionized several surgical fields, yet robotic-assisted neurosurgery is limited by available technology.

The current testing protocols for biomechanical evaluation of lumbar spinal implants in laboratory setting: a review of the literature.

In vitro biomechanical investigations have become a routinely employed technique to explore new lumbar instrumentation. One of the most important advantages of such investigations is the low risk present when compared to clinical trials. However, the best use of any experimental data can be made when standard testing protocols are adopted by investigators, thus allowing comparisons among studies.

Balancing rigidity and safety of pedicle screw fixation via a novel expansion mechanism in a severely osteoporotic model.

Many successful attempts to increase pullout strength of pedicle screws in osteoporotic bone have been accompanied with an increased risk of catastrophic damage to the patient. To avoid this, a single-armed expansive pedicle screw was designed to increase fixation strength while controlling postfailure damage away from the nerves surrounding the pedicle. The screw was then subsequently tested in two severely osteoporotic models: one representing trabecular bone (with and without the presence of polymethylmethacrylate) and the other representing a combination of trabecular and cortical bone.

Biomechanical comparison of an interspinous fusion device and bilateral pedicle screw system as additional fixation for lateral lumbar interbody fusion.

Background: This investigation compares an interspinous fusion device with posterior pedicle screw system in a lateral lumbar interbody lumbar fusion.

Methods: We biomechanically tested six cadaveric lumbar segments (L1-L2) under an axial preload of 50N and torque of 5Nm in flexion-extension, lateral bending and axial rotation directions. We quantified range of motion, neutral zone/elastic zone stiffness in the following conditions: intact, lateral discectomy, lateral cage, cage with interspinous fusion, and cage with pedicle screws.

Designs and techniques that improve the pullout strength of pedicle screws in osteoporotic vertebrae: current status.

Osteoporosis is a medical condition affecting men and women of different age groups and populations. The compromised bone quality caused by this disease represents an important challenge when a surgical procedure (e.g.

Spinal neoplastic instability: biomechanics and current management options.

Background: Often the spine is afflicted from primary or metastatic neoplastic disease, which can lead to instability. Instability can cause deformity, pain, and spinal cord compression and is an indication for surgery. Although overt instability is uniformly agreed upon, it is sometimes difficult for specialists to agree on subtle degrees of instability due to lack of objective criteria.

In vitro evaluation of a lateral expandable cage and its comparison with a static device for lumbar interbody fusion: a biomechanical investigation.

Object: Through in vitro biomechanical testing, the authors compared the performance of a vertically expandable lateral lumbar interbody cage (EC) under two different torque-controlled expansions (1.5 and 3.0 Nm) and with respect to an equivalent lateral lumbar static cage (SC) with and without pedicle screw fixation.

Axial rotation mechanics in a cadaveric lumbar spine model: a biomechanical analysis.

Background Context: Postoperative patient motions are difficult to directly control. Very slow quasistatic motions are intuitively believed to be safer for patients, compared with fast dynamic motions, because the torque on the spine is reduced. Therefore, the outcomes of varying axial rotation (AR) angular loading rate during in vitro testing could expand the understanding of the dynamic behavior and spine response.

Biomechanical analysis of an interspinous fusion device as a stand-alone and as supplemental fixation to posterior expandable interbody cages in the lumbar spine.

Object: In this paper the authors evaluate through in vitro biomechanical testing the performance of an interspinous fusion device as a stand-alone device, after lumbar decompression surgery, and as supplemental fixation to expandable cages in a posterior lumbar interbody fusion (PLIF) construct.

Methods: Nine L3-4 human cadaveric spines were biomechanically tested under the following conditions: 1) intact/control; 2) L3-4 left hemilaminotomy with partial discectomy (injury); 3) interspinous spacer (ISS); 4) bilateral pedicle screw system (BPSS); 5) bilateral hemilaminectomy, discectomy, and expandable posterior interbody cages with ISS (PLIF-ISS); and 6) PLIF-BPSS. Each test consisted of 100 N of axial preload with ± 7.

Feasibility and biomechanical performance of a novel transdiscal screw system for one level in non-spondylolisthetic lumbar fusion: an in vitro investigation.

Background Context: The bilateral pedicle screw system (BPSS) is currently the "gold standard" fusion technique for spinal instability. A new stabilization system that provides the same level of stability through a less invasive procedure will have a high impact on clinical practice. A new transdiscal screw system is investigated as a promising minimally invasive device.

Biomechanical comparison of a two-level anterior discectomy and a one-level corpectomy, combined with fusion and anterior plate reconstruction in the cervical spine.

Background: Common fusion techniques for cervical degenerative diseases include two-level anterior discectomy and fusion and one-level corpectomy and fusion. The aim of the study was to compare via in-vitro biomechanical testing the effects of a two-level anterior discectomy and fusion and a one-level corpectomy and fusion, with anterior plate reconstruction.

Methods: Seven fresh frozen human cadaveric spines (C3-T1) were dissected from posterior musculature, preserving the integrity of ligaments and intervertebral discs.

Comparative analysis of posterior fusion constructs as treatments for middle and posterior column injuries: an in vitro biomechanical investigation.

Background: Titanium pedicle screw-rod instrumentation is considered a standard treatment for spinal instability; however, the advantages of cobalt-chromium over titanium is generating interest in orthopedic practice. The aim of this study was to compare titanium versus cobalt-chromium rods in posterior fusion through in vitro biomechanical testing.

Methods: Posterior and middle column injuries were simulated at L3-L5 in six cadaveric L1-S1 human spines and different pedicle screw constructs were implanted.