Patients Achieving 90°/45°/0° Intraoperative Stability Do Not Require Hip Precautions Following Posterior Approach Total Hip Arthroplasty: A Prospective Randomized Study.

BACKGROUND: Hip precautions are traditionally employed after posterior total hip arthroplasty (THA). The primary purpose was to investigate the necessity of hip precautions after posterior approach THA. We hypothesized that eliminating precautions in patients that achieved appropriate intraoperative stability would not increase the dislocation rate. METHODS: Randomized controlled trial of 346 consecutive eligible patients undergoing primary THA with a mean follow-up of 2.3 years (range 11 months to 3.7 years). EXCLUSION CRITERIA: lumbar fusion, scoliosis, abductor insufficiency, inability to achieve intraoperative stability with combined 90° flexion and 45° internal rotation in 0° adduction. Fisher's exact test was used to compare dislocation rates between the hip precaution (HP) control group and no hip precaution (NP) study group. In addition, Mann-Whitney U test was used to compare differences in HOOS JR scores at 2, 6, 12 weeks between groups. RESULTS: The dislocation rate was not increased in the NP (0/172: 0%) group compared to the HP group 4/174 (2.29%) (P = .418). All dislocations occurred in the precautions group, two of which required revision. There were no differences in mean HOOS Jr. scores at any 2, 6, or 12 weeks (P > .05 at all timepoints) (secondary outcome). CONCLUSION: Eliminating hip precautions in patients undergoing posterior approach THA that achieve 90°/45°/0° intraoperative stability does not increase the rate of dislocation. In fact, every dislocation occurred in patients receiving hip precautions. Short-term patient-reported outcome measures were not affected by hip precautions. Surgeons may discontinue the use of hip precautions as the standard of care in patients achieving 90°/45°/0° stability.

Successful transplantation of human hepatic stem cells with restricted localization to liver using hyaluronan grafts.

Cell therapies are potential alternatives to organ transplantation for liver failure or dysfunction but are compromised by inefficient engraftment, cell dispersal to ectopic sites, and emboli formation. Grafting strategies have been devised for transplantation of human hepatic stem cells (hHpSCs) embedded into a mix of soluble signals and extracellular matrix biomaterials (hyaluronans, type III collagen, laminin) found in stem cell niches. The hHpSCs maintain a stable stem cell phenotype under the graft conditions. The grafts were transplanted into the livers of immunocompromised murine hosts with and without carbon tetrachloride treatment to assess the effects of quiescent versus injured liver conditions. Grafted cells remained localized to the livers, resulting in a larger bolus of engrafted cells in the host livers under quiescent conditions and with potential for more rapid expansion under injured liver conditions. By contrast, transplantation by direct injection or via a vascular route resulted in inefficient engraftment and cell dispersal to ectopic sites. Transplantation by grafting is proposed as a preferred strategy for cell therapies for solid organs such as the liver.

Recurrent Hemarthrosis Secondary to Erosive Patellofemoral Arthritis Treated with Arthroplasty: A Report of 3 Cases.

CASE: Three patients presented with recurrent hemarthrosis secondary to erosive patellofemoral arthritis. Recurrent hemarthrosis from the eroded patellofemoral subchondral bone has not been well described. Each patient presented with symptoms secondary to painful effusions that were identified by aspiration. Each patient was successfully treated with patellofemoral or total knee arthroplasty. CONCLUSION: Spontaneous or recurrent effusions in the setting of erosive patellofemoral arthritis should prompt orthopaedic surgeons to consider hemarthrosis as the cause of such effusions. Patellofemoral or total knee arthroplasty is effective in resolving the hemarthroses, resolving pain, and restoring function in these patients.

Giardia lamblia Reactive Arthritis Mimicking Acute Periprosthetic Knee Infection: A Case Report.

CASE: A healthy 49-year-old man with a well-functioning total knee replacement developed a painful swollen knee. The erythrocyte sedimentation rate was 12 mm/hour, and C-reactive protein was 20.3 mg/L. Aspiration revealed 24,440 white blood cells and 5% neutrophils. His 2018 International Consensus Meeting (ICM) definition score of 5 met criteria for "possibly infected." He was diagnosed with reactive arthritis (ReA) secondary to Giardia lamblia, mimicking acute periprosthetic infection. He was successfully treated with a 10-week course of multiple oral antiparasitic medications. CONCLUSION: Systemic parasitic infectious ReA can mimic acute infection in the presence of total knee arthroplasty. Careful application of the 2018 ICM criteria can be critical for workup and the treatment of suspected periprosthetic infection.

Comparison of the sensitivity of three lung derived cell lines to metals from combustion derived particulate matter.

