[Short term clinical observation of cervical anterior Hybrid surgery].

OBJECTIVE: To investigate the short-term clinical effect of the cervical anterior Hybrid surgery in the treatment of two-segment and three-segment cervical spondylosis. METHODS: From January 2018 to January 2019, 108 patients who were performed anterior Hybrid surgery with cervical degenerative diseases were collected. The patients were divided into a two-segment group with 52 patients and a three-segment group with 56 patients according to surgical segments. In two-segment group, there were 24 males and 28 females, aged from 35 to 67 years old with an average of(45.94±14.67) years old. In three-segment group, there were 23 males and 33 females, aged from 32 to 65 years old with an average of (47.54±15.34) years old. The outcome indicators of the two groups were compared. Clinical indicators:neck disability index(NDI) was used to evaluate daily life ability, Japanese Orthopedic Association(JOA) score was used to evaluate neurological function improvement, visual analogue scale(VAS) was used to evaluate pain intensity, and general clinical results were graded according to Odom's score. Cervical range of motion (ROM), fusion and complications were measured by X-ray, CT and MRI. RESULTS: All operations were successfully completed and all patients were followed up for more than 12 months. The operation time of two-segment group and three-segment group were 95 to 180 min with an average of(152.30±44.74) min and 110 to 210 min with an average of (165.18±45.86) mins, the blood loss were 20 to 100 ml with an average of (32.88±8.75) ml and 20 to 150 ml with an average of(34.64±10.63) ml respectively which has no statistical differences between the two groups (P>0.05). Compared with those before surgery, NDI, JOA, VAS and Odom's scores between two groups were significantly improved at 12 months after operation(P<0.05). However, there was no significant difference in the NDI, JOA and Odom's scores between two groups (P>0.05), and VAS in three-segment group was higher than that in two-segment group. There was no significant difference in C3-C7 cervical mobility between two groups. Surgical incisions healed smoothly in all patients without complication such as spinal cord injury and cerebrospinal fluid leakage. The bone fusion of the two groups were 43 cases (82.69%) and 45 cases(80.35%) respectively. In two-segment group, there were 2 cases of adjacent segmental hyperosteogeny, and there were 3 cases of adjacent segmental hyperosteogeny and 1 case of adjacent posterior longitudinal ligament ossification in the three-segment group. In addition, in three-segment group, there was 1 case of looseness of implants with no obvious clinical symptoms. CONCLUSION: The anterior Hybrid surgery in treating multi-level cervical spondylosis could not only improve clinical symptoms of patients but also preserve mobility. Meanwhile, the efficacy and safety of Hybrid surgery in different multi-level cervical disc diseases are confirmed, proving its value in clinical practice.

[Efficacy of Hybrid anterior cervical spine surgery on range of motion and curvature in the treatment of cervical degenerative diseases].

OBJECTIVE: To observe the change of cervical curvature and range of motion (ROM) on imaging at 6 months after Hybrid surgery. METHODS: A total of 29 patients with cervical degenerative disease who underwent Hybrid surgery from January 2017 to July 2018 were retrospectively analyzed. Also, they all met the inclusion criteria and had complete preoperative and 6 months postoperative imaging data. There were 11 males and 18 females, aged from 34 to 76 (55.86±10.69) years, and the operation time was from 2 to 4(3.03±0.51) hours. The Cobb angle method was used to measure the changes of cervical curvature and ROM of C2-C7, replacement segments, fusion segments, and upper adjacent segments on cervical lateral X-rays before and 6 months after surgery. RESULTS: There was no statistically significant difference in C2-C7 curvature and ROM between 6 months after operation and before operation (P>0.05). The degree of curvature and ROM of the replacement segment increased compared with that before operation (P<0.05). The curvatureof the fusion segment was increased than that before operation (P<0.05). There was no statistically significant difference in ROM of the fusion segment compared with that before operation (P>0.05). There was no statistically significant difference in the curvature and ROM of the upper adjacent segments compared with those before operation (P>0.05). There was no significant difference in the curvature between the replacement and fusion segments before and 6 months after operation (P>0.05);the ROM of the replacement segment was higher than that of the fusion segment at 6 months after operation (P<0.05). CONCLUSION: Hybrid surgery reconstructs the lordotic curvature of the entire cervical spine and the responsible segment, retains the ROM of the cervical replacement segment, and restores the biomechanical function of cervical spine.

