Effects Of Different Fixation Methods Research Articles

Finite Element Analysis of Six Internal Fixations in the Treatment of Pauwels Type III Femoral Neck Fracture.

The current investigation sought to utilize finite element analysis to replicate the biomechanical effects of different fixation methods, with the objective of establishing a theoretical framework for the optimal choice of modalities in managing Pauwels type III femoral neck fractures. The Pauwels type III fracture configuration, characterized by angles of 70°, was simulated in conjunction with six distinct internal fixation methods, including cannulated compression screw (CCS), dynamic hip screw (DHS), DHS with de-rotational screw (DS), CCS with medial buttress plate (MBP), proximal femoral nail anti-rotation (PFNA), and femoral neck system (FNS). These models were developed and refined using Geomagic and SolidWorks software. Subsequently, finite element analysis was conducted utilizing Ansys software, incorporating axial loading, torsional loading, yield loading and cyclic loading. Under axial loading conditions, the peak stress values for internal fixation and the femur were found to be highest for CCS (454.4; 215.4 MPa) and CCS + MBP (797.2; 284.2 MPa), respectively. The corresponding maximum and minimum displacements for internal fixation were recorded as 6.65 mm for CCS and 6.44 mm for CCS + MBP. When subjected to torsional loading, the peak stress values for internal fixation were highest for CCS + MBP (153.6 MPa) and DHS + DS (72.8 MPa), while for the femur, the maximum and minimum peak stress values were observed for CCS + MBP (119.3 MPa) and FNS (17.6 MPa), respectively. Furthermore, the maximum and minimum displacements for internal fixation were measured as 0.249 mm for CCS + MBP and 0.205 mm for PFNA. Additionally, all six internal fixation models showed excellent performance in terms of yield load and fatigue life. CCS + MBP had the best initial mechanical stability in treatment for Pauwels type III fracture. However, the MBP was found to be more susceptible to shear stress, potentially increasing the risk of plate breakage. Furthermore, the DHS + DS exhibited superior biomechanical stability compared to CCS, DHS, and PFNA, thereby offering a more conducive environment for fracture healing. Additionally, it appeared that FNS represented a promising treatment strategy, warranting further validation in future studies.

Uncemented Tibial Fixation Has Comparable Prognostic Outcomes and Safety Versus Cemented Fixation in Cruciate-Retaining Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials

Cemented and uncemented fixation are the primary methods of tibial prosthesis fixation in total knee arthroplasty. However, the optimal fixation method remains controversial. This article explored whether uncemented tibial fixation has better clinical and radiological outcomes, fewer complications, and revision rates compared to cemented tibial fixation. We searched the PubMed, Embase, Cochrane Library, and Web of Science databases up to September 2022 to identify randomized controlled trials (RCTs) that compared uncemented total knee arthroplasty (TKA) and cemented TKA. The outcome assessment consisted of clinical and radiological outcomes, complications (aseptic loosening, infection, and thrombosis), and revision rate. Subgroup analysis was used to explore the effects of different fixation methods on knee scores in younger patients. Nine RCTs were finally analyzed with 686 uncemented knees and 678 cemented knees. The mean follow-up time was 12.6 years. The pooled data revealed significant advantages of uncemented fixations over cemented fixations in terms of the Knee Society Knee Score (KSKS) (p = 0.01) and the Knee Society Score-Pain (KSS-Pain) (p = 0.02). Cemented fixations showed significant advantages in maximum total point motion (MTPM) (p < 0.0001). There was no significant difference between uncemented fixation and cemented fixation regarding functional outcomes, range of motion, complications, and revision rates. When comparing among young people (<65 years), the differences in KSKS became statistically insignificant. No significant difference was shown in aseptic loosening and the revision rate among young patients. The current evidence shows better knee score, less pain, comparable complications and revision rates for uncemented tibial prosthesis fixation, compared to cemented, in cruciate-retaining total knee arthroplasty.