While the effects of inhalation of combustion-derived particulate matter have received extensive study, there remains no reliable means to rapidly quantify inhalation toxicity outside of a laboratory setting. Cell-based biosensors provide a potential solution, but few comparisons have been made of the sensitivity of various cell lines to the wide range of inhalation health hazards that are likely to be encountered. This work compares the response of three immortalized lung cell lines (A549 human epithelia, RLE-6TN rat type II epithelia, and NR8383 rat alveolar macrophages) to metals commonly present in combustion-derived particulate matter. Quantifications of the cell response involved measurement of inhibition of cell culture metabolism (mitochondrial succinate dehydrogenase activity) and cell death (release of lactate dehydrogenase). While these three cell types generally ranked metals in ED50 values similarly (V

Hyaluronan-supplemented buffers preserve adhesion mechanisms facilitating cryopreservation of human hepatic stem/progenitor cells.

The supply of human hepatic stem cells (hHpSCs) and other hepatic progenitors has been constrained by the limited availability of liver tissues from surgical resections, the rejected organs from organ donation programs, and the need to use cells immediately. To facilitate accessibility to these precious tissue resources, we have established an effective method for serum-free cryopreservation of the cells, allowing them to be stockpiled and stored for use as an off-the-shelf product for experimental or clinical programs. The method involves use of buffers, some serum-free, designed for cryopreservation and further supplemented with hyaluronans (HA) that preserve adhesion mechanisms facilitating postthaw culturing of the cells and preservation of functions. Multiple cryopreservation buffers were found to yield high viabilities (80-90%) of cells on thawing of the progenitor cells. Serum-free CS10 supplemented with 0.05% hyaluronan proved the most effective, both in terms of viabilities of cells on thawing and in yielding cell attachment and formation of expanding colonies of cells that stably maintain the stem/progenitor cell phenotype. Buffers to which 0.05 or 0.1% HAs were added showed cells postthaw to be phenotypically stable as stem/progenitors, as well as having a high efficiency of attachment and expansion in culture. Success correlated with improved expression of adhesion molecules, particularly CD44, the hyaluronan receptor, E-cadherin, ß4 integrin in hHpSCs, and ß1 integrins in hepatoblasts. The improved methods in cryopreservation offer more efficient strategies for stem cell banking in both research and potential therapy applications.

Regulation of hepatic stem/progenitor phenotype by microenvironment stiffness in hydrogel models of the human liver stem cell niche.

Human livers have maturational lineages of cells within liver acini, beginning periportally in stem cell niches, the canals of Hering, and ending in polyploid hepatocytes pericentrally and cholangiocytes in bile ducts. Hepatic stem cells (hHpSCs) in vivo are partnered with mesenchymal precursors to endothelia (angioblasts) and stellate cells, and reside in regulated microenvironments, stem cell niches, containing hyaluronans (HA). The in vivo hHpSC niche is modeled in vitro by growing hHpSC in two-dimensional (2D) cultures on plastic. We investigated effects of 3D microenvironments, mimicking the liver's stem cell niche, on these hHpSCs by embedding them in HA-based hydrogels prepared with Kubota's Medium (KM), a serum-free medium tailored for endodermal stem/progenitors. The KM-HA hydrogels mimicked the niches, matched diffusivity of culture medium, exhibited shear thinning and perfect elasticity under mechanical loading, and had predictable stiffness depending on their chemistry. KM-HA hydrogels, which supported cell attachment, survival and expansion of hHpSC colonies, induced transition of hHpSC colonies towards stable heterogeneous populations of hepatic progenitors depending on KM-HA hydrogel stiffness, as shown by both their gene and protein expression profile. These acquired phenotypes did not show morphological evidence of fibrotic responses. In conclusion, this study shows that the mechanical properties of the microenvironment can regulate differentiation in endodermal stem cell populations.

Cytotoxicity of bacterial-derived toxins to immortal lung epithelial and macrophage cells.

Health risks associated with inhalation and deposition of biological materials have been a topic of great concern due to highly publicized cases of inhalation anthrax, of new regulations on the release of particulate matter, and to increased concerns on the hazards of indoor air pollution. Here, we present an evaluation of the sensitivity of two immortal cell lines (A549, human lung carcinoma epithelia) and NR8383 (rat alveolar macrophages) to a variety of bacterial-derived inhalation hazards and simulants including etoposide, gliotoxin, streptolysin O, and warfarin. The cell response is evaluated through quantification of changes in mitochondrial succinate dehydrogenase activity, release of lactate dehydrogenase, initiation of apoptosis, and through changes in morphology as determined by visible light microscopy and scanning electron microscopy. These cells display dose-response relations to each toxin, except for triton which has a step change response. The first observable responses of the epithelial cells to these compounds are changes in metabolism for one toxin (warfarin) and alterations in membrane permeability for another (gliotoxin). The other four toxins display a similar time course in response as gauged by changes in metabolism and loss of membrane integrity. Macrophages are more sensitive to most toxins; however, they display a lower level of stability. This information can be used in the design of cell-based sensors responding to these and similar hazards.