A translational murine model of aseptic loosening with osseointegration failure.

An in vivo animal model of a weight-bearing intra-articular implant is crucial to the study of implant osseointegration and aseptic loosening caused by osseointegration failure. Osseointegration, defined as a direct structural and functional attachment between living bone tissue and the surface of a load-carrying implant, is essential for implant stability and considered a prerequisite for the long-term clinical success of implants in total joint arthroplasty. Compared to large animal models, murine models offer extensive genetic tools for tracing cell differentiation and proliferation. The 18- to 22-week-old C57BL/6J background mice underwent either press-fitted or loose implantation of a titanium implant, achieving osseointegration or fibrous integration. A protocol was developed for both versions of the procedure, including a description of the relevant anatomy. Samples were subjected to microcomputed tomography and underwent biomechanical testing to access osseointegration. Lastly, samples were fixed and embedded for histological evaluation. The absence of mineralized tissue and weakened maximum pull-out force in loose implantation samples indicated that these implants were less mechanically stable compared to the control at 4 weeks postoperation. Histological analysis demonstrated extensive fibrotic tissue in the peri-implant area of loose implantation samples and excellent implant osseointegration in press-fitted samples at 4 weeks. Both mechanically stable and unstable hemiarthroplasty models with either osseous ingrowth or a robust periprosthetic fibrosis were achieved in mice. We hope that this model can help address current limitations for in vivo study of aseptic loosening and lead to necessary translational benefits.

Anger, frustration, boredom and the Department of Motor Vehicles: Can negative emotions impede organ donor registration?

RATIONALE: The IIFF Model (Information, Immediate and Complete Registration Mechanism, Focused Engagement, Favorable Activation) offers a checklist of considerations for interventions seeking to influence organ donor registration behavior. One aspect of the model, favorable activation, recommends considering the emotional and motivational state of a potential donor registrant. Given that most donor registrations occur at the Department of Motor Vehicles (DMV), we considered whether emotions experienced while at the DMV could influence registration rates. OBJECTIVE: The current research effort investigated the emotions people experience while visiting the DMV, explored whether these emotions are associated with donor registration intentions, and experimentally assessed whether DMV experiences influence donor registration. METHODS: Three studies were conducted through Amazon's Mechanical Turk. In Study 1, we randomly assigned participants to either recall a prior DMV experience or to a comparison condition. Emotions associated with the recalled experiences were the dependent variable. Study 2 assessed the correlations between nine different emotions and donor registration intentions. Study 3 randomly assigned participants to recall a prior frustrating DMV experience or to a comparison condition. Intention to register to donate was the dependent variable. RESULTS: Study 1 found that recalling a prior DMV experience was associated with more negative and less positive emotions than the comparison condition. Study 2 found that increased levels of negative emotion could be problematic, as negative emotions were associated with decreased donor intentions. Study 3 found that recalling a frustrating DMV experience resulted in significantly lower intentions to register as an organ donor (vs. a control condition). CONCLUSION: Although not all DMV experiences are negative, these data indicated a relationship between the DMV and negative emotions; an association between negative emotions and lower donor registration intentions; and, a causal relationship between negative DMV experiences and decreased registration intentions.

The impact of overtly listing eligibility requirements on MTurk: An investigation involving organ donation, recruitment scripts, and feelings of elevation.

RATIONALE: Investigations conducted through Amazon's Mechanical Turk (MTurk) sometimes explicitly note eligibility requirements when recruiting participants; however, the impact of this practice on data integrity is relatively unexplored within the MTurk context. OBJECTIVE: Contextualized in the organ donor registration domain, the current study assessed whether overtly listing eligibility requirements impairs the accuracy of data collected on MTurk. METHODS: On day 1, the first and third round of data collection did not list eligibility requirements; the second and fourth round overtly listed a qualification requirement: status as a non-registered organ donor. On day 2, the approach was identical, except the order was reversed-the first and third round overtly listed the study qualifications, while the second and fourth did not. These procedures provided eight different waves of data. In addition, all participants were randomly assigned to read an elevating (i.e., morally inspiring) story or a story not intended to elicit any emotion. Regardless of recruitment approach, only participants who were not registered as donors were included in the analysis. RESULTS: Results indicated that the recruitment script that explicitly requested non-registered donors resulted in the collection of participants with higher mean intentions scores than the script that did not overtly list the eligibility requirements. Further, even though the elevation induction increased intentions to register as a donor, there was not a significant interaction between recruitment approach and the influence of the elevation manipulation on registration intentions. CONCLUSION: Explicitly listing eligibility requirements can influence the accuracy of estimates derived from data collected through MTurk.