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The diagnosis of fracture risk relies almost solely on quantifying bone mass, yet bone strength is governed by factors at multiple scales including composition and structure that contribute to fracture resistance. Furthermore, aging and conditions such as diabetes mellitus alter fracture incidence independently of bone mass. Therefore, it is critical to incorporate other factors that contribute to bone strength in order to improve diagnostic specificity of fracture risk. We examined the correlation between femoral neck fracture strength in aging female cadavers and areal bone mineral density, along with other clinically accessible measures of bone quality including whole-bone cortical porosity (Ct.Po), bone material mechanical behavior measured by reference point indentation (RPI), and accumulation of advanced glycation end-products (AGEs). All measurements were found to be significant predictors of femoral neck fracture strength, with areal bone mineral density (aBMD) being the single strongest correlate (aBMD: r = 0.755, p < 0.001; Ct.Po: r = −0.500, p < 0.001; RPI: r = −0.478, p < 0.001; AGEs: r = −0.336, p = 0.016). RPI-derived measurements were not correlated with tissue mineral density or local cortical porosity as confirmed by micro–computed tomography (μCT). Multiple reverse stepwise regression revealed that the inclusion of aBMD and any other factor significantly improve the prediction of bone strength over univariate predictions. Combining bone assays at multiple scales such as aBMD with tibial Ct.Po (r = 0.835; p < 0.001), tibial difference in indentation depth between the first and 20th cycle (IDI) (r = 0.883; p < 0.001), or tibial AGEs (r = 0.822; p < 0.001) significantly improves the prediction of femoral neck strength over any factor alone, suggesting that this personalized approach could greatly enhance bone strength and fracture risk assessment with the potential to guide clinical management strategies for at-risk populations

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Background: Corticosteroid injections are a common treatment for rotator cuff tears. Because of concerns of infection, a surgical procedure is often delayed following injections. The purpose of this investigation was to determine if there is a temporal relationship between corticosteroid injections and the risk of surgical site infection after arthroscopic rotator cuff repair. We hypothesized that the incidence of surgical site infection is higher in patients who received a preoperative injection and this relationship exists in a temporal manner as those patients receiving an injection closer to the operative date have a higher risk of infection. Methods: The PearlDiver database was reviewed for patients undergoing arthroscopic rotator cuff repair from 2007 to 2016. Patients were stratified into 2 cohorts: those undergoing arthroscopic rotator cuff repair within 1 year of injection (n = 12,060), and those undergoing arthroscopic rotator cuff repair without prior injection (n = 48,763). Patients with preoperative injections were further stratified by the duration in months that the injection was performed prior to the surgical procedure. Surgical site infection within 6 months of the surgical procedure was recorded. Statistical analysis included chi-square and multivariate binomial logistic regression analyses to identify risk factors for surgical site infection. Results were considered significant at p < 0.05. Results: There was no significant difference in the incidence of surgical site infection in patients receiving a shoulder injection at 0.7% compared with the control cohort at 0.8% (odds ratio [OR], 0.9 [95% confidence interval (CI), 0.7 to 1.1]; p = 0.2). However, patients receiving an injection within 1 month prior to operative management had a significantly higher rate of surgical site infection overall at 1.3% compared with the control group at 0.8% (OR, 1.7 [95% CI, 1.0 to 2.9]; p = 0.04). On multivariate analysis, male sex (OR, 1.7 [95% CI, 1.4 to 1.9]; p = 0.001), obesity (OR, 1.4 [95% CI, 1.2 to 1.6]; p < 0.001), diabetes (OR, 1.3 [95% CI, 1.1 to 1.5]; p < 0.001), smoking status (OR, 1.7 [95% CI, 1.4 to 1.9], p < 0.001), and preoperative corticosteroid injections within 1 month of the surgical procedure (OR, 2.1 [95% CI, 1.5 to 2.7]; p < 0.001) were independent risk factors for development of a surgical site infection. Conclusions: Injections within 1 month of arthroscopic rotator cuff repair significantly increases the risk of surgical site infection. However, there is no increased risk of infection if the surgical procedure is delayed by 1 month following an injection. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

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