A probabilistic model for fracture events of Petermann ice islands under the influence of atmospheric and oceanic conditions

Four calving events of Petermann Glacier happened in 2008, 2010, 2011, and 2012, which resulted in the drift and deterioration of numerous ice islands, some reaching as far as offshore Newfoundland. The presence of these ice islands in the eastern Canadian Arctic increases the risk of interaction with offshore operations and shipping activities. This study uses the recently developed Canadian Ice Island Drift, Deterioration and Detection database to investigate the fracture events that these ice islands experienced, and it presents a probabilistic model for the conditional occurrence of such events by analyzing the atmospheric and oceanic conditions that drive the causes behind the ice island fracture events. Variables representing the atmospheric and oceanic conditions that the ice islands were subjected to are extracted from reanalysis datasets and then interpolated to evaluate their distributions for both fracture and non-fracture events. The probability of fracture event occurrence for different combinations of input variable conditions is quantified using Bayes' theorem. Out of the seven variables analyzed in this study, water temperature and ocean current speed are identified as the most and least important contributors, respectively, to the fracture events of the Petermann ice islands. It is also revealed that the ice island fracture probability increases to 75 % as the ice islands encounter extreme (very high) atmospheric and oceanic conditions. A validation scheme is presented using the cross-validation approach and Pareto principle, and an average error of 13 %–39 % is reported in the fracture probability estimations. The presented probabilistic model has a predictive capability for future fracture events of ice islands and could be of particular interest to offshore and marine ice and risk management in the eastern Canadian Arctic. Future research, however, is necessary for model training and testing to further validate this ice island fracture model.

A probabilistic model for fracture events of Petermann ice islands under the influence of atmospheric and oceanic conditions

Four calving events of Petermann Glacier happened in 2008, 2010, 2011, and 2012, which resulted in the drift and deterioration of numerous ice islands, some reaching as far as offshore Newfoundland. The presence of these ice islands in the eastern Canadian Arctic increases the risk of interaction with offshore operations and shipping activities. This study used the recently developed Canadian Ice Island Drift, Deterioration and Detection database to investigate the fracture events that these ice islands experienced, and presented a probabilistic model for the conditional occurrence of such events by analyzing the atmospheric and oceanic conditions that drive the causes behind the ice island fracture events. Variables representing the atmospheric and oceanic conditions that the ice islands were subjected to were extracted from reanalysis datasets and then interpolated to evaluate their distributions for both fracture and non-fracture events. The probability of fracture event occurrence for different combinations of input variable conditions were quantified using Bayes theorem. Out of the seven variables analyzed in this study, water temperature and ocean current speed were identified as the most and least important contributors, respectively, to the fracture events of the Petermann ice islands. It was also revealed that the ice island fracture probability increased to 75 % as the ice islands encountered extreme (very high) atmospheric and oceanic conditions. A validation scheme was presented using cross-validation approach and Pareto principle, and an average error of 13–39 % was reported in the fracture probability estimations. The presented probabilistic model has a predictive capability for future fracture events of ice islands and could be of particular interest to offshore and marine activities in the eastern Canadian Arctic. Future research, however, is necessary for model training and testing to further validate the presented ice island fracture model.

From Theory to Practice: Bone Health in Women with Early Breast Cancer Treated with Aromatase Inhibitors

Aromatase inhibitors (AI) are extensively used as adjuvant endocrine therapy in post-menopausal women with hormone receptor-positive early breast cancer (HR+ EBC), but their impact on bone health is not negligible. This work aimed to assess bone loss, fracture incidence, and risk factors associated with these events, as well as the prognostic influence of fractures. We have conducted a retrospective cohort study of women with HR+ EBC under adjuvant therapy with AI, during a 3-year period. Four-hundred-and-fifty-one eligible women were reviewed (median age 68 years). Median time under AI was 40 months. A fracture event occurred in 8.4%, mostly in the radium and femoral neck and in older women (mean 74 vs. 68 years, p = 0.006). Age (OR 1.01, 95% CI 1.01–1.07, p = 0.024) and time under AI (OR 1.02, 95% CI 1.00–1.04, p = 0.037) were independent predictors of fracture, with a fair discrimination (AUC 0.71). Analysis of disease-free survival according to fracture event varied between groups, disfavoring the fracture cohort (at 73 months, survival 78.6%, 95% CI, 47.6–92.4 vs. 95.6%, 95% CI, 91.2–97.8, p = 0.027). The multivariate model confirmed the prognostic impact of fracture occurrence (adjusted HR of 3.17, 95% CI 1.10–9.11; p = 0.032). Bone health is often forgotten, despite its great impact in survivorship. Our results validate the pathophysiologic link between EBC and bone metabolism, which translates into EBC recurrence. Further research in this area may help refine these findings. Moreover, early identification of women at higher risk for fractures is warranted.

