Risk factors for early complications following arthroplasty in elderly patients with a femoral neck fracture
Abstract
BACKGROUND:
Early complications after arthroplasty for geriatric femoral neck fractures are known to negatively affect postoperative recovery and increase postoperative mortality. Identifying risk factors associated with early complications after arthroplasty may offer an opportunity to address and prevent these complications in many patients.
OBJECTIVE:
To evaluate preoperative risk factors for early complications after arthroplasty in elderly patients with a femoral neck fracture.
METHODS:
119 elderly patients with femoral neck fractures who had been treated with arthroplasty (hemiarthroplasty or total hip arthroplasty) between December 2015 and December 2018 were retrospectively analysed. Early complications were defined as any complications that did not exist preoperatively, and occurred during hospital stay after arthroplasty Preoperative clinical, epidemiological and laboratory data were collected. Binary univariable and multivariable logistic regression analysis were applied to identify predictors of early complications after arthroplasty for geriatric femoral neck fractures.
RESULTS:
Median age of all patients was 80.0 (IQR 74.0–84.0) years. We identified 28 (23.5%) early complications after arthroplasty. Univariable logistic regression analysis found that preoperative body mass index (BMI
CONCLUSION:
Our results demonstrate that obesity and hypoalbuminemia are independent predictors for early complications during hospital stay after arthroplasty, which should be meticulously noted to minimize these risk factors in geriatric femoral neck fractures.
1.Introduction
Femoral neck fracture is a common orthopedic emergency and represents the majority of hip fractures. Geriatric femoral neck fractures are mostly fragility-type fractures caused by low-energy injuries. Due to the existence of several risk factors, such as advanced age, malnutrition, and systemic complications, if not treated in time, geriatric femoral neck fracture will significantly impair the post-traumatic quality of life, and is even associated with short-term and intermediate-term death [1].
Arthroplasty (hemiarthroplasty or total hip arthroplasty) is generally preferred for the management of geriatric femoral neck fractures if other treatment options (e.g., DHS) are not indicated, which provides quick mobilization after operation, and avoids the occurrence of systemic complications caused by immobilization [2, 3]. However, for patients with geriatric femoral neck fractures, despite aggressive management including arthroplasty and rehabilitation, the 1-year mortality is still as high as 20% after surgery, which usually stems from the occurrence of various postoperative complications [4]. Therefore, the prevention and treatment of postoperative complications in geriatric femoral neck fractures are of utmost importance, and are also huge clinical challenges. In addition, identifying risk factors associated with early complications after arthroplasty in femoral neck fractures also may offer an opportunity to address and prevent these potential complications by preoperative correction and treatment in many patients.
Currently, although much research has been done on the risk factors associated with complications following arthroplasty in geriatric femoral neck fractures, and obesity, hypoalbuminemia and preoperative C-reactive protein/albumin ratio were found to be risk factors for complications after hip arthroplasty, they usually only focus on a single complication or long-term postoperative complications, such as periprosthetic joint infection, dislocation, delirium or mortality [5, 6, 7, 8, 9]. Only a few studies focus on the risk profile of postoperative early multi-system complications during hospital stay after arthroplasty, which is a more common issue requiring more attention. Although these complications might not be fatal, they could delay hospitalization, increase medical cost, and affect the patient’s postoperative recovery process. Therefore, in the present study, we aimed to identify possible independent risk factors associated with early multi-system complications during hospital stay following arthroplasty in elderly patients with a femoral neck fracture.
2.Materials and methods
2.1Study population
We retrospectively analysed 119 elderly patients with femoral neck fractures who had been admitted and treated definitively with arthroplasty at the Department of Orthopedics, Peking University International Hospital between December 2015 and December 2018. Inclusion criteria were an age of 65 years or older, initial treatment with arthroplasty, a postoperative follow-up during hospital stay and a complete data set (including all parameters in data collection). Patients that received arthroplasty secondary to a failed internal fixation of a femoral neck fracture, those with general multiple injuries those who cannot tolerate arthroplasty and those with a pathological fracture due to malignancy were excluded. The study followed the principles of the Declaration of Helsinki in 2013 (seventh revision) and was approved by the ethics committee of Peking University International Hospital (2021-028(BMR)). Because of the retrospective nature of this study, and the personnel identifiers were removed from the database, the ethical committee of Peking University International Hospital approved the research protocol and waived the need for informed consent, and waiving informed consent will not adversely affect the rights and health of the study subjects.
