1 Introduction

Acetabular fractures are complex injuries that often result from high-energy trauma, such as motor vehicle collisions (MVC) or falls from height.^1,2 In older adults, however, low-energy mechanisms like ground-level falls can result in significant injury due to decreased bone quality.^1–3 These injuries occur at an estimated incidence of 3 per 100,000 individuals annually.⁴ Surgical fixation is frequently required to restore anatomic alignment and preserve function, but the procedure carries a risk of complications.⁵ Infection and unplanned reoperation, including conversion to total hip arthroplasty (THA), are among the most common adverse events and may impact recovery and long-term outcomes.^6–12

The long-term impact of postoperative complications on patient-reported outcomes remains poorly defined in orthopaedic trauma. Patient-Reported Outcomes Measurement Information System (PROMIS) scores are a validated way to assess recovery from the patient's perspective, including measures such as physical function, pain interferences, and mental health.^13,14 Although PROMIS measures have been widely applied in orthopaedics, limited data exists on their application in trauma patients, particularly those with pelvic and/or acetabular injuries.^15–20

This study aims to determine whether complications following surgical fixation of acetabular fractures are associated with worse PROMIS outcomes at six months postoperatively. We hypothesized that patients who experience postoperative complications will report significantly worse patient-reported outcomes compared to those without complications.

2 Methods

3 Results

Of 456 patients who underwent operative fixation of acetabular fractures during the study period, 109 patients completed postoperative surveys and were included in the analysis. Baseline patient demographics and comorbidities are presented in Table 1. The mean age of this cohort was 50.6 years (range: 16–91 years), and 64.2 % were male (Table 1). The mean follow-up duration was 218.7 days (range, 180–1106 days). The majority of patients identified as White (60.6 %), followed by Black (36.7 %). The average BMI was 30.3 kg/m² (range: 18.3–58.1 kg/m²) (Table 1). Hypertension was documented in 34.9 % of patients and diabetes in 11.0 %. Tobacco use was reported by 29.4 % of patients, and 27.5 % reported alcohol use. Most patients were classified as ASA III (65.1 %) (Table 1). When stratified by complication status, there were no statistically significant differences in baseline characteristics or comorbidities (Table 1).

Injury characteristics are summarized in Table 2. High-energy trauma was the predominant mechanism of injury, with motor vehicle collisions accounting for 60.6 % of cases. Polytrauma was present in 34.9 % of patients, and 45.0 % had associated hip dislocations. The most frequently encountered fracture patterns were transverse plus posterior wall (25.7 %), posterior wall (24.8 %), and anterior column/posterior hemitransverse (17.4 %) (Table 2). Overall, 61.6 % of fractures were classified as complex patterns. When stratified by complication status, patients who developed postoperative complications were significantly more likely to present with an associated dislocation compared to those without complications (63.6 % vs. 40.2 %, p = 0.049) (Table 2).

Surgical characteristics are shown in Table 3. The Kocher-Langenbeck approach was used most commonly (55.9 %) (Table 3). Staged fixation was performed in 9.2 % of cases. The mean operative time was 145.7 min (range: 19–981 min), and the average estimated blood loss was 443.6 mL (Table 3). Intraoperative blood transfusion was required in 18.3 % of patients, and tranexamic acid was administered in 44.0 % of cases (Table 3). When stratified by postoperative complication status, there were no statistically significant differences in surgical characteristics between the two groups (Table 3).

Postoperative complications are detailed in Table 4. Over the course of follow-up, 22 patients (20.2 %) experienced at least one complication. The most common was conversion to THA, which occurred in 13 patients (11.9 %) (Table 4). The average time to THA was 256.2 days (range: 95–595 days). Six patients (5.5 %) developed FRI, four patients (3.7 %) developed heterotopic ossification (Brooker III-IV), and two patients (1.8 %) experienced venous thromboembolism (Table 4).

When stratified by postoperative complication status (Table 5), patients who experienced any complication reported significantly worse patient-reported outcome scores at 6 months compared to those without complications, including lower PF (31.9 vs 40.2, p = 0.002), GPH (35.2 vs 42.8, p = 0.002), and GMH (39.5 vs. 45.8, p = 0.021). They also reported higher PI (65.1 vs 59.2, p = 0.016) (Table 5).

When stratified by FRI status (Table 6), patients with postoperative FRI had significantly worse PF scores compared to those without FRI (28.8 vs 39.2, p = 0.021). Differences in other PROMIS measures, percent of normal, and BRS scores did not reach statistical significance (Table 6).

Patients who required conversion to THA (Table 7) demonstrated significantly lower PROMIS PF (31.4 vs 39.5, p = 0.020) and GPH (34.4 vs 42.3, p = 0.007) compared to patients who did not require THA (Table 7). Differences in other measures were not statistically significant (Table 7).

One-year patient-reported outcomes are shown in Table 8. At one year, patients with complications continued to report lower patient-reported outcome scores across all domains; however, none of these differences reached statistical significance (Table 8).

4 Discussion

In this retrospective cohort study, postoperative complications following surgical fixation of acetabular fractures were associated with significantly lower patient-reported outcomes at 6 months, as measured by PROMIS, BRS, and percent of normal function. Patients with postoperative complications reported lower PROMIS PF, GPH, and GMH scores, along with greater pain interference. Notably, both postoperative FRI and conversion to THA were associated with significantly reduced physical function, while conversion to THA was also associated with lower global physical health at the 6-month time point. These differences, while still present at one year, did not reach statistical significance, suggesting that early complications may have a more pronounced effect on short-term outcomes.

These findings were consistent with prior studies demonstrating that postoperative complications, such as infection and reoperation, can negatively impact functional outcomes after pelvic and acetabular surgery.^12,32 In contrast to other studies that primarily focused on radiographic or clinical measures, the current study utilized PROMIS, a validated, patient-centered metric that captures both physical and mental health outcomes. This is particularly relevant in orthopaedic trauma populations, where recovery can vary widely and may not be fully reflected by imaging or objective tests alone.³³

In this cohort, there was an 11.9 % rate of conversion to THA, a rate that is consistent with current literature (5.7–17.8 %).^{2,6,12,32,34–36} Patients who required conversion to THA demonstrated significantly lower PF and GPH scores compared to those who did not. It is important to note that, although this conversion rate aligns with reported literature, patient-reported outcomes were assessed only at 6 months, which may not fully capture the long-term impact of conversion to THA on patient-reported outcomes.

Patients who developed postoperative FRI in this cohort reported significantly lower physical function. This aligns with broader trends observed in orthopedic trauma, where FRI has been associated with poorer functional recovery and quality of life, and may contribute to lasting deficits and greater hospitalization burden.^37,38 The observed rate of FRI (5.5 %) in the current study is slightly higher than, but overall comparable to, rates reported in the literature (3.5–5.0 %),^39–41 underscoring the importance of ongoing efforts in prevention, early recognition, and management of this complication.

While differences in patient-reported outcomes were significant at 6 months, these differences were no longer statistically significant at 1 year. This may suggest a degree of functional recovery over time, or it may reflect a smaller sample of patients with 1-year data, limiting the ability to detect differences. Houwen et al. reported that PROMIS PF and PI were most impaired shortly after fracture, but continued to improve over the first year in both upper and lower extremity injuries, suggesting a broader trend of early deficits and gradual recovery over time.⁴²

While several patient-reported outcome domains demonstrated statistically significant differences between patients with and without complications, it is also important to consider whether these differences meet the threshold for minimal clinically importance difference (MCID), which varies widely depending on calculation method and patient population. Thorne et al. established MCID thresholds for patients with acetabular and pelvic fractures, reporting distribution-based and anchor-based MCIDs for PROMIS physical function (5.19–7.18), pain interference (3.97–8.03), anxiety (4.33–5.85), and depression (4.41–5.00) scores.¹⁴ In this cohort, differences in PF (8.3 points), GPH (7.6 points), and GMH (6.3 points) exceeded these thresholds, suggesting that the observed differences in scores are both statistically and clinically significant. Although some differences, such as PI and BRS, did not consistently exceed MCID thresholds, the trends support the overall conclusion that early postoperative complications may lead to meaningful decrements in recovery at the six-month time point.

This study provided insight into the impact of early complications on patient-perceived recovery at six months following acetabular fracture fixation. By using PROMIS, differences across multiple domains of patients' perceived health were captured that might not have been identified with traditional outcome measures.

5 Conclusion

Postoperative complications, including FRI and conversion to THA, were associated with significantly lower patient-reported outcomes at six months following acetabular fracture fixation. These findings were still present at the one-year timepoint, though were not statistically significant. Overall, PROMIS represents a viable option for tracking recovery, guiding patient-centered care, and setting expectations for both clinicians and patients.

JOO ethical statement - ethical approval

This study was conducted in accordance with the ethical standards of the institutional and national research committees and with the 1964 Declaration of Helsinki and its later amendments. Institutional Review Board approval was obtained from the University of Alabama at Birmingham (IRB # 300008798). Given the retrospective design of the study, informed consent was waived. All patient data were de-identified prior to analysis to ensure privacy and confidentiality.

Guardian/patient's consent

JOO Patient Consent.

This study was approved by the University of Alabama at Birmingham Institutional Review Board (IRB #300008798). The requirement for informed consent was waived due to the retrospective nature of the study and the use of de-identified data.

CRediT author statement

Mary Jane McConnell: Data curation, Formal analysis, Writing = Original draft preparation.

Robin M. Litten: Data curation, Formal analysis, Visualization, Writing = Review and Editing.

Humza S. Bhatti: Data curation, Writing = Review and Editing.

Ryan N. McIlwain: Data curation, Writing = Review and Editing.

Decorian D. North: Methodology, Supervision, Writing = Review and Editing.

Clay A. Spitler: Conceptualization, Methodology, Supervision, Writing = Review and Editing.

Joey P. Johnson: Conceptualization, Methodology, Supervision, Project administration, Writing = Review and Editing.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.