MANAGEMENT OF ENDOCRINE DISEASE: Male osteoporosis: diagnosis and management - should the treatment and the target be the same as for female osteoporosis?

Male osteoporosis has been neglected for too long time and there is need for a change. This condition is clearly under-estimated, under-diagnosed and under-treated. The diagnosis is often made late in the natural history of the pathology or even after a fracture event. Guidelines on screening politics do not agree whether and when men should be considered, and clinical trials are far less performed in men with respect to women. Actually, most of our knowledge on male osteoporosis, especially regarding treatment, is extrapolate from the female counterpart. Male osteoporosis is frequently secondary to other conditions and often associated with comorbidities. Therefore, identification of specific causes of male osteoporosis is essential to drive a correct and personalized treatment. Moreover, men have more osteoporosis-related complications and higher mortality rate associated with fractures. Furthermore, not only fewer men receive a correct and timely diagnosis, but also fewer men receive adequate treatment, and adherence to therapy is far less in men than in women. Of note, very few studies assessed the effect of antiosteoporotic treatments in men and most of them considered only bone density as primary endpoint. This review focuses on the areas that are still nebulous in male osteoporosis field, from identification of subjects who need to be evaluated for osteoporosis and screening programs dealing with primary prevention to diagnostic procedures for good estimates of bone quantity and quality and precise calculation of fracture risk and personalized treatment that take into account the pathophysiology of osteoporosis.

Ice island thinning: rates and model calibration with in situ observations from Baffin Bay, Nunavut

A 130 km2 tabular iceberg calved from Petermann Glacier in northwestern Greenland on 5 August 2012. Subsequent fracturing generated many individual large “ice islands”, including Petermann ice island (PII)-A-1-f, which drifted between Nares Strait and the North Atlantic. Thinning caused by basal and surface ablation increases the likelihood that these ice islands will fracture and disperse further, thereby increasing the risk to marine transport and infrastructure as well as affecting the distribution of freshwater from the polar ice sheets. We use a unique stationary and mobile ice-penetrating radar dataset collected over four campaigns to PII-A-1-f to quantify and contextualize ice island surface and basal ablation rates and calibrate a forced convection basal ablation model. The ice island thinned by 4.7 m over 11 months. The majority of thinning (73 %) resulted from basal ablation, but the volume loss associated with basal ablation was ∼12 times less than that caused by areal reduction (e.g. wave erosion, calving, and fracture). However, localized thinning may have influenced a large fracture event that occurred along a section of ice that was ∼40 m thinner than the remainder of the ice island. The calibration of the basal ablation model, the first known to be conducted with field data, supports assigning the theoretically derived value of 1.2×10−5 m2∕5 s-1/5 ∘C−1 to the model's bulk heat transfer coefficient with the use of an empirically estimated ice–ocean interface temperature. Overall, this work highlights the value of systematically collecting ice island field data for analyzing deterioration processes, assessing their connections to ice island morphology, and adequately developing models for operational and research purposes.

Long-Term Outcomes after Colton Type I and II Fractures of the Olecranon

Background: It is unclear if the outcomes differ in different subtypes of olecranon fractures. Objective: Evaluate the outcomes of different Colton types of olecranon fractures, and if outcomes differ in dominant and non-dominant arms and in men and women. Methods: We evaluated primary journals and radiographs in 40 men and 55 women with isolated olecranon fractures and classified fractures according to Colton. Mean 19 years after fracture event, we re-examined subjective, clinical and radiographic outcomes in the former patients, using the uninjured arms as controls. Results: 89% of patients with Colton type I fractures reported at follow-up no subjective differences between the elbows, 84% with type II oblique/transverse fractures and 84% with type II comminuted fractures (p=0.91). The uninjured to former fractured arm differences in elbow range of motion and strength were no different in the 3 fracture types, the proportions of individuals with radiographic elbow degenerative changes were greater in type II than in type I factures (p<0.001), and there were no differences between the proportions of individuals with reduced joint space in the 3 groups (p=0.40). The outcomes were no different if the fractures had occurred in the dominant or non-dominant arms (p=0.43), or in men or women (p=0.43). Conclusion: There were no different outcomes after Colton type I, type II oblique/transverse or type II comminuted fractures, no different outcomes between fractures in dominant or non-dominant arms and no different outcomes in men and women.