2.2Treatment algorithm
Blood samples for routine laboratory parameters in particular myocardial injury markers and arterial blood gas analysis, were drawn immediately after admission to the emergency room. Urinary, stool tests, electrocardiography, echocardiography and chest x-rays/CT were also performed as routine to determine whether there were related complications before surgery.
Total hip arthroplasty was performed if patient is relatively healthy, has no cognitive impairment, and ambulates independently. The implant brands (including DePuy, Indiana USA and AK Medical, Beijing, China) were selected according to the patient’s personal choice and economic situation. All surgeries were performed with cementless stems using the modified Hardinge approach. All patients received a single-shot of 1.5 g cefuroxime (or clindamycin in case of hypersensitivity to penicillin or cefuroxime) prior to surgery and continued to use until 24 hours after surgery. Patients were mobilized with full weightbearing postoperatively as soon as their clinical state allowed.
Table 1
Patient characteristics
| Total study cohort ( | |
| Age (years), median (IQR) | 80.0 (74.0–84.0) |
| Females | 86 (72%) |
| BMI (kg/m | 22.8 (4.1) |
| Time from onset to arthroplasty (days), median (IQR) | 6.0 (3.5–14.0) |
| ASA classification | |
| I–II | 62 (52.1%) |
| III–IV | 57 (47.9%) |
| WBC (10 | 7.6 (6.0–10.0) |
| CRP (mg/L), median (IQR) | 33.8 (10.3–85.5) |
| ESR (mm/h), median (IQR) | 28 (18–44) |
| D-dimer (ng/mL), median (IQR) | 817 (453–1900) |
| Serum Albumin (g/L), mean (SD) | 37.0 (3.9) |
| HGB (g/L), mean (SD) | 122.0 (16.7) |
| Duration of operation (mins), mean (SD) | 75.1 (19.7) |
| General anesthesia | 20 (16.8%) |
| Hemiarthroplasty | 69 (58.0%) |
| Diabetes mellitus | 24 (20.2%) |
| Hypertension | 62 (52.1%) |
| Coronary artery disease | 12 (10.1%) |
| Early complications following arthroplasty | 28 (23.5%) |
Values are given as absolute numbers (percentage), if not otherwise specified.
2.3Data collection
The following data before arthroplasty were extracted from medical records: demographic data such as age, sex, body mass index (BMI); clinical data including the time from onset to arthroplasty, the American Society of Anaesthesiologists (ASA) score [10], the anesthetize mode (general or epidural anesthesia), the surgery time the surgical options (hemiarthroplasty or total hip arthroplasty) and the preoperative comorbidities; lab test results including white blood cell count (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), D-Dimer, hemoglobin (HGB) and serum Albumin.
The outcome variable was postoperative early complications occurring during hospital stay after arthroplasty, which was defined as any complications that did not exist preoperatively. The primary outcome was characterized as a binary variable.
2.4Statistical analysis
Sample size calculations determined that 81 subjects were required in random sampling to have 90% power and testing with a two-sided 95% confidence interval in this study (the incidence of postoperative early complications in our pre-survey was 30%). Data were analysed using GraphPad Prism (version 9; GraphPad Software Inc., San Diego, CA, USA). The Shapiro-Wilk test was used to test continuous variables for normal distribution. Normal distributed values are presented as mean (standard deviation, SD), not normal distributed values are given as median (interquartile range, IQR 25–75 percentile), while incidences are presented with counts (percentages). In binary univariable logistic regression analysis, the continuous variables were analyzed based on the original data, the categorical variables were analyzed after converting to 0 and 1. Only variables that showed statistical significance in the univariate analysis were included in the multivariate logistic regression analysis. Preoperative BMI, CRP and serum Albumin were stratified according to previous research [11, 12, 13, 14], and used for multivariable logistic regression analysis. The results were reported as odds ratio (OR) with 95% confidence interval (CI), two-sided
Table 2
Univariable analysis of risk factors for early complications (
| Parameter | Complications-free ( | Complications ( | OR (95% CI) | |
|---|---|---|---|---|
