The effect of K-line classification in different cervical dynamic position on surgical outcomes in patients with ossification of the posterior longitudinal ligament after anterior controllable antedisplacement and fusion.

Purpose: To investigate whether the K-line classification in different cervical dynamic position of patients with Ossification of the Posterior Longitudinal Ligament (OPLL) affects clinical outcome after Anterior Controllable Antedisplacement and Fusion (ACAF) surgery. Methods: A total of 93 patients who suffered from cervical spondylosis caused by OPLL underwent ACAF surgery between June 2015 and December 2017 in a single institution. Neutral, neck-flexed and neck-extended cervical radiographs were obtained from every patient. Subsequently they were classified into K-line (+) and K-line (-) with reference to the K-line classification criteria. Clinical outcomes were assessed by the JOA score, improvement rate (IR) and visual analogue scale (VAS). Radiological assessment included Cobb angle and occupation ratio (OR) of OPLL. Correlations between the long-term surgical outcomes and classification of K-line in different dynamic position were analyzed by one-way analysis of variance. Results: Significant improvements were shown in all postoperative clinical and radiographic assessments (P < 0.05). There were no differences in IR, Cobb angle and VAS among flexion K-line (-), flexion K-line (+), extension K-line (-) and extension K-line (+) at the 2-year follow-up (P > 0.05). However, the OR of extension K-line (-) (16.13% ± 11.58%) was higher than that of extension K-line (+) (9.00% ± 10.27%) and flexion K-line (+) subgroup (9.47% ± 9.97%) (P < 0.05). Conclusion: The ACAF procedure has shown satisfactory surgical outcomes in various K-line classifications in different dynamic position.

CaCO3 blowing agent mixing method for biomass composites improved buffer packaging performance.

Biodegradable composites with an open-cell structure were developed to replace petroleum-based buffer packaging materials. To overcome the problem of uneven and insufficient foam in the composites, CaCO3 was used as a nucleating agent to prepare porous composites. At 5 wt% CaCO3, more uniform and dense composite cells with better cushioning performance were obtained. A further increase in the CaCO3 content caused the density of the cells and the cushioning properties of the composites to decrease. The addition of CaCO3 improved the thermal stability and water barrier properties. The moisture absorption was reduced by 15%. X-ray diffraction analysis indicated that the addition of CaCO3 destroyed the crystalline structure of the starch and produced a new crystalline peak, resulting in a significant reduction in the crystallinity. The decrease in the crystallinity of the starch resulted in the formation of a homogeneous slurry that produced a uniform foam in the composites.

Snake-Eye Screwing: A Novel Free-Hand Technique of Pedicle Screw Placement in Cervicothoracic Spine and Preliminary Clinical Results.

OBJECTIVE: To propose a novel technique of free-hand pedicle screw placement in cervicothoracic spine (snake-eye method) and evaluate the preliminary effects and safety in clinical practice. METHODS: This is a retrospective study and we defined the period of this study as from December 2017 to April 2019 in our institution. Forty patients were included in this study who underwent cervicothoracic internal fixation in our hospital, and all patients undergoing implantation of 200 pedicle screws were divided into two groups. Twenty-two patients (108 screws) had screw placement using traditional method, while 18 patients (92 screws) had screw placement using snake-eye method. To reduce the possible selection bias, the patients we recruited in this study was originally performed on by one radiological doctor who was blind to the objective of this study. Patient demographics, including patient age, sex, obesity, smoking, and hypertension, were evaluated to figure out baseline differences between groups. Medical information was recorded including time, accuracy, and immediate (within 30 days after surgery) postoperative complications of pedicle screw placement (including pulmonary embolism or other thromboembolic events, surgical site infection, neurovascular injury, and mortality). RESULTS: There were 24 males and 16 females, with an average age of 52.2 years (range, 24-77). Finally, a total of 200 screws were successfully inserted in these patients, including fifteen patients with four pedicle screws, four patients with six screws, three patients with eight screws in traditional method group, and 12 patients with four pedicle screws, two patients with six screws, four patients with eight screws in snake-eye method group. Patient demographic and comparison of two surgery methods are shown in Tables 1 and 2. The data baselines of the two groups were comparable because no impact of the two groups on population characteristics was demonstrated in the presented experiment. Also, we noticed that time and accuracy of the two groups were different with statistical significance at the level of P = 0.05. We observed that immediate (within 30 days after surgery) postoperative complications, including pulmonary embolism (PE), surgical site infection (SSI), neurovascular injury (NI), and mortality, in the two groups did not differ. CONCLUSION: This study highlights a safe and effective technique for pedicle screw placement in cervicothoracic spine named snake-eye method, and this technique may be particularly useful in emergency conditions with limited resources.

