Acute orthopedic trauma represents one of the most common injuries in workplace accidents, traffic accidents, and other types of accidents (1). It is also responsible for individual disability and loss of workdays and implies a substantial economic and societal burden (2, 3). According to the official statistical report of the Swiss accident insurance fund, among 850,000 accidents reported (8.7 million inhabitants) in 2018, orthopedic trauma accounts for 85% of all injuries (4). The mean direct and indirect costs due to orthopedic trauma in Switzerland between 2014 and 2018 were 3.96 billion euros (4). According to a systematic review of 204 studies in 2020, 13% of patients sustaining orthopedic trauma had lost employment at 1 year postinjury, and the mean number of days absent from work was 102 days (3).

Based on these data, return to work (RTW) after orthopedic trauma has become a key outcome for people of working age. RTW marks a return to financial independence for the individual and the end of compensation benefits for society. From an individual point of view, RTW is associated with better psychological well-being, self-esteem, and social connectedness (5). However, the definition and measurement of RTW outcome remain highly heterogeneous from study to study (6). A synthesis of the measurement of RTW outcome in the literature may help to clarify its operationalization.

Furthermore, the identification of prognostic factors for RTW remains the focus of many studies in the field. RTW seems to be influenced by different personal and environmental determinants due to its complex and multidimensional nature (7). Indeed, the usual biomedical model cannot fully explain the RTW process for patients with musculoskeletal disorders (8). The biomedical model, based on a dualistic mind-body viewpoint, fails to take into account psychological, social, and health system aspects. These psychosocial factors were, however, widely recognized as having an independent influence on RTW (7–9). Another limitation of the biomedical model is its inability to explain the interaction between injury severity and other psychosocial factors in predicting the long-term outcome. The biopsychosocial (BPS) model developed by George Engel in 1977 (10), based on a holistic approach, might overcome the limitations of the traditional biomedical framework for predicting multidimensional outcomes such as RTW (11). The underlying assumptions of the BPS model rely on the complex and non-linear interactions between the biological, psychological, and social determinants that affect disease outcomes (12). Based on this model, the RTW process depends not only on biomedical characteristics but also on personal and environmental factors (workplace, healthcare system, compensation policy) (13). Early identification of BPS factors associated with RTW is of importance to help in developing effective interventions to prevent work disability and subsequently in reducing the personal and societal burden of orthopedic trauma.

In 2010, the prognostic factors involved in the RTW process in patients with orthopedic trauma were presented in a systematic review by Clay et al. (9). At that time, the literature was scarce, and the quality of the studies was limited. According to an earlier review (9), two factors of strong evidence identified were educational levels and blue-collar work, whereas three factors of moderate evidence were self-efficacy, injury severity, and compensation status. Over the past 10 years, the emergence of new evidence has raised the need to perform an updated review on this topic.

In this systematic review, we updated the latest evidence on prognostic factors for RTW in employed populations sustaining acute orthopedic trauma by reviewing studies indexed in three large databases between 2010 and 2020. Prognostic factors were evaluated using a two-tiered strategy (significant and non-significant effects) and classified into the early or late phase postinjury using a 6-month cutoff. This cutoff point was used when assuming that some orthopedic injuries (for example, fractures) might take up to 6 months to recover (3) and that the influence of some prognostic factors on RTW might vary in a timely fashion (14).

In this updated systematic review of 30 studies between 2010 and 2020, we were able to extract 33 significant factors for RTW in the early phase and 46 prognostic factors in the late phase. In agreement with the previous review of 15 studies published in 2010 (9), blue-collar work and educational level were supported by strong evidence. In addition, we found strong evidence for two new factors (age and level of pain) and moderate evidence for another two new factors (physical workload and recovery expectations). Importantly, injury severity, self-efficacy, and compensation status have been upgraded from moderate evidence (9) to strong evidence in this updated review. An earlier review in 2010 (9) did not have enough evidence to support the role of older age, injury severity, level of pain, self-efficacy, recovery expectations, and physical workload as the key barriers to RTW. The identification of these new factors was in accordance with evidence of predictors from the synthesis of 56 reviews on RTW in various conditions and injuries (7). Contrary to the earlier review in 2010 (9), the role of gender on RTW was inconsistent, as contradictory results were reported in the included studies (27, 46, 49).

The classification of predictors into early and late phase postinjury was one of the main differences between ours and the previous review (9). In the early phase following acute orthopedic trauma, strong evidence was found for injury severity only. A number of psychosocial factors, including self-efficacy, recovery expectations, blue-collar work, and physical demand, had limited evidence in the early phase but became more evident in the late phase postinjury. This is likely because while most of the injured workers return to work in a straightforward pathway soon after the acute phase, a proportion of patients might turn into the chronic work disability process. In these patients, psychosocial problems might play an important role in the late phase and interact with other factors as the key barriers to RTW. Another explanation was that the longer the duration of follow-up, the greater the likelihood of recognizing the significant effects of psychosocial problems on RTW.

