[A medium term analysis on of therapeutic effects of bio-lengthend stem hemiarthroplasty in the treatment of unstable osteoporotic intertrochanteric fractures in elderly patients].

OBJECTIVE: To retrospectively study medium term follow up outcomes effects of effect of bio-lengthend stem hemiarthroplasty in the treatment of unstable osteoporotic intertrochanteric fractures in elderly patients. METHODS: Total of 32 elderly patients with the osteoporotic intertrochanteric fractures were treated with bio-lengthend stem hemiarthroplasty from Jan. 2016 to Jan. 2019 including 14 males and 22 females, aged from 85 to 95 years old with an average of (89.5±4.5) years old. According to classification of Evans, there were 12 cases with type Ⅲ, 11 with type Ⅳ and 9 with type Ⅳ. The time from injury to operation ranged from 0.5 to 9 days with an average of (4.5±3.9) days. The operation time, blood loss and postoperative complications were analyzed. Functional outcome was assessed by Parker Palmer mobility score(PPMS) and Harris hip score. RESULTS: Four patients died within one year after operation, and the mortality was 12.5%. The follow up time for the rest 28 patients ranged from 24 to 60 months with an average of (28.5±4.5) months. The mean operative time was (54.2±22.5) min;the mean blood loss (hidden blood loss+obvious blood loss) was (450±140) ml;the first weight bearing was (3.35±1.35) days. No perioperative death occurred. PPMS were(6.63±1.25), (6.94±1.18), (7.11±0.83), (7.32±1.11) and Harris scores were(67.85±6.19), (71.42±5.57), (73.41±5.62), (77.32±5.24) respectively at 1, 3, 6 months and the final follow-up after operation. There were no significant difference in PPMS and Harris score at 1, 3, 6 months after operation and the final follow-up(P>0.05). There were no complications such as joint dislocation and prosthesis loosening occure at the final follow-up. CONCLUSION: On the premise of strictly mastering the case selection criteria, the bio-lengthend stem hemiarthroplasty in the treatment of unstable osteoporotic intertrochanteric fractures in elderly patients has a satisfied medium term follow-up outcomes. It can restore hip function in the early stage and improve the quality of life of patients.

[Estimation of biomechanical behavior in deep wedge-shaped defects restored by different methods under static and dynamic loads: a 3D finite analysis].

PURPOSE: To analyze the biomechanical properties of the right mandibular second premolar with deep wedge-shaped defects under static and dynamic loads by finite element method, so as to select appropriate repair method in clinic. METHODS: To establish the deep wedge-shaped defect model of the right mandibular second premolar, the unrepaired model after root canal treatment was used as the control group, and resin filling (group A), resin filling after post restoration (group B), crown restoration after resin filling (group C), post and crown restoration after resin filling (group D) were used as the experimental groups. According to different materials, group B and group D were further divided into fiber post (B1, D1) group and pure Ti post (B2, D2) group. Static and dynamic loading were applied by three dimensional finite element analysis software, and the stress and strain were analyzed before and after restoration. RESULTS: Compared with the control group, the stress values under static loading was much lower than that under dynamic loading. Von Mises and the maximum principal stress in each experimental group decreased significantly under static and dynamic loading. In the post group, the stress distribution of fiber post was more uniform than that of pure Ti post. CONCLUSIONS: Dynamic load has great influence on the stress distribution. Full crown restoration is beneficial to the stress distribution of the teeth with deep wedge-shaped defects. If a post is necessary, fiber post should be selected.

[Clinical application of lower cervical spinous process laminar screw technique in open door laminoplasty].

OBJECTIVE: To investigate the clinical outcomes of lower cervical spinous process laminar screw technique in open door laminoplasty. METHODS: From February 2005 to June 2010,12 patients with cervical myelopathy were treated with open door laminoplasty by lower cervical spinous process laminar screw technique. There was intervertebral disc herniation with degenerative stenosis in 5 patients, ossification of posterior longitudinal ligament with osteophyte in 6 patients, cervical traumatic instability with spinal cord injuries in 1 patient. Nerve function, complications, and the cervical canal to body ratio (CBR), range of motion (ROM) and the anteroposterior serial alignment were observed by Japanese Orthopedic Association (JOA) score, X-ray, CT and MRI. RESULTS: The surgical time was from 1.5 to 2 h with an average of 110 min; blood loss during operation was from 450 to 800 ml with an average of 580 ml. Postoperative complication occurred in 1 case with upper limb pain and 1 case with cerebrospinal fluid leakage. All patients were followed up from 1 to 2 years with an average of 21.8 months. JOA score improved from preoperative 9.5 +/- 1.8 to postoperative 13.6 +/- 2.4 (P < 0.01). X-ray, CT, MRI showed CBR increased obviously (P < 0.01); ROM on flexion-extension and cervical lordosis decreased respectively from (40.0 +/- 10.0) degrees and (65.0 +/- 12.0)% before operation to (15.0 +/- 5.0) degrees and (42.0 +/- 8.0) % at the final follow-up (P < 0.01). CONCLUSION: Lower cervical spinous process laminar screw technique in open door laminoplasty for cervical syndrome is safe and can obtain satisfactory effects, has strong internal fixation and reduce the risk of re-closure.

