Hip fracture, as a common type of fragility fracture, has attracted attention because of its high perioperative risk and excess standardized mortality rate and re-fracture risk even after fracture surgery. At present, the recognized risk factors of hip fracture death include old age, male gender, place of residence, chronic disease, fracture type, anti-osteoporosis medicine et al[13-15]. While, with the co management of orthopedics and geriatrics, our all-cause mortality decreased significantly, 1-year mortality rate was 4.5% compare with 17.47%, which was from a systematic analysis data after femoral intertrochanteric fracture between the years 2000 and 2018 in Mainland China . Therefore, this article explored whether the risk factors of all-cause mortality changed under this model.
In recent years, many guidelines and expert consensus recommend that the multi department cooperative treatment group should be established in the treatment of hip fracture in elderly patients to improve perioperative safety, and operate as soon as possible (within 48 h), and then accelerate rehabilitation under the guidance of rehabilitation doctors [17-19]. In the process of multi department collaborative treatment, the cooperation between orthopedics and geriatrics is very important. Grigoryan et al.  summarized 18 studies through meta-analysis and found that the cooperative treatment of elderly hip fractures by orthopedics doctors and geriatricians can shorten the length of hospital stay and reduce the in-hospital mortality and long-term mortality. It is a more efficient way to establish a special ward and adopt the co management mode between orthopedics and geriatrics (or internal medicine). Biber et al.  pointed out that the establishment of elderly fracture co management ward can shorten the preoperative waiting time and hospitalization time of elderly patients with femoral neck fracture. Through a prospective randomized controlled study, Prestmo et al.  found that the establishment of a special elderly hip fracture ward could improve the treatment results compared with the conventional orthopedic treatment mode.
Under the co management mode of orthopedics and geriatrics, from our data, risk factors of all-cause mortality were older age, CCI and early use of ZOL; they were consistent with previous studies [13,15,23-24]. While male gender was not risk factor. It is speculated that different data have different gender and age distribution; it is also possible that the number of data in this paper is still insufficient and cannot show the difference. To the dosing of ZOL, we summarized different studies about all-cause mortality after bisphosphonates treatment in patients with hip fracture (Table3), from the hazard ratios, it seems China hip fracture population had better effects. The influence of ethnicity is huge. Such as, Chinese people are prone to atypical fracture after continuous BPs [25-27].
Hip fracture is the peak period of osteoporosis. It is very important to bring fragile hip fracture patients into the prevention and treatment program of osteoporosis. The difference between using ZOL to patients who are healing after fracture and to patients who have healed after fracture and patients with osteoporosis is that patients who suffering fracture are in the period of rich callus formation, and their bone metabolism is more active than those who not; therefore, after using ZOL during fracture healing, patients will retain more ZOL in the bone, which can play a more effective and longer anti-osteoporosis effect.
For the mechanism displayed, bisphosphonates (BPs) binds to hydroxyapatite crystals in bone, especially at sites with high bone turnover , which means BPs bind strongly at sites of new mineral deposition, also bind well to resorption sites. And more BPs is taken up by trabecular bone than cortical bone, for a higher rate of turnover and greater surface area available in trabecular bone . BPs released from bone may undergo re-uptake onto bone surfaces, so they can be detected in urine for years after treatment discontinuation [30-31].
This mechanism suggests that the researchers should treat fracture and osteoporosis differently when it comes to the therapeutic effect of BPs. For the drug will leave more in the bone of fracture patients, will play a longer role, and maybe play different roles under different stress states. Therefore, the timing of using BPs after hip fracture surgery is very critical. Theoretically, it should be used within the callus formation period to achieve this effect. But we have no data to support this speculation.
The feature of this study was that ZOL is used within 3 days after surgery, which is early; for most of the published studies on the use of BPs after hip fracture have been used for 2-4 weeks or later. On the other hand, it verified that the early use of ZOL did not bring more adverse. Another feature of the study was that ZOL was used only once during the observation period of 2-3 years, due to the less attention paid to osteoporosis treatment by patients and their families and the inconvenient activities of patients. For ZOL effects on BMD and fracture risk persist for at least two years [32-34], it makes ZOL a more attractive proposition.
Determination of risk factors supports doctors to identify patients who were at high risk for mortality and enables accurate preoperative risk assessment. A known high risk for mortality can support appropriate informed consent (patient and family), timing of surgery, and enable possibilities for intervention with respect to perioperative management. Clinically, we should pay attention to the elderly patients with femoral intertrochanteric fracture complicated with a variety of basic medical diseases, and give anti osteoporosis treatment if allowed.
There are still some deficiencies in our research. 1. It is real-world research, as ZOL has a clear benefit for patients with osteoporosis, it is not possible to perform double blind study; 2. Many follow-up visits are telephone follow-up, so there are subjective factors.