| Age (years), median (IQR) | 79.0 (74.0–84.0) | 82.0 (75.3–85.8) | 1.039 (0.981–1.105) | 0.210 |
| Females | 64 (70.3%) | 22 (78.6%) | 1.547 (0.591–4.578) | 0.397 |
| BMI (kg/m | 22.3 (3.6) | 24.2 (5.2) | 1.126 (1.013–1.260) | 0.031 |
| Time before arthroplasty (days), median (IQR) | 6.0 (4.0–15.0) | 4.0 (2.0–10.0) | 0.998 (0.977–1.013) | 0.834 |
| ASA classification | 1.970 (0.839–4.787) | 0.124 | ||
| I–II | 51 (56.0%) | 11 (39.3%) | ||
| III–IV | 40 (44.0%) | 17 (60.7%) | ||
| WBC (10 | 7.6 (5.9–9.7) | 8.0 (6.5–10.3) | 1.044 (0.931–1.164) | 0.427 |
| CRP (mg/L), median (IQR) | 27.3 (10.0–75.6) | 54.3 (18.8–127.6) | 1.008 (1.001–1.015) | 0.017 |
| ESR (mm/h), median (IQR) | 30 (18–50) | 27 (14–44) | 0.994 (0.974–1.005) | 0.489 |
| D-dimer (ng/mL), median (IQR) | 765 (438–2223) | 950 (540–1261) | 1.000 (1.000–1.000) | 0.655 |
| Serum Albumin (g/L), mean (SD) | 37.6 (3.6) | 35.2 (4.3) | 0.840 (0.737–0.946) | 0.006 |
| HGB (g/L), mean (SD) | 121.1 (15.4) | 125.0 (20.3) | 1.014 (0.989–1.041) | 0.285 |
| Duration of operation (mins), mean (SD) | 73.9 (20.2) | 79.2 (17.7) | 1.014 (0.992–1.036) | 0.216 |
| General anesthesia | 15 (16.5%) | 5 (17.9%) | 1.101 (0.330–3.197) | 0.865 |
| Hemiarthroplasty | 49 (53.8%) | 20 (71.4%) | 2.143 (0.881–5.632) | 0.104 |
| Diabetes mellitus | 17 (18.7%) | 7 (25.0%) | 1.451 (0.505–3.865) | 0.468 |
| Hypertension | 48 (52.7%) | 14 (50.0%) | 0.896 (0.382–2.102) | 0.799 |
| Coronary artery disease | 8 (8.8%) | 2 (7.1%) | 1.093 (0.230–3.995) | 0.899 |
Values are given as absolute numbers (percentage), if not otherwise specified.
Table 3
Multivariable analysis of risk factors for early complications (
| Predictor | Regression coefficient | OR (95% CI) | |
|---|---|---|---|
| BMI | 2.346 | 10.440 (2.674–41.170) | 0.001 |
| CRP | 0.878 (0.240–2.812) | 0.833 | |
| Serum Albumin | 1.369 | 3.933 (1.509–10.800) | 0.006 |
3.Results
3.1Patient characteristics
A total of 119 elderly patients with femoral neck fractures were treated with arthroplasty at the Peking University International Hospital between December 2015 and December 2018. Preoperative baseline characteristics of the 119 femoral neck fracture patients are shown in Table 1. For demographic and clinical data, female patients represented 72.0% (
Overall, we identified 28 patients (23.5%) with early complications after arthroplasty (multiple complications occurred in some cases), including high fever (2 cases, temperature
3.2Univariable regression analysis referring to early complications
Univariable logistic regression analysis revealed preoperative BMI (
3.3Multivariate regression analysis referring to early complications
Preoperative BMI, CRP and serum Albumin levels were stratified and used for multivariable regression analysis. The multivariate logistic regression analysis referring to early complications showed that preoperative higher BMI (
4.Discussion
A number of studies so far have suggested elderly patients with a femoral neck fracture are at substantial risk for death, health complications, and reduced quality of life [3, 15, 16]. At present, the way in which femoral neck fractures in elderly patients should be managed surgically is relatively clear. Options include hemiarthroplasty and total hip arthroplasty, which have greater advantages with regard to patient’s postoperative function and quality of life [4]. However, elderly patients often had multiple preoperative comorbidities, poor nutritional status and weak surgical tolerance, who undergoing arthroplasty had an evidently higher incidence of serious adverse events. All these factors increase the treatment difficulty for geriatric femoral neck fractures.
In the present study, we identified 28 patients with early complications during hospital stay following arthroplasty, the rate of early complications was 23.5%. The top three complications were respiratory infection (21.4%), urinary system infection (17.9%) and thrombosis related diseases (14.3%). Although most of these postoperative complications were not immediate life-threatening, but they affected the rehabilitation of patients, prolonged the length of hospital stay and increased the economic burden on family and society. Therefore, it is of great clinical significance to preoperatively identify the possible independent risk factors associated with early complications following arthroplasty.
