Biomechanics and Pathoanatomy of Posterior Shoulder Instability.

Posterior glenohumeral instability represents a wide spectrum of pathoanatomic processes. A key consideration is the interplay between the posterior capsulolabral complex and the osseous anatomy of the glenoid and humeral head. Stability is dependent upon both the presence of soft tissue pathology (eg, tears to the posteroinferior labrum or posterior band of the inferior glenohumeral ligament, glenoid bone loss, reverse Hill Sachs lesions, and pathologic glenoid retroversion or dysplasia) and dynamic stabilizing forces. This review highlights unique pathoanatomic features of posterior shoulder instability and associated biomechanics that may exist in patients with posterior glenohumeral instability.

Statistical Fragility Analysis of Open Reduction Internal Fixation vs Primary Arthrodesis to Treat Lisfranc Injuries: A Systematic Review.

BACKGROUND: There is a lack of consensus in the use of open reduction internal fixation (ORIF) vs primary arthrodesis (PA) in the management of Lisfranc injuries. Statistical fragility represents the number of events needed to flip statistical significance and provides context to interpret P values of outcomes from conflicting studies. The current study evaluates the statistical fragility of existing research with an outcome-specific approach to provide statistical clarity to the ORIF vs PA discussion. We hypothesized that statistical fragility analysis would offer clinically relevant insight when interpreting conflicting outcomes regarding ORIF vs PA management of Lisfranc injuries. METHODS: All comparative studies, RCTs, and case-series investigating ORIF vs PA management of Lisfranc injuries published through October 5, 2023, were identified. Descriptive characteristics, dichotomous outcomes, and continuous outcomes were extracted. Fragility index and continuous fragility index were calculated by the number of event reversals needed to alter significance. Outcomes were categorized by clinical relevance, and median FI and CFI were reported. RESULTS: A total of 244 studies were screened. Ten studies and 67 outcomes (44 dichotomous, 23 continuous) were included in the fragility analysis. Of the 10 studies, 4 studies claimed PA to correlate with superior outcomes compared to ORIF with regard to functional scores and return to function outcomes. Of these 4 studies, 3 were statistically robust. Six studies claimed PA and ORIF to have no differences in outcomes, in which only 2 studies were statistically robust. CONCLUSION: The overall research regarding ORIF vs PA is relatively robust compared with other orthopaedic areas of controversy. Although the full statistical context of each article must be considered, studies supporting PA superiority with regard to functional scores and return to function metrics were found to be statistically robust. Outcome-specific analysis revealed moderate fragility in several clinically relevant outcomes such as functional score, return to function, and wound complications.

Diversity, Equity, and Inclusion in Orthopaedic Surgery: Local and National Efforts.

Orthopaedic surgery has not experienced the same increase in diversity as other surgical subspecialties over time. Professional orthopaedic societies across the nation, including the American Academy of Orthopaedic Surgeons, are now making sincere efforts to improve diversity, equity, and inclusion (DEI) within the field. Several national groups provide funding to support DEI -related research as well as scholarships to national meetings. Others are more focused on mentorship and mitigation of residency attrition amongst underrepresented minorities (URMs). Individual residency programs, including the Department of Orthopaedics at Brown University, are engaging in community outreach to attract more diverse candidates to orthopaedics and providing away rotation scholarship support for medical students that identify as female or URMs. These local and national efforts will hopefully lead to a more inclusive environment for all trainees and practitioners within orthopaedics and ultimately improved orthopaedic care for all patients.

Genome-wide analysis of an avirulent strain that induces protective immunity against challenge with virulent Streptococcus suis serotype 2.

