Bone Union Rate Following Instrumented Posterolateral Lumbar Fusion: Comparison between Demineralized Bone Matrix versus Hydroxyapatite

Study DesignRetrospective study.PurposeTo compare the union rate of posterolateral lumbar fusion (PLF) using demineralized bone matrix (DBM) versus hydroxyapatite (HA) as bone graft extender.Overview of LiteratureTo our knowledge, there has been no clinical trial to compare the outcomes of DBM versus HA as a graft material for PLF.MethodsWe analyzed prospectively collected data from consecutive 79 patients who underwent instrumented PLF. Patients who received DBM were assigned to group B (n=38), and patients who received HA were assigned into group C (n=41). The primary study outcome was fusion rate assessed with radiographs. The secondary outcomes included pain intensity using a visual analogue scale, functional outcome using Oswestry disability index score, laboratory tests of inflammatory profiles and infection rate.ResultsOne year postoperatively, bone fusion was achieved in 73% in group B and 58% in group C without significant difference between the groups (p=0.15). There were no differences between the groups with respect to secondary outcomes.ConclusionsDBM would provide noninferior outcomes compared to the HA as a fusion material for PLF, and could be a notable alternative

A Prospective Randomized Clinical Trial Comparing Bone Union Rate Following Anterior Cervical Discectomy and Fusion Using a Polyetheretherketone Cage: Hydroxyapatite/B-Tricalcium Phosphate Mixture versus Hydroxyapatite/Demineralized Bone Matrix Mixture

Study DesignProspective randomized noninferiority trial.PurposeTo evaluate whether the union rate of anterior cervical discectomy and fusion (ACDF) using a polyetheretherketone (PEEK) cage filled with a mixture of hydroxyapatite (HA) and demineralized bone matrix (DBM) is inferior to that of a mixture of β-tricalcium phosphate (β-TCP) and HA.Overview of LiteratureThere have been no clinical trials investigating the outcomes of a mixture of HA and DBM in a PEEK cage in ACDF.MethodsEighty-five eligible patients were randomly assigned to group B (n=43), in which a PEEK cage with a mixture of HA and DBM was used, or group C (n=42), in which a PEEK cage with a mixture of HA and β-TCP was used. The primary study endpoint was the fusion rate, which was assessed with dynamic radiographs and computed tomography (CT) scans. Secondary endpoints included pain intensity using a visual analogue scale, functional outcome using a neck disability index score, laboratory tests of inflammatory profiles, and the infection rate.ResultsSeventy-seven patients (38 in group B and 39 in group C) were included in the final analysis. One year postoperatively, bone fusion was achieved in 87% of group B patients and 87% of group C patients on dynamic radiographs, and 87% of group B patients and 72% of group C patients on CT scans (p=1.00 and 0.16, respectively). There were also no between-groups differences with respect to the secondary endpoints.ConclusionsA HA/DBM mixture inside a PEEK cage can provide noninferior outcomes compared to a HA/TCP mixture in ACDF

Position Estimator Design for a MEMS Top-Drive Electrostatic Rotary Actuator

The capacitance and rotor angle of a MEMS top-drive electrostatic rotary actuator do not have a linear relationship due to the non-ignorable fringe effect and low aspect ratio of the electrodes. Therefore, the position estimation is not as straightforward as that for a comb-drive linear actuator or a side-drive rotary actuator. The reason is that the capacitance is a nonlinear and periodic function of the rotor angle and is affected by the three-phase input voltages. Therefore, it cannot be approximated as a simple two-plate capacitor. Sensing the capacitance between a rotor and a stator is another challenge. The capacitance can be measured in the electrodes (stators), but the electrodes also have to perform actuation, so a method is needed to combine actuation and sensing. In this study, a nonlinear capacitance model was derived as a data-driven model that effectively represents the nonlinear capacitance with sufficient accuracy. To measure the capacitance accurately, the stator parts for actuation and those for sensing are separated. Using the nonlinear model and the capacitance measurement, an unscented Kalman filter was designed to mitigate the large estimation error due to the periodic nonlinearity. The proposed method shows stable and accurate estimation that cannot be achieved with a simple two-plate capacitor model. The proposed approach can be applied to a similar system with highly nonlinear capacitance

Distraction Arthrodesis of the C1-C2 Facet Joint with Preservation of the C2 Root for the Management of Intractable Occipital Neuralgia Caused by C2 Root Compression

Study Design. Prospective observational cohort study. Objective. To compare the outcomes of our new technique, distraction arthrodesis of C1–C2 facet joint with C2 root preservation (Study group), to those of conventional C1–C2 fusion with C2 root transection (Control group) for the management of intractable occipital neuralgia caused by C2 root compression. Summary of Background Data. We are not aware of any report concerning C2 root decompression during C1–C2 fusion. Materials and Methods. Inclusion criteria were visual analogue scale (VAS) score for occipital neuralgia 7 or more; C2 root compression at the collapsed C1–C2 neural foramen; and followup 12 months or more. The Study group underwent surgery with our new technique including (1) C1–C2 facet joint distraction and bone block insertion while preserving the C2 root; and (2) use of C1 posterior arch screws instead of conventional lateral mass screws during C1–C2 segmental screw fi xation. The Control group underwent C2 root transection with C1–C2 segmental screw fi xation and fusion. We compared the prospectively collected outcomes data. Results. There were 15 patients in the Study group and 8 in the Control group. Although there was no signifi cant difference in the VAS score for the occipital neuralgia between the 2 groups preoperatively (8.2 ± 0.9 vs. 7.9 ± 0.6, P = 0.39), it was signifi cantly lower in the Study group at 1, 3, and 6 months postoperatively ( P < 0.01, respectively). At 12 months, it was 0.4 ± 0.6 versus 2.5 ± 2.6 ( P = 0.01). There was no signifi cant difference in improvement in the VAS score for neck pain and neck disability index and Japanese Orthopedic Association recovery rate, which are minimally infl uenced by occipital neuralgia. Conclusion. Our novel technique of distraction arthrodesis with C2 root preservation can be an effective option for the management of intractable occipital neuralgia caused by C2 root compression.OAIID:oai:osos.snu.ac.kr:snu2015-01/102/0000004226/20ADJUST_YN:NEMP_ID:A079510DEPT_CD:801CITE_RATE:2.297FILENAME:spine-2015_yeom_distraction arthrodesis of the c1c2 facet joint with preservation.pdfDEPT_NM:의학과SCOPUS_YN:YCONFIRM: