Hip fracture stands out as a predominant traumatic disease among the elderly, attributable to aging, bone degeneration, and accidental fall. With the accelerated pace of global aging, the incidence of hip fracture has surged, emerging as a global health concern (1, 2). China faces an impending “aging tsunami” mirroring global trends (3). Notably, the majority of hip fracture cases in urban China were found to affect individuals aged 75 years and older, with those aged 85 years and older representing 11.5% of the total cases (4). The aftermath of hip fracture is profound, often leading to post-fracture disabilities and alarmingly high 1-year mortality rates ranging from 20 to 30%, rendering it a devastating event for the elderly population (5, 6).

Elderly hip fracture patients frequently encounter a variety of postoperative complications. These may include pneumonia, hypotension, gastrointestinal hemorrhage, stroke, acute renal failure (7, 8), and, in severe cases, potentially life-threatening multiple organ dysfunction syndrome (MODS). There is no doubt that the vulnerability of elderly patients with hip fracture has significantly lowered the threshold for developing MODS. Chinese scholars have formulated diagnostic criteria for multiple organ dysfunction in the elderly (MODSE) based on the characteristics of elderly patients (Supplementary Table S1) (9, 10). Unlike the organ dysfunction scoring systems typically employed in intensive care unit (such as Sequential Organ Failure Assessment, Logistic Organ Dysfunction System, and Multiple Organ Dysfunction Score) (11), the MODSE diagnostic criteria include a broader range of organs or systems and their corresponding indicators. Furthermore, within these diagnostic criteria, organ dysfunction is classified into stages of pre-failure and failure. This could facilitate early detection of organ dysfunction in vulnerable patients after experiencing a hip fracture. Nonetheless, there has been no systematic research specifically investigating MODSE following hip fracture.

Our hypothesis is that elderly patients with hip fracture are at high risk of developing MODSE, and that the presence of MODSE during hospitalization may be associated with long-term prognosis. The aim of this study was to investigate the risk factors and outcomes of MODSE following hip fracture surgery in patients aged 80 years and older.

In our study, all 252 patients underwent surgical treatment for hip fractures, including 107 femoral neck fractures treated with hip arthroplasty via the posterolateral approach (13 hemi-arthroplasties and 94 total hip arthroplasties) and 145 intertrochanteric fractures treated with proximal femoral nail fixation (114 standard intramedullary nails and 31 extended nails). There was no difference in the constituent ratio of surgical methods between the two groups (p = 0.054).

Early surgical treatment is a standard practice in hip fracture management, yet there’s insufficient evidence on perioperative care (22). Postoperative risk factors logically have a greater impact on 30-day outcomes compared to preoperative factors (23). The majority of deaths within 30 days following hip fracture occurred in the hospital, predominantly within the first 10 days of admission (24). Our cohort study focused on prevalent systemic complications that occur following surgery. Specifically, we aimed to identify postoperative MODSE as a composite adverse outcome during hospitalization and determine its significance as the primary exposure factor for long-term mortality. MODSE entails dysfunction across eight organs or systems and is defined by clear diagnostic criteria (Supplementary Table S1) (9, 10). Besides rare or local complications, the diagnostic criteria for MODSE cover the majority of systemic complications typically observed following hip fracture surgery. Among our study population, MODSE incidence was 26.6% (67 out of 252), with 85.1% (57 out of 67) categorized as pre-failure cases, suggesting a relatively low threshold for diagnosing MODSE. Notably, mild or early organ function impairment is common in these patients, underscoring the need for early warning and multidisciplinary interventions. Distinct differences in clinical characteristics were observed between patients with and without MODSE throughout the hospitalization period. Patients with MODSE tended to be older, with a higher proportion experiencing intertrochanteric fracture and exhibiting significantly elevated aCCI. Moreover, they demonstrated lower Barthel Index and greater swallowing impairment. On the day of surgery, patients with MODSE received higher volumes of fluids, while their hourly urine output markedly decreased. Subsequently, laboratory results obtained on the first postoperative day revealed signs of multiple organ damage in these patients. The above findings show that systemic pathophysiological changes following hip fracture and/or surgery in the elderly may involve ongoing processes affecting multiple organs or systems. These changes can manifest as either acute dysfunction or exacerbations of pre-existing chronic organ impairments.