Effect of different fixation methods on biomechanical property of cervical vertebral body replacement and fusion

BackgroundThe main purpose of this study was to examine the effect of different fixation methods (anterior fixation, self-stabilizing fixation and anterior-posterior fixation) on biomechanical property of vertebral body replacement and fusion. MethodsThree finite element models of cervical vertebral body replacement and fusion were established. The implanted models included artificial vertebral body and fixation system, and the loads imposed on the models included 75 N compression load and 1 Nm moment load. FindingsFor anterior-posterior fixation, the cervical load was mainly transmitted by the posterior pedicle screw and rod (more than 50%), and the stress shielding problem was the most significant than the self-stabilizing and anterior fixation. Self-stabilizing fixation was more helpful to the fusion of implant and vertebrae, but the higher risk of vertebral body collapse was worthy of attention if the cervical spine with osteoporosis. The stress of bone was mainly concentrated around the screw hole. The maximum stress (20.03 MPa) was lower than the yield stress of cortical bone and the possibility of fracture around the fixation device of cervical spine was low. The anterior fixation could meet the requirement of vertebral body replacement and fusion, and the addition of posterior pedicle screws and rods might obtain better treatment in cases of severe spine injury or osteoporosis. InterpretationThe findings of this study may provide guidance on clinical treatments for choosing more appropriate fixation methods for different patients.

Investigation of Methods and Influencing Factors to Increase the Positive Rate of Cytological Pathology of Cerebrospinal Fluid from Lung Cancer Leptomeningeal Metastases

In advanced non-small cell lung cancer (NSCLC), leptomeningeal metastases (LM) is a common consequence with rapid progression and a poor prognosis. LM affects roughly 3% to 5% of NSCLC patients, and it affects as many as 9.4% of individuals with epidermal growth factor receptor (EGFR) mutations. Cerebrospinal fluid cytology is the gold standard for diagnosing LM, while conventional cytopathology has a positive detection rate of less than 50%, resulting in a delay in diagnosis and treatment of LM. The fixation treatment of cerebrospinal fluid samples has a significant impact on the positive cytology detection rate, and how to improve the positive cytopathology detection rate of cerebrospinal fluid is a hot topic in clinical research. From June 2019 to November 2021, 105 cases diagnosed with LM based on clinical symptoms and positive imaging were collected and retrospectively evaluated in the second ward of the Department of Oncology of The Second Affiliated Hospital of Harbin Medical University. The effect of different fixation methods on the positive rate of cerebrospinal fluid cytopathology was investigated, and specimens of cerebrospinal fluid were collected and sent for examination using different delivery methods, including the application of the TIB cell preservation solution kit (experimental group) and the routine application of sterile plastic tubes in lumbar puncture bags (control group). Biochemical assays (glucose and total protein) were performed on the cerebrospinal fluid fluid, and Logistic regression analysis and receiver operating characteristic (ROC) curve were used to evaluate the supplementary diagnostic value for LM patients with lung cancer. The relevance of chemical indexes in the assessment of therapeutic efficacy was examined, and biochemical (glucose, total protein) indices and cytological changes in cerebrospinal fluid fluid after pemetrexed intrathecal injection therapy were dynamically monitored. In the control group, 24 (45.28%) patients were positive for the first time, while 42 (80.77%) patients were positive for the first time and 10 (19.23%) patients were negative for the first time in the experimental group. Significant differences existed between the two groups (P<0.001). The results of Logistic regression analysis of patients with the first cerebrospinal fluid biochemical test showed that the risk of positive cerebrospinal fluid biochemical pathology with less than 2.5 mmol/L was 2.456 times greater than 2.5 mmol/L of cerebrospinal fluid glucose (OR=2.456, P<0.05), and total cerebrospinal fluid biochemical protein greater than 430 mg/L was 2.647 times less than 430 mg/L (OR=2.647, P>0.05). The ROC curve showed glucose sensitivity of 76.9% in cerebrospinal fluid, the specificity of 54.5%, Youden index of 0.315 and area under the curve (AUC) of 0.620, total protein sensitivity in cerebrospinal fluid of 44.4%, 90.6%, Youden index of 0.350 and AUC of 0.671. After 2 cycles of pemetrexed intrathecal treatment with complete cerebrospinal fluid cytology and cerebrospinal fluid biochemical (glucose, total protein) tests in 73 and 50 patients, respectively, the rate of cerebrospinal fluid cytology turning negative was gradually increased. Cerebrospinal fluid glucose levels increased after 2 cycles of treatment compared with the first time, with a statistically significant difference (P<0.001). The use of a cell preservation solution kit to immediately fix cerebrospinal fluid samples following isolation in patients with clinical symptoms and positive imaging greatly enhances the rate of positive cerebrospinal fluid cytology detection. The effect of treatment can be assessed and predicted by continuous dynamic monitoring of cerebrospinal fluid biochemistry and cytology.

