Concerns About Ankle Injury Prophylaxis and Acceptance of the Parachute Ankle Brace Among Jumpmaster Students.

Introduction: Several studies have shown that the parachute ankle brace (PAB) is safe, cost-effective, and reduces the rates of ankle injuries during military parachuting. However, the acceptability and usability of the PAB has not been well established in units that regularly do airborne exercises. Many anecdotal concerns in the past may be limiting common use. The purpose of the study is to ascertain the attitudes toward the PAB among experienced paratroopers. Methods: One hundred experienced paratroopers training to be jumpmasters at the Advanced Airborne School (Fort Bragg, NC) voluntarily responded to a 13-item, paper questionnaire to assess attitudes toward the PAB, its use, and concerns about future ankle injuries. The survey was offered to all 100 students enrolled in an Advanced Airborne School course. Results were input into an online database using Qualtrics and qualitative responses were evaluated for thematic content and categorized appropriately. Analysis was performed using Qualtrics and SPSS for descriptive statistics, two-sample t-tests, and chi-square tests. The Wilcoxon signed-rank test was used to evaluate Likert-type responses. Results: Of the 100 paratroopers who responded to the survey 32% had over 10 yr of military service, 58% had over 5 yr of service, and 32% had over 5 yr on active jump status. Results show that none of the respondents had ever used the PAB; 62% had never heard of the PAB, and 72% had never observed use of the PAB. A majority of respondents (87%) had never injured an ankle during a parachute landing fall (PLF), but 79% believed that an ankle injury could affect their career potential as a paratrooper. Almost one-half of the respondents (47%) had seen that ankle injuries affect another paratrooper's career. A third of the respondents (35%) said that they had concerns that would keep them from using the PAB, whereas 21% were uncertain, as they had never heard of it. Only 19% of the respondents were willing to use measures such as taping, lace-up bracing, semi-rigid brace inside a normal boot, specialized jump boot with stabilizing braces built in, or outside-the-boot braces to prevent ankle injury. However, 40% said that they were likely to use these measures on jumps after experiencing an ankle injury. Discussion: Previous research clearly establishes the advantages of the PAB. None of the participants had ever used the PAB but expressed a fear about how an ankle injury might impact their future career potential. Yet half of the jumpmasters indicated a willingness to use prophylactic measures after an ankle injury. Conclusion: This survey assessed the attitude and knowledge related to the PAB among jumpmaster students. Results show that despite the benefits of the PAB, a negative attitude exists toward the PAB, and it is not currently being used. This survey clearly demonstrates the need either to educate paratroopers on the existence of the PAB or to explore other designs that may be more readily accepted in the airborne community.

An orthopedic tissue adhesive for targeted delivery of intraoperative biologics.

Tissue adhesives can bind together damaged tissues and serve as tools to deliver and localize therapeutics to facilitate regeneration. One emerging therapeutic trend in orthopedics is the use of intraoperative biologics (IOB), such as bone marrow (BM) and platelet-rich plasma (PRP), to stimulate healing. Here, we introduce the application of the biomaterial chondroitin sulfate succinimidyl succinate (CS-NHS) to deliver IOB in a hydrogel adhesive. We demonstrate the biomaterial's ability to bind various tissue types and its cellular biocompatibility with encapsulated human mesenchymal stem cells (hMSCs). Further, we examine in detail the CS-NHS adhesive combined with BM aspirate for use in bone applications. hMSCs were encapsulated in CS-BM and cultured for 5 weeks in osteogenic medium. Quantitative RT-PCR demonstrated osteogenesis via upregulation of the osteogenic transcription factor Runx2 and bone markers alkaline phosphatase and osteocalcin. Significant deposition of calcium and osteocalcin was detected using biochemical, histological, and immunohistochemical techniques. Shear testing demonstrated that the CS-BM adhesive exhibited an adhesive strength approximately an order of magnitude stronger than fibrin glue and approaching that of a cyanoacrylate adhesive. These results indicate that CS-NHS is a promising delivery tool for IOB in orthopedic applications requiring a strong, degradable, and biocompatible adhesive that supports bone growth.

Hyaluronic acid-binding scaffold for articular cartilage repair.

