Mortality, complications and long-term functional outcome in elderly patients with fragility fractures of the acetabulum

Over the past decades andwith an ageing population, fragility fractures of the acetabulum have become more common and thus a greater concern [1].

A nationwide study covering the population of Finland, reported an increase by 30% in the incidence of acetabular fractures in individuals aged older than 65 within the past 20 years, with the incidence now being 23/100,000 per year [2]. Ferguson et al. even found a more than twofold increase amongst North American patients beyond the age of 60 within a similar time period [3].

Whereas the main mechanism of injury for younger patients is high-energy-trauma, the majority of acetabular fractures in the elderly are a result of a fall from standing height [2‐5].

Like in geriatric fractures of the hip, the very similar impact of acetabular fractures on walking ability has the potential of high morbidity and mortality due to immobilization and complications associated with bedrest.

The treatment of displaced acetabular fractures in younger patients usually consists of open reduction and internal fixation, but since most of the elderly patients present with various comorbidities and decreased bone quality, an individualized treatment approach is necessary. Furthermore, patients of greater age are in need of early mobilization with regard to these comorbidities, and usually cannot follow partial weight-bearing protocols [6]. Treatment may vary from non-operative treatment, open reduction and internal fixation, minimally invasive percutaneous screw fixation to even primary total arthroplasty of the hip [7, 8].

It has been suggested, that operative treatment of these fractures may reduce pain, allow for earlier mobilization and shorter hospitalization time, thus leading to less associated complications [8, 9]. In contrast, as suggested by a smaller cohort study, operative treatment may also lead to more conversions to total hip arthroplasty [10].

It remains unclear, whether these potential short-term benefits also translate into better functional outcome and a lower mortality rate and would accordingly justify the perioperative risks of a surgical intervention.

The aim of this study was therefore to assess mid- to long-term mortality and functional outcome after geriatric acetabular fractures and to compare the outcome after surgical and conservative treatment in elderly patients.

One hundred seventy-six patients (n = 176; mean age 78, SD 10 years; 73 female) were available for final analysis of mortality data (Fig. 1). Of those who had survived at the time of data acquisition (n = 77), 47 patients were available for functional outcome assessment. Mean ASA-Score (American Society of Anesthesiologists Scale) was 2.8 ± 0.5. Patients who were treated non-operatively were more likely to have an ASA score > 2 (56/67, 83.6%) when compared to patients who were treated operatively (75/109, 68.8%, p = .03).

In 15 patients, the acetabular fracture occurred in the presence of a total hip implant in terms of a periprosthetic fracture. Of the remaining 161 patients with fractures of the native acetabulum, 67/161 patients (41.6%) were treated non-operatively, 10 patients (6.2%) by percutaneous fixation, 82 patients by open fixation (Fig. 2), and two patients (1.1%) received THA as primary treatment.

At the time of final follow up (68 months, SD 26, range, 24 to 129), 99/176 patients (56.3%) had deceased. Forty-four patients deceased during the first year after the hospitalization (1-year-mortality: 25%) and 2-year mortality was 35.8% (63/176 patients). The type of treatment (non-operative vs. operative) did not affect mortality at 1 and 2 years (p = .65 and p = .10, Table 1).

Complications during the hospitalization occurred in 41/176 patients (23.2%). Hospital-acquired infections like surgical-site infections, pneumonia and urinary tract infections were observed in 31/176 cases (17.6%), thromboembolic events and a delirium were documented each in 6 patients (3.4%). Ten patients (5.7%) died during prolonged hospitalizations secondary to pneumonia (n = 4), pulmonary embolism (n = 3), myocardial infarction (n = 1), and delirium (n = 1). Patients who underwent operative treatment were more likely to have an in-hospital infection (p = .02) but less likely to sustain thromboembolic events (p = .03, Table 1).

The mean duration of the hospitalization was 14 days (SD 10 days, range, 1 to 66). Prior to the acetabulum fracture, 143/176 patients (81.3) had lived at home (43 with home care). After the fracture, only 93 (65.0%) of these 143 patients were able to eventually return to their homes (31 with home care). Patients with operative treatment stayed longer in the hospital than patients with non-operative treatment (p < .001, Table 1).

The mean modified Merle d’Aubigné Score of those patients who had survived and were available for a final follow-up by phone (n = 47; follow-up 56 months, SD 28, range, 24 to 115) was 14/18 points, SD 3, range 7 to 18). Functional results at final follow-up were not different between survivors who had been treated operatively and non-operatively (Table 2).

