Frailty is a state of vulnerability associated with aging, physiological decline, and depleted reserves. Frail people have impaired homoeostasis. As such, a relatively minor stressor event (such as a fall from a standing height) brings with it a disproportionately high risk of adverse outcomes including disability, prolonged hospitalization, and mortality.

In musculoskeletal medicine, the term “frailty” calls to mind osteoporosis and weakening of the bones, Additionally, there is loss of muscle mass (so-called sarcopenia), and with that, muscle weakness and impaired exercise tolerance. Nonetheless, even within musculoskeletal medicine, frailty is best understood as a whole-person concept, incorporating not only senescence of the musculoskeletal system, but declining endocrine, neurological, cardiovascular, immune and psychological function as well.

Because frailty increases with age, and because the world’s population is getting older, it is likely that the incidence of frailty-associated injuries will rise as well. To optimize outcomes if an injury is sustained despite efforts at prevention, it is important to recognize frailty, if present, and to choose treatments appropriate for a patient's fragile state.

Structure and Function

Patients with advanced age, co-morbidities, and disabilities are at increased risk for frailty. Nevertheless, frailty can exist independent of these factors, so physicians must remain vigilant to detect frailty in all patients. The hallmark of frailty is a physiologic decline in systems leading to decreased reserve. That is, frail patients may succumb to stressors that would not cause lasting effects in otherwise healthy, non-frail patients.

Structurally, musculoskeletal decline manifests as osteoporosis, or loss of healthy bone mass, and sarcopenia, or loss of muscle mass. Functionally, loss of muscle leads to poor balance, weakness and decreased endurance. These functional impairments increase the risk of falls, and are compounded by increased injury susceptibility to injury if a fall were sustained. As such, structural and functional deficits should be addressed to reduce patient risk.

In addition to its overt objective signs, frailty has psychological and social components that may further decrease patient resilience. Depression, social isolation, and poverty are psychosocial factors associated with frailty that may impair resistance to external stressors.

Patient Presentation

Frailty can be defined with two different models. The frail phenotype model defines frailty through observable physical characteristics while the frailty index model defines frailty based on the accumulation of functional deficits.

In In the frail phenotype model, frailty is diagnosed based on the presence or absence of five variables: unintentional weight loss, self-reported exhaustion, low energy expenditure, slow walking speed, and weakness (Table 1). Patients with three or more of these variables present are characterized with frail, and patients with one or two of these variables are considered “pre-frail”.

In the frailty index model, frailty is seen as a quantifiable property of multidimensional risks, rather than a binary state of “present” or “absent”. In this model, frailty is represented as a cumulative decline of function across multiple physiological systems.

To provide a compressive and reliable quantitation, a frailty index should consider many variables covering multiple organ systems and patient characteristics. These include reported symptoms, functional deficits, chronic diseases, and laboratory abnormalities. Each variable is considered as binary, either present or absent. The presence of a variable thereby indicates a discrete increase in the overall frailty metric. The frailty index is then calculated as the percent of variables which are present. Individuals above a certain, pre-established threshold are considered “frail”.

For example, consider a frailty index with 80 variables and a frailty threshold of 20%. A patient who has 20 variables present will have a frailty index of 25%. Such a patient is designated as frail because the threshold was crossed, but likewise, the severity of the frailty can be measured. Also, one can assess changes in the score over time, especially after injury or in response to treatment.

Because of the significant resources required to conduct the comprehensive evaluations an index demands, a preliminary assessment tool, such as the “Frailty Assessment Form” may be useful (Figure 1, Fairhall et al.). This form can help the clinician decide whether a more comprehensive frailty index assessment should be performed and may help identify the frailty phenotype.

Research is ongoing for the development and validation of trauma-specific frailty indices. This research aims to identify the most sensitive and specific variables that predict poor outcomes after trauma. At the least, a validated trauma specific frailty index may help identify those patients in need of particular attention, or to help guide the appropriate treatment after injury. Just as standard treatment approaches may not apply in the case of fractures caused by metastatic cancer, standard treatment approaches might need to be altered for frail patients as well. This requires, foremost, identifying frailty in the initial assessment.

Objective Evidence

Objective markers of frailty in the musculoskeletal system can be quantified with imaging modalities. Dual-energy X-ray absorptiometry scans can be used to track bone mineral density changes and diagnose osteopenia and osteoarthritis.

