Radiation therapy (RTx) is associated with increased risk for late-onset fragility fractures in bone tissue underlying the radiation field. Bone tissue outside the RTx field is often selected as a "normal" comparator tissue in clinical assessment of fragility fracture risk, but the robustness of this comparison is limited by an incomplete understanding of the systemic effects of local radiotherapy. In this study, a mouse model of limited field irradiation was used to quantify longitudinal changes in local (irradiated) and systemic (non-irradiated) femurs with respect to bone density, morphology, and strength. BALB/cJ mice aged 12 weeks underwent unilateral hindlimb irradiation (4 Â 5 Gy) or a sham procedure. Femurs were collected at endpoints of 4 days before treatment and at 0, 1, 2, 4, 8, 12, and 26 weeks post-treatment. Irradiated (RTx), Contralateral (non-RTx), and Sham (non-RTx) femurs were imaged by microcomputed tomography and mechanically tested in three-point bending. In both the RTx and Contralateral non-RTx groups, the longer-term (12-to 26-week) outcomes included trabecular resorption, loss of diaphyseal cortical bone, and decreased bending strength. Contralateral femurs generally followed an intermediate response compared with RTx femurs. Change also varied by anatomic compartment; post-RTx loss of trabecular bone was more profound in the metaphyseal than the epiphyseal compartment, and cortical bone thickness decreased at the mid-diaphysis but increased at the metaphysis. These data demonstrate that changes in bone quantity, density, and architecture occur both locally and systemically after limited field irradiation and vary by anatomic compartment. Furthermore, the severity and persistence of systemic bone damage after limited field irradiation suggest selection of control tissues for assessment of fracture risk or changes in bone density after radiotherapy may be challenging.
We sought to demonstrate whether there is a difference in the local mesenchymal stem cells (MSC) niche obtained from patients undergoing their first total joint replacement surgery versus those patients undergoing a revision surgery for an failing total joint implant. Bone marrow aspirates collected from patients undergoing revision total joint arthroplasty were observed to be less clonal and the expression of PDGFRa, CD51, ALCAM, endoglin, CXCL12, nestin, and nucleostemin were decreased. Revision MSC were also less able to commit to an osteoblast-lineage or an adipocyte-lineage. Further, in revision MSC, OPG, and IL6 expression were increased. Monocytes, derived from revision whole marrow aspirates, were less capable of differentiating into osteoclasts, the cells implicated in the pathologic degradation of bone. Osteoclasts were also not observed in tissue samples collected adjacent to the implants of revision patients; however, the alternatatively activated M2-macrophage phenotype was observed in parallel with pathologic accumulations of amyloid-b, t-protien and 3-nitrotyrosine. Despite the limited numbers of patients examined, our data suggest that nucleostemin may be a useful functional marker for MSC while the observation of M2-macrophage infiltration around the implant lays the foundation for future investigation into a novel mechanism that we propose is associated with loose total joint implants. ß
(1) Background: To critically evaluate dorsal onlay buccal mucosal graft urethroplasty (DOBMGU) for posterior urethral stenosis repair following transurethral resection and other endoscopic prostate procedures. (2) Methods: A retrospective multi-institutional review of patients with membranous or bulbomembranous urethral stenosis for whom treatment with DOBMGU was conducted after receipt of prostate endoscopic procedures. Baseline data, peri-operative care, post-operative care and patient-reported outcomes were analyzed. The primary outcomes were procedural failure and development of de novo stress urinary incontinence (SUI). The secondary outcomes were changes in voiding, sexual function and patient satisfaction. (3) Results: A total of 107 men with a mean age of 69 ± 9.5 years and stenosis length of 3.5 ± 1.8 cm were included. Prior endoscopic procedures among participants were 47 patients (44%) with monopolar TURP, 33 (30.8%) with bipolar TURP, 16 (15%) with Greenlight laser, 9 (8.4%) with Holmium laser enucleation and 2 (1.9%) with bladder neck incision. At a mean follow-up time of 59.3 ± 45.1 months, stenosis recurred in 10 patients (9.35%). Multivariate analysis confirmed that postoperative complications (OR 12.5; p = 0.009), history of radiation (OR 8.3; p = 0.016) and ≥2 dilatations before urethroplasty (OR 8.3; p = 0.032) were independent predictors of recurrence. Only one patient (0.9%) developed de novo SUI. Patients experienced significant improvement in PVR (128 to 60 cc; p = 0.001), Uroflow (6.2 to 16.8 cc/s; p = 0.001), SHIM (11.5 to 11.7; p = 0.028), IPSS (20 to 7.7; p < 0.001) and QoL (4.4 to 1.7; p < 0.001), and 87 cases (81.3%) reported a GRA of + 2 or better. (4) Conclusions: DOBMGU is an effective and safe option for patients with posterior urethral stenosis following TURP and other prostate endoscopic procedures. This non-transecting approach minimizes external urinary sphincter manipulation, thus limiting postoperative risk of SUI or erectile dysfunction.
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