European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society
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To gain insight into a new technology, a novel facet arthroplasty device (TFAS) was compared to a rigid posterior fixation system (UCR). The axial and bending loads through the implants and at the bone-implant interfaces were evaluated using an ex vivo biomechanical study and matched finite element analysis. Kinematic behaviour has been reported for TFAS, but implant loads have not. Implant loads are important indicators of an implant's performance and safety. The rigid posterior fixation system is used for comparison due to the extensive information available about these systems. ⋯ These results are most applicable to the immediate post-operative period prior to remodelling of the bone-implant interface since the UCR and TFAS implants are intended for different service lives (UCR--until fusion, TFAS--indefinitely). TFAS reproduced intact-like anterior column load-sharing--as measured by disc pressure. The highest bone-implant moment of 3.1 Nm was measured in TFAS and for the same loading condition the UCR interface moment was considerably lower (0.4 Nm). For other loading conditions, the differences between TFAS and UCR were smaller, with the UCR sometimes having larger values and for others the TFAS was larger. The long-term physiological meaning of these findings is unknown and demonstrates the need for a better understanding of the relationship between spinal arthroplasty devices and the host tissue as development of next generation motion-preserving posterior devices that hope to more accurately replicate the natural functions of the native tissue continues.
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The SRS-24 questionnaire was originally validated using methods of classical test theory, but internal construct validity has never been shown. Internal construct validity, i.e. unidimensionality and linearity, is a fundamental arithmetic requirement and needs to be shown for a scale for summating any set of Likert-type items. Here, internal construct validity of the SRS-24 questionnaire in adolescent idiopathic scoliosis (AIS) patients is analyzed. ⋯ The SRS-24 score is a non-linear and multidimensional construct. Adding the items into a single value is therefore not supported and invalid in principle. Making profound changes to the questionnaire yields a score which fulfills the properties of internal construct validity and supports its use a change score for outcome measurement.
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To evaluate the effectiveness of posterior occipitocervical reconstruction using the anchors of cervical pedicle screws and plate-rod systems for patients with congenital osseous anomalies at the craniocervical junction. ⋯ The results of the present study indicate that posterior occipitocervical reconstruction using the anchors of cervical pedicle screws and plate-rod systems is an effective technique for treatment of deformities and/or instability caused by congenital osseous anomalies at the craniocervical junction.
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Free disc fragments end often up in the concavity of the anterior epidural space. This space consists of two compartments. The discrepancy between the impressive magnetic resonance imaging findings, clinical symptoms in patients and the problem of treatment options led us to the anatomical determination of anterior epidural space volumes. ⋯ This volume is large enough to hold average-sized slipped discs without causing neurological deficits. A better understanding of the anterior epidural space may allow a better distinction of patient treatment options.
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Spinal fusion as a treatment for degenerative disc disease is controversial. Prior authors have identified various MRI findings as being pain generators, which might help guide patient selection for lumbar fusion procedures. These findings have included disc desiccation, disc contour, high-intensity zone annular disruption, the presence of Modic endplate changes, and disc space collapse. The purpose of this study is to investigate which MRI findings in patients with degenerative disc disease predict clinical improvement with lumbar fusion. ⋯ Several commonly utilized MRI criteria proposed as indications for lumbar fusion do not seem to correlate with 2-year improvement in clinical outcomes. Discs which are narrowed and collapsed, preoperatively, demonstrate better improvement at 2 years postoperatively as compared to discs which have maintained disc height. Significant disc space collapse may represent a subset of "degenerative disc disease" which responds more favorably to treatment with fusion.