scholarly journals Osteochondral Allograft Transplantation: Identifying the Biomechanical Impact of Using Shorter Grafts and Pulsatile Lavage on Graft Stability

2019 ◽  
Vol 7 (7_suppl5) ◽  
pp. 2325967119S0028
Author(s):  
Jacob Babu ◽  
Jonathan D. Hodax ◽  
Paul D. Fadale ◽  
Brett D. Owens
Keyword(s):  
Structural Integrity ◽  
Tensile Force ◽  
Osteochondral Allograft ◽  
Pull Out ◽  
Tensile Forces ◽  
Compressive Loads ◽  
Post Hoc ◽  
Pulsatile Lavage ◽  
Osteochondral Allografts

Objectives: This study seeks to identify the ability of shorter Osteochondral Allografts (OCAs) to resist displacement/failure. Additionally, this study seeks to evaluate the effect of pulsatile lavage on the biomechanical stability of the OCA graft. Methods: Fifteen millimeter diameter, human cadaveric, osteochondral allografts of 4 mm, 7 mm, and 10 mm in depth were harvested for comparison of resistance to compressive and tensile loads. For each group 7 specimens were subjected to tensile loads and 3 specimens subjected to compressive loads until failure (pull-out or subsidence). An additional study group of 10 pulsatile lavaged (PL) osteochondral allografts of 15 mm in diameter and 7 mm in depth were introduced for comparison to the original 7 mm depth OCA group. Results: The average tensile forces for failure for the 4 mm, 7 mm, and 10 mm plugs were 23.74 N, 199.57 N and 197.69 N respectively (p=1.5x10-5). After post-hoc analysis of the tensile groups, significant differences in the mean tensile force to failure were appreciated between the 4 mm and 7 mm groups (p=4.12 x10-5) and the 4 mm and 10 mm groups (p=1.78x10-5), but not between the 7 mm and 10 mm groups (p=.9601). There were no significant differences between the average tensile forces resulting in failure for the 7 mm and 7mm-PL groups (199.57 N and 205.2 N, p=.90) or compressive forces to failure respectively (733.6 N and 656 N, p=.7062). Conclusion: For OCAs of 15 mm in diameter, a commonly used size in practice, we recommend that plugs of 7 mm in depth be utilized. Pulsatile lavage of allografts prior to insertion does not appear to take away from the structural integrity and stability of the plug, however an adequately powered study should confirm this. With many described theoretical benefits of decreased immunogenicity and better long term graft incorporation after lavage, we recommend that this practice continue. [Table: see text]

Osteochondral Allograft Transplantation: Identifying the Biomechanical Impact of Using Shorter Grafts and Pulsatile Lavage on Graft Stability

2018 ◽  
Vol 33 (01) ◽  
pp. 029-033
Author(s):  
Jacob M. Babu ◽  
Jonathan D. Hodax ◽  
Paul D. Fadale ◽  
Brett D. Owens
Keyword(s):  
Structural Integrity ◽  
Tensile Force ◽  
Osteochondral Allograft ◽  
Biomechanical Stability ◽  
Pull Out ◽  
Tensile Forces ◽  
Compressive Loads ◽  
The Mean ◽  
Post Hoc ◽  
Pulsatile Lavage

