Is Routine Use of Drain Really Necessary for Posterior Lumbar Interbody Fusion Surgery? A Retrospective Case Series with a Historical Control Group.

STUDY DESIGN: A retrospective case-control study. OBJECTIVES: The usefulness of a drain in spinal surgery has always been controversial. The purposes of this study were to determine the incidence of hematoma-related complications after posterior lumbar interbody fusion (PLIF) without a drain and to evaluate its usefulness. METHODS: We included 347 consecutive patients with degenerative lumbar disease who underwent single- or double-level PLIF. The participants were divided into 2 groups by the use of a drain or not; drain group and no-drain group. RESULTS: In 165 cases of PLIF without drain, there was neither a newly developed neurological deficit due to hematoma nor reoperation for hematoma evacuation. In the no-drain group, there were 5 (3.0%) patients who suffered from surgical site infection (SSI), all superficial, and 17 (10.3%) patients who complained of postoperative transient recurred leg pain, all treated conservatively. Days from surgery to ambulation and length of hospital stay (LOS) of the no-drain group were faster than those of the drain group (P < 0.001). In a multiple regression analysis, a drain insertion was found to have a significant effect on the delayed ambulation and increased LOS. No significant differences existed between the 2 groups in additional surgery for hematoma evacuation, or SSI. CONCLUSIONS: No hematoma-related neurological deficits or reoperations caused by epidural hematoma and SSI were observed in the no-drain group. The no-drain group did not show significantly more frequent postoperative complications than the drain use group, hence the routine insertion of a drain following PLIF should be reconsidered carefully.

Current Concepts in the Management of Osteoporotic Vertebral Fractures: A Narrative Review.

Vertebral fractures are the most common type of osteoporotic fracture and can increase morbidity and mortality. To date, the guidelines for managing osteoporotic vertebral fractures (OVFs) are limited in quantity and quality, and there is no gold standard treatment for these fractures. Conservative treatment is considered the primary treatment option for OVFs and includes pain relief through shortterm bed rest, analgesics, antiosteoporotic drugs, exercise, and braces. Studies on vertebral augmentation (VA) including vertebroplasty and kyphoplasty have been widely reported, but there is still debate and controversy regarding the effectiveness of VA when compared with conservative treatment, and the routine use of VA for OVF is not supported by current evidence. Although most OVFs heal well, approximately 15%-35% of patients with unstable fractures, chronic intractable back pain, severely collapsed vertebra (leading to neurological deficits and kyphosis), or chronic pseudarthrosis frequently require surgery. Given that there is no single technique for optimizing surgical outcomes in OVFs, tailored surgical techniques are needed. Surgeons need to pay attention to advances in osteoporotic spinal surgery and should be open to novel thoughts and techniques. Prevention and management of osteoporosis is the key element in reducing the risk of subsequent OVFs. Bisphosphonates and teriparatide are mainstay drugs for improving fracture healing in OVF. The effects of bisphosphonates on fracture healing have not been clinically evaluated. The intermittent administration of teriparatide significantly enhanced spinal fusion and fracture healing and reduced mortality risk. Based on the current literature, there is still a lack of standard management strategies for OVF. There is a need for greater efforts through multimodal approaches including conservative treatment, surgery, osteoporosis treatment, and drugs that promote fracture healing to improve the quality of the guidelines.

Monolithic polarization maintaining fiber chirped pulse amplification (CPA) system for high energy femtosecond pulse generation at 1.03 µm.

A monolithic polarization maintaining fiber chirped pulse amplification system with 25 cm Yb(3+)-doped high efficiency media fiber that generates 62 µJ sub-400 fs pulses with 25 W at 1.03 µm has recently been demonstrated.

Monolithic fiber chirped pulse amplification system for millijoule femtosecond pulse generation at 1.55 µm.

A monolithic fiber chirped pulse amplification system that generates sub-500 fs pulses with 913 µJ pulse energy and 4.4 W average power at 1.55 µm wavelength has recently been demonstrated. The estimated peak power for the system output approached 1.9 GW. The pulses were near diffraction-limited and near transform-limited, benefiting from the straight and short length of the booster amplifier as well as adaptive phase shaping for the overall mitigation of the nonlinear phase accumulation. The booster amplifier employs an Er(3+)-doped large mode area high efficiency media fiber just 28 cm in length with a fundamental mode (LP(01)) diameter of 54 µm and a corresponding effective mode area of 2290 µm(2).

