A comprehensive finite element model of surgical treatment for cervical myelopathy.

Background: Cervical myelopathy is a common and debilitating chronic spinal cord dysfunction. Treatment includes anterior and/or posterior surgical intervention to decompress the spinal cord and stabilize the spine, but no consensus has been made as to the preferable surgical intervention. The objective of this study was to develop an finite element model of the healthy and myelopathic C2-T1 cervical spine and common anterior and posterior decompression techniques to determine how spinal cord stress and strain is altered in healthy and diseased states.

Biomechanical Analysis of the Cervical Spine Following Disc Degeneration, Disc Fusion, and Disc Replacement: A Finite Element Study.

Background: Discectomy and fusion is considered the "gold standard" treatment for clinical manifestations of degenerative disc disease in the cervical spine. However, clinical and biomechanical studies suggest that fusion may lead to adjacent-segment disease. Cervical disc arthroplasty preserves the motion at the operated level and may potentially decrease the occurrence of adjacent segment degeneration.

Measurement of in vivo spinal cord displacement and strain fields of healthy and myelopathic cervical spinal cord.

Objective: Cervical myelopathy (CM) is a common and debilitating form of spinal cord injury caused by chronic compression; however, little is known about the in vivo mechanics of the healthy spinal cord during motion and how these mechanics are altered in CM. The authors sought to measure 3D in vivo spinal cord displacement and strain fields from MR images obtained during physiological motion of healthy individuals and cervical myelopathic patients.

Methods: Nineteen study participants, 9 healthy controls and 10 CM patients, were enrolled in the study.

Electrospun PLGA and β-TCP (Rebossis-85) in a Lapine Posterolateral Fusion Model.

Background: Calcium phosphate materials have been employed clinically as bone void fillers for several decades. These materials are most often provided in the form of small, porous granules that can be packed to fill the wide variety of size and shape of bony defects encountered. ReBOSSIS-85 (RB-85) is a synthetic bioresorbable bone void filler for the repair of bone defects with handling characteristics of glass wool-like (or cotton ball-like).

Biomechanical assessment of proximal junctional semi-rigid fixation in long-segment thoracolumbar constructs.

OBJECTIVEProximal junctional kyphosis (PJK) and failure (PJF) are potentially catastrophic complications that result from abrupt changes in stress across rigid instrumented and mobile non-fused segments of the spine (transition zone) after adult spinal deformity surgery. Recently, data have indicated that extension (widening) of the transitional zone via use of proximal junctional (PJ) semi-rigid fixation can mitigate this complication. To assess the biomechanical effectiveness of 3 semi-rigid fixation constructs (compared to pedicle screw fixation alone), the authors performed cadaveric studies that measured the extent of PJ motion and intradiscal pressure changes (ΔIDP).

Volume of Brain Herniation After Decompressive Craniectomy in Patients with Traumatic Brain Injury.

Background: The decompressive hemicraniectomy operation is highly effective in relieving refractory intracranial hypertension. However, one limitation of this treatment strategy is the requirement to perform a subsequent cranioplasty operation to reconstruct the skull defect-an expensive procedure with high complication rates. An implant that is capable of accommodated post-hemicraniectomy brain swelling, but also provides acceptable skull defect coverage after brain swelling abates, would theoretically eliminate the need for the cranioplasty operation.

Survey of the functional priorities in patients with disability due to neuromuscular disorders.

Title: Survey of the functional priorities in patients with disability due to neuromuscular disorders.

Objective: This study attempts to determine the functional priorities for patients with neuromuscular disorders.

Methods: A survey asking about functional priorities with respect to activities of daily living, ankle foot orthotic design, and assistive device design, was distributed to patients with neuromuscular disorders to assess the needs of patients from their perspectives.

Finite Element Analysis of Patella Alta: A Patellofemoral Instability Model.

Background: This study aims to provide biomechanical data on the effect of patella height in the setting of medial patellofemoral ligament (MPFL) reconstruction using finite element analysis. The study will also examine patellofemoral joint biomechanics using variable femoral insertion sites for MPFL reconstruction.

Methods: A previously validated finite element knee model was modified to study patella alta and baja by translating the patella a given distance to achieve each patella height ratio.

Effect of Surgery on Gait and Sensory Motor Performance in Patients With Cervical Spondylotic Myelopathy.

Background: Cervical spondylotic myelopathy (CSM) is a common disease of aging that leads to gait instability resulting from loss of leg sensory and motor functions. The results of surgical intervention have been studied using a variety of methods, but no test has been reported that objectively measures integrative leg motor sensory functions in CSM patients.

Objective: To determine the feasibility of using a novel single leg squat (SLS) test to measure integrative motor sensory functions in patients with CSM before and after surgery.

Volume of Brain Herniation in Patients with Ischemic Stroke After Decompressive Craniectomy.

Background: Decompressive craniectomy procedures are performed in patients with malignant intracranial hypertension. A bone flap is removed to relieve pressure. Later, a second operation is performed to reconstruct the skull after brain swelling has resolved.

Comparison of Two Synthetic Bone Graft Products in a Rabbit Posterolateral Fusion Model.

Background: The drawbacks of iliac crest autograft as graft material for spine fusion are well reported. Despite continued modifications to improve bone healing capacity, the efficacy of synthetic graft materials as stand-alone replacements remains uncertain. The rabbit posterolateral fusion model is an established environment for testing of fusion concepts.

Effects of brain derived neurotrophic factor Val66Met polymorphism in patients with cervical spondylotic myelopathy.