AbstractThis study seeks to identify the ability of shorter osteochondral allografts (OCAs) to resist displacement/failure. Additionally, this study seeks to evaluate the effect of pulsatile lavage (PL) on the biomechanical stability of the OCA. Fifteen-millimeter diameter, human cadaveric, OCAs of 4, 7, and 10 mm in depth were harvested for comparison of resistance to compressive and tensile loads. For each group, seven specimens were subjected to tensile loads and three specimens subjected to compressive loads until failure (pullout or subsidence). An additional study group of 10 pulsatile-lavaged OCAs of 15 mm in diameter and 7 mm in depth were introduced for comparison to the original 7 mm depth OCA group. The average tensile forces for failure for the 4, 7, and 10 mm plugs were 23.74, 199.57, and 197.69 N, respectively (p = 1.5 × 10−5). After post hoc analysis of the tensile groups, significant differences in the mean tensile force to failure were appreciated between the 4 and 7 mm groups (p = 4.12 × 10−5) and the 4 and 10 mm groups (p = 1.78 × 10−5) but not between the 7 and 10 mm groups (p = 0.9601). There were no significant differences between the average tensile forces resulting in failure for the 7 mm and 7 mm PL groups (199.57 and 205.2 N, p = 0.90) or compressive forces to failure, respectively (733.6 and 656 N, p = 0.7062). For OCAs of 15 mm in diameter, a commonly used size in practice, plugs of 7 mm in depth showed comparable resistance to pull out and subsidence as 10 mm plugs and significantly better resistance to pull out than 4 mm grafts. PL of allografts prior to insertion did not take away from the structural integrity and stability of the plug.

scholarly journals The Effect of Patellar Surface Morphology On Subchondral Bone Alignment When Matching Patellar Osteochondral Allografts (206)

2021 ◽  
Vol 9 (10_suppl5) ◽  
pp. 2325967121S0031
Author(s):  
Mithun Neral ◽  
Karan Patel ◽  
Michael Getty ◽  
Nabeel Salka ◽  
John Grant
Keyword(s):  
Surface Morphology ◽  
Subchondral Bone ◽  
Osteochondral Allograft ◽  
Force Distribution ◽  
Bone Surface ◽  
Cartilage Surface ◽  
Significant Difference ◽  
Surface Deviation ◽  
Osteochondral Allografts

Objectives: Recent research has shown that implanting a patellar osteochondral allograft with a non-matched surface morphology (i.e., Wiberg classification) does not create increased chondral surface deviation or circumferential step-off in the donor plug compared to the native patella. While much of the research on patellar osteochondral allografts has been focused on chondral surface matching, little has been done to determine if the subchondral bone alignment at the donor:native interface plays a role in graft healing, local force distribution, and long term success of the allograft transplant. Previous work in our lab demonstrated that even when the patellar cartilage surface was well matched, notable differences in subchondral bone alignment were observed. The purpose of this study was therefore to use surface contour mapping of subchondral bone to determine if differences in Wiberg classification play a role in the ability of donor patellar osteochondral allograft subchondral bone to align with the native patellar subchondral bone when treating osteochondral defects of the patellar apex. The hypothesis was that patellar surface morphology would have an effect on subchondral bone surface height deviation and circumferential step-off when performing osteochondral allograft transplants of the patellar apex. Methods: Sixty fresh frozen human patellae were acquired from a national donor procurement company. Twenty (10 Wiberg I and 10 Wiberg II/III) patellae were designated as the recipient and then nano-CT scanned. Each recipient was size-matched (within ±2mm tibial width) to both a Wiberg I and a Wiberg II/III patellar donor. A 16mm circular osteochondral “defect” centered on the central ridge of the patella was then created in the recipient patella. A randomly-ordered donor Wiberg I or Wiberg II/III plug was harvested from a homologous location and transplanted into the recipient. The recipient was then nano-CT scanner, digitally reconstructed, and superimposed on the initial nano-CT scan of the native recipient patella. After careful atraumatic removal of the first donor plug, the process was repeated using the other allograft plug. MATLAB was used to determine the root mean square (RMS) surface height deviation between the native and donor subchondral bone surfaces. Dragonfly 3D imaging software was used to measure the RMS subchondral bone step-off height at 3° increments around the circumference of the graft. Surface height deviation and circumferential step-off height were analyzed for the whole surface and by quadrant to determine if there were local differences. ANOVA was used to compare surface deviation and step-off heights between matched and unmatched grafts. Sidak’s multiple comparison test was used to complete sub-analysis between patellar graft quadrants. Comparisons were made between matched and unmatched grafts in terms of the RMS surface height deviation and step-off, as well as in the percentage of measurements that were more than 0.5mm, 1mm, and 2mm proud or sunken relative to the native surface. Results: There were no significant differences in RMS subchondral bone surface height deviation between matched and unmatched Wiberg plugs as a whole or by quadrant (RMS range = 0.69 to 0.97mm, p = 0.45 – 1.0). There was a significant difference in RMS circumferential step-off height between matched (1.14 ± 0.52mm) and unmatched (1.38 ± 0.49mm) Wiberg plugs ( p=0.015). The majority of these increased step-off measurements occurred in the lateral quadrant with lateral quadrant RMS step-off of 0.89 ± 0.43mm in matched grafts and 1.60 ± 0.78mm in unmatched grafts ( p=0.007). There was also a significant difference in the percent of step-off measurements greater than 2mm sunken in the lateral quadrant between matched and unmatched grafts (5.17 ± 20.87% matched, 24.5 ± 36.39% unmatched, p=0.028). There were no significant differences between matched and unmatched grafts for any other comparison using 0.5, 1, or 2mm cut-offs for circumferential step-off or surface height deviation. Combining all allografts, the respective proportion of surface deviation and circumferential step-off height measurements that were above the stated thresholds were as follows: 31% and 34% for a 0.5mm threshold, 15% and 21% for a 1mm threshold, and 2% and 8% for a 2mm threshold. Conclusions: While unmatched Wiberg patella osteochondral allograft implantation did not result in significantly different subchondral bone surface height deviations, there were significant differences in circumferential subchondral bone step-off heights. The majority of step-off height differences between Wiberg matched and unmatched osteochondral allografts occurred in the lateral quadrant. In comparison to previous data evaluating differences in the cartilage surface match in these patellar OCA transplants, the deviations and step-off heights in the subchondral bone identified in the current study were approximately 0.5mm greater than the differences in the cartilage surface. These findings therefore suggest there is greater variability in the alignment of the subchondral bone in these patellar osteochondral allografts than there is in the cartilage surface. Further investigation using finite element analysis modeling will help determine the implications of subchondral bone surface deviation and circumferential step-off on local cartilage:bone compression and shear force distribution. These studies may shed light on the mechanisms of failure in patellar osteochondral transplants and may help to better understand the contribution of subchondral bone alignment in OCA healing and long-term outcome.