The multivariate analysis revealed that the aCCI, impaired swallowing, and early postoperative APACHE II scores synergistically delineate a pathological continuum from chronic vulnerability to acute multi-organ dysfunction in elderly hip fracture patients. Elevated aCCI scores, reflecting pre-existing multimorbidity and diminished physiological reserve, establish a baseline susceptibility to systemic decompensation. In our study, this susceptibility is further substantiated by its direct correlation with MODSE and alignment with prior research demonstrating associations between comorbidities, skeletal complications, and increased mortality risk (25–27). This chronic frailty is exacerbated by acute physiological insults captured through APACHE II scoring within 24 h post-surgery, which not only quantifies immediate postoperative instability but also aligns with emerging evidence of its prognostic utility in optimizing surgical timing and complication mitigation (28). Impaired swallowing, a prevalent issue among frail elderly individuals, may serve as a critical nexus linking these domains: it significantly heightens the risk of aspiration, malnutrition (29), and pulmonary interleukin-6 mediated inflammatory cascades (30, 31), potentially escalating localized respiratory compromise into systemic cytokine storm syndromes. From a clinical perspective, incorporating APACHE II scoring alongside dysphagia screening within the first 24 h postoperatively could provide a strategic approach for early identification of high-risk patients.

Our model identifies PCT, PT and hs-cTnT as independent predictors, reflecting the trauma-induced nexus of inflammatory, coagulopathic (32, 33), and cardiovascular cascades that drive multi-organ dysfunction. Elevated PCT levels (>0.25 μg/L) on the first postoperative day, even below conventional sepsis thresholds, signify subclinical inflammation capable of triggering organ dysfunction, consistent with evidence that minor PCT rises (>0.39 μg/L) predict mortality in orthopedic cohorts (34). Concurrently, PT abnormalities revealed a dual thrombotic-hemorrhagic tendency, likely driven by fracture-induced tissue factor release (35), preoperative polypharmacy, and vitamin K deficiency (36, 37). Crucially, extending our prior finding that admission hs-cTnT predicts MODSE risk (38), this study demonstrates that postoperative Day 1 hs-cTnT elevation retains prognostic significance. These findings highlight the importance of early postoperative biomarker monitoring, even within subcritical ranges, to guide timely preemptive interventions.

The progression from hip fracture to death often involves the development of vital organ failure, particularly evident in patients who experience early mortality post-fracture. In this study, patients who progressed to the MODSE failure stage exhibited a 30-day mortality rate of up to 50%. Postoperative MODSE was also significantly associated with long-term mortality. The 1-year mortality rate following hip fracture in mainland China is lower than in many other countries (12). Our study demonstrated a more favorable 1-year mortality rate of 11.1%. Even so, developing MODSE post-hip fracture surgery substantially increased both 1-year and 2-year mortality rates by 3.13-fold and 2.88-fold, respectively. Prior studies have shown that frail elderly individuals with hip fractures, managed non-surgically, face significantly heightened long-term mortality due to complications across multiple organs or systems (39, 40). Consequently, whether treated surgically or not, the high 30-day and long-term mortality rates associated with hip fracture can be primarily linked to organ dysfunction. Perioperative management of hip fracture in the elderly prioritizes the preservation of vital organ function, with early restoration of limb function aimed at averting organ failure and mortality.

The study has several limitations. Firstly, in this study, we strictly followed the published diagnostic standards of MODSE (Supplementary Table S1) to divide patients into two groups. All research team members received unified training before study beginning, and used same case report forms to ensure the criteria applied consistently. But we deeply realize that external validation is still lacking, this is because our current research mainly focused on clinical application. Moreover, the factors contributing to poor outcomes after hip fracture surgery are multifaceted and complex, certain variables that potentially influence postoperative MODSE may still have been omitted. Second, this research is a single-center observational study with a limited sample size, which inevitably introduces potential biases. Finally, due to some patients passing away at home rather than in a medical facility, their families were unable to provide an accurate cause of death. Consequently, further analysis regarding the cause of death could not be conducted in this study.

The occurrence of postoperative MODSE in elderly patients with hip fracture is not uncommon. Accurate prediction of MODSE is crucial and feasible because it not only represents a poor outcome during hospitalization but also correlates with prolonged hospital stay, increased 30-day mortality rates following surgery, as well as higher mortality rates at 1 and 2 years after discharge.