Biomechanical comparison of cervical discectomy/fusion model using allograft spacers between anterior and posterior fixation methods (lateral mass and pedicle screw)

BackgroundThe purpose of this study is to investigate effects of different fixation methods on the physical stress on allospacers, endplate-vertebral body, and implants using finite element model analyses. MethodsStress distribution and subsidence risk according to the fixation methods under the condition of hybrid motion control were analyzed. The detailed finite element model of a previously validated, three-dimensional, intact cervical spinal segment model, with C5–C6 segmental fusion using allospacer, was used to evaluate the biomechanical characteristics of different fixation combinations, such as anterior plate/screws, lateral mass screw, and posterior pedicle screw. FindingsThe load sharing on allospacers increased in extension in order of posterior pedicle screws (21.4%), lateral mass screws (31.5%), and anterior plate/screws (56.6%). lateral mass screw demonstrated the highest load sharing (68.1%) on the allospacer in flexion. The Peak von Mises stress of the allospacer was the lowest in flexion and axial rotation but the highest in extension with anterior plate/screws. Allospacer subsidence risk was the lowest in extension, lateral bending, and axial rotation with posterior pedicle screws but the lowest in flexion with anterior plate/screws. The bone-screw loosening risk was the lowest in all modes with posterior pedicle screws but the highest with anterior plate/screws. InterpretationPosterior pedicle screws demonstrated the best mechanical stability of allospacer failure-subsidence and the lowest risk of screw loosening. Different motion restrictions depending on the fixation method should be considered for implant and allospacer safety.

Comparison of the effects of different fixation methods in the treatment of intercondylar comminuted fracture of the femur

Objective To compare the effects of different fixation methods in the treatment of femoral intercondylar comminuted fracture. Methods From May 2015 to May 2017, 88 cases with femoral intercondylar comminuted fracture in Jiaxing Hospital of Zhejiang Armed Police Corps were selected in the research.According to the different fixation methods, the patients were divided into two groups.The control group(n=46) received dynamic condylar screw internal fixation treatment, the observation group(n=42) received the combination of fixed bridge treatment system.The related indicators of perioperative period, recovery of function after surgery, incidence of complications were compared between the two groups. Results The operation time, amount of bleeding, postoperative drainage, fracture healing time, postoperative weight-bearing time of the observation group were (104.36±20.72)min, (180.62±12.65)mL, (93.47±9.16)mL, (9.42±0.51)weeks, (4.62±1.81)weeks, respectively, which of the control group were (120.36±17.18)min, (269.74±20.24)mL, (62.31±7.34)mL, (10.32±0.67) weeks, (10.33±1.75)weeks, respectively, there were statistically significant differences between the two groups(t=3.96, 24.49, 17.50, 7.04, 15.04, all P<0.05). The joint function recovery rate of the observation group was 95.24%, which was higher than 76.09% of the control group(χ2=6.40, P<0.05). The incidence rate of complications in the observation group(4.76%) was lower than that in the control group(21.74%)(χ2=5.37, P<0.05). Conclusion The effect of bridged composite fixation system in the treatment of femoral intercondylar comminuted fracture is more effective than dynamic intercondylar screw fixation, and the clinical application value is higher than dynamic intercondylar screw fixation. Key words: Femoral fractures; Fracture fixation; Controlled clinical trial

Comparison of the effects of different fixation methods on open-door side in posterior expansive open-door laminoplas-ty

