The geriatric population represents the fastest growing demographic of acetabular fractures.1 In the past 3 decades, there has been a 2.4-fold increase in the number of acetabular fractures in patients older than 60 years, with elderly patients now representing about 24% of all acetabular fractures.2 Prolonged bed rest is detrimental to the health of elderly patients, and operative intervention for fractures is often required.3,4 Acetabular fractures sustained by elderly individuals are frequently unstable, involving the weight-bearing dome, disruption of the quadrilateral plate, or severe comminution of the posterior wall.3,5 As attempted mobilization with these injuries can cause pain or further fracture displacement, some surgeons may choose operative intervention to avoid prolonged bed rest with nonoperative management.
Studies have reported 1-year mortality rates between 16% and 33% for geriatric patients who have sustained an acetabular fracture.6–10 The studies comparing mortality between different treatment modalities failed to show a significant difference between operative and nonoperative treatment.7,10 Advancing age, male sex, higher mechanism of injury, complex fracture patterns, and sarcopenia have been associated with higher 1-year mortality in geriatric patients with acetabular fractures.7,11,12
Time to surgical intervention has proven a significant factor in predicting mortality in geriatric patients with hip fractures.7,13 Surgical intervention for hip fractures in the elderly is generally recommended within 48 hours of injury. A similar reduction in mortality with early operative intervention has been reported for geriatric distal femur fractures.14 To the best of our knowledge, the relationship between time to surgery and mortality in geriatric patients with acetabular fractures has not yet been investigated. The purpose of our study is to compare mortality rates between geriatric patients with acetabular fractures operatively treated within 48 hours of injury and those treated after 48 hours.
PATIENTS AND METHODS
Institutional review board approval was obtained for retrospective evaluation of a prospectively collected acetabular fracture database. The database included patients treated by 3 fellowship-trained trauma surgeons at a university level I trauma center from 2002 to 2017. Eighty percent of fractures were treated by one surgeon. Inclusion criteria consisted of all patients 65 years or older operatively treated for an acetabular fracture. Patients treated nonoperatively were excluded. Indications for fixation included significant fracture displacement, unstable fracture pattern, and physiologic stability of the patient to undergo surgical treatment. The data extracted from the database included patient age at the time of surgery, sex, date of injury, mechanism of injury, fracture classification, date of surgery, estimated blood loss (EBL), comorbidities, length of hospital stay, presence of postoperative deep vein thrombosis, quality of reduction, and date of death. Fractures were classified by the operating surgeon according to the OTA/AO and Letournel–Judet systems.15 Patient comorbidities were quantified using the Charlson comorbidity index (CCI), which is a validated health measure based on a patient's medical history.16 Quality of reduction was assessed using standard postoperative radiographs (anteroposterior and Judet views). The quality was determined by measuring the maximum articular displacement of the weight-bearing dome of the acetabulum, where displacement less than 1 mm was considered to be an anatomic reduction, a displacement between 1 and 3 mm was considered to be an imperfect reduction, and a displacement of greater than 3 mm was considered to be a poor reduction.17 The primary outcome measure was mortality, and the electronic medical record and an obituary search engine were used to determine the 30-day, 6-month, and 1-year mortality.
For initial univariate analysis, patients were placed into two groups: those operatively treated within 48 hours and those treated after 48 hours. This time frame was chosen based on the current recommendation for hip fractures. We performed an additional analysis at 72 hours, taking into consideration the fact that the fixation of acetabular fractures requires the expertise of a subspecialist, and operative intervention on an urgent basis is often not feasible. This additional time frame was chosen because the median number of days to surgery in our institution's full acetabular fracture database was 3 days.
T tests and 1-way analysis of variance were used to compare continuous variables between groups. Chi-square and Fisher exact tests were used to compare categorical variables. To determine the relationship of the individual variables to mortality, a Cox proportional hazards model was used. For simplification of the model, binary categories were developed for the categorical variables. Fracture classifications were grouped as elementary or associated based on the Letournel–Judet system, and mechanisms of injury were grouped as high energy or low energy. Univariate and multivariate cox regressions were performed. All statistics were performed using R software. A P value less than 0.05 was considered significant. A power analysis was performed for the primary outcome of mortality, which determined that 82 subjects were needed to achieve 80% power for a χ2 test of association with medium effect size.