[Anatomic study of lower cervical spinous process for laminar screw fixation].

OBJECTIVE: To measure anatomic data of spinous process and vertebral plate and evaluate the possibility of fixation of spinous process and vertebral plate. METHODS: Twenty cadaveric cervibal spines of C3-C7 were dissected to expose vertebral plate and spinous process, and were measured by two methods, one was manual measured using digital caliper and the other was computed tomography scaning. Parameters were measured manually including vertebral plate height and width. The screw was inserted from the boundary of the vertebral plate and spinous process, and gone out from the top of vertebral plate back of opposite side. Then through the CT reconstruction, angle of screw insertion, length of screw trajectory and distance between the screw tip and vertebral artery and spinal cord were measured. Additionally, spinous process width and vertebral plate thickness of 100 patients' CT scans of C3-C7 cervical segment were measured to evaluate possibility of screw insertion at spinous process and vertebral plate. RESULTS: The screw fixation of lower cervical spinous process and vertebral plate were successfully placed,without impingement of spinal cord and vertebral artery. There was no statistic difference on the data of lamina height and width of 20 cadaver specimens between manual and CT measurements (P>0.05). Height and width of vertebral plate was (12.4 +/- 1.2) to (13.7 +/- 1.3) mm and (4.5 +/- 0.9) to (5.4 +/- 1.1) mm respectively and increased gradually from C3 to C7 (P<0.05). The trajectory length was (13.7 +/- 1.2) to (15.8 +/- 1.8) mm and increased gradually from C3 to C7 (P<0.05). The distance between screw tip and vertebral artery and spinal cord was (20.1 +/- 2.7) to (25.8 +/- 2.9) mm and (4.1 +/- 1.8) to (5.0 +/- 1.2) mm respectively. The angles of screws insertion were (73.0 +/- 9.9) degrees to (85.3 +/- 10.1) degrees in the axial plane (P>0.05). Based on the CT measurements of 100 patients,the data of the spinous process width and lamina thickness varied from a minimum of (8.5 +/- 1.1) mm and (4.3 +/- 0.5) mm for the C4, to a maximum of (14.5 +/- 2.0) mm and (6.0 +/- 1.1) mm for the C7 respectively. CONCLUSION: Lower cervical spinous process and vertebral plate screw fixation is feasible, which is a safe and stable screw approach for spinous process and vertebral plate fixation.

[Anatomic comparison between spinous process screws and pedicle screws techniques of the second cervical vertebar].

OBJECTIVE: To compare anatomic difference between spinous process screws and pedicle screws techniques of the second cervical vertebra. METHODS: Ten human cadaveric of cervical spine (5 male, 5 female) were harvested and had no gross deformities such as scoliosis and/or kyphosis were found in the study. The average age of the subjects was 60.5 years. The specimens were placed in the prone position. Posterior cervical exposure was attained by dissecting all soft tissue off the posterior aspect of the second cervical vertebra. After clear exposure of the lateral mass,the spinous process screw and pedicle screw insertion techniques were performed in this study. Each technique involved ten specimens and 10 screws inserted into C2 bilaterally. The one side of C2 was randomly selected for the spinous process screw and the other side was designate for the pedicle screw. This point then was drilled with a 3 mm drill, and followed by placement of a 4.0 mm cortical screw. The starting point for spinous process screw insertion was located at the junction of the lamina and the spinous process and the direction of the screw was about 0 degrees caudally in the sagittal plane and about O0 medially in the axial plane. The starting point of pedicle screw should be the midpoint of the base of inferior articular facet of the axis. The drilling angle was 15 degrees to 20 degrees in the superior direction and 30 degrees in the medial direction. After screw placement, all the specimens were CT scaned. On the CT scan,the length of the spinous process screw and pedicle screw trajectory were measured. Results were recorded for each screw that violated impinged of the pedicle, spinal canal and transverse process foramen. RESULTS: All the C2 spinous process screws were successfully placed, without impingement the spinal cord, the vertebral artery and the breakage of the spinous process. There was one pedicle screw breaking the pedicle into the vertebral artery foramen. The trajectory length for the spinous process screws were (21.4 +/- 1.4) mm,compared with the pedicle screws (23.7 +/- 1.0) mm. But there was no significant differences between spinous process screws and pedicle screws techniques (t = -4.387, P > 0.05). CONCLUSION: The C2 spinous process screw fixation has the anatomic feasibility and is easier to perform than pedicle screw fixation.

