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The use of the direct anterior approach, a muscle-sparing technique for THA, has increased over the years; however, this approach is associated with longer procedure times and a more expensive direct cost. Furthermore, studies have shown a higher revision rate in the early stages of the learning curve. Whether the clinical advantages of the direct anterior compared with the posterior approach-such as less soft tissue damage, decreased short-term postoperative pain, a lower dislocation rate, decreased length of stay in the hospital, and higher likelihood of being discharged home-outweigh the higher cost is still debatable. Determining the cost-effectiveness of the approach may inform its utility and justify its use at various stages of the learning curve.We used a Markov modeling approach to ask: (1) Is the direct anterior approach more likely to be a cost-effective approach than the posterior approach over the long-term for more experienced or higher volume hip surgeons? (2) How many procedures does a surgeon need to perform for the direct anterior approach to be a cost-effective choice?A Markov model was created with three health states (well-functioning THA, revision THA, and death) to compare the cost-effectiveness of the direct anterior approach with that of the posterior approach in five scenarios: surgeons who performed one to 15, 16 to 30, 31 to 50, 51 to 100, and more than 100 direct anterior THAs during a 6-year span. Procedure costs (not charges), dislocation costs, and fracture costs were derived from published reports, and model was run using two different cost differentials between the direct anterior and posterior approaches (USD 219 and USD 1800, respectively). The lower cost was calculated as the total cost differential minus pharmaceutical and implant costs to account for differences in implant use and physician preference regarding postoperative pain management. The USD 1800 cost differential incorporated pharmaceutical and implant costs. Probabilities were derived from systematic review of the evidence as well as from the Australian Orthopaedic Association National Joint Replacement Registry. Utilities were estimated from best available literature and disutilities associated with dislocation and fracture were incorporated into the model. Quality of life was expressed in quality-adjusted life years (QALYs), which are calculated by multiplying the utility of a health state (ranging from 0 to 1) by the duration of time in that health state. The primary outcome measure was the incremental cost-effectiveness ratio, or the change in costs divided by the change in QALYs when the direct anterior approach was used for THA. USD 100,000 per quality-adjusted life years was used as a threshold for willingness to pay. One-way and probabilistic sensitivity analyses were performed for the scenario in which the direct anterior approach is cost-effective to further account for uncertainty in model inputs.At a cost differential of USD 219 (95% CI 175 to 263), the direct anterior approach was associated with lower cost and higher effectiveness compared with the posterior approach for surgeons with an experience level of more than 100 operations during a 6-year span. At a cost differential of USD 1800 (95% CI 1440 to 2160), the direct anterior approach remained a cost-effective strategy for surgeons who performed more than 100 operations. At both cost differentials, the direct anterior approach was not cost-effective for surgeons who performed fewer than 100 operations. One-way sensitivity analyses revealed the model to be the most sensitive to fluctuations in the utility of revision THA, probability of revision after the posterior approach THA, probability of dislocation after the posterior approach THA, fluctuations in the probability of dislocation after direct anterior THA, cost of direct anterior THA, and probability of intraoperative fracture with the direct anterior approach. At the cost differential of USD 219 and for surgeons with a surgical experience level of more than 100 direct anterior operations, the direct anterior approach was still the cost-effective strategy for the entire range of values.For high-volume hip surgeons, defined here as surgeons who perform more than 100 procedures during a 6-year span, the direct anterior approach may be a cost-effective strategy within the limitations imposed by our analysis. For lower volume hip surgeons, performing a more familiar approach appears to be more cost-effective.

Adult stem cells provide a renewable source of differentiated cells for a wide variety of tissues and generally give rise to multiple cell types. Basic principles of stem cell organization and regulation underlying this behaviour are emerging. Local niche signals maintain stem cells, while different sets of signals act outside the niche to diversify initially equivalent stem cell progeny. Here we show that Drosophila ovarian follicle stem cells (FSCs) produced two distinct cell types directly. This cell fate choice was determined by the anterior-posterior position of an FSC and by the magnitude of spatially graded Wnt pathway activity. These findings reveal a paradigm of immediate diversification of stem cell derivatives according to stem cell position within a larger population, guided by a graded niche signal. We also found that FSCs strongly resemble mammalian intestinal stem cells in many aspects of their organization, including population asymmetry and dynamic heterogeneity.

Introduction Partial cystectomy use has historically been limited by stringent selection criteria. We compared outcomes following partial cystectomy at our institution with those in other contemporary series. Also, we specifically characterized outcomes in patients with tumors in bladder locations traditionally considered unamenable to partial cystectomy. Methods Patients who underwent partial cystectomy for primary bladder cancer from 1990 to 2012 were identified from our database. Clinical and pathological data were reviewed. Survival analyses were performed using Kaplan-Meier methods. Cox regression was done to identify factors associated with survival and recurrence. Results A total of 55 patients were included in analysis. Five-year overall, disease specific and recurrence-free survival was 70.3%, 77.0% and 39.4%, respectively. When controlling for clinical and pathological covariates, lymphovascular invasion predicted decreased recurrence-free survival (HR 10.6, p = 0.025). Perioperative morbidity and mortality rates were 4% and 5%, respectively. In 8 patients (15%) trigone tumors required ureteral reimplantation. Two of the 8 patients (25%) experienced complications, including hydronephrosis and bladder neck contracture, which were treated conservatively. Cancer recurred in 2 of the 8 patients (25%) and both were treated successfully. None of the 8 patients died of bladder cancer. Conclusions Patients treated with partial cystectomy for primary bladder cancer had satisfactory cancer control and favorable perioperative morbidity consistent with other contemporary reports. Patients with tumors in the bladder trigone, historically considered poor candidates for partial cystectomy, also had good oncologic outcomes without significant complications related to reimplantation. Our data further support partial cystectomy in select patients with bladder cancer.