Rod fractures in thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis: long-term follow-up of a prospective, multicenter cohort of 160 patients.

Objective: Previous reports of rod fracture (RF) in adult spinal deformity are limited by heterogeneous cohorts, low follow-up rates, and relatively short follow-up durations. Since the majority of RFs present > 2 years after surgery, true occurrence and revision rates remain unclear. The objectives of this study were to better understand the risk factors for RF and assess its occurrence and revision rates following primary thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis (ASLS) in a prospective series with long-term follow-up.

Proximal junctional failure in primary thoracolumbar fusion/fixation to the sacrum/pelvis for adult symptomatic lumbar scoliosis: long-term follow-up of a prospective multicenter cohort of 160 patients.

Objective: Proximal junctional failure (PJF) is a severe form of proximal junctional kyphosis. Previous reports on PJF have been limited by heterogeneous cohorts and relatively short follow-ups. The authors' objectives herein were to identify risk factors for PJF and to assess its long-term incidence and revision rates in a homogeneous cohort.

The impact of lumbar alignment targets on mechanical complications after adult lumbar scoliosis surgery.

Purpose: The purpose of this study was to determine the discriminatory ability of age-adjusted alignment offset and the global alignment and proportion (GAP) score parameters to predict postoperative mechanical complications.

Methods: Surgical patients from the Adult Symptomatic Lumbar Scoliosis cohort were reviewed at 2 year follow up. Age-adjusted alignment offsets and GAP parameters were calculated for each patient.

A Novel Weave Tether Technique for Proximal Junctional Kyphosis Prevention in 71 Adult Spinal Deformity Patients: A Preliminary Case Series Assessing Early Complications and Efficacy.

Background: Proximal junctional kyphosis (PJK) rates may be as high as 69.4% after adult spinal deformity (ASD) surgery. PJK is one of the greatest unsolved challenges in long-segment fusions for ASD and remains a common indication for costly and impactful revision surgery.

Contribution of Neural Elements to Thoracic Stability.

Aim: Studies of spinal biomechanics typically do not focus on the contributions to range of motion (ROM) of the primary components of the spinal canal, dura, arachnoid, pia, spinal cord, nerve roots, ligaments, and vessels. We sought to determine the stability offered by these soft tissues in vitro.

Material And Methods: Human cadaveric segments were tested intact, after osteoligamentous destabilization, and after transection of T8-9 spinal canal components.

Biomechanics of dynamic rod segments for achieving transitional stiffness with lumbosacral fusion.

Background: Transitioning from rigid to flexible hardware at the distal rostral or caudal lumbar or lumbosacral level hypothetically maintains motion at the transition level and protects the transition level and intact adjacent levels from stresses caused by fusion.

Objective: To biomechanically compare transitional and rigid constructs with uninstrumented specimens in vitro.

Methods: Human cadaveric L2-S1 segments were tested (1) intact, (2) after L5-S1 rigid pedicle screw-rod fixation, (3) after L4-S1 rigid pedicle screw-rod fixation, and (4) after hybrid fixation rigidly spanning L5-S1 and dynamically spanning L4-L5.

Characteristics of immediate and fatigue strength of a dual-threaded pedicle screw in cadaveric spines.

Background Context: Novel dual-threaded screws are configured with overlapping (doubled) threads only in the proximal shaft to improve proximal cortical fixation.

Purpose: Tests were run to determine whether dual-threaded pedicle screws improve pullout resistance and increase fatigue endurance compared with standard pedicle screws.

Study Design/setting: In vitro strength and fatigue tests were performed in human cadaveric vertebrae and in polyurethane foam test blocks.

Biomechanical contribution of the rib cage to thoracic stability.

Study Design: In vitro assessment of rib cage biomechanics in the region of true ribs with the ribs intact then sequentially resected in 5 steps.

Objective: To determine the contribution of the rib cage to thoracic spine stability and kinematics.

Summary Of Background Data: Previous in vitro studies of rib cage biomechanics have used animal spines or human cadaveric spines with ribs left unsecured, limiting the ability of the ribs to contribute to stability.

Analysis of in vivo kinematics of 3 different cervical devices: Bryan disc, ProDisc-C, and Prestige LP disc.

Object: Cervical arthroplasty has emerged as a means of preventing adjacent segment disease by preserving motion, restoring sagittal balance, and mimicking natural spinal kinematics. The purpose of this retrospective in vivo study was to characterize the impact of arthroplasty on sagittal balance and segmental kinematics of the cervical spine.

Methods: Sixty patients receiving the Bryan disc, ProDisc-C, or Prestige LP disc were retrospectively analyzed.

Biomechanics of thoracic short versus long fixation after 3-column injury.

Object: Posterior screw-rod fixation for thoracic spine trauma usually involves fusion across long segments. Biomechanical data on screw-based short-segment fixation for thoracic fusion are lacking. The authors compared the effects of spanning short and long segments in the thoracic spine.

