Search

Reverse shoulder arthroplasty, as originally designed by Grammont, has revolutionized the treatment of rotator cuff arthropathy as well as fractures about the proximal humerus. The original design consisted of glenoid and humeral components with a medialized center or rotation compared to the native shoulder. Long term outcome studies on this design demonstrated high rates of scapular notching as well as significant loss of external rotation. To combat these flaws, prosthesis design has evolved to include the concept of lateralization whereby the center of rotation is moved laterally compared to the Grammont prosthesis via either the glenoid or humeral components. Lateralization via the glenoid component has sought to reduce scapular notching, however, concerns over early loosening have been raised secondary to increasing stress at the glenosphere/glenoid interface. Lateralization via the humeral component has been theorized to improve the mechanics of the remaining rotator cuff and deltoid musculature while avoiding the problems inherent with glenoid lateralization. While limited clinical evidence is available currently to support one design over the other, multiple biomechanical studies have shown improvements in rates of scapular notching and post-operative external rotation for lateralized humeral and glenoid components. Future research should aim to delineate advantages of one design over the other or optimal combinations of the two designs., Competing Interests: The Author(s) declare(s) that there is no conflict of interest., (© 2020 Professor P K Surendran Memorial Education Foundation. Published by Elsevier B.V. All rights reserved.)

Skin flora organisms (SFOs) isolated from 1 to 2 tissue samples during shoulder and elbow revision arthroplasty are difficult to distinguish as contamination or infection. We examined the change in clinical care after implementation of an Arthroplasty Infection Protocol by increasing the number of intraoperative samples held for 10-day incubation to a minimum of 5., Methods: Infection was defined as ≥3 cultures growing the same SFO or any one culture growing any other virulent organism. SFOs growing in 1 to 2 samples were defined as skin flora contaminant. All cases were compared with pre-Arthroplasty Infection Protocol institution standard to determine changes in microbiological diagnosis and resultant antibiotic treatment., Results: Forty cases fulfilled the inclusion criteria: 50% of these were culture negative, and 35% grew Propionibacteria . When compared with the standard of obtaining one sample, this protocol altered the microbiological diagnosis and subsequent antibiotic treatment in 45% of cases (95% confidence interval 29% to 62%). This protocol had a predictive value of joint sterility in 95% of culture-negative cases (95% confidence interval 74% to 99%)., Discussion: The addition of 5 or more samples held for 10-day incubation reliably differentiated between joint infection, contamination, and sterility, which changed the course of care in 45% of surgical cases., (Copyright © 2019 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Orthopaedic Surgeons.)

Leishmania donovani is a parasite that causes visceral leishmaniasis by infecting and replicating in macrophages of the bone marrow, spleen, and liver. Severe anemia and leucopenia is associated with the disease. Although immune defense mechanisms against the parasite have been studied, we have a limited understanding of how L. donovani alters hematopoiesis. In this study, we used Syrian golden hamsters to investigate effects of L. donovani infection on erythropoiesis. Infection resulted in severe anemia and leucopenia by 8 weeks post-infection. Anemia was associated with increased levels of serum erythropoietin, which indicates the hamsters respond to the anemia by producing erythropoietin. We found that infection also increased numbers of BFU-E and CFU-E progenitor populations in the spleen and bone marrow and differentially altered erythroid gene expression in these organs. In the bone marrow, the mRNA expression of erythroid differentiation genes (α-globin, β-globin, ALAS2) were inhibited by 50%, but mRNA levels of erythroid receptor (c-kit, EpoR) and transcription factors (GATA1, GATA2, FOG1) were not affected by the infection. This suggests that infection has a negative effect on differentiation of erythroblasts. In the spleen, erythroid gene expression was enhanced by infection, indicating that the anemia activates a stress erythropoiesis response in the spleen. Analysis of cytokine mRNA levels in spleen and bone marrow found that IFN-γ mRNA is highly increased by L. donovani infection. Expression of the IFN-γ inducible cytokine, TNF-related apoptosis-inducing ligand (TRAIL), was also up-regulated. Since TRAIL induces erythroblasts apoptosis, apoptosis of bone marrow erythroblasts from infected hamsters was examined by flow cytometry. Percentage of erythroblasts that were apoptotic was significantly increased by L. donovani infection. Together, our results suggest that L. donovani infection inhibits erythropoiesis in the bone marrow by cytokine-mediated apoptosis of erythroblasts.