A total of 250 patients 65 years of age and older were treated for acetabular fractures at our institution (Figs. 1–3). One hundred eighty-three patients were treated operatively and thus met inclusion criteria for our study. One hundred twenty-one (66%) patients were men, and 62 (34%) were women (Table 1). The average age at time of surgery was 76 ± 8.5 (range 65–98) years. The overall 1-year morality was 15%. The most common mechanism of injury was a low fall (n = 102, 56%). The remaining injuries were sustained by high-energy mechanisms, most commonly motor vehicle accident (n = 50, 27%). By the Judet–Letournel classification system, 34 (23%) of fractures were elementary and 140 (77%) were associated. The most common fracture pattern was anterior column posterior hemitransverse (n = 78, 43%), followed by both column (n = 27, 15%).
Forty-eight (26%) patients were treated within 48 hours, and 135 (74%) were treated after 48 hours. When patients were grouped by time to surgery (fracture fixation within 48 hours or after 48 hours), we found no statistically significant differences in age, sex, mechanism of injury, fracture pattern, presence of concomitant pelvic ring injury, CCI, EBL, length of hospital stay, presence of deep vein thrombosis, or quality of reduction. Thirty-day mortality was higher in the group treated within 48 hours (n = 5, 10%) than the group treated after 48 hours (n = 5, 4%), but this difference was not statistically significant (P = 0.13). We found no statistically significant differences in 6-month or 1-year mortality between groups (P = 0.37 and P = 0.84, respectively). When patients were grouped by fracture fixation within 72 hours or after 72 hours, differences in 30-day, 6-month, and 1-year mortality were not statistically significant (Table 2).
The multivariate Cox regression model of survival demonstrated no difference in mortality between patients treated within 48 hours and those treated after 48 hours (see Table, Supplemental Digital Content 1, http://links.lww.com/JOT/A957). Increasing age was associated with a significantly increased hazard of death with a hazard ratio of 1.09 (95% confidence interval, 1.05–1.13) per year of age (P < 0.001). Patient sex, mechanism of injury, fracture pattern, EBL, and CCI were not significant predictors of mortality. When a multivariate Cox regression model of survival was used to compare mortality between patients treated within 72 hours and those treated after 72 hours, the difference was not statistically significant (P = 0.85).
Increased time to surgery has been associated with higher mortality in geriatric patients who have sustained proximal femur fractures.18,19 Recently, this association has also been reported for geriatric patients with distal femur fractures.14 As the population ages and more patients suffer fragility fractures with high risk of morbidity and mortality, determining the optimal time to surgery is increasingly important. In our study, we did not find a significant difference in the 30-day, 6-month, or 1-year mortality between geriatric patients treated within 48 hours for acetabular fractures and those treated after 48 hours.
In the current study, increasing age was independently associated with higher mortality. This result is not surprising as advanced age carries greater risk of morbidity and mortality after surgical procedures.20 Gary et al7 came to a similar conclusion in a retrospective analysis of 454 geriatric patients treated for acetabular fractures. However, Gary et al additionally found that male sex, greater CCI, high energy mechanism of injury, and associated fracture patterns were predictors of higher mortality, which differs from our results. In our study, patient sex, CCI, mechanism of injury, and fracture pattern were not significantly associated with mortality. A possible explanation for this difference may be that our study group was restricted to operatively treated patients, who likely represent a more homogenous patient population. Gary et al noted significant differences in age, length of hospital stay, injury severity scores, and CCI between their operative and nonoperative groups.
The overall 1-year mortality rate in our study population was 15%. This rate was slightly lower than those previously reported for geriatric acetabular fractures, which range from 16% to 33%.6–10 The reason for the lower mortality rate is unclear. Although the previous studies included patients treated nonoperatively, no studies have shown significant differences in mortality based on modality of treatment for acetabular fractures.7,9,10 Walley et al,10 in a retrospective review of 243 geriatric acetabular fractures, reported a higher mortality rate in nonoperatively treated patients (22%) when compared with those operatively treated (19%). This difference was not statistically significant. Gary et al7 similarly reported a higher mortality rate for their nonoperatively treated patients, but, when adjusted for cofounders such as age, sex, mechanism, and CCI, the difference was likewise not statistically significant.