Combination of Plasma Electrolytic Processing and Mechanical Polishing for Single-Crystal 4H-SiC.

Single-crystal 4H-SiC is a typical third-generation semiconductor power-device material because of its excellent electronic and thermal properties. A novel polishing technique that combines plasma electrolytic processing and mechanical polishing (PEP-MP) was proposed in order to polish single-crystal 4H-SiC surfaces effectively. In the PEP-MP process, the single-crystal 4H-SiC surface is modified into a soft oxide layer, which is mainly made of SiO2 and a small amount of silicon oxycarbide by plasma electrolytic processing. Then, the modified oxide layer is easily removed by soft abrasives such as CeO2, whose hardness is much lower than that of single-crystal 4H-SiC. Finally a scratch-free and damage-free surface can be obtained. The hardness of the single-crystal 4H-SiC surface is greatly decreased from 2891.03 to 72.61 HV after plasma electrolytic processing. By scanning electron microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS) observation, the plasma electrolytic processing behaviors of single-crystal 4H-SiC are investigated. The scanning white light interferometer (SWLI) images of 4H-SiC surface processed by PEP-MP for 30 s shows that an ultra-smooth surface is obtained and the surface roughness decreased from Sz 607 nm, Ra 64.5 nm to Sz 60.1 nm, Ra 8.1 nm and the material removal rate (MRR) of PEP-MP is about 21.8 µm/h.

[Clinical observation on the treatment of cervical degenerative diseases with Hybrid surgery].

OBJECTIVE: To investigate the clinical effect of anterior cervical Hybrid surgery in the treatment of cervical degenerative diseases (CDD) and observe the incidence of heterotopic ossification of disc replacement segment at 1 year after surgery. METHODS: From January 2015 to April 2018, 35 patients who received anterior cervical hybrid surgery met the inclusion and exclusion criteria and the complete clinical follow up data were analyzed retrospectively. Complete imaging follow-up data were obtained from 24 patients. There were 15 males and 20 females, aged from 39 to 70(55.57±7.73) years old. The amount of bleeding was for 20 to 100 (40.29±18.39) ml, and the hospitalstay was for 4 to 28(11.03±4.63) days, and the follow-up time was(12.97±1.36) months. Clinical outcomes were assessed by the Tanaka Yasushi cervical spondylitis symptom scale 20 score (YT20), and Japanese Orthopaedic Association (JOA) score. The occurrence of heterotopic ossification after Hybrid surgery was evaluated by X-ray according to McAfee standard one year after operation. Patients with or without heterotopic ossificationwere divided into two groups and their clinical effects were compared. RESULTS: At the final follow up, the mean YT20 score and JOA score were significantly higher than those before operation (P <0.05), and the average improvement rate of JOA was (70.66 ±0.44)%. One year after operation, the heterotopic ossification occurred in 10 of 24 segments, with incidence of 41.70%(10/24), including 29.20% in gradeⅠand 12.50% in gradeⅡ. The results of clinical efficacy comparison between patients with and without heterotopic ossification were as follows:there was no significant difference in JOA score before and after operation (P>0.05);there was no significant difference in YT20 score before operation (P>0.05), and YT20 score in patients with heterotopic ossification was significantly lower than that in patients without heterotopic ossification(P<0.05). CONCLUSION: The short-term clinical effect of Hybrid surgery is satisfactory for cervical degenerative diseases, and the cause of heterotopic ossification still needs tobe further explored.

Investigation of oxidation mechanism of SiC single crystal for plasma electrochemical oxidation.