Novel Technique as a Revision Surgery for Failed Anterior Cervical Corpectomy and Fusion in the Treatment of Cervical Myelopathy Due to Ossification of the Posterior Longitudinal Ligament.

OBJECTIVE: This article aimed to introduce a novel technique, the "seesaw technique," for failed anterior cervical corpectomy and fusion (ACCF) in the treatment of cervical ossification of the posterior longitudinal ligament. METHODS: A patient who underwent ACCF 12 years ago and suffered gradually deteriorating neurologic function was referred to our institution. Preoperative imaging showed residual ossified mass at C5/6 level, causing compression to his spinal cord. He patient was treated by the seesaw technique. The main surgical procedures include removal of the plate and screws, removal of the osteophytes and diskectomy of C4/5, resection of the anterior part of C5 vertebral body, establishment of a transverse hinge at C7 vertebral body, installation of cervical plate and hoisting tool, and antedisplacement of C5 vertebral body and titanium mesh. Images were investigated before and after the procedure. The Japanese Orthopaedic Association score was used to evaluate his neurologic function, and surgery-related complications were also analyzed. RESULTS: The patient acquired significant improvement of his neurologic function 2 days after the surgery, and he could walk by himself without assistance. Postoperative images showed his spinal canal was enlarged sufficiently and the compression at C5/6 level was also released. At 13 months follow-up, his Japanese Orthopaedic Association score increased from 9 before surgery to 14, with an improvement rate of 62.5%. No surgery-related complications were observed during the whole follow-up. CONCLUSION: The seesaw technique provides satisfactory outcomes with wide enough decompression window and serves as a safe, effective surgical alternative for patients with failed ACCF.

Computer-assisted virtual operation planning in anterior controllable anterior-displacement and fusion surgery for ossification of the posterior longitudinal ligament based on actual computed tomography data.

OBJECTIVES: To investigate the effect of computer-assisted virtual operation planning (CAVOP) on anterior controllable anterior-displacement and fusion (ACAF) surgery for ossification of the posterior longitudinal ligament (OPLL). PATIENTS AND METHODS: A total of 25 patients with OPLL were enrolled in the study from September 2017 to December 2017. Preoperative Computed tomography (CT) scanning data were input into Mimics software to reconstruct three-dimensional (3D) models of actual cervical OPLL.Preoperative simulation of each surgical procedure and measurement of main parameters for intraoperative decision were conducted. Postoperative CT were used to test the clinical value of the preoperative planning. Width of vertebrae-OPLL complex (VOC), thickness of resected vertebral body (VB), height of intervertebral spacer, and length of screws and anterior plate were analyzed. RESULTS: There were no significant differences between the length of screws, width of VOC, and thickness of anterior resection of vertebrae in preoperative CT and postoperative CT. Statistical differences were found between preoperative and postoperative height of intervertebral space and length of anterior plate. CONCLUSION: A virtual ACAF surgical procedure for OPLL is feasible and useful clinically in surgical planning. It may provide a valuable tool for surgeons in formulating an appropriate surgical plan.

Effect of poly-methyltriethoxysilane on the waterproof property of starch/fiber composites with open cell structures.