Individual differences in white and grey matter structure associated with verbal habits of thought

2019 ◽  
Author(s):  
Justin C. Hayes ◽  
Katherine L Alfred ◽  
Rachel Pizzie ◽  
Joshua S. Cetron ◽  
David J. M. Kraemer
Keyword(s):  
Individual Differences ◽  
White Matter ◽  
Cognitive Processing ◽  
Grey Matter ◽  
Structural Changes ◽  
Structural Integrity ◽  
Diffusion Tensor ◽  
Self Report ◽  
White Matter Tracts

Modality specific encoding habits account for a significant portion of individual differences reflected in functional activation during cognitive processing. Yet, little is known about how these habits of thought influence long-term structural changes in the brain. Traditionally, habits of thought have been assessed using self-report questionnaires such as the visualizer-verbalizer questionnaire. Here, rather than relying on subjective reports, we measured habits of thought using a novel behavioral task assessing attentional biases toward picture and word stimuli. Hypothesizing that verbal habits of thought are reflected in the structural integrity of white matter tracts and cortical regions of interest, we used diffusion tensor imaging and volumetric analyses to assess this prediction. Using a whole-brain approach, we show that word bias is associated with increased volume in several bilateral language regions, in both white and grey matter parcels. Additionally, connectivity within white matter tracts within an a priori speech production network increased as a function of word bias. These results demonstrate long-term structural and morphological differences associated with verbal habits of thought.

scholarly journals Disability improvement as a clinically relevant outcome in clinical trials of relapsing forms of multiple sclerosis

2021 ◽  
pp. 135245852110002
Author(s):  
Bruce AC Cree ◽  
Jeffrey A Cohen ◽  
Anthony T Reder ◽  
Davorka Tomic ◽  
Diego Silva ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Clinical Trials ◽  
Therapeutic Benefit ◽  
Disease Modifying Therapies ◽  
Long Term Follow Up ◽  
Post Hoc ◽  
Switch Group ◽  
Relevant Outcome

