scholarly journals Cyclic Damage Accumulation in the Femoral Constructs Made With Cephalomedullary Nails

2021 ◽  
Vol 8 ◽  
Author(s):  
Farah Hamandi ◽  
Alyssa Whitney ◽  
Mark H. Stouffer ◽  
Michael J. Prayson ◽  
Jörn Rittweger ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Damage Accumulation ◽  
Bending Tests ◽  
Kaplan Meier ◽  
Axial Cyclic Loading ◽  
Load To Failure ◽  
Failure Loads ◽  
Biomechanical Evaluation ◽  
And Gender ◽  
Cyclic Damage

Background: The purpose of this study was to evaluate the risk of peri-prosthetic fracture of constructs made with cephalomedullary (CM) long and short nails. The nails were made with titanium alloy (Ti-6Al-4V) and stainless steel (SS 316L).Methods: Biomechanical evaluation of CM nail constructs was carried out with regard to post-primary healing to determine the risk of peri-implant/peri-prosthetic fractures. Therefore, this research comprised of, non-fractured, twenty-eight pairs of cadaveric femora that were randomized and implanted with four types of fixation CM nails resulting in four groups. These constructs were cyclically tested in bi-axial mode for up to 30,000 cycles. All the samples were then loaded to failure to measure failure loads. Three frameworks were carried out through this investigation, Michaelis–Menten, phenomenological, and probabilistic Monte Carlo simulation to model and predict damage accumulation.Findings: Damage accumulation resulting from bi-axial cyclic loading in terms of construct stiffness was represented by Michaelis–Menten equation, and the statistical analysis demonstrated that one model can explain the damage accumulation during cyclic load for all four groups of constructs (P > 0.05). A two-stage stiffness drop was observed. The short stainless steel had a significantly higher average damage (0.94) than the short titanium nails (0.90, P < 0.05). Long titanium nail group did not differ substantially from the short stainless steel nails (P > 0.05). Results showed gender had a significant effect on load to failure in both torsional and bending tests (P < 0.05 and P < 0.001, respectively).Interpretation: Kaplan–Meier survival analysis supports the use of short titanium CM nail. We recommend that clinical decisions should take age and gender into consideration in the selection of implants.

Biomechanical characteristics of allogeneic cortical bone pins designed for fracture fixation

2008 ◽  
Vol 21 (02) ◽  
pp. 140-146
Author(s):  
M. R. Edwards ◽  
S. P. James ◽  
W. S. Dernell ◽  
R. J. Scott ◽  
A. M. Bachand ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Cortical Bone ◽  
Fracture Fixation ◽  
Impact Testing ◽  
Left Tibia ◽  
Four Point Bending ◽  
And Gender ◽  
The Right ◽  
Biomechanical Comparison ◽  
Better Than

SummaryThe biomechanical characteristics of 1.2 mm diameter allogeneic cortical bone pins harvested from the canine tibia were evaluated and compared to 1.1 mm diameter stainless steel pins and 1.3 mm diameter polydioxanone (PDS) pins using impact testing and four-point bending. The biomechanical performance of allogeneic cortical bone pins using impact testing was uniform with no significant differences between sites, side, and gender. In four-point bending, cortical bone pins harvested from the left tibia (204.8 ± 77.4 N/mm) were significantly stiffer than the right tibia (123.7 ± 54.4 N/mm, P=0.0001). The site of bone pin harvest also had a significant effect on stiffness, but this was dependent on interactions with gender and side. Site C in male dogs had the highest mean stiffness in the left tibia (224.4 ± 40.4 N/mm), but lowest stiffness in the right tibia (84.9 ± 24.2 N/mm). Site A in female dogs had the highest mean stiffness in the left tibia (344.9 ± 117.4 N/mm), but lowest stiffness in the right tibia (60.8 ± 3.7 N/mm). The raw and adjusted bending properties of 1.2 mm cortical bone pins were significantly better than 1.3 mm PDS pins, but significantly worse than 1.1 mm stainless steel pins (P<0.0001). In conclusion, cortical bone pins may be suitable as an implant for fracture fixation based on initial biomechanical comparison to stainless steel and PDS pins used in clinical practice.

scholarly journals Influence of peracetic acid-ethanol sterilisation on the biomechanical properties of human meniscus transplants

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Volker Eras ◽  
Josefine Graffunder ◽  
Norus Ahmed ◽  
Jan C. Brune
Keyword(s):  
Peracetic Acid ◽  
Biomechanical Properties ◽  
Bone Block ◽  
Test Device ◽  
Level Of Evidence ◽  
Load To Failure ◽  
Graft Extrusion ◽  
Fresh Frozen ◽  
Failure Loads ◽  
N Loading