Objective To investigate the clinical outcome and complications of different types of expansive open door laminoplasty in cervical spondylotic myelopathy. Methods From December 2008 to June 2012, 221 patients with cervical spondylotic myelopathy treated with expansive open-door laminoplasty were divided into micro-titanium plate fixed group (96 cases), wire hanging fixed group(66 cases), anchor suspension fixed group (59 cases). The clinical outcome was evaluated in-cluding JOA score, operation time, bleeding volume, spinal cord pressure (a/M), cervical range of motion (ROM), open door an-gle, posterior shift distance of spinal cord and postoperative complications. Results All patients were followed up for more than 2 years. There were no significant differences in general condition, operation time, intraoperative blood loss, preoperative and post-operative 2 years JOA score, JOA score improvement rate, spinal cord shift distance, spinal cord compression among three groups; In the incidence of C5 nerve root paralysis, there was no significant difference between the silk suspension fixation group (12.1%) and the anchored suspension group (11.9%). The incidence of C5 nerve root paralysis for microplate fixation group (2.1%) was sig-nificantly lower than that of the silk suspension fixation group and anchored suspension fixation group, and the difference was sta-tistically significant. There was no significant difference in the fusion rate between the 3-month and 6-month portal arteries in the group of silk suspension fixation group(65%, 82%) and anchor fixation group(61%, 82%). The fusion rate of the microtiter plate fix-ation group(90%, 98%) was significantly higher than that of the silk suspension group and the anchorage group at 3 months and 6 months after operation. There were no significant differences in the incidence of recurrence, the total amount of cervical spine loss and the incidence of axial symptoms after 6 months of operation in the suspension group and the anchor suspension group. The in-cidence of occlusion, the total amount of cervical spine loss and the incidence of axial symptoms were significantly lower in the mi-cro titanium plate fixation group than those in the silk suspension group and the anchorage fixation group, the difference was statis-tically significant. Conclusion Using micro-titanium plate to fix the side of open door could achieve full spinal cord decompres-sion and access to satisfactory neurological improvement rate. At the same time, compared with the traditional silk or anchor sus-pension, the use of micro-titanium plate is more conducive to the door axis bone healing, prevent the occurrence of reclosing, sig-nificantly reduce the loss of postoperative cervical range of motion, and reduce the incidence of axial symptoms with the satisfac-tion of the clinical outcome. Key words: Cervical vertebrae; Spinal cord compression; Decompression, surgical; Postoperative complications; Radicu-lopathy

Opipramol for antidepressant therapy in early pregnancy

Society of Toxicologic Pathology has recommended mDF to fix testes since 2002. However, subsequent studies showed that false TUNEL-positive cells were observed in mDF-fixed testes. This study compared the effects of different fixation methods on histology and TUNEL staining in mouse testes. Results showed that fixation for 24 or 36 h in mDF provided better morphologic details in untreated testes, but markedly enhanced false TUNEL-positive staining. To optimize the fixation, testes were fixed using mDF for 6 h and then PFA for 18 h. Interestingly, fixation using mDF/PFA manifested better morphologic details, and rarely caused false TUNEL-positive cells in testes. Finally, we examined germ cell apoptosis in testes using mDF/PFA fixation in cadmium-treated mice. As expected, cadmium triggered germ cell apoptosis which was well visualized in the mDF/PFA fixed testes. Taken together, mDF plus PFA fixation not only minimizes false TUNEL-positive cells, but also provides integrated morphologic details in testes.

Different fixative methods influence histological morphology and TUNEL staining in mouse testes.

Society of Toxicologic Pathology has recommended mDF to fix testes since 2002. However, subsequent studies showed that false TUNEL-positive cells were observed in mDF-fixed testes. This study compared the effects of different fixation methods on histology and TUNEL staining in mouse testes. Results showed that fixation for 24 or 36h in mDF provided better morphologic details in untreated testes, but markedly enhanced false TUNEL-positive staining. To optimize the fixation, testes were fixed using mDF for 6h and then PFA for 18h. Interestingly, fixation using mDF/PFA manifested better morphologic details, and rarely caused false TUNEL-positive cells in testes. Finally, we examined germ cell apoptosis in testes using mDF/PFA fixation in cadmium-treated mice. As expected, cadmium triggered germ cell apoptosis which was well visualized in the mDF/PFA fixed testes. Taken together, mDF plus PFA fixation not only minimizes false TUNEL-positive cells, but also provides integrated morphologic details in testes.

Density and hydration of fresh and fixed human skeletal muscle

The maximum tetanic tension of skeletal muscle ( P 0) is often estimated based on calculation of physiological cross-sectional area (PCSA). PCSA depends on muscle volume, pennation angle, and fiber length. Studies documenting PCSA in fixed human muscles usually compute muscle volume by dividing muscle mass by density. These studies use a density value of 1.0597 g/cm 3, which was originally based on unfixed rabbit and canine muscle tissue. Due to the dehydration effects of different fixation methods, the variable hydration that occurs when fixed tissue is stored in buffered saline, and the potential for species-specific muscle density, this value may be incorrect and an accurate value for fixed human muscle density is needed. To obtain an accurate density and water content values, 4% formaldehyde-fixed ( n = 54 ) and 37% formaldehyde-fixed ( n = 54 ) cadaveric human muscle samples were divided into 6 groups (0, 6, 12, 18, 24, or 30 h) for hydration in phosphate buffered saline (PBS). Measurements of volume, water content, and mass were made enabling calculation of muscle density. Additionally, water content was measured in living muscle ( n = 4 ) to determine the appropriate hydration time in PBS. Comparisons among groups demonstrated a significant increase in muscle water content and muscle volume over time, reaching living tissue levels after 24 h, but, interestingly, the hydration process did not affect muscle density. These data yield a density value (mean±SE) of 1.112±0.006 g/cm 3 in 4% formaldehyde-fixed muscle and 1.055±0.006 g/cm 3 in 37% formaldehyde-fixed muscle. These results indicate that the use of inappropriate hydration times or density values can produce PCSA errors of 5–10%.