Background: Disease-modifying therapies (DMTs) can reduce the risk of disability worsening in patients with relapsing forms of multiple sclerosis (RMS). High-efficacy DMTs can lead to confirmed or sustained disability improvement (CDI and SDI). Objective and Methods: Post hoc analyses of data from the TRANSFORMS, FREEDOMS, and FREEDOMS II trials and their extensions assessed the effects of fingolimod (0.5–1.25 mg/day) on stabilizing or improving disability over ⩽8 years in participants with RMS. CDI and SDI rates were compared between participants initially randomized to fingolimod, interferon (IFNβ-1a), or placebo. Results: At 8 years’ follow-up in TRANSFORMS, 35.1% (95% confidence interval [CI], 28.2%–43.1%) of assessed participants in the IFNβ-1a–fingolimod switch group and 41.9% (36.6%–47.6%) on continuous fingolimod experienced CDI; disability did not worsen in approximately 70%. Similar results were seen in the combined FREEDOMS population. Proportionally fewer TRANSFORMS participants achieved SDI in the IFNβ-1a–fingolimod switch group than on continuous fingolimod (5.4% [3.0%–9.5%] vs 14.2% [10.8%–18.4%], p = 0.01). Conclusion: CDI and SDI are outcomes of interest for clinical trials and for long-term follow-up of participants with RMS. Monitoring CDI and SDI in addition to disability worsening may facilitate understanding of the therapeutic benefit of RMS treatments.

Long term habitual vigorous physical activity is associated with lower visit-to-visit systolic blood pressure variability

2020 ◽  
Author(s):  
Xiaoyong Xu ◽  
Xianghong Meng ◽  
Shin-ichi Oka
Keyword(s):  
Physical Activity ◽  
Blood Pressure ◽  
Standard Deviation ◽  
Systolic Blood Pressure ◽  
Blood Pressure Variability ◽  
Vigorous Physical Activity ◽  
Systolic Blood Pressure Variability ◽  
Average Real Variability ◽  
Post Hoc

Abstract Objective Our work aimed to investigate the association between vigorous physical activity and visit-to-visit systolic blood pressure variability (BPV). Methods We conducted a post hoc analysis of SPRINT (Systolic Blood Pressure Intervention Trial), a well-characterized cohort of participants randomized to intensive (<120 mmHg) or standard (<140 mmHg) SBP targets. We assessed whether patients with hypertension who habitually engage in vigorous physical activity would have lower visit-to-visit systolic BPV compared with those who do not engage in vigorous physical activity. Visit-to-visit systolic BPV was calculated by standard deviation (SD), average real variability (ARV), and standard deviation independent of the mean (SDIM) using measurements taken during the 1-, 2-, 3-, 6-, 9- and 12-month study visits. A medical history questionnaire assessed vigorous physical activity, which was divided into three categories according to the frequency of vigorous physical activity. Results A total of 7571 participants were eligible for analysis (34.8% female, mean age 67.9±9.3 years). During a follow-up of 1-year, vigorous physical activity could significantly reduce SD, ARV, and SDIM across increasing frequency of vigorous physical activity. There were negative linear trends between frequency of vigorous physical activity and visit-to-visit systolic BPV. Conclusions Long-term engagement in vigorous physical activity was associated with lower visit-to-visit systolic BPV.

Overlapping Allografts Provide Superior and More Reliable Surface Topography Matching Than Oblong Allografts: A Computer-Simulated Model Study

2021 ◽  
pp. 036354652110030
Author(s):  
Hailey P. Huddleston ◽  
Atsushi Urita ◽  
William M. Cregar ◽  
Theodore M. Wolfson ◽  
Brian J. Cole ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Surface Topography ◽  
Osteochondral Allograft ◽  
Cartilage Defects ◽  
Radius Of Curvature ◽  
Cartilage Surface ◽  
3 Dimensional ◽  
Cloud Models ◽  
And Cartilage ◽  
Osteochondral Allografts