1288. Bone Safety Outcomes with F/TAF vs. F/TDF for PrEP in the DISCOVER Trial

Background In the DISCOVER PrEP trial, emtricitabine/tenofovir alafenamide (F/TAF) was noninferior to emtricitabine/tenofovir disoproxil fumarate (F/TDF) for HIV prevention. Here we report the bone safety outcomes of F/TAF and F/TDF. Methods Men who have sex with men (MSM) and transgender women (TGW) at risk of HIV were randomized 1:1 to receive blinded F/TDF or F/TAF, taken once daily. Those on PrEP with F/TDF were eligible to enroll. Bone densitometry (DXA) of the hip and spine were performed in a subset of participants (BMD subset). Fracture events were compared in all study participants. Week 48 data are presented. Results 5387 participants were enrolled in the main study, with 383 included in the BMD subset. In the BMD subset, the median age was 37 (IQR 29, 46); 0.8% were TGW, 9.4% were black, and 20.6% were Hispanic or Latinx. Fifty-three BMD subset participants were on baseline F/TDF PrEP at enrollment, 26 of whom were randomized to F/TAF. F/TAF was associated with more favorable changes in hip and spine BMD compared with F/TDF (Table 1); these differences were similar when participants on baseline PrEP were excluded. Participants age <35 on F/TAF gained BMD, whereas those on F/TDF lost BMD (Table 1). BMD decreases of ≥3% were less frequent in the F/TAF group than the F/TDF group at the hip (3.8% vs. 18.4%, P < 0.001) and spine (10.1% vs. 26.9%, P < 0.001). Osteopenia was more frequently diagnosed in the spine in participants on F/TDF compared with F/TAF (Figure 1, P = 0.007); but not in the hip. Fracture event frequency was the same (53 [2.0%] per group, P = 1.00). One pathological fracture was reported in the F/TAF group compared with two in the F/TDF group (P = 0.57). In participants on baseline F/TDF PrEP, those randomized to F/TAF had significantly improved hip BMD compared with baseline (median percent change 1.13 [IQR −0.86, 3.47], P = 0.027), while spine BMD was unchanged. Conclusion Through 48 weeks, DXA subset participants taking F/TAF for PrEP had significantly less change in BMD than those taking F/TDF, and were less likely to develop spine osteopenia. The incidence of fracture was similar, and pathological fractures were rare. F/TAF for PrEP is effective and has a superior bone safety profile compared with F/TDF. Disclosures All authors: No reported disclosures.

Ice island thinning: Rates and model calibration with in situ observations from Baffin Bay, Nunavut

A 130 km2 tabular iceberg calved from Petermann Glacier in northwest Greenland on 5 August 2012. Subsequent fracturing generated many individual large “ice islands”, including “Petermann Ice Island (PII)-A-1-f”, that drifted between Nares Strait and the North Atlantic. Thinning caused by basal and surface ablation increases the likelihood that these ice islands will fracture and disperse further, thereby increasing the risk to marine transport and infrastructure as well as the distribution of freshwater from the polar ice sheets. We use a unique stationary and mobile ice penetrating radar dataset collected over four campaigns to PII-A-1-f to quantify and contextualize ice island surface and basal ablation rates and calibrate a forced convection basal ablation model. The ice island thinned by 4.7 m over 11 months. The majority of thinning (73 %) resulted from basal ablation, but the associated volume loss was ~ 12 times less than that caused by areal reduction (e.g. wave erosion, calving, and fracture). However, localized thinning may have influenced a large fracture event that occurred along a section of ice that was ~ 40 m thinner than the remainder of the ice island. The calibration of the basal ablation model, the first with such field data, supports assigning the theoretically-derived value of 1.2 × 10−5 m2/5 s−1/5 °C−1 to the model's bulk heat transfer coefficient. Overall, this work highlights the value of systematically collecting ice island field data for analyzing deterioration processes, assessing their connections to ice island morphology, and adequately developing models for operational and research purposes.