Lectin binding to rat spermatogenic cells: effects of different fixation methods and proteolytic enzyme treatment.

The binding of a panel of eight different fluorescein-conjugated lectins to rat spermatogenic cells was investigated. Particular attention was paid to the effects of different fixation methods and proteolytic enzyme digestion on the staining pattern. Concanavalin A (Con A), wheatgerm agglutinin (WGA), succinylated WGA (s-WGA) and agglutinin from gorse (UEA I) stained the cytoplasm of most germ cells as well as the spermatid acrosome. In contrast, peanut agglutinin (PNA), castor bean agglutinin (RCAI) and soy bean agglutinin (SBA) mainly stained the acrosome. The staining pattern varied depending on the fixation method used. PNA was particularly sensitive to formalin fixation, while SBA, DBA and UEA I showed decreased binding and Con A, WGA, s-WGA and RCA I were insensitive to this type of fixation. Pepsin treatment of the sections before lectin staining caused marked changes in the staining pattern; staining with PNA in formalin-fixed tissue sections was particularly improved but there was also enhanced staining with SBA and horse gram agglutinin (DBA). On the other hand, in Bouin- and particularly in acetone-fixed tissue sections, pepsin treatment decreased the staining with several of the lectins, for example WGA and UEA I.

Fetal transcutaneous carbon dioxide monitoring--the effect of different fixation methods.

Fetal transcutaneous carbon dioxide tension (tc-Pco2) was monitored simultaneously by two electrodes fixed with glue or suction during 10 deliveries. There were no differences in success rate, tc-Pco2 readings or stabilization time between the two fixation methods, but the glue fixation method was more time consuming, caused more discomfort to the patient and generally did not permit reapplication of the electrode.

The distribution of a proctolin-like immunoreactive material in the terminal ganglion of the cockroach, Periplaneta americana L.

Neurons with proctolin-like immunoreactivity were mapped in the terminal ganglion of Periplaneta americana. The effect of different fixation methods on the variability of immunostaining is described and discussed. The appearance of immunoreactive presynaptic terminals, described here for the first time in insects, points to a function of proctolin as neurotransmitter or neuromodulator in the central nervous system of P. americana besides its known role in the periphery. Proctolin-like immunoreactivity was shown in pre- and postsynaptic profiles. Synaptic contacts are described in detail.

Comparative effects of fixation methods using tannic acid on contrast of stained and unstained sections from Spurr-embedded plant leaves

The comparative effects of different fixation methods using tannic acid (TA) on contrast of stained and unstained sections from Spurr-embedded apple leaves were examined. A tetrafixation method, glutaraldehyde (GA) – osmium tetroxide (OsO4) – TA – OsO4, gave the best contrast in the unstained sections while double-fixed (GA – OsO4 and GA∙TA – OsO4) specimens showed low contrast. The unstained sections from triple-fixed (GA – OsO4 – TA and GA – TA – OsO4) leaves resulted in medium contrast. Another tetrafixation method (GA – TA – OsO4 – TA) gave fairly good contrast in unstained sections. The enhancing effect of TA on contrast was still more increased by brief double stain (uranyl acetate – lead citrate) or lead citrate alone. The results showed that the former tetrafixation method was very useful for observing the fine ultrastructure of stained and unstained sections from Spurr-embedded plant tissues. In the tetrafixed leaf cells, electron-dense cellular structures were found at the peripheral area of cells. Some rough endoplasmic reticulum (ER), some Golgi bodies, vesicles beneath plasma membranes, cell walls, plasma membranes, and amorphous materials between cell walls and plasma membranes showed increased contrast in the stained and unstained tissues. The vesicles were often found to be continuous with plasma membranes. Taking into account the distribution and function of the electron-dense organelles, the ER, Golgi bodies, and vesicles may be associated with cell wall synthesis.