[Biomechanical study on the posterior screw fixation in the lower cervical spine].

So far, the fixation in the lower cervical spine through posterior approach technology has commonly been used, besides the lateral screw and pedicle screw techniques, transarticular screw and laminar screw techniques have being paid more attention recently. This article introduced four screw fixation ways in the lower cervical spine through posterior approach and reviewed the recent biomechanics studies of four screw fixation techniques. The biomechanics study includes stabilization, pollout strength, insertion technique, and screw characteristic and so on. Lateral screw and pedicle screw techniques have become an effective internal fixation way for the lower cervical spine instability because of their superior stabilization and higher pollout strength. Transarticular screw fixation has become a new way to fix the lower cervical spine through posterior approach, which has widely surgical indications. Besides, this technique is relatively safe, simple and has achieved favorable curative effect in clinic. Laminar screw fixation technique is rarely used in clinic, but the study of anatomy and biomechanics confirmed that this technique can be applied as a salvage technique in clinic. Above four techniques of the screw fixation in the lower cervical spine through posterior approach have advantages and disadvantages, respectively, and the application in clinic is different. Through the biomechanics study of these techniques will contribute to the development of the techniques of the screw fixation in the lower cervical spine through posterior approach and guide the clinical work effectively.

[Study on the feasibility of posterior thoracic transarticular screw fixation].

OBJECTIVE: To study the feasibility and technical parameters of posterior transarticular screw fixation in the thoracic spine. METHODS: Since September 2009 to December 2009, 20 thoracic cadaveric spines (12 males and 8 females) were dissected. The lateral masses and pedicles were exposed carefully. After the entrance point of transarticular screws was determined, posterior transarticular screws implantation was performed under direct visualization into T(1,2), T(5,6) and T(9,10). Then CT scan was performed. On the CT scan,the angle and length of the transarticular screw trajectory were measured. RESULTS: The thoracic transarticular screw trajectory were caudal tilting in the sagittal plane and lateral tilting in the coronal plane with successful placement. There was little differences between different segmental of thoracic vertebrae of the angle, but without significance (P > 0.5). The average angles of the screws were (52.6 +/- 5.9) degrees caudal tilting in the sagittal plane and (12.4 +/- 2.9)0 lateral tilting in the coronal plane. The average trajectory lengths were (22.5 +/- 1.9) mm. There was significant differences statistically among T(1,2), T(5,6) and T(9,10) (P < 0.01). CONCLUSION: Posterior transarticular screw fixation is feasible. Transarticular screw fixation in the thoracic spine affords an alternative to standard pedicle screw placement for thoracic stabilization.

[An anatomic study of posterior C(2) spinous process laminar screw fixation].

OBJECTIVES: To explore the feasibility and the technical parameters in posterior C2 spinous process laminar screw fixation, and discuss the clinic significance of C2 spinous process laminar screws. METHODS: Twenty cervical cadaveric spines of C2 were dissected, with care taken to expose the lamina and spinous process. After the entrance point of spinous process screw were determined, posterior C2 spinous process laminar screw implantation was performed under visual control. On the morphologic CT scan, the angle and length of the spinous process laminar screw trajectory and the distance between the tip of the screw and the spinal cord and the vertebral artery were measured. RESULTS: The C2 spinous process laminar screws were successfully placed, without impingement of the spinal cord and the vertebral artery. There were little differences between superior and inferior screws in the angle, trajectory length and the distance between the tip of the screw and the spinal cord and the vertebral artery, but without significance (P > 0.05). The placed angles of the screws were 76.8° ± 10.6° in the axial plane. The distance between the tip of the screw and the spinal cord and the vertebral artery was (5.3 ± 1.6) mm and (17.4 ± 3.7) mm respectively. The trajectory length was (23.1 ± 3.2) mm. CONCLUSIONS: Posterior C2 spinous process laminar screw fixation is feasible. C2 spinous process laminar screw fixation affords an alternative to standard screw placement for plate fixation and cervical stabilization.

[Indirect determination of trace mercury ion by flame AAS].

In this paper, the method of indirect analysis of trace Hg2+ has been researched. In the HAc-NaAc buffer solution (pH = 5.0), copper can enrich and displace Hg2+ in solution of sample. The calibration curve of Hg2+ and Cu2+ is linear within in the range of 0-0.4 microgram.mL-1 of Hg2+. The trace mercury ion can be indirect determined by FAAS without separation. The recovery is 90%-110%, and the RSD is 3.5%. The method has been used for determining the trace Hg2+ in human hair with satisfactory results. The Hg2+ in solution is determined without any interference of common ions. Thus the method selection is excellent.