In the current study, no significant difference in mortality was found between patients treated within 48 hours and those treated after 48 hours. This finding differs from what has been reported for geriatric proximal femur fractures. In elderly patients with proximal femur fractures, a benefit to prompt surgical intervention is early mobilization and prevention of the life-threatening complications associated with bed rest.4 By contrast, patients treated for acetabular fractures are generally placed on a restricted weight-bearing protocol after surgery. Even if they are allowed to weight bear as tolerated, they are often incapable of doing so. Therefore, time to surgery may be less important in geriatric patients with acetabular fractures because postoperative mobility may be limited regardless of fixation status.
Although our study was unable to show an apparent benefit to mortality with early fixation of acetabular fractures, previous studies have demonstrated improved outcomes in other areas with early reduction of acetabular fractures. Quality of anatomic reduction has been reported superior in patients with early operative intervention.17,21 The quality of anatomic reduction is important as it has been linked to an increased likelihood of achieving good functional outcome.17,22 Although poorer reduction has been associated with increased age, elderly patients have been observed to better tolerate malreduction than younger patients.17,21,23 In our study, there was no significant difference in quality of reduction between patients treated within 48 hours and those treated after 48 hours. This finding may have been due to the fact that achieving an anatomic reduction is more difficult in elderly patients. Accordingly, the overall rate of anatomic reduction (77%) was lower in this patient cohort than the rate previously reported for a larger patient cohort at our institution (85%).21 Therefore, age may have played a larger role than time to intervention.
Time to operative fixation of acetabular fractures is dependent on multiple factors. As fixation of acetabular fractures usually requires the expertise of an orthopaedic trauma specialist, such a surgeon may not always be immediately available. In addition, medical optimization is important, especially in an elderly population in which patients often have multiple comorbidities. Patients involved in higher energy mechanisms of injury may have additional injuries that require prioritized treatment. Despite the apparent benefits to early treatment of proximal femur fractures, the results of our study suggest that quicker time to surgical intervention is not associated with decreased mortality rates in geriatric acetabular fractures.
This study is not without limitations. Fortunately, the major limitation to this study is that our institution did not have a large enough number of patient deaths in the observed time-frame to be adequately powered for the Cox regression model. To detect a hazard ratio of 2 at 80% power for the 1-year mortality time point would have required 130 patient deaths which did not occur at our institution over the study period. Another limitation to our study was the possibility that a patient's death was not captured in the electronic medical record or in an obituary search engine. To address this limitation, the electronic medical record was used to confirm if a patient had survived longer than a year by finding records of clinic visits, emergency room visits, or hospitalizations for dates following 1 year after surgery. In addition, we were unable to determine the medical optimization status of the patients, which likely played a role in the time to surgery. Evaluating the extent of medical optimization achieved before surgery would have been helpful in determining its significance on mortality. We also did not report functional outcomes. As preoperative ambulation status was not well documented, postoperative functional outcomes would be difficult to interpret in this elderly population. Finally, we did not report on the presence or absence of sarcopenia in the patients of our study. Such information would have been useful to include in our analysis as sarcopenia has recently been reported to be associated with increased mortality in elderly patients with acetabular fractures.11 The presence or absence of sarcopenia could therefore have potentially acted as a cofounding factor.
In contrast to the decreased mortality associated with early surgical intervention in geriatric patients with proximal femur fractures, the results of our study suggest that surgical intervention after 48 hours of injury is not associated with increased mortality rates in geriatric patients with acetabular fractures. However, the study was underpowered to prove a lack of association. Increased mortality was independently associated with advancing age. Sex, mechanism of injury, and facture pattern were not associated with mortality. Time to surgery in geriatric patients with acetabular fractures should be determined on an individual basis.
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