The aim of this study was to evaluate mortality and functional outcome of patients with geriatric fracture of the acetabulum, more than 2 years after treatment.

It was shown, that in this cohort of geriatric patients with fragility fractures of the acetabulum, all-cause mortality and in-hospital complications were high, regardless whether the patients underwent non-operative or operative treatment. While operatively treated patients were more susceptible to infection, thromboembolic events occurred more often in the non-operatively treated group. The conversion-rate to secondary total hip arthroplasty was 12.4%, with no significant difference between the groups. Patients surviving until final follow-up showed fair functional outcome and no difference between operative versus non-operative treatment occurred. We found no differences between the operative and the non-operative group in regards to all-cause 1-year-mortality. This finding is consistent with a previous studies that conclude that there is no difference in 1-year mortality between operative and non-operative management, once comorbidities are taken into account [4, 10].

Existing literature states 1-year mortality rates of 16 to 35% for non-operative treatment [10, 12‐14] and of 4 to 21% for operative treatment [10, 12, 13]. Reasons for the higher mortality in the present study include the fact that a follow-up of 100% was achieved for mortality data by the use of the national social insurance database. In addition, only patients with a low-energy trauma were included. Patients older than 60 years of age with acetabular fracture as a result of high energy accidents are possibly in a better state of general health and live a more active lifestyle, than patients whose acetabular fracture is a result of same level falling and thus a representation of comorbidity.

The average duration of hospital stay was long (14 days, SD 10 days), compared to other studies that state a median hospitalisation of 8 to 11 days [10, 14, 15].Operatively treated patients had a longer average hospitalisation time, which is consistent with the findings of one previous publication on this topic [15].

The 47 patients that had survived until final follow up in the present study showed a fair functional outcome and no difference between operatively and non-operatively treated patients. While there seems to be consensus that good functional outcomes can be achieved by operative treatment of acetabular fractures in the elderly [12, 16‐18], there is little data available on functional outcome after non-operative treatment. A recent retrospective case series of elderly patients with acetabular fractures that met criteria for surgery found that these patients can have good functional outcome also with non-operative treatment [14].

Secondary conversion rate to THA was 12.4% in the whole cohort and there was no significant difference between the operative and the non-operative group. Secondary conversion rates to THA have been reported to range from 10 to 37% [16] for patients in this age group when treated by open reduction and internal fixation and 15% when treated non-operatively [14]. A recent registry analysis of 678 acetabular fractures among all age groups reported that 19.8% of the patients required secondary THA [19]. Hence, the conversion rates found in our cohort are comparable to what is found in the literature.

The limitations of this study are inherent with its retrospective design. Therefore, selection bias for operative treatment is possible, since fractures with a less complex morphology were more likely to be assigned to non-operative treatment. Patients in the non-operative group had a higher ASA-Score, illustrating that these patients were in a worse state of general health and less amenable for both, primary and secondary operative interventions. No physical follow-up examinations were performed for functional outcome assessment. However, conducting follow-up interviews by phone enabled us to also assess patients, that were not able to leave their homes or nursing facilities and otherwise could not have been included. Still, we were able to only assess the functional outcome of 47 of 77 surviving patients resulting in a loss to follow-up of 39%. This comes with no surprise with regard to the geriatric population of this study and a follow-up interval of up to 10 years (129 months). Functional outcome was assessed mean 68 months after the trauma and in a small sample of patients who had mainly been treated operatively. This may provide a selection bias towards patients with better function resulting in better survival.

In conclusion, mortality and in-hospital complications remain high among geriatric patients with low-energy fractures of the acetabulum even when treated operatively. Secondary conversion rates to THA are similar to those seen in younger patients. Mid-term functional outcome in those surviving is fair.

Treatment decisions for these fractures in the elderly depend on multiple factors and can only be done individualized. The findings of this study may help surgeons in the decision-making and management of acetabular fractures after low-energy trauma in geriatric patients. The knowledge about the high rate of mortality and complications may guide surgeons towards non-operative treatment in very old patients with serious comorbidities. It may also be that selected elderly patients with acetabular fractures would benefit from primary THA as this usually allows for earlier mobilisation with full-weight bearing. Future prospective studies with larger cohorts need to further investigate the potential benefits of these different therapeutic strategies.

All-cause mortality and in-hospital complications remain high among geriatric patients with low-energy fractures of the acetabulum even when treated operatively. Secondary conversion rates to THA are similar to those seen in younger patients. Mid-term functional outcome in those surviving is fair.