Adjacent segment degeneration after lumbar dynamic stabilization using pedicle screws and a nitinol spring rod system with 2-year minimum follow-up.

STUDY DESIGN: Prospective study evaluating the adjacent segment degeneration after lumbar dynamic stabilization using pedicle screws and a Nitinol spring rod system. OBJECTIVE: To assess the changes of the adjacent and implantation segments after lumbar dynamic stabilization surgery using magnetic resonance imaging (MRI). SUMMARY OF BACKGROUND DATA: Lumbar fusion operations can accelerate the degeneration of adjacent levels. Recently, motion preservation surgery has been attempted for the treatment of lumbar degenerative diseases to prevent degeneration of adjacent levels. However, there is a controversy over whether lumbar dynamic stabilization accelerates degeneration of adjacent levels. METHODS: We performed the dynamic stabilization procedure in patients with grade 1 degenerative lumbar spondylolisthesis, lumbar spondylotic stenosis with segmental instability, or a herniated lumbar disc with segmental instability. Postoperative MRI scans were taken for >2 years in all enrolled 25 patients. We compared the findings regarding disc degeneration in the cranial, implantation, and caudal segments between the preoperative period and 2-year-plus postoperative period using T2-weighted sagittal MR images. In addition, we investigated the progression of the central and foraminal stenosis of the adjacent cranial and caudal levels. RESULTS: Three of the 25 cranial adjacent discs (12.0%) and 4 of the 25 (16%) caudal adjacent discs demonstrated progression of degeneration after dynamic stabilization. One of the 13 discs in the implantation segment demonstrated progression of degeneration, and 2 of the 13 discs in the implantation segment showed improvement of their disc degeneration (disc rehydration). A total of 5 (10.0%) of the 50 segments (3 cranial and 2 caudal adjacent) showed increased spinal stenosis postoperatively. Among the 5 cases, 3 patients had symptomatic adjacent stenosis. CONCLUSION: According to our results, lumbar dynamic stabilization using pedicle screws and a Nitinol spring rod system may not prevent adjacent level degeneration completely.

Single pixel transmissive and reflective liquid crystal display using broadband cholesteric liquid crystal film.

We propose a single mode transflective liquid crystal display (LCD) which is operated as the transmissive and reflective modes in a single pixel without dividing into sub-pixels. The single pixel transflective LCD was composed of the cross-polarized nematic LCD as a light modulator and the broadband cholesteric liquid crystal film (BCLCF) as a half mirror. The BCLCF, simply prepared by the exposure of ultraviolet light to the mixture of the nematic LC and the reactive mesogen with chirality, selectively reflects a certain circular polarization but transmits the orthogonal circular polarization in entire visible light. The electro-optical properties in both transmissive and reflective modes coincide with each other.

Two-dimensional heterospectral correlation analysis of X-ray photoelectron spectra and infrared spectra for spin-coated films of biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymers.

We investigated the thermal behavior of spin-coated films of biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(HB-co-HHx)) copolymers at the molecular level. To better understand details of thermal behavior of spin-coated films of P(HB-co-HHx) copolymers, we applied two-dimensional (2D) correlation analysis to the spectra of P(HB-co-HHx) (HHx = 12.0, 10.0, and 3.8 mol %) copolymers during the heating process from 30 to 150 degrees C as obtained by temperature-dependent infrared-reflection absorption spectroscopy and X-ray photoelectron spectroscopy (XPS). 2D IR and 2D XPS correlation spectra of spin-coated films of P(HB-co-HHx) copolymers clearly revealed the sequence of intensity changes with increasing temperature: an amorphous band increases first and then a band for less ordered secondary crystals decreases before a band for well-ordered primary crystals. Furthermore, the synchronous 2D heterospectral XPS/IR correlation spectrum elucidated the correlation between the IR and XPS bands, confirming their band assignments. The asynchronous 2D heterospectral correlation spectrum revealed the probe-dependent asynchronicity between XPS and IR signals arising from the same species even under identical perturbation conditions because of the different scales of molecular changes probed. It clearly provides a complete interpretation of the phase transition phenomenon of P(HB-co-HHx) copolymers, which could not have been obtained through XPS or IR study alone, and also, the results obtained thereof offer a new insight into the molecular interactions as well observed by two different probes.