Stabilization of the atlantoaxial joint with C1-C3 lateral mass screw constructs: biomechanical comparison with standard technique.

Background: Anatomically and biomechanically, the atlantoaxial joint is unique compared with the remainder of the cervical spine.

Objective: To assess the in vitro stability provided by 2 C2 screw sparing techniques in a destabilized model of the atlantoaxial joint and compare with the gold standard system.

Methods: The 3-dimensional intervertebral motion of 7 human cadaveric cervical spine specimens was recorded stereophotogrammetrically while applying nonconstraining, nondestructive pure moments during flexion-extension, left and right axial rotation, and left and right lateral bending.

Biomechanical evaluation of posterior thoracic transpedicular discectomy.

Object: The authors investigated the biomechanical properties of transpedicular discectomy in the thoracic spine and compared the effects on spinal stability of a partial and total facetectomy.

Methods: Human thoracic specimens were tested while intact, after a transpedicular discectomy with partial facetectomy, and after an additional total facetectomy was incorporated. Nonconstraining pure moments were applied under load control (maximum 7.

Effect of arthroplasty design on cervical spine kinematics: analysis of the Bryan Disc, ProDisc-C, and Synergy disc.

Object: Cervical total disc replacement has emerged as a surgical option to preserve motion and potentially avoid adjacent-segment disease after anterior cervical discectomy and fusion. Recently, much attention has been directed at the ability of a given device to maintain and/or restore normal segmental alignment. Nonphysiological disc and segmental angulation could result in increased stresses transmitted to the facet joints and posterior elements, conflicting with the essence of arthroplasty and potentially leading to adjacent-segment disease.

Quantitative analysis of misplaced pedicle screws in the thoracic spine: how much pullout strength is lost?: presented at the 2009 Joint Spine Section Meeting.

Object: The object of this study was to investigate the effects of iatrogenic pedicle perforations from screw misplacement on the mean pullout strength of thoracic pedicle screws.

Methods: Forty human thoracic vertebrae (T6-11) from human cadavers were studied. Before pedicle screws were inserted, the specimens were separated into 4 groups according to the type of screw used: 1) standard pedicle screw (no cortical perforation); 2) screw with medial cortical perforation; 3) screw with lateral cortical perforation; and 4) "airball" screw (a screw that completely missed the vertebral body).

Biomechanical comparison of costotransverse process screw fixation and pedicle screw fixation of the upper thoracic spine.

Objective: To compare the biomechanics of costotransverse process screw fixation with those of pedicle screw fixation in a cadaveric model of the upper thoracic spine.

Methods: Ten human thoracic spines were instrumented across the T3-T4 segment with costotransverse and pedicle screws. Nonconstraining pure moments (maximum, 6.

Biomechanics of a novel minimally invasive lumbar interspinous spacer: effects on kinematics, facet loads, and foramen height.

Objective: To study the alteration to normal biomechanics after insertion of a lumbar interspinous spacer (ISS) in vitro by nondestructive cadaveric flexibility testing.

Methods: Seven human cadaveric specimens were studied before and after ISS placement at L1-L2. Angular range of motion, lax zone, stiff zone, sagittal instantaneous axis of rotation (IAR), foraminal height, and facet loads were compared between conditions.

Tectal plate tumors.

Tectal plate is a rare location for a tumor. Many papers have described different types of pathology arising in that location including tumors, vascular lesions, inflammatory and infectious processes. In this paper we describe our experience in treating seven patients with tectal plate lesions, with different ages and types of pathology: five patients presented with low grade gliomas, one with lung cancer metastasis and the last presenting with a tectal plate cavernoma.

Remote hemorrhage from the site of craniotomy.

Postoperative intracranial hemorrhage is a serious and sometimes a fatal neurosurgical complication. Hemorrhage occurring at regions remote from the site of intracranial operations comprises an uncommon affection, most ignored by the assistant physicians. It bares a still incomprehensive pathophysiology, despite several theories trying to explain it.

Surgical management of cerebrospinal fluid rhinorrhea under endoscopic control.

The surgical management of cerebrospinal fluid (CSF) rhinorrhea has changed after the introduction of functional endoscopic sinus surgery.The following three cases illustrate the repair of CSF leaks with the use of rigid endoscope. Two patients had the diagnosis and the site confirmed after intrathecal fluoresceine saline injection.

Malignant paraganglioma with vertebral metastasis: case report.

A paraganglioma is a rare tumor, composed of chromaffin cells, groups of cells associated to the autonomous system. When the tumor occurs in the adrenal gland, it is called pheochromocitoma. The malignant paraganglioma is a very rare presentation; it is diagnosed by local recurrence after total resection of the primary mass, or findings of distant metastases.