Background: Osteochondral allograft transplantation is 1 treatment option for focal articular cartilage defects of the knee. Large irregular defects, which can be treated using an oblong allograft or multiple overlapping allografts, increase the procedure’s technical complexity and may provide suboptimal cartilage and subchondral surface matching between donor grafts and recipient sites. Purpose: To quantify and compare cartilage and subchondral surface topography mismatch and cartilage step-off for oblong and overlapping allografts using a 3-dimensional simulation model. Study Design: Controlled laboratory study. Methods: Human cadaveric medial femoral hemicondyles (n = 12) underwent computed tomography and were segmented into cartilage and bone components using 3-dimensional reconstruction and modeling software. Segments were then exported into point-cloud models. Modeled defect sizes of 17 × 30 mm were created on each recipient hemicondyle. There were 2 types of donor allografts from each condyle utilized: overlapping and oblong. Grafts were virtually harvested and implanted to optimally align with the defect to provide minimal cartilage surface topography mismatch. Least mean squares distances were used to measure cartilage and subchondral surface topography mismatch and cartilage step-off. Results: Cartilage and subchondral topography mismatch for the overlapping allograft group was 0.27 ± 0.02 mm and 0.80 ± 0.19 mm, respectively. In comparison, the oblong allograft group had significantly increased cartilage (0.62 ± 0.43 mm; P < .001) and subchondral (1.49 ± 1.10 mm; P < .001) mismatch. Cartilage step-off was also found to be significantly increased in the oblong group compared with the overlapping group ( P < .001). In addition, overlapping allografts more reliably provided a significantly higher percentage of clinically acceptable (0.5- and 1-mm thresholds) cartilage surface topography matching (overlapping: 100% for both 0.5 and 1 mm; oblong: 90% for 1 mm and 56% for 0.5 mm; P < .001) and cartilage step-off (overlapping: 100% for both 0.5 and 1 mm; oblong: 86% for 1 mm and 12% for 0.5 mm; P < .001). Conclusion: This computer simulation study demonstrated improved topography matching and decreased cartilage step-off with overlapping osteochondral allografts compared with oblong osteochondral allografts when using grafts from donors that were not matched to the recipient condyle by size or radius of curvature. These findings suggest that overlapping allografts may be superior in treating large, irregular osteochondral defects involving the femoral condyles with regard to technique. Clinical Relevance: This study suggests that overlapping allografts may provide superior articular cartilage surface topography matching compared with oblong allografts and do so in a more reliable fashion. Surgeons may consider overlapping allografts over oblong allografts because of the increased ease of topography matching during placement.

scholarly journals Impact of Prolonged Exposure of Eleven Years to Hot Seawater on the Degradation of a Thermoset Composite

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2154
Author(s):  
Amir Hussain Idrisi ◽  
Abdel-Hamid I. Mourad ◽  
Muhammad M. Sherif
Keyword(s):  
Exposure Time ◽  
Prolonged Exposure ◽  
Mechanical Performance ◽  
Matrix Cracking ◽  
Pull Out ◽  
Strength Based ◽  
Different Temperatures ◽  
River Line ◽  
Composite Samples

This paper presents a long-term experimental investigation of E-glass/epoxy composites’ durability exposed to seawater at different temperatures. The thermoset composite samples were exposed to 23 °C, 45 °C and 65 °C seawater for a prolonged exposure time of 11 years. The mechanical performance as a function of exposure time was evaluated and a strength-based technique was used to assess the durability of the composites. The experimental results revealed that the tensile strength of E-glass/epoxy composite was reduced by 8.2%, 29.7%, and 54.4% after immersion in seawater for 11 years at 23 °C, 45 °C, and 65 °C, respectively. The prolonged immersion in seawater resulted in the plasticization and swelling in the composite. This accelerated the rate of debonding between the fibers and matrix. The failure analysis was conducted to investigate the failure mode of the samples. SEM micrographs illustrated a correlation between the fiber/matrix debonding, potholing, fiber pull-out, river line marks and matrix cracking with deterioration in the tensile characteristics of the thermoset composite.

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