The data in this study showed that in a population with an age over 50-years-old, with the increase in age, the incidence of hip fractures increased and 70-89-years-old is the high incidence age of fragile hip fractures because of the decrease in activity and the number of cases reduced in the elderly aged over 90-years-old. The mortality of patients with fragile hip fractures increased with age. Previous studies also revealed that advanced age increased the 1-year mortality of hip fracture patients [10, 19]. Statistical data in this study revealed that the 3-month, 1-year,and total mortality during the follow-up period of patients with an age > 75-years-old were higher than those in patients with an age ≤ 75-years-old. Among the patients over 75-years-old, the 1-year mortality was 20.14%, and the total mortality during the follow-up period was as high as 30.92%.The difference was statistically significant compared with the patients with an age ≤ 75-years-old. The multivariate analysis also confirmed that age was an independent risk factor for short-term mortality in patients with fragile hip fractures.
Women are also more likely to have hip fractures than men; in the present study, the ratio of male to female was 1:1.95. Previous studies have revealed that the male gender was a major risk factor for mortality from fragile hip fractures [15, 16]. After the hip fracture occurs, the life expectancy of the elderly will be greatly reduced and the physical life of females was decreased by 4 years when compared with the life expectancy, while that of males was decreased by 5 years . Kannegaard et al.  reported that compared with females, the average age of onset of fragile hip fractures was 4 years younger in males and mortality was significantly higher. However, some reports revealed that mortality in patients with fragile hip fractures was not related to gender [13, 21]. This study revealed that when compared with females, the average age of onset of fragile hip fractures was 4.24 years younger in males, the 3-month, 1-year,and total mortality during the follow-up period were higher in males than in females, and the differences in the 1-year and total mortality during the follow-up period between males and females were statistically significant. This result suggests that although the incidence and age of onset of fragile hip fractures were lower in males, the mortality was higher in males than in females, and this was established by the multivariate analysis, showing that the male gender was an independent risk factor for short-term mortality in patients with fragile hip fractures. This is consistent with the findings of previous studies conducted by many scholars [15, 16].
The purpose of fragile hip fracture treatment is to allow patients to continue with painless activities and get out of bed to reduce the complications caused by long-term bed rest and reduce the fatality and disability rate. Currently, the treatment of fragile hip fractures is mainly surgery and conservative treatment. In general, tibial tubercle bone traction or lower extremity skin traction are used for conservative treatment. However, this requires patients needing long-term bed rest and possibly induces pulmonary infection, bedsores, urinary system infection, lower limb venous thrombosis, and other complications while significantly reducing the patients' quality of life and the fatality rate is high. Therefore, surgery remains the main treatment for hip fracture patients with fairly stable general conditions and patients that are tolerable to surgery. The main surgical methods are internal fixation and artificial joint replacement . In the present study, the 3-month, 1-year,and total mortality during the follow-up period was 3.76%, 9.48%, and 18.33%, respectively in the operation group and were far lower than in the non-operation group (29.11%, 60.52%, and 71.05%, respectively), the differences were statistically significant. It was also confirmed by multivariate analysis that the non-operative treatment was an independent risk factor for short-term mortality in patients with fragile hip fractures. This fully demonstrates that the operation treatment of fragile hip fracture has a significant positive effect.
The association between delayed surgery and mortality after fragile hip fractures in the elderly population remains a major issue [23, 24]. Some scholars consider that the earlier the operation and even the emergency operation is performed, the better the effect is. Shiga et al.  reported that an operation completed at more than 48 hours after the fragile hip fracture will increase the 1-month and 1-year mortality in patients. Some other scholars believe that the operation should not be performedina rush and that there should be enough time to treat the internal diseases of the elderly patients before surgery. Preoperative preparation and evaluation should also be enhanced to reduce the risk of the operation and its success rate. Vidal et al.  showed in their studies that the time from injury to operation was not associated with the in-hospital and 1-year mortality after surgery while Kim et al.  showed that a delayed operation would not affect the postoperative complications of hip fractures. In the present study, all the patients had slight trauma and no obvious trauma, some of the patients did not even realize that they had afracture but were admitted to the hospital after the pain was not improved for 1–2 days. After admission, due to the advanced age of the patients, the hospital had no preoperative green channel for hip fractures, so preoperative preparations required 3–4 days. Therefore, in the present study, an interval from injury to the operation of 5 days was set as the grouping boundary. The researchers observed that although the 3-month, 1-year,and total mortality during the follow-up period were lower in patients with the interval from injury to the operation of ≤ 5 days than in patients with the interval from injury to the operation of > 5 days, the differences were statistically significant. However, it was established by multivariate analysis that the interval from injury to operation was not an independent risk factor for short-term mortality in patients with fragile hip fractures. Therefore, the researchers considered that the selection of operation time for elderly patients with hip fractures should follow the principle of individualization and should be lengthily measured according to the patient's physical condition. Patients that can tolerate the operation should be operated as early as possible to reduce the difficulties of bed rest while the patients with poor physical conditions should have enough time for the preoperative planning.
