Aurora kinases are highly conserved, essential regulators of cell division. Two Aurora kinase isoforms, A and B (AURKA and AURKB), are expressed ubiquitously in mammals, whereas a third isoform, Aurora C (AURKC), is largely restricted to germ cells. Because AURKC is very similar to AURKB, based on sequence and functional analyses, why germ cells express AURKC is unclear. We report that Aurkc −/− females are subfertile, and that AURKB function declines as development progresses based on increasing severity of cytokinesis failure and arrested embryonic development. Furthermore, we find that neither Aurkb nor Aurkc is expressed after the one-cell stage, and that AURKC is more stable during maturation than AURKB using fluorescently tagged reporter proteins. In addition, Aurkc mRNA is recruited during maturation. Because maturation occurs in the absence of transcription, posttranscriptional regulation of Aurkc mRNA, coupled with the greater stability of AURKC protein, provides a means to ensure sufficient Aurora kinase activity, despite loss of AURKB, to support both meiotic and early embryonic cell divisions. These findings suggest a model for the presence of AURKC in oocytes: that AURKC compensates for loss of AURKB through differences in both message recruitment and protein stability.A urora kinases are highly conserved cell-cycle regulators with essential roles in chromosome segregation. There are three Aurora kinases in mammals: Aurora kinases A and B (AURKA or -B) are ubiquitously expressed and their functions have been extensively studied, whereas AURKC is largely limited to germ cells (1-3); many human cancer cell lines express AURKC (4) and some somatic tissues express AURKC at low levels (5-7). It is not clear, however, why germ cells require a third AURK. Because isoforms can have different functions, it is tempting to speculate that AURKC exists because its mitotic counterparts simply cannot execute unique features of meiosis.One unique feature of meiosis is the generation of haploid gametes from diploid precursor cells by a reductional chromosome segregation during meiosis I (MI) followed by an equational division at meiosis II (MII) without an intervening round of DNA replication. In oocytes, another unique feature is that meiosis is not a continuous process because there is a growth period during a prolonged arrest at prophase I, followed by a cell division cycle during oocyte maturation, and a second arrest at metaphase of MII, until fertilization, which triggers completion of MII. Furthermore, proteins in the oocyte must support the first mitotic cell cycles of the embryo before zygotic genome activation. Despite these obvious differences, several observations suggest that AURKC may not have a specialized function. AURKB and AURKC are highly similar in sequence (61% identical), and AURKC can functionally compensate for loss of AURKB when ectopically expressed in somatic cells (8, 9). Furthermore, embryos that lack AURKB can develop to but not beyond the blastocyst, as long as AURKC is present, consis...

Background: Total ankle arthroplasty (TAA) is an increasingly popular option for the operative treatment of ankle arthritis. The Cadence TAA entered clinical use in 2016 and was designed to address common failure modes of prior systems. We report early complications and radiographic and clinical outcomes of this total ankle system at a minimum of 2 years of follow-up. Methods: We performed a retrospective review of a consecutive cohort of patients undergoing primary Cadence TAA by a single surgeon from 2016 to 2017. Complications and reoperations were documented using the American Orthopaedic Foot & Ankle Society (AOFAS) TAA reoperation coding system. Patients completed the Foot and Ankle Ability Measure (FAAM) Activities of Daily Living (ADL) and Sport subscales, SF-12 Mental (MCS) and Physical (PCS) Component Summaries, and visual analog scale (VAS) pain rating (0-100). Radiographic evaluation was performed to assess postoperative range of motion (ROM) of the sole of the foot relative to the long axis of the tibia, alignment, and implant complications. Results: Fifty-eight patients with a mean age of 63.3 years and mean body mass index of 31.9 kg/m2 were included. Twelve of 58 patients (20.7%) underwent an additional procedure(s) within 2 years, including 3 (5.2%) who required removal of one or both components, 2 for infection and 1 for osteolysis. Forty-three patients were followed for a minimum of 2 years with radiographic imaging; 1 patient’s (2.3%) radiographs had signs of peri-implant osteolysis, with no cases demonstrating loosening or subsidence. FAAM-ADL, FAAM-Sport, SF-12 PCS, and VAS pain scores all improved at a mean of 27.4 months postoperatively, with mean score changes (± SD) of 16.3 (± 22.0), 25.3 (± 24.5), 6.0 (± 11.1), and −32.3 (± 39.8), respectively. Radiographic analysis revealed that average coronal alignment improved from 6.9 degrees from neutral preoperatively to 2.3 degrees postoperatively. The average ROM of the foot relative to the tibia was 36.5 degrees total arc of motion based on lateral radiographs. Conclusion: Early experience with this 2-component total ankle replacement was associated with a high component retention rate, improved coronal plane alignment, good postoperative ROM, radiographically stable implants, and improved patient function. Level of Evidence: Level IV, case series.

The reported combined rates of intraoperative and postoperative periprosthetic humeral fractures range widely, from 1.2% to 19.4%. » The risk factors for an intraoperative humeral fracture and literaturereported strength of association include a press-fit humeral component (relative risk [RR], 2.9), revision arthroplasty (RR, 2.8), history of instability (odds ratio [OR], 2.65), female sex (OR, 4.19), and posttraumatic arthritis (RR, 1.9). The risk factors for a postoperative humeral fracture include osteonecrosis and increased medical comorbidity index (OR, 1.27).» Intraoperative fractures, in order of decreasing frequency, most often occur during implant removal in cases of revision arthroplasty (up to 81%), during reaming or broaching of the humerus (up to 31%), during trial or implant insertion (up to 18% to 19%), or because of excessive humeral torque or forceful retractor placement during exposure or reduction (up to 13% to 15%). Postoperative fractures typically occur from a fall onto the outstretched extremity or through an area of osteolysis.» The treatment of intraoperative or postoperative fractures is based on fracture location, prosthesis type and stability, rotator cuff status, and available bone stock. » Nonoperative treatment for periprosthetic humeral fractures appears to have high failure rates. When treating a periprosthetic humeral fracture operatively, surgical techniques for tuberosity fractures include suture repair, cerclage wiring, or revision to reverse components. For humeral shaft fractures, techniques include revision to a long-stem component, cerclage wiring, plate-and-screw fixation, and use of a strut allograft. For extensive humeral bone loss, techniques include component-allograft composites or humeral endoprostheses. All techniques have the goals of permitting early range of motion and preserving function. RevisionRevision reverse total shoulder arthroplasty *NA 5 not applicable.