Root cause analysis and solution to the degradation of wavelength division multiplexing (WDM) couplers in high power fiber amplifier system.

In the evaluation a fused biconical taper 1480/1580 nm WDM's ability to handle high power cascaded Raman laser throughput (>100 W) a significant degradation in performance was observed. A systematic root cause investigation was conducted and it is experimentally confirmed that the WDM degradation was caused by an interaction between the high power 1480 nm line, an out-of-band Stokes line, and the -OH content of the glass optical fiber. Slanted fiber Bragg grating (SFBG) was introduced to filter out the 1390 nm out-of-band Stokes line in an attempt to avoid this interaction. Ultimately a series of tests were conducted and it was confirmed that the addition of a 1390 nm SFBG in between a high power Raman laser and the high power WDM has successfully prevented the degradation which therefore allowed the continued high power operation of the WDM. NAVAIR Public Release SPR 2013-469 Distribution Statement A-"Approved for Public release; distribution is unlimited".

High efficiency, monolithic fiber chirped pulse amplification system for high energy femtosecond pulse generation.

A novel monolithic fiber-optic chirped pulse amplification (CPA) system for high energy, femtosecond pulse generation is proposed and experimentally demonstrated. By employing a high gain amplifier comprising merely 20 cm of high efficiency media (HEM) gain fiber, an optimal balance of output pulse energy, optical efficiency, and B-integral is achieved. The HEM amplifier is fabricated from erbium-doped phosphate glass fiber and yields gain of 1.443 dB/cm with slope efficiency >45%. We experimentally demonstrate near diffraction-limited beam quality and near transform-limited femtosecond pulse quality at 1.55 µm wavelength. With pulse energy >100 µJ and pulse duration of 636 fs (FWHM), the peak power is estimated to be ~160 MW. NAVAIR Public Release Distribution Statement A-"Approved for Public release; distribution is unlimited".

Higher-order mode fiber enables high energy chirped-pulse amplification.

Energy scaling of femtosecond fiber lasers has been constrained by nonlinear impairments and optical fiber damage. Reducing the optical irradiance inside the fiber by increasing mode size lowers these effects. Using an erbium-doped higher-order mode fiber with 6000 µm(2) effective area and output fundamental mode re-conversion, we show a breakthrough in pulse energy from a monolithic fiber chirped pulse amplification system using higher-order mode propagation generating 300 µJ pulses with duration <500 fs (FWHM) and peak power >600 MW at 1.55 µm. The erbium-doped HOM fiber has both a record large effective mode area and excellent mode stability, even when coiled to reasonable diameter. This demonstration proves efficacy of a new path for high energy monolithic fiber-optic femtosecond laser systems.

1.4kW high peak power generation from an all semiconductor mode-locked master oscillator power amplifier system based on eXtreme Chirped Pulse Amplification(X-CPA).

The concept of eXtreme Chirped Pulse Amplification (X-CPA) is introduced as a novel method to overcome the energy storage limit of semiconductor optical amplifiers in ultrashort pulse amplification. A colliding pulse mode-locked semiconductor laser is developed as a master oscillator and generates 600fs pulses with 6nm bandwidth at 975nm. Using a highly dispersive chirped fiber Bragg grating (1600ps/nm) as an extreme pulse stretcher and compressor, we demonstrate ~16,000 times extreme chirped pulse amplification and recompression generating optical pulses of 590fs with 1.4kW of peak power. These pulses represent, to our knowledge, the highest peak power generated from an all semiconductor ultrafast laser system.

External-cavity, actively mode-locked grating-coupled surface-emitting laser and amplification characteristics of a grating-coupled semiconductor optical amplifier.

An external-cavity, actively mode-locked grating-coupled surface-emitting semiconductor laser (GCSEL) is demonstrated for the first time to the authors' knowledge. The mode-locked oscillator generates a train of optical pulses at a 297-MHz pulse-repetition frequency. The optical pulse from the oscillator has a width of 22.6 ps and a spectral bandwidth of 0.07 nm at 975.9 nm, giving a time-bandwidth product of 0.50. In addition, amplification characteristics of a grating-coupled semiconductor optical amplifier are studied with a continuous-wave external-cavity GCSEL.