Although sarcopenia is typically first identified with a clinical muscle strength assessment, imaging with CT or MRI scans can confirm the diagnosis (Figure 2). Abdominal CT scan may be particularly useful for making the diagnosis of sarcopenia: decreased cross sectional area of the psoas major muscle at the L4-L5 intervertebral disc level as seen on CT correlates with increased need for dependent living support.

Epidemiology

Because of the strong correlation between aging and frailty, the aging of the world's population is expected to increase the incidence and prevalence of frailty. In 2004, there were approximately 461 million people older than 65 years; by 2025, there will be an estimated 2 billion people older than 65 years, with most of the growth in the cohort older than 80 years.

Globally, the reported prevalence of frailty rises from 4% for people 65-69 years of age to 26% for those older than 85 (Figure 3).

Frailty is also more common among biological females. The incidence of frailty in females is higher because they typically have less bone and muscle mass at baseline. Additionally, the prevalence of frailty in females is higher because females tend to live longer than males. In the United States, for example, approximately 75% of all people older than 90 years are female.

Data from an Australian trauma registry showed older patients accounted for one-third of all major trauma cases in 2010. The relative contribution of falls to major trauma cases increased from 46% in 1990 to 69% in 2010 (an average of 2.1% per year).

Treatment Options and Outcomes

When treating patients after acute trauma, consideration of frailty risk is paramount. Notably, higher scores on frailty indexes are independent predictors of in-hospital complications, increased likelihood of dependency upon discharge, and death. Despite the higher risk for adverse outcomes in frail patients overall, conscientious, frailty-informed care can limit the risks.

When treating frail patients in the acute trauma setting, appropriate fluid resuscitation and maintenance is critical. Frail patients require meticulous hemodynamic monitoring so that adequate resuscitation is achieved without volume overload. Similarly, pain management must be carefully and sparingly dosed, to avoid adverse effects of too much medication.

Because injured frail patients have lower physiologic reserves and are vulnerable to relatively minor physiological stress, “damage control orthopaedics” may be preferable for them. Damage control orthopaedics limits the initial treatment to simple stabilization techniques. This allows the patient to at least partially recover from the physiologic stress of injury prior to definitive surgical intervention. After a period of recovery following injury and damage control treatment, additional surgical intervention may be pursued, if the patient’s condition allows it. Attempting definitive orthopaedic care at the outset increases the risk of hypothermia, acidosis, coagulopathy, adult respiratory distress syndrome, and multiple organ dysfunction, among others.

In addition to using a damage control approach, orthopaedic surgeons should carefully consider whether any surgical intervention should be chosen. For many frail patients, non-operative care alone might be sufficient for achieving reasonable treatment goals and will reduce unnecessary medical risk.

Independent of the question whether the injured frail patient should be admitted to a medical service or to the orthopaedic service, it should go without saying that all caregivers must be aware of, and attentive to, the patient’s physiological vulnerability. Evidence supports this interdisciplinary approach: older patients with hip fractures achieve better outcomes when their care is managed jointly by geriatricians and orthopaedic surgeons.

Best practice for management of older patients also includes consideration of advance directives and wishes for end-of-life care.

In addition to these strategies, progress over the last 20 years has focused on improving management of older trauma patients from the time of presentation. For example, a collaborative effort between emergency medicine, geriatrics, and nursing organizations yielded guidelines for establishing geriatric emergency departments. These specialized departments implement gerontology principles universally to improve management of trauma in the acute setting as well as management of possible comorbidities (e.g., dementia, delirium, and malnutrition).

Risk Factors and Prevention

The main risk for developing frailty is aging. In turn, frailty, as a marker of vulnerability, is itself a risk factor for poor outcomes after trauma.

A glib means of avoiding frailty is to not live long, just as one can avoid all income taxes by not earning any money. Neither are necessarily appealing solutions.

Although conclusive evidence showing how to reduce frailty is lacking, there are many proposed steps that seem to have the capacity to improve quality of life with little risk. Such steps include optimizing nutrition, exercising, ensuring adequate sleep and rest, and maintaining social connection and self-expression.

Sarcopenia and weight loss may be ameliorated by exercise programs and nutrition supplementation.

Efforts to reduce polypharmacy are imperative to minimize medication-related adverse events. Moreover, patients with frailty should be assessed for visual and hearing difficulties as sensory deficits can lead to falls and social isolation.

Key Terms

Damage Control Orthopaedics, frail phenotype, frailty index, sarcopenia, trauma specific frailty index