Background/Objectives: The os supranaviculare (OSSN), also known as os talonaviculare dorsale, astragalo-scaphoid ossicle, or Pirie’s bone, is a small extra bone that was first described in 1921 by A.H. Pirie and is located at the top front part of the navicular bone or talonavicular joint. The knowledge regarding the epidemiology of the OSSN is scarcely established, as its prevalence remains unknown and varies significantly among multiple studies. This meta-analysis aims to clarify and systematically summarize all available data on the characteristics and prevalence of the OSSN. Methods: Four major databases (PubMed/Medline, Embase, ScienceDirect, Scopus) were thoroughly searched for studies reporting original data regarding the OSSN up until May 2025. The protocol of this study was pre-registered on PROSPERO (ID: CRD42025638111) and adhered to PRISMA guidelines. To evaluate the between-study heterogeneity, the 95% prediction intervals (95%PI) were calculated; I² statistic and Chi² test were also used. The AQUA-tool was used to assess the quality of included studies. Results: In total, 13 studies (18,745 feet) qualified for inclusion in the quantitative analysis. The pooled prevalence estimate (PPE) of the OSSN in the general population was found to be 0.88% (95%CI: 0.62–1.24%). The PPE of the OSSN was higher in males (0.87%, 95%CI: 0.58–1.32%) than in females (0.48%, 95%CI: 0.14–1.64%). The os supranaviculare was similarly prevalent in both European (1.04%, 95%CI: 0.55–1.96%) and Asian (0.87%, 95%CI: 0.66–1.13%) populations. Conclusions: the os supranaviculare is a very rare anatomical variation that is present in less than one in a hundred feet. Moreover, although usually asymptomatic, it can occasionally be associated with dorsal foot pain or navicular stress fractures. Accurate differentiation from avulsion fractures is essential to avoid unnecessary invasive treatment.

Background/Objectives: Hyponatremia is associated with increased mortality in the general hospital population. We sought to investigate whether hyponatremia affects the long-term survival of patients following a myocardial infarction (MI) in both ST-segment elevation (STEMI) and non-ST elevation (NSTEMI) presentations. Methods: In this study, 862 MI patients who were hospitalized between 2012 and 2017 were retrospectively followed-up within the median time period of 41.9 [28.2–73.5] months. All participants were assigned to a hyponatremic or normonatremic group with hyponatremia defined as a sodium level of less than 135 mEq/L on admission. Results: In the acute phase of an MI, hyponatremia was diagnosed in 31 (3.6%) patients. The patients with hyponatremia were less often male (38.7 vs. 70.4%, p < 0.001), and less frequently had Killip class I (63.3 vs. 80%) but more often had Killip class IV on admission (16.7 vs. 4.2%, p = 0.024) and more often had a history of impaired renal function (32.3 vs. 15.5%, p = 0.013) than those with normonatremia. Hyponatremic patients had higher troponin T levels on admission by 75.1% (p = 0.003), a higher isoenzyme MB of creatine kinase level by 34.4% (p = 0.006), and lower hemoglobin (by 8.5%, p = 0.001) levels as compared to the normonatremia group. Long-term mortality was significantly higher in the patients with hyponatremia versus normonatremia (18 [58.1%] vs. 243 [29.2%], log-rank p < 0.001). This was driven by differences in the NSTEMI population (65 vs. 30.5%, p < 0.001). By a Cox proportional hazard regression analysis, hyponatremia was associated with a higher long-term mortality (hazard ratio [HR] of 2.222, a 95% confidence interval [CI] of 1.309–3.773, and p = 0.003). Conclusions: Hyponatremia rarely identified in acute phase of MI was associated with higher long-term mortality, particularly in the NSTEMI population.