Silicon carbide (SiC) is a hard-to-machine material due to its high hardness and chemical stability, and usually an essential step in chemical mechanical polishing (CMP) is to modify the SiC surface without introducing damage or other elements, then to polish the modified surface. For high quality and high efficiency surface modification of SiC, a green and promising oxidation approach named plasma electrochemical oxidation (PECO) is proposed. Experiments were conducted to investigate the oxidation mechanism of PECO to enable its application for CMP. The oxidized surface was detected by scanning electron microscope (SEM) and atomic force microscopy (AFM), many atomic-scale protuberances were confirmed to be introduced in the PECO process. Through the analysis of energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), it is proved that the SiC surface has been oxidized into SiO2 and a transition layer (silicon oxycarbide) is formed between SiO2 and SiC. Based on the analysis of the cross section image of the oxidized layer, electrolyte-SiC interface chemical reaction and oxidation layer formation mechanism are illustrated to explain the oxidation mechanism. Silicon dioxide growth process model is proposed and illustrated that the phrase of protuberances growth change from charge transfer to diffusion. The present work offers an alternative approach to modify SiC surface, and provides a reference for chemical and mechanical synergetic effect applied in CMP.

Mechanical Behavior Investigation of 4H-SiC Single Crystal at the Micro-Nano Scale.

In this paper, theoretical models of the critical indentation depth and critical force on brittle materials using cleavage strength and contact theory are proposed. A Berkovich indenter is adopted for nanoindentation tests on a 4H-SiC single crystal sample to evaluate its mechanical behaviors. The stages of brittle material deformation (elastic, plastic, and brittle) can be characterized by the load versus indentation depth curves through the nanoindentation test. The curve of the elastic deformation stage follows the Hertz contact theory, and plastic deformation occurs at an indentation depth of up to 10 nm. The mechanism of 4H-SiC single crystal cracking is discussed, and the critical indentation depth and critical force for the plastic-brittle transition are obtained through the occurrence of the pop-in point. This shows that the theoretical results have good coherence with the test results. Both the values of the elastic modulus and hardness decrease as the crack length increases. In order to obtain more accurate mechanical property values in the nanoindentation test for brittle materials such as SiC, GaN, and sapphire, an appropriate load that avoids surface cracks should be adopted.

Long-Term Clinical Outcomes of Percutaneous Cervical Nucleoplasty for Cervical Degenerative Diseases with Neck Pain and Cervical Vertigo.

BACKGROUND: Good short- and mid-term clinical efficacy of percutaneous cervical nucleoplasty (PCN) for cervical degenerative diseases (CDD) with neck pain has been reported. However, few studies have assessed its long-term influence in patients with both neck pain and cervical vertigo. This study aimed to evaluate the curative efficacy of PCN for CDD with neck pain and cervical vertigo with minimum of 6 years of follow-up. METHODS: Inpatients who underwent PCN for CDD with neck pain and cervical vertigo between April 2010 and March 2013 were enrolled. Clinical outcomes were assessed using the Cervical Vertigo Evaluation Scale (CVES); greater CVES scores reflected less impairment. Additional open surgeries were recorded. RESULTS: Among 40 patients, 100% completed the 1-year short-term and 3-year mid-term follow-up (FU); 85% completed the 6-year long-term FU. Clinical effective rates were 67.5%, 67.5%, and 52.94% at short-, mid-, and long-term FU, respectively. CVES scores were greater than the preoperative CVES scores at all FU timepoints (P < 0.01). However, the CVES score was lower at the final FU than at the 3-year FU (P < 0.05). The neck pain score significantly decreased over time and was lower than the cervical vertigo score at the final FU (P > 0.05). Reoperation rates were 1/40 (2.50%) and 3/34 (8.82%) at mid- and long-term FU, respectively. CONCLUSIONS: PCN in patients with CDD neck pain and cervical vertigo showed satisfactory clinical efficacy at short- and mid-term FU, and it was fair at long-term FU. Thus, PCN could be a complementary operation for CDD.