Elderly patients with hip fractures regularly have multiple internal diseases and poor organ compensatory function. Surgery will worsen the existing combined medical diseases and even lead to death. A previous study described that the mortality after hip fractures was associated with chronic diseases such as hypertension, diabetes, ischemic heart disease, and stroke . Moran et al.  showed that the risk of death 30 days after surgery in patients with fragile hip fractures combined with internal diseases was 2.5 times higher than in patients without internal diseases. The findings of the present study are similar; of these 690 patients, 441 patients had various internal chronic diseases, up to 63.91%, of patients had2 or more chronic diseases, the 3-month mortality was 10.96%, the 1-year mortality was 23.88%, and the total mortality was 30.26%.All the results were higher than the mortality of patients with < 2 medical chronic diseases. In patients who had cardiovascular diseases or chronic respiratory system diseases before the operation, the mortality was also statistically and significantly increased. The multivariate analysis revealed that the number of internal diseases before the injury was an independent risk factor for short-term mortality in patients with fragile hip fractures. The treatment of medical diseases before surgery is directly associated with the success of the operation and the prognosis in patients. Therefore, after admission, patients should actively collaborate with the physician to treat their combined diseases and physicians should measure patients’ tolerance to surgery to select a tolerable operation to reduce the mortality in elderly patients with fragile hip fractures.
The incidence of difficulties after fragile hip fractures is high and the main complications include pulmonary infection, heart event, deep vein thrombosis of the lower extremity, delirium, and cerebrovascular accidents. Fang et al.  consider that pulmonary infection and respiratory failure are frequently the main causes of death in these patients. In the present study, pulmonary infection occurred in 115 patients during hospitalization, 37 of them died during hospitalization and the follow-up period and the 3-month, 1-year,and total mortality during the follow-up period were significantly higher in patients with in-hospital pulmonary infection than in patients without in-hospital pulmonary infection; the differences were statistically significant. These findings indicate that in-hospital pulmonary infection is a significant risk factor for short-term mortality in patients with fragile hip fractures. However, given the interaction between various factors, the multivariate analysis showed that in-hospital pulmonary infection was not an independent risk factor for short-term mortality in patients with fragile hip fractures.
Anti-osteoporosis treatment has been confirmed to effectively reduce the risk of succeeding fractures and improves the functional outcome of hip fracture patients . This leads to a hypothesis, that is, osteoporosis drug treatment can reduce the risk of death in patients with fragile hip fractures. Zoledronic acid has also been confirmed to significantly increase bone mineral density in the hip and lumbar spine, reduce the risk of new clinical fractures by 35% and reduce the risk of death in patients with recurrent fractures within 3 years by 28% . In the present study, it was also confirmed that anti-osteoporosis treatment (including Bisphosphonates and non-Bisphosphonates) was significantly related to a reduction in short-term mortality in fragile hip fractures. Furthermore, it was established by the multivariate analysis that the absence of anti-osteoporosis treatment was an independent risk factor for short-term mortality in patients with fragile hip fractures.
This retrospective study had several limitations. Firstly, only 56.98% of the hip fracture patients were followed-up successfully and this was a retrospective and not a randomized study.
Secondly, the present study did not include all the aspects that may affect the prognosis of patients with fragile hip fractures, such as the patients’ activity function before the injury, ASA score before surgery, and the surgeons’ surgical skills. Thirdly, whether the basis for grouping the factors involved in this study was reasonable, for example, 75-years-old was set as the boundary of age and 5 days was set as the boundary of the interval from injury to operation, needs to be studied further.