Abstract Purpose Meniscus allograft transplantation (MAT) is a possible treatment for patients suffering with pain after meniscectomy. Here, peracetic acid (PAA) sterilised meniscus transplants were investigated on whether they would provide an adequate alternative to fresh-frozen transplants in their viscoelastic and mechanical properties. Methods In this analysis, 31 menisci donors (26 male and 5 female) were included. The average donor age was 49.87 years, ranging from 32 to 65 years. Menisci of matched pairs of knees underwent chemical sterilisation while counterparts were left fresh-frozen. Stiffness and load to failure were determined via suture retention. Further menisci were analysed while attached to the tibial bone block using a novel test device to mimic physiological load distribution. Meniscus relaxation, stiffness and failure loads were determined. Histology and biphasic properties of the menisci were examined and results were analysed using paired t-tests. Results A novel custom built test device allowed the application of physiological loads for suture retention testing and revealed no significant differences between PAA sterilised (14.85 ± 4.46 N/mm, 50.49 ± 17.01 N) and fresh-frozen (18.26 ± 4.46 N/mm, 59.49 ± 21.07 N) regarding stiffness and failure load, respectively. Furthermore, initial 200 N loading showed significantly higher strain in sterilised menisci (18.87 ± 1.56) compared to fresh frozen (13.81 ± 1.04). Load relaxation experiments demonstrated significantly lower relaxation for sterilised menisci (77.71 ± 1.62) compared to fresh-frozen (89.11 ± 1.00, p-value < 0.0001). Conclusion Peracetic acid sterilised human menisci performed equally to fresh-frozen counterparts in a suture retention test and in physiological failure testing providing an adequate alternative. However, meniscus relaxation, biphasic properties and strain were shown to be significantly different between the groups. A common problem of MAT is graft extrusion or shrinkage, therefore the parameters measured here should be considered and may influence meniscus extrusion after transplantation. Level of evidence n/a (experimental study)

Biomechanical Evaluation of Polylactide Absorbable Screws Used for Syndesmosis Injury Repair

1997 ◽  
Vol 18 (10) ◽  
pp. 622-627 ◽  
Author(s):  
David B. Thordarson ◽  
Thomas P. Hedman ◽  
Dominic Gross ◽  
George Magre
Keyword(s):  
Computed Tomography ◽  
Fatigue Testing ◽  
Clinical Situation ◽  
Stainless Steel Screw ◽  
Syndesmosis Injury ◽  
Computed Tomography Scans ◽  
Load To Failure ◽  
Fresh Frozen ◽  
Biomechanical Evaluation ◽  
And Control

Simulated syndesmosis injuries were created in 12 fresh-frozen, below-knee cadaver specimens. Six specimens were repaired with a 4.5 mm stainless steel screw, and six were repaired with a 4.5 mm polylactide screw. Three specimens of each group were tested in load to failure by axially loading with 1400 N and externally rotating to 90°. Three specimens in each group underwent fatigue testing by axially loading with 700 N and applying 2.5 N-m of torque for 57,700 cycles. Radiographs and computed tomography scans were evaluated. None of the screws broke or failed. Similar load to failure was noted in polylactide and control groups. Fatigue testing revealed no significant change in stiffness. No significant screw damage was evident on radiographic or computed tomography evaluation. The data suggest that a polylactide screw has sufficient fatigue and failure strength to allow for healing of this injury in a clinical situation.

scholarly journals Interface Characteristics and Properties of a High-Strength Corrosion-Resistant Stainless Steel Clad Rebar

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 373
Author(s):  
Xuming Liu ◽  
Guanghong Feng ◽  
Xin Liu ◽  
Baoshan Wang ◽  
Hongliang Zhang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Transition Zone ◽  
High Strength ◽  
Martensite Phase ◽  
Duplex Structure ◽  
Bending Tests ◽  
Metallurgical Bonding ◽  
Interface Characteristics ◽  
Rolling Method ◽  
Negative Bending

This paper aims at manufacturing stainless steel clad (SSC) rebars by metal deposition and a hot rolling method as well as characterizing its interface features and mechanical properties. The interface of the SSC rebar is relatively flat and clean, exhibiting a metallurgical bonding state at the microscale. Decarburization occurred at the interface in the carbon steel side of the SSC rebar. The diffusion of C, Cr, as well as Mn was measured across the interface of the SSC rebar, and the diffusion distance of Cr and Mn was found at 32 µm and 25 µm, respectively. The Vickers hardness testing in the transition zone of the SSC rebar near the carbon side showed 545 HV0.2 due to the martensite phase formed by the diffusion of key elements C, Cr, and Mn. The microstructure in the transition zone near the stainless steel reveals the duplex structure of martensite and ferrite. The carbide precipitations were observed near the interface, both in the transition zone and in the base metal of the stainless steel zone. The yield strength, tensile strength, and elongation of the SSC rebar were found as 423 MPa, 602 MPa, and 22%. No macroscopic crack was observed after the positive or negative bending tests.

scholarly journals Comparison of Survival Rates of Stainless-Steel Crowns Placed with and without Pulpotomy: A Two-Year Retrospective Study

