Introduction: Hip fractures can be divided into intra-capsular and extra-capsular fracture based on fracture location; these two types of fracture have different pathogeneses, treatments and prognoses. Many factors influence the patterns of hip fractures, including the injury mechanism, areal bone mineral density and the geometry of the hip. However, the relationship between body composition and hip fracture pattern has not yet been discussed. In this investigation, an analysis of the body compositions of geriatric patients with hip fractures were conducted to identify differences between fat and muscle distributions between patients with intra- and extra-capsular hip fractures. Material and methods: From December 2017 to February 2019, 139 patients with a hip fracture were prospectively enrolled in this study. The groups of patients that were diagnosed as having intra- and extra-capsular hip fractures were compared in terms of patient demographics, pre-operative laboratory data, bone mineral density (BMD) and body composition including muscle and fat distributions obtained using dual-energy X-ray absorptiometry (DXA). Results: Eighty-six and 53 patients were diagnosed with intra-capsular and extra-capsular hip fractures, respectively. A significantly higher serum glucose level, a lower hemoglobin level, a lower T-score level in the proximal femur region, a lower T-score of all parts of interest, and a lower percentage fat content on the region of bilateral proximal hips (gynoid region) and in the lower limb region, were observed in patients with an extra-capsular hip fracture than in those with an intra-capsular hip fracture. However, with all confounding factors controlled for, only the T-score at the proximal femur, percentage fat content in the region of bilateral proximal hips and the ratio of android fat content to gynoid fat content (A/G ratio) are the most relevant factors in predicting the patterns of hip fracture in geriatric patients after falling. Conclusion: This work demonstrates that lower fat content in the region of bilateral proximal hips and a lower BMD on the proximal femur may predict greater vulnerability of geriatric patients to extra-capsular rather than intra-capsular hip fracture after a falling accident.
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