A retrospective study was conducted on the clinical data of 254 cases of pelvic fracture hospitalized in the department of Orthopedics of our hospital from August 2017 to August 2021. Univariate and Logistic analysis of risk factors showed that: Age > 60 years, Tile type B2 or higher, and high ISS were independent risk factors for pelvic fracture complicated with humerus fracture, while BMI, injury cause, and gender were not independent risk factors for pelvic fracture combined with humerus fracture. In this study, we retrospectively collected nearly three years of 254 patients with pelvic fractures were admitted in our hospital orthopedics, among them, 24 cases of pelvic fractures combination with humerus fracture, for most of all a single combined injury, and after the single factor analysis respectively, statistically significant only the pelvic fractures combination of humerus fracture. This discovery has not been mentioned in previous literature reports[1, 2, 4–10, 12–23]. The results of counting the causes of injuries show that there are 115 cases of car accidents, 79 cases of falls, 48 cases of high falls and 12 cases of crush injuries. The injury mechanism was analyzed, and it was found that when patients suffered from pelvic fracture, most patients would fall to the ground on the side, resulting in shoulder or elbow joint landing, resulting in humeral fracture. Shoulder joint landing is common, so the probability of proximal humeral fracture is high[19]. On the basis of screening out that pelvic fracture combined with humeral fracture accounts for the highest proportion in all single pelvic fracture combined injuries, and has statistical significance, we also made logistic analysis on the related risk factors of pelvic fracture combined with humeral fracture. In logistic analysis, we tested the likelihood ratio test (LR), odds ratio (OR), confidence interval (95%CI), probability (P) and other indicators, thus avoiding the error caused by single indicator analysis.
Why age, ISS score and Tile score of pelvic fracture would be independent risk factors was analyzed by referring to a large number of literatures, and the results are as follows:
1. Age factor
In the data analysis of Table. 2, we found that the probability of humeral fracture combined with injury in patients with pelvic fracture over 60 years old (P = 0.006; 95%CI = 0.087–0.665; OR = 10.258) was significantly larger than that of patients with pelvic fracture aged < 60 years. This may be related to patients' old age, poor bone condition and brittle fracture after osteoporosis. Court-Brown et al.[13] reported the findings of a 5-year prospective epidemiological study of 1,027 proximal humeral fractures in Edinburgh, UK. Humeral fractures in patients aged 65 years account for 73% of all humeral fractures, with the highest incidence occurring in women aged 80–89 years and less than 20% of fractures occurring in patients younger than 50 years. Breuil et al.[23] found through a large number of epidemiological studies that the incidence of senile osteoporotic pelvic fractures is related to age and gender: there are more women than men, and the incidence increases with age. After the elderly patients with pelvic fracture and humeral fracture, because the elderly are not sensitive to pain, the patients stay in bed for a long time after the fracture, and there are not many opportunities for upper limb exertion. When the proximal humeral fracture (Neer type I or II) occurs, the humeral shaft is intact, and the upper limb movement is only slightly limited, clinicians tend to ignore the existence of pelvic fracture and injuries, and miss the diagnosis of humeral fracture[16]. In order to avoid missed diagnosis, it is particularly important to ask the patient's medical history and physical examination at the time of admission. Elderly patients should also take into account the sensitivity and responsiveness to pain and the mental state after injury, and have a careful physical examination[3].
2. Injury severity score (ISS)
ISS fully reflected the intensity of violence at the time of injury, and the statistical results of this group (P = 0.002; 95%CI = 1.839 4.445; OR = 8.721) showed that the greater the degree of trauma, the higher the incidence of humeral fractures in patients with pelvic fractures (Table. 4). When the body is subjected to violence, on the one hand, individuals instinctively extend their upper limbs for support, and the violence reaches the upper arm through conduction, which may lead to a humeral fracture. On the other hand, as the protruding part of the body, the bilateral shoulders are more vulnerable to the impact of the violence that causes the humeral fracture at the moment when the trauma force causes the body to fly out and touch the ground. When the shoulder joint is dislocated, proximal humerus fractures are likely due to rotator cuff pull [10]. Bao-guo Jiang et al.[11] believed that there are two age peaks in patients with humeral fracture, which are around 30 years old and over 60 years old respectively, and humeral fracture around 30 years old is mostly caused by high-energy injury.
3. Tile classification score of pelvic fracture
In this group, the pelvic fractures were classified by Tile B2 or above (P = 0.01; 95%CI = 22.554–87.419; OR = 22.736) is significantly higher than that of patients with Tile B2 or below (Table. 4). After analyzing the injury mechanism of patients corresponding to the Tile scores of each pelvic fracture, it was found that the injury mechanism was firstly directly related to the great violence suffered by the body during the trauma[9]; Secondly, in patients with high Tile classification of pelvic fractures, the violence suffered by trauma is often not unidirectional, and multi-directional violence is more likely to cause multiple fractures, while humeral fractures have the highest incidence among pelvic fractures combined with injuries[24]. In clinical work, patients with severe pelvic fractures are often combined with hemodynamic instability and damage to the thoracic and abdominal internal organs, which is life-threatening. at this time, saving life is the first element[4]. Patients often enter the intensive care unit for treatment after thoracic, abdominal or craniocerebral operations, while orthopedic treatment is often the last treatment to exclude other combined injuries. At this time, it is more likely to miss the diagnosis of fractures in other parts with unclear malformations[17]. Therefore, for severe pelvic fractures, when we pay attention to the pelvic fractures and life-threatening combined injuries, we should also pay attention to the timely detection of non-fatal combined injuries, such as humerus fractures, and early treatment, so as to strive to achieve the best curative effect for patients[12].
In this study, the clinical data of 254 cases of pelvic fractures in the past three years were collected and analyzed by univariate and logistic analysis, but there are still many shortcomings. First, this study is a single center, which can only represent the situation of patients with pelvic fractures in this area, but can't cover all the risk factors. Secondly, the sample size is relatively small, which has the disadvantage of insufficient sample size, and the collected data may have selective deviation; Third, the accuracy of the definition of the assignment of some variables needs further evaluation; Fourthly, this study is a retrospective study and does not further track the treatment and prognosis of patients, which has an impact on the authenticity of the results. Therefore, a multi-center, long-term prospective study combined with multiple hospitals is needed in order to provide more convincing evidence. Also, is there a statistical significance of pelvic fractures with other single injuries as the sample size increases? And are there other independent risk factors for pelvic fractures combined with humerus fractures? These all need to be further studied before they can be confirmed.