Cervical spondylotic myelopathy (CSM) is the leading cause of spinal cord related disability in the elderly. It results from degenerative narrowing of the spinal canal, which causes spinal cord compression. This leads to gait instability, loss of dexterity, weakness, numbness and urinary dysfunction.

From Finite Element Meshes to Clouds of Points: A Review of Methods for Generation of Computational Biomechanics Models for Patient-Specific Applications.

It has been envisaged that advances in computing and engineering technologies could extend surgeons' ability to plan and carry out surgical interventions more accurately and with less trauma. The progress in this area depends crucially on the ability to create robustly and rapidly patient-specific biomechanical models. We focus on methods for generation of patient-specific computational grids used for solving partial differential equations governing the mechanics of the body organs.

A Finite Element Analysis of Medial Patellofemoral Ligament Reconstruction.

Background: The medial patellofemoral ligament is the primary soft-tissue restraint to lateral patella translation. Medial patellofemoral ligament reconstruction has become a viable surgical option to provide patellar stability in patients with recurrent instability. The primary goal of this study was to determine the effect of medial patellofemoral ligament reconstruction on the lateral force-displacement behavior of the patella using finite element analyses.

Biomechanical Analysis of Cervical Disc Replacement and Fusion Using Single Level, Two Level, and Hybrid Constructs.

Study Design: A biomechanical study comparing arthroplasty with fusion using human cadaveric C2-T1 spines.

Objective: To compare the kinematics of the cervical spine after arthroplasty and fusion using single level, 2 level and hybrid constructs.

Summary Of Background Data: Previous studies have shown that spinal levels adjacent to a fusion experience increased motion and higher stress which may lead to adjacent segment disc degeneration.

Vertebroplasty plus short segment pedicle screw fixation in a burst fracture model in cadaveric spines.

The current project investigates the role of vertebroplasty in supplementing short segment (SS) posterior instrumentation, only one level above and below a fracture. In the treatment of thoracolumbar burst fractures, long segment (LS) posterior instrumentation two levels above and below the fracture level has been used. In our study, burst fractures were produced at L1 in eight fresh frozen human cadaveric spines.

The effect of multi-level laminoplasty and laminectomy on the biomechanics of the cervical spine: a finite element study.

Laminectomy has been regarded as a standard treatment for multi-level cervical stenosis. Concern for complications such as kyphosis has limited the indication of multi-level laminectomy; hence it is often augmented with an instrumented fusion. Laminoplasty has emerged as a motion preserving alternative.

Sheep cervical spine biomechanics: a finite element study.

Introduction: Animal models are often used to make the transition from scientific concepts to clinical applications. The sheep model has emerged as an important model in spine biomechanics. Although there are several experimental biomechanical studies of the sheep cervical spine, only a limited number of computational models have been developed.

Biomechanical analysis of anterior versus posterior instrumentation following a thoracolumbar corpectomy: Laboratory investigation.

Object: The objective of this study was to evaluate the biomechanical properties of lateral instrumentation compared with short- and long-segment pedicle screw constructs following an L-1 corpectomy and reconstruction with an expandable cage.

Methods: Eight human cadaveric T10-L4 spines underwent an L-1 corpectomy followed by placement of an expandable cage. The spines then underwent placement of lateral instrumentation consisting of 4 monoaxial screws and 2 rods with 2 cross-connectors, short-segment pedicle screw fixation involving 1 level above and below the corpectomy, and long-segment pedicle screw fixation (2 levels above and below).

Spinal motion and intradiscal pressure measurements before and after lumbar spine instrumentation with titanium or PEEK rods.

Spinal instrumentation and fusion have been incriminated as contributing to adjacent segment degeneration (ASD). It has been suggested that ASD results from increased range of motion and intradiscal pressure (IDP) adjacent to instrumentation. Posterior dynamic stabilization with polyetheretherketone (PEEK) rods has been proposed as potentially advantageous compared to rigid instrumentation with titanium (Ti) rods in reducing the incidence of ASD.

Biomechanical evaluation of medial patellofemoral ligament reconstruction.

Background: The medial patellofemoral ligament (MPFL) is the most frequently injured soft tissue structure following acute lateral patellar dislocation. MPFL reconstruction has become a popular option to restore patellar stability following lateral patellar dislocation due to the high incidence of recurrent instability following conservative management. Anatomic reconstruction of the MPFL minimizes graft length changes during full knee range of motion and restores patellar stability.

Assessment of BioPlex interbody fusion device in a sheep lumbar fusion model.

Objective: The purpose of this study was to evaluate the bioPlex bioresorbable interbody device in a sheep lumbar fusion model and compare it to the concorde, a standard carbon fiber interbody cage.

Background: Lumbar interbody fusion devices are made from a variety of materials, including titanium alloys, carbon-fiber, and PEEK. The BioPlex Continuous Phase Composite (CPC) is a unique bioresorbable material comprised of Pro Osteon 500R and 70:30 Poly (L/D, L-lactic acid).

Posterior ligamentous complex healing following disruption in thoracolumbar fractures.

Classification schemes for thoracolumbar fractures attempt to categorize them as either stable or unstable. Stable fractures heal with conservative treatment strategies such as bracing, while unstable fractures require operative internal fixation. Until recently, most classification schemes recognized the importance of the pattern and location of bony disruption in segregating stable and unstable fractures.

Considerations for the use of C7 crossing laminar screws in subaxial and cervicothoracic instrumentation.

Study Design: Radiographical and biomechanical analyses.

Objective: To determine the applicability of C7 laminar screw fixation using radiographical and biomechanical analysis.

Summary Of Background Data: The unique anatomy of C7 creates a challenge during instrumentation at the caudal aspect of the cervical spine and cervicothoracic junction.