0. Further analysis showed that the fraction of dosage-sensitive housekeeping genes on the X/Z chromosome is significantly correlated with the SA ratio. In addition, the degree of degeneration of the Y chromosome may be responsible for the change in the SA ratio in mammals without a dosage compensation mechanism. Our observations offer unequivocal support for the sex chromosome insensitivity hypothesis in animals and suggest that dosage sensitivity states of sex chromosomes are a major factor underlying different evolutionary strategies of dosage compensation.Gnathic osteosarcoma is a rare malignant mesenchymal neoplasm showing evidence of osteoid matrix formation. Clinical behaviour and radiological appearances overlap with benign osseous lesions and are prone to misdiagnosis. Early diagnosis of osteosarcoma plays a crucial role in the treatment plan and prognosis. Herein a rare case of parosteal osteosarcoma of fibroblastic histologic subtype affecting the angle of the mandible in a 12-year-old female is presented.Angiosarcoma is a malignancy of endothelial tumor and represents 1-2% of all soft tissue sarcomas, uncommonly found in the head and neck region. The etiology is not clear but there are definite risk factors including chronic lymphoedema, history of radiation, environmental carcinogens and certain familial syndromes. Presented here is a case of a patient treated due to the skull base trauma and diagnosed with this type of tumor. Optimizing surgical trays to improve operating room efficiency and reduce costs in instrument processing is an under-appreciated strategy for cost containment. This study aimed to assess the economic impact of instrument tray optimization in total joint arthroplasty. Thirty-five randomly selected elective primary total knee arthroplasty and total hip arthroplasty performed by 4 fellowship-trained surgeons were analyzed. Type and number of instruments used as well as timing of different steps in the sterilization process were recorded by an independent observer. Using Lean methodology, surgeons identified redundant or underutilized instruments and agreed upon the fewest number needed for each tray. Instrument utilization rates and processing time were analyzed before and after tray modifications. Annual cost savings were calculated based on a processing factor of $0.59-$11.52 per instrument. Only 45.5% of instruments opened for total knee arthroplasty were utilized. After optimization, 28 of 87 (32.2%) instruments were removed and the remainder could be stored in one tray. Mean set-up time decreased from 20.7 to 14.2minutes, while 40-75minutes were saved during the sterilization process. For total hip arthroplasty, only 36.0% of instruments were utilized. INCB024360 Using Lean methods, 46 of 112 (41.1%) instruments were removed and tray count was reduced to 2 trays. Mean set-up time decreased from 27.9 to 18.6minutes, while 45-150minutes were saved during processing. Average annual savings amounted to $281,298.05. Lean methodology can be used to eliminate redundant or underutilized instruments in total joint arthroplasty, improving surgical efficiency and generating substantial cost savings.Lean methodology can be used to eliminate redundant or underutilized instruments in total joint arthroplasty, improving surgical efficiency and generating substantial cost savings. Surgeons utilize a combination of preoperative tests and intraoperative findings to diagnose periprosthetic joint infection (PJI); however, there is currently no reliable diagnostic marker that can be used in isolation. The purpose of our study is to evaluate the utility of frozen section histology in diagnosis of PJI. Retrospective analysis of 614 patients undergoing revision total joint arthroplasty with frozen section histology from a single institution was performed. Discriminatory value of frozen section histology was assessed using univariate analysis and evaluation of area under the curve (AUC) of a receiver operating characteristic curve comparing frozen section histology results to the 2018 International Consensus Meeting (ICM) PJI criteria modified to exclude the histology component. The sensitivity of the frozen section histology was 53.6% and the specificity was 95.2%. There was 99.2% concordance between the permanent section and frozen section results. The receiver operating characteristic curve for frozen section yielded an AUC of 0.744 (95% confidence interval 0.627-0.860) and the modified ICM score yielded an AUC of 0.912 (95% confidence interval 0.836-0.988) when compared to the full score. The addition of frozen section histology changed the decision to infected in 20% of "inconclusive" cases but less than 1% of total cases. In comparison to the modified ICM criteria, intraoperative frozen section histology has poor sensitivity, strong specificity, and acceptable overall discrimination for diagnosing PJI. This test appears to be of particular value for patients deemed "inconclusive" for infection using the remaining ICM criteria.In comparison to the modified ICM criteria, intraoperative frozen section histology has poor sensitivity, strong specificity, and acceptable overall discrimination for diagnosing PJI. This test appears to be of particular value for patients deemed "inconclusive" for infection using the remaining ICM criteria. The most common treatment for periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is a 2-stage revision. Few studies have compared different articulating spacer constructs. This study compares the outcomes of real-component and all-cement articulating spacers for TKA PJI treatment. This retrospective observational study examined the arthroplasty database at 3 academic hospitals for articulating spacers placed for TKA PJIs between April 2011 and August 2020. Patients were categorized as receiving a real-component or an all-cement articulating spacer. Data on demographics, surgical information, and outcomes were collected. One-hundred sixty-four spacers were identified 72 all-cement and 92 real-component spacers. Patients who received real-component spacers were older (67 ± 10 vs 63 ± 12 years; P= .04) and more likely to be former smokers (50.0% vs 28.6%; P= .02). Real-component spacers had greater range of motion (ROM) after Stage 1 (84° ± 28° vs 58° ± 28°; P < .01) and shorter hospital stays after Stage 1 (5.