Hyaluronic acid (HA) is an extracellular matrix molecule with multiple physical and biological functions found in many tissues, including cartilage. HA has been incorporated in a number of biomaterial and scaffold systems. However, HA in the material may be difficult to control if it is not chemically modified and chemical modification of HA may negatively impact biological function. In this study, we developed a poly(ethylene glycol) hydrogel with noncovalent HA-binding capabilities and evaluated its ability to support cartilage formation in vitro and in an articular defect model. Chondrogenic differentiation of mesenchymal stem cells encapsulated in the HA-interactive scaffolds containing various amounts of exogenous HA was evaluated. The HA-binding hydrogel without exogenous HA produced the best cartilage as determined by biochemical content (glysocaminoglycan and collagen), histology (Safranin O and type II collagen staining), and gene expression analysis for aggrecan, type I collagen, type II collagen, and sox-9. This HA-binding formulation was then translated to an osteochondral defect model in the rat knee. After 6 weeks, histological analysis demonstrated improved cartilage tissue production in defects treated with the HA-interactive hydrogel compared to noninteractive control scaffolds and untreated defects. In addition to the tissue repair in the defect space, the Safranin O staining in cartilage tissue surrounding the defect was greater in treatment groups where the HA-binding scaffold was applied. In sum, incorporation of a noncovalent HA-binding functionality into biomaterials provides an ability to interact with local or exogenous HA, which can then impact tissue remodeling and ultimately new tissue production.

Evaluating Osteoarthritic Chondrocytes through a Novel 3-Dimensional In Vitro System for Cartilage Tissue Engineering and Regeneration.

OBJECTIVE: To characterize and evaluate osteoarthritic (OA) chondrocytes, in comparison to normal chondrocytes, through a novel 3-dimensional (3-D) culture system, poly(ethylene-glycol) diacrylate (PEGDA). The cytokine interleukin 1ß (IL-1ß) was also used to simulate an in vitro OA model. METHODS: Normal and OA chondrocytes were cultured in monolayer and analyzed for changes in cartilage-specific gene expressions due to passage number. Then, cells were encapsulated in PEGDA to evaluate phenotype and matrix production capabilities through the in vitro culture system. Characterization was conducted with polymerase chain reaction (PCR), biochemical analyses, and histological staining. 3-D encapsulated chondrocytes (human and bovine) were also treated with IL-1ß to characterize how the cytokine affects gene transcription and extracellular matrix (ECM) content. RESULTS: In 2-dimensional monolayer, anabolic genes were down-regulated significantly in both normal and OA chondrocytes. In 3-D culture, OA chondrocytes demonstrated significantly higher expressions of catabolic genes when compared to normal cells. Differentiation medium resulted in significantly more matrix production than growth medium from OA chondrocytes, indicated through histological staining. In addition, normal chondrocytes responded more significantly to exogenous administration of IL-1ß than OA chondrocytes. Temporary initial stimulation of IL-1ß to OA chondrocytes resulted in comparable gene expressions to untreated cells after 3 weeks of in vitro culture. CONCLUSIONS: Our findings demonstrate the use of OA chondrocytes in tissue engineering and their significance for potential future cartilage regeneration research through their matrix production capabilities and the use of a hydrogel culture system.

Transvenous intramyocardial cellular delivery increases retention in comparison to intracoronary delivery in a porcine model of acute myocardial infarction.

BACKGROUND: Clinical trials using intracoronary (IC) delivery of cells have addressed efficacy but the optimal delivery technique is unknown. Our study aimed to determine whether transvenous intramyocardial (TVIM) approach was advantageous for cellular retention in AMI. METHODS: Domestic pigs (n = 4) underwent catheterization with coronary angiography and ventriculography prior to infarction and pre- and post-cells. Pigs underwent 90-minute balloon occlusion of the left anterior descending artery (LAD). After one week they were prepared for IC (n = 2) or TVIM (n = 2) delivery of bone marrow mononuclear cells (MNC) labeled with GFP. IC infusion used an over-the-wire catheter to engage the LAD and balloon inflation to prevent retrograde flow. Venography via the coronary sinus was used for TVIM delivery. The anterior interventricular vein was engaged with a guidewire allowing use of the TransAccess catheter that is outfitted with an ultrasound tip for visualization. Animals were sacrificed one hour after delivery and tissue was analyzed. RESULTS: Procedures were performed without complication and monitoring was uneventful. 1 x 10(8) MNC were isolated from each bone marrow (BM) preparation and 1 x 10(7) MNC delivered. Ventriculography at one week revealed wall motion abnormalities consistent with an anterior AMI. TVIM and IC delivery revealed mean 452 cells per section and 235 cells per section on average, respectively, in the infarct zone (P = 0.01). CONCLUSION: We have demonstrated that TVIM approach for cell delivery is feasible and safe. Moreover, this approach may provide an advantage over IC infusion in retention of the cellular product; however, larger studies will be necessary.