Novel starch/fiber composites with open cell structures were proposed through thermo-cavity molding. To overcome the disadvantage of the water sensitivity of the resulting composites, poly-methyltriethoxysilane (PTS) was added as a waterproofing agent. The results showed that the addition of PTS improved the waterproof property of the composites. The composites with 15 g PTS (PTS-15) exhibited an optimal waterproof property. The water contact angle and drop absorption of the PTS-15 composites improved by 59.9% and 223.5%, respectively, compared with the values for those without PTS. Moreover, the addition of PTS could effectively prevent the degradation of the mechanical properties of the composites after water absorption. The rate of tensile property degradation for the PTS-15 composites reached 5.3%, whereas that for the PTS-0 composites totaled 56.6%. The chemical bonds and micro-structure of the composites were investigated to reveal the inherent mechanism of property changes. Fourier transform infrared spectra revealed the formation of new hydrogen bonds between starch and PTS. Hydrophobic groups, including Si-O-Si, Si-C, and Si-OH, were found in the resulting composites, thereby explaining the waterproof property changes. Scanning electron microscopy images showed that the open cell structure of the composites initially became denser and then loosened with the increase in the PTS content, resulting in the initial enhancement and the subsequent weakening of their mechanical properties.

Optimisation of compatibility for improving elongation at break of chitosan/starch films.

When chitosan/starch films were used as agricultural mulch films, the problem of rupture often occurred. In order to improve the elongation at break, chitosan/starch blend films were prepared by casting with different formulations (different ratios of chitosan to starch, different plasticizing components and different plasticizer ratios) in this research. The elongation at break of the film reached up to 104.1% when chitosan was plasticized with 10% glycerol and 0.94% ethylene glycol alone and then mixed according to a 1 : 0.6 chitosan-starch ratio. The fact that plasticizing starch, plasticizing chitosan or co-plasticizing starch and chitosan made a big difference to the mechanical properties of the films was discovered for the first time. The films with different plasticizing components were characterized by their mechanical properties, crystal structures and surface morphologies. Mechanical properties of the films were related to their crystallinity. The higher the crystallinity, the higher the elongation at break. Plasticizing starch alone facilitated the formation of hydrogen bonds and massive structures. Plasticizing chitosan alone was beneficial to the formation of network structures of the films and exhibited anti-plasticization at low plasticizer concentration.

Can K-Line Predict the Clinical Outcome of Anterior Controllable Antedisplacement and Fusion Surgery for Cervical Myelopathy Caused by Multisegmental Ossification of the Posterior Longitudinal Ligament?

OBJECTIVE: To analyze the correlation between the K-line-based classification of patients with ossification of the posterior longitudinal ligament (OPLL) and their outcome after anterior controllable antedisplacement and fusion (ACAF) surgery. METHODS: A series of 24 patients with multisegmental OPLL were enrolled. All patients underwent ACAF surgery. First, the patients were classified into 2 groups according to their K-line classification. Then, we separated the patients into subgroups according to their OPLL thickness. The Japanese Orthopaedic Association scores before and 6 months after surgery were studied, and the recovery rate (RR) was calculated. The preoperative and postoperative radiologic parameters were also investigated. RESULTS: Clinical and radiographic assessments showed no significant correlation between the K-line-based classification of patients with OPLL and their outcome of ACAF surgery (P > 0.05). When the OPLL was ≤6 mm thick, K-line-based classification groups had a similar change of occupation ratio and RR (P > 0.05). However, when the OPLL was >6 mm thick, the mean RR was 61.8% ± 14.0% in the K-line (+) group and 78.3% ± 9.7% in the K-line (-) group (P < 0.05), and the mean was 16.0% ± 4.2% in the K-line (+) group and 28.0% ± 7.1% in the K-line (-) group (P < 0.05). CONCLUSIONS: This study shows that K-line can predict the clinical outcome of ACAF surgery for multisegmental OPLL in a different way from posterior decompression surgery. When the OPLL was thin, the outcome was satisfactory and there was no correlation with K-line-based classification of patients with OPLL. When the OPLL was >6 mm thick, the K-line (-) group patients had a better outcome than did K-line (+) group patients.