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Fatmah N. AlMotawah ◽  
Sharat Chandra Pani ◽  
Tala AlKharashi ◽  
Saleh AlKhalaf ◽  
Mohammed AlKhathlan ◽  
...  
Keyword(s):  
Stainless Steel ◽  
General Anesthesia ◽  
Survival Rates ◽  
Survival Outcome ◽  
Survival Outcomes ◽  
Proximal Caries ◽  
Kaplan Meier ◽  
Significant Difference ◽  
Chi Squared

Aim. This study aimed to retrospectively compare the survival outcomes over two years between teeth with proximal dental caries that were restored with stainless-steel crowns to those that were pulpotomized and then restored with a stainless-steel crown in patients who were rehabilitated under general anesthesia. Participants and Methods. The records of 131 patients aged between two to six years who had stainless-steel crowns placed under general anesthesia and had two-year follow-up were screened. 340 teeth with moderate proximal caries on the radiograph (D2) were included in the study. Of these, 164 teeth were treated with a pulpotomy and stainless-steel crown, while 176 teeth were crowned without a pulpotomy. The type of each tooth was compared using the Chi-squared test and Kaplan–Meier survival analysis, and curves were plotted based on the two-year outcomes. Results. Treatment: the sample comprised 59 males (mean age 4.73 years, SD ± 1.4 years) and 72 females (mean age 5.2 years, SD ± 2.0 years). The Kaplan–Meier regression model showed no significant difference in survival outcomes between teeth that had been pulpotomized and those that had not ( p  = 0.283). Conclusion. Within the limitations of the current study, we can conclude that performing a pulpotomy does not influence the survival outcome of mild/moderate proximal caries restored with stainless-steel crowns under general anesthesia.

scholarly journals A Preliminary Study of microRNA-208b after Acute Myocardial Infarction: Impact on 6-Month Survival

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Mostafa Alavi-Moghaddam ◽  
Mohammad Chehrazi ◽  
Shamila D. Alipoor ◽  
Maryam Mohammadi ◽  
Alireza Baratloo ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Survival Time ◽  
Term Survival ◽  
Relative Expression ◽  
Kaplan Meier ◽  
Healthy Control ◽  
And Gender

Introduction. miRNAs contribute to a variety of essential biological processes including development, proliferation, differentiation, and apoptosis. Circulating microRNAs are very stable and have shown potential as biomarkers of cardiovascular disease. microRNA-208b expression was increased in the blood of patients with acute myocardial infarction (AMI) and has been proposed as a biomarker for early diagnosis. In this pilot study, we investigate the potential of circulating miR-208b as a prognostic biomarker of 6-month survival in AMI patients. Methods. Plasma samples from 21 patients and 8 age- and gender-matched healthy adults were collected, and circulating levels of miR-208b were detected using quantitative real-time PCR. Results. miR-208b levels were higher in healthy control subjects (9.6-fold; P≤0.05). Within the AMI patients, the levels of miR-208b were significantly lower in the survivor versus nonsurvivor group (fold change = 6.51 and 14.1, resp.; P≤0.05). The Kaplan-Meier curve revealed that the 6-month survival time was significantly higher among AMI patients with a relative expression of miR-208b lower than 12.38. The hazard ratio (HR) for the relative expression of miR-208b (<12.38 was the reference) was 5.08 (95% CI: 1.13–22.82; P=0.03). Conclusion. Our results showed that elevated miR-208b expression was associated with reduced long-term survival in AMI patients. These pilot data indicate the need for a large follow-up study to confirm whether miR-208b can be used as a predictor of 6-month survival time after AMI.

Biomechanical Evaluation of a Four-Strand Modification of the Tang Method of Tendon Repair

2005 ◽  
Vol 30 (4) ◽  
pp. 374-378 ◽  
Author(s):  
Y. CAO ◽  
J. B. TANG
Keyword(s):  
Ultimate Strength ◽  
Testing Machine ◽  
Tendon Repair ◽  
Gap Formation ◽  
Single Cycle ◽  
Tensile Testing Machine ◽  
Load To Failure ◽  
Biomechanical Evaluation ◽  
Finger Motion ◽  
Initial Force

We report a four-strand modification of the Tang technique of tendon repair that uses fewer sutures and fewer knots on the tendon surface. This repair consists of four longitudinal and two horizontal strands that form a “U” configuration within the tendon made with a single looped suture. Thirty-four fresh pig flexor tendons were divided into 3 groups and repaired with the four-strand modified Tang method, a double-looped four-strand method or a double Kessler repair (four-strand). The tendons were subjected to a single cycle of load-to-failure test in a tensile testing machine. The initial force, 2-mm gap formation force and ultimate strength of the four-strand modified Tang repair were statistically identical to those of the double looped suture and were superior to those of the double Kessler repair. Ultimate strength was 43.4 ± 4.3 N for the four-strand modified Tang method, 45.2 ± 4.0 N for the double-looped method and 39.1 ± 4.0 N for the double Kessler repair. The four-strand modification of the Tang method appears to have strength sufficient for protected active finger motion. Given our preliminary clinical experience with this method, we recommend this new and simplified technique for clinical flexor tendon repairs.

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