BACKGROUND: It was previously reported in China that two recent large-scale outbreaks of Streptococcus suis serotype 2 (S. suis 2) infections in human were caused by two highly virulent S. suis 2 strains, from which a novel genomic island (GEI), associated with disease onset and progression and designated 89 K, was identified. Here, an avirulent strain, 05HAS68, was isolated from a clinically healthy pig. RESULTS: By comparing the genomes of this avirulent strain with virulent strains, it was found that massive genomic rearrangements occurred, resulting in alterations in gene expression that caused enormous single gene gain and loss. Important virulent genes were lost, such as extracellular protein factor (ef) and suilysin (sly) and larger mutants, such as muramidase-released protein (mrp). Piglets vaccinated with the avirulent strain, 05HAS68, had increased TNF-α and IFN-γ levels in the peripheral blood and were fully protected from challenge infection with the most virulent S. suis 2 strain, 05ZYH33. Transfusion of T cells and plasma from vaccinated pigs resulted in protection of recipient animals against the 05ZYH33 challenge. CONCLUSION: These results suggest that analysis genome of the avirulent strains are instrumental in the development of vaccines and for the functional characterization of important of genetic determinants.

Pathogenic Streptococcus strains employ novel escape strategy to inhibit bacteriostatic effect mediated by mammalian peptidoglycan recognition protein.

Pathogenic streptococcal species are responsible for some of the most lethal and prevalent animal and human infections. Previous reports have identified a candidate pathogenicity island (PAI) in two highly virulent clinical isolates of Streptococcus suis type 2, a causative agent of high-mortality streptococcal toxic shock syndrome. This PAI contains a type-IVC secretion system C subgroup (type-IVC secretion system) that is involved in the secretion of unknown pathogenic effectors that are responsible for streptococcal toxic shock syndrome caused by highly virulent strains of S. suis. Both virulence protein B4 and virulence protein D4 were demonstrated to be key components of this type-IVC secretion system. In this study, we identify a new PAI family across 3 streptococcal species; Streptococcus genomic island contains type-IV secretion system, which contains a genomic island type-IVC secretion system and a novel PPIase molecule, SP1. SP1 is shown to interact with a component of innate immunity, peptidoglycan recognition protein (PGLYRP-1) and to perturb the PGLYRP-1-mediated bacteriostatic effect by interacting with protein PGLYRP-1. Our study elucidates a novel mechanism by which bacteria escape by components of the innate immune system by secretion of the SP1 protein in pathogenic Streptococci, which then interacts with PGLYRP-1 from the host. Our results provide potential targets for the development of new antimicrobial drugs against bacteria with resistance to innate host immunity.

ADS-J1 inhibits HIV-1 infection and membrane fusion by targeting the highly conserved pocket in the gp41 NHR-trimer.

We previously identified a potent small-molecule human immunodeficiency virus type 1 (HIV-1) fusion inhibitor, termed ADS-J1, and hypothesized that it mainly targeted the hydrophobic pocket in the gp41 N-terminal heptad repeat (NHR) trimer. However, this hypothesis has been challenged by the fact that ADS-J1 cannot induce drug-resistance mutation in the gp41 pocket region. Therefore, we show herein that HIV-1 mutants resistant to T2635, a peptide derived from the gp41 C-terminal heptad repeat (CHR) region with pocket-binding domain (PBD), were also resistant to ADS-J1. We also show that pseudoviruses with mutations at positions 64 and 67 in the gp41 pocket region were highly resistant to ADS-J1 and C34, another CHR-peptide with PBD, but relatively sensitive to T20, a CHR-peptide without PBD. ADS-J1 could effectively bind to N36Fd, a mimic of the gp41 NHR-trimer with pocket exposed, and block binding of C34 to N36Fd trimer to form six-helix bundle (6-HB). However, ADS-J1 was less effective in binding to N36Fd trimer with mutations in the gp41 pocket region, such as N36(Q64A)Fd, N36(Q64L)Fd, N36(A67G)Fd, N36(A67S)Fd, and N36(Q66R)Fd, as well as less effective in blocking 6-HB formation between C34 and these mutant N36Fd trimers. These results confirm that ADS-J1 mainly targets the pocket region in the HIV-1 gp41 NHR trimer and suggest that it could be used as a lead for developing small-molecule HIV fusion inhibitors and as a molecule probe for studying the mechanisms of gp41-mediated membrane fusion.