To exclude the potential risk factors, we focused on the demographic data, clinical data and lab test results, and analyzed the early complications in univariable and multivariable logistic regression model. The models ultimately revealed obesity (BMI
Previous studies have shown that obesity is a recognized risk factor for a series of acute and chronic diseases such as diabetes mellitus, hypertension, cardiovascular diseases, cerebrovascular diseases and tumors [17]. Obesity not only associates with earlier hip fracture and higher post-fracture mortality [18], but also with impaired wound healing and prosthetic joint infection after arthroplasty [19]. Our study revealed that obese patients (BMI
Malnutrition is very prevalent in elderly patients with femoral neck fracture. Nevertheless, its importance has not been fully recognized. Malnutrition in the elderly increases an individual’s risk of a variety of chronic diseases, such as cardiovascular diseases, cachexia and sarcopenia, and further affects the emotional state, bone metabolism, and contributes to the development of femoral neck fracture [20, 21, 22, 23]. Malnutrition and obesity are not contradictory, and there is also malnutrition in obese elderly patients [24]. Recent research shows that hip fracture patients who are both obese and malnourished, have significantly and substantially worse clinical outcomes than their well-nourished counterparts [25]. The serum Albumin level is one of several laboratory parameters commonly used to diagnose malnutrition, which is obviously related to the incidence of morbidity and mortality in hospitalized patients [26]. Low levels of Albumin are associated to worse recovery following acute pathologies, are also associated to a higher risk of post-surgery complications, especially infections [27]. Meanwhile, serum Albumin was also an independent risk factor for postoperative delirium and pneumonia in elderly subjects after arthroplasty [28, 29]. In the present study, preoperative hypoalbuminemia (serum Albumin
CRP is a non-specific reactive protein that plays a protective role in acute injury or infection. Some chronic diseases also have elevated CRP levels [30]. The role of preoperative CRP levels on the incidence of complications after arthroplasty is discussed controversially [31, 32]. Although this study found that CRP was a potential risk factor for early complications in univariate logistic regression analysis, but through multivariate logistic regression analysis, we ultimately confirmed elevated CRP was not an independent risk factor for early complications. Since a large number of previous studies have suggested that there is a relationship between elevated CRP and many systemic comorbidities, we believe there might be some interactions between preoperative CRP levels and other preoperative comorbidities [33, 34, 35]. Confounding factors such as femoral neck fractures, cardiovascular diseases, etc., might lead to increases in preoperative CRP levels. This result also reminds us, for elderly patients with elevated CRP before arthroplasty, we should actively evaluate whether there are some occult infections or undetected preoperative comorbidities, which will help us reduce the incidence of early complications after arthroplasty.
5.Limitations
We acknowledge several limitations in our study. First, one limitation of this study is its retrospective design, which potentially implicated a study bias. Although numerous confounding variables were considered in this multivariable regression model, some unknown or unmeasured confounders were likely disregarded. Second, the study was also limited to the single center and small sample size. So, our findings need to be validated by future perspective studies with larger sample sizes. Third, CRP is a time-sensitive parameter, although we analyzed time before arthroplasty as a potential risk factor in univariable regression analysis, the time prior surgery might still affect the level of CRP at admission.
6.Conclusion
The results demonstrate that obesity and hypoalbuminemia are independent predictors for early complications during hospital stay after arthroplasty, which should be meticulously noted to minimize these risk factors in geriatric femoral neck fractures. Preoperative CRP level is not an independent risk factor for early complications. Some confounding factors such as femoral neck fractures, cardiovascular diseases, etc., might lead to increases in preoperative CRP levels. These findings could contribute to further understand the preoperative risk factors for femoral neck fractures in elderly patients. Awareness of these risk factors and consideration in perioperative treatment protocols offer an opportunity to decrease these postoperative complications in geriatric femoral neck fractures.
Author contributions
JW: Designed and performed the study, first draft of the manuscript and illustrations, analysis and interpretation of data. CZ: Investigation, resources, data curation. BY: Conceived the study and critical review of the manuscript.
Funding
This study was supported by the National Natural Science Foundation of China (81802233).
Availability of data and materials
The source data are available from the corresponding author upon reasonable request.
Acknowledgments
The authors would like to thank all research participants for their active participation in this project.
Conflict of interest
None of the authors have any conflicts of interest to declare.
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