Development of a novel radiographic measure of lumbar instability and validation using the facet fluid sign.

Background: Lumbar spinal instability is frequently referenced in clinical practice and the scientific literature despite the lack of a standard definition or validated radiographic test. The Quantitative Stability Index (QSI) is being developed as a novel objective test for sagittal plane lumbar instability. The QSI is calculated using lumbar flexion-extension radiographs.

Optimizing success with lumbar disc arthroplasty.

Purpose: This study aimed at determining the variables that may prove useful in predicting clinical outcomes following lumbar disc arthroplasty.

Methods: Pre- and post-operative imaging assessments were obtained for 99 single-level lumbar disc arthroplasty patients from a prospective IDE study. The assessments and patient demographics were tested to identify variables that were significantly associated with clinical outcomes.

Asymmetric motion distribution between components of a mobile-core lumbar disc prosthesis: an explanation of unequal wear distribution in explanted CHARITÉ polyethylene cores.

Background: The biconvex mobile core of the CHARITÉ lumbar disc prosthesis forms two joints (spherical bearings) with the metal end plates. We quantified the intra-prosthesis motion to test the hypothesis that the total prosthesis motion would not be equally distributed between the two bearings of implanted CHARITÉ discs, which might explain the unequal wear distribution reported in explanted cores.

Methods: The hypothesis was tested by studying the flexion-extension motion responses of (1) twenty-six monosegmental CHARITÉ III discs implanted in nineteen human cadaveric lumbar spines, and (2) twenty-one CHARITÉ III discs (fifteen monosegmental, six bisegmental) implanted in eighteen patients in other published clinical studies.

Sagittal alignment after Bryan cervical arthroplasty.

Study Design: Prospective, randomized, Food and Drug Administration Investigational Device Exemption trial from one study site.

Objective: Examine the radiographic sagittal alignment of the Bryan cervical disc for one-level disease.

Summary Of Background Data: Prospective, randomized studies demonstrate Bryan arthroplasty provides statistically better functional outcomes than anterior cervical discectomy and fusion.

Prospective analysis of imaging prediction of pseudarthrosis after anterior cervical discectomy and fusion: computed tomography versus flexion-extension motion analysis with intraoperative correlation.

Study Design: A prospective comparison of quantitative motion analyzed (QMA) flexion/extension radiographs versus computed tomography (CT) as an analytical predictor of cervical pseudarthrosis. Intraoperative confirmation of the fusion was performed.

Objective: To prospectively compare motion analyzed flexion/extension radiographs to CT to predict pseudarthroses.

ProDisc-C: an in vivo kinematic study.

Study Design: A prospective study of 22 patients with single-level cervical spondylosis.

Objective: To quantify the changes in the biomechanics of the cervical spine after the insertion of a ProDisc-C (Synthes Spine, Paoli, PA) artificial disc.

Summary Of Background Data: Cervical arthroplasty is designed to maintain cervical motion of the functional spinal unit (FSU) after cervical discectomy.

Determination of the in vivo posterior loading environment of the Coflex interlaminar-interspinous implant.

Background Context: The in vivo loading environment of load-bearing implants is generally largely unknown. Loads are typically approximated from cadaver tests or biomechanical calculations for the preclinical assessment of a device's safety and efficacy.

Purpose: To determine the actual in vivo loading environment of an elastic interlaminar-interspinous implant (Coflex).

Sagittal balance influences range of motion: an in vivo study with the ProDisc-C.

Background Context: Cervical arthroplasty is designed to maintain cervical motion of the functional spinal unit after cervical discectomy. The impact of the ProDisc-C (Synthes Spine, Paoli, PA) on in vivo kinematics and sagittal alignment requires further assessment.

Purpose: The purpose of this study is to test the hypothesis that the ProDisc-C increases range of motion (ROM) in flexion and extension at the surgical level, and assess its impact on cervical alignment.

Short-term comparison of cervical fusion with static and dynamic plating using computerized motion analysis.

Study Design: This study is a retrospective review of fusion rates for cervical plates, analyzed by means of computerized analysis.

Objectives: This study compares the fusion rates for two-level anterior cervical discectomy and fusion between patients with static versus dynamic plates.

Summary Of Background Data: Anterior cervical plating has been shown to decrease the pseudarthrosis rate.

Defining pseudoarthrosis in the cervical spine with differing motion thresholds.

Study Design: Calculate the apparent pseudarthrosis rate for anteriorly plated cervical spine fusions using different threshold levels of intervertebral rotation.

Objectives: Determine whether the apparent pseudarthrosis rate depends on the amount of intervertebral rotation used to characterize a fusion as a pseudarthrosis.

Summary Of Background Data: Intervertebral motion at a spine fusion site is an important outcome measure in most spine fusion research studies.