Bone Turnover Biomarkers and Hip Fracture Patterns in Older Adults: A Retrospective Cohort Study

Background: Hip fractures represent a major public health challenge in aging populations and are associated with high morbidity, mortality, and healthcare costs. While osteoporosis is the main underlying cause, biochemical markers of bone metabolism may provide additional insight into skeletal remodeling processes. However, the relationship between bone turnover biomarkers and specific hip fracture patterns remains poorly understood. Methods: A retrospective observational study was conducted, including patients admitted with hip fractures between January 2022 and December 2023 at our institution. Serum levels of vitamin D, parathyroid hormone (PTH), N-terminal propeptide of type I collagen (PINP), and beta-C-terminal telopeptide of type I collagen (β-CTX) were analyzed. Fractures were classified as intracapsular or extracapsular. Continuous variables were compared using the Mann-Whitney U test. Multivariable logistic regression analysis was performed to identify factors independently associated with extracapsular fractures. Results: A total of 131 patients were included, comprising 57 intracapsular fractures and 74 extracapsular fractures. Patients with extracapsular fractures were significantly older (83 (75-89) vs. 80 (71-86) years; p = 0.0079). No significant differences were observed in vitamin D levels between fracture groups (p = 0.446). PTH levels were higher in extracapsular fractures (p = 0.030), while β-CTX levels tended to be lower (p = 0.080). In multivariable logistic regression analysis, age remained independently associated with extracapsular fracture pattern (OR 1.05, 95% CI 1.01-1.09; p = 0.03). Higher β-CTX levels were inversely associated with extracapsular fractures (OR 0.65, 95% CI 0.43-0.96; p = 0.03), whereas vitamin D levels were not independently associated with fracture type. Conclusions: Extracapsular hip fractures were primarily associated with older age in this cohort. Among bone metabolism biomarkers, β-CTX showed an inverse association with extracapsular fracture pattern after adjustment for confounding factors. These findings should be interpreted with caution and considered exploratory, highlighting the need for prospective studies to clarify their clinical significance.