Another difference was that we assessed both the significant and non-significant effects of all reported predictors. For example, increasing age showed no relationship with RTW in three studies (37, 39, 45), but it significantly predicted RTW in the other six studies (23, 27, 30, 32, 33, 42). The difference might be due to selection bias. For studies demonstrating the impact of age, over half of the injured population were blue-collar or immigrant workers (32, 33, 42). In other words, older blue-collar workers are likely to have more difficulty reentering the labor market than young white-collar workers. The predictive validity of age, therefore, must be interpreted in conjunction with the BPS context, for example, with the occupation. Careful interpretation is also needed for educational level, as this factor has shown no significant effect on RTW in two studies (39, 42), whereas other studies have demonstrated a significant correlation (32, 33, 43, 49). The discrepancy between these studies might be due to the different categories of predictors and duration of follow-up.

Understanding the levels of evidence of prognostic factors for postinjury employment helps to identify patients at high risk for poor RTW outcomes and to improve guidance for RTW. According to our results, injury severity was recognized as one of the principal barriers to RTW in workers; therefore, public health and work environments should pay attention to serious injury prevention, as the majority of accidents are preventable (51). Whereas, the prevalence of workplace injuries seemed to be reduced from 2010 to 2018 in Europe thanks to the European strategic framework on health and safety at work (52), the prevalence of non-work injuries (domestic, road, and leisure time injuries) remained high. Public health should take action to improve road safety legislation, road infrastructure, and first trauma care as core measures for reducing the burden of road accidents. Prevention campaigns for other injury causes, especially sports injuries, are necessary as well.

Older injured workers might need special promoting policies to enhance RTW, especially blue-collar workers, including adapting work accommodations. In addition, providing access to interdisciplinary treatment for pain is also of importance. Health professionals, however, should remain mindful that non-biological factors such as self-efficacy, recovery expectations, blue-collar work, and physical workload also contribute significantly to the RTW outcome. Adapting physical workload, for example, offering lighter or modified or graded work exposure or performing onsite work evaluation, may help to increase the success of RTW. Our findings support the “seven principles for successful RTW” previously established for enhancing RTW in musculoskeletal or pain-related conditions (53–55). It is also suggested that self-efficacy and recovery expectations are relevant factors that need to be screened in workers as early as possible after injury. Higher self-efficacy and recovery expectations can be obtained by support from leaders and coworkers to promote RTW (56). Surprisingly, work-related factors such as support from leaders and coworkers were not reported in the included studies. Hopefully, future researchers will strive to improve reporting on this factor.

Worker compensation has been supported in our updated review by strong evidence. However, workers' compensation systems are different from country to country, and the interpretation of this finding needs to be cautious. For example, most European countries compensate workers for both professional and non-professional accidents, and coverage is provided regardless of fault. Another important issue of concern in workers' compensation is the source of insurance. In many European countries, public organizations control workers' compensation insurance policies, whereas in some countries (for example, Australia, UK), insurance can be provided either directly through the employer or through a private insurance provider. The negative impact of compensation on RTW was reported in countries where private insurance companies were involved in the sick pay scheme (27, 30, 43). Workers' compensation status was not related to RTW in Taiwan (33), where the public labor system pays injured workers their lost wages for 2 years postinjury.

It should be noted that other factors (depression, psychological disorders, social support, vocational training, etc.) were rated as limited evidence in the early and late phases because the number of high-quality studies required for qualification has not been reached. They should not be interpreted as factors of limited importance. These factors may need to be addressed in further high-quality studies to determine whether they are relevant in the RTW process after orthopedic trauma. Many of these factors are potentially amenable to intervention. For example, psychological disorders may benefit from psychological care or cognitive behavioral therapy; computer skills can be acquired from vocational training.

From the methodological point of view, the inclusion and exclusion criteria were quite similar between ours and the previous review (inclusion of longitudinal studies of patients sustaining orthopedic trauma, and exclusion of studies that did not recognize the multifactorial nature of RTW) (9). Unlike the specific criteria applied in the previous review (9), we used the QUIPS, a recently validated tool, to assess the risk of bias of all included studies. For one study presenting the predictive model (42), the risk of bias was also assessed by PROBAST, which resulted in the same level of risk of bias. We found that study attribution and confounding were the most common types of bias risk. Some contributing studies did not clearly describe the rates of loss to follow-up or the potential impact of subjects lost to follow-up (33, 35, 39), which are important elements affecting study attribution. The methods for missing data have not been appropriately handled in some studies (31, 34, 50), resulting in a source of reduced statistical power. Apart from the assessment of the risk of bias, the quality of all included cohorts was also evaluated by the NOS. It was demonstrated that all seven studies with a low risk of bias were rated as having high quality. Two studies with a high risk of bias were rated as having medium quality. The remaining 11 studies of moderate risk of bias were rated as having high quality in nine studies and medium quality in two studies.

There has been a lack of consistency in the definition of the RTW outcome, as it can be defined as sustained RTW, fitness to work, or simply yes/no status. Likewise, the prognostic factors were measured in different ways (even for age: continuously and dichotomously) at different time points after the traumatic event. It should be noted that until present, most of the included studies were predicting factor studies that focus only on the associative relationship between prognostic factors and RTW outcome. Studies evaluating the predictive model's performance, for example, the external validation of the model, remain limited.

In this updated systematic review of 30 studies between 2010 and 2020, injury severity was identified as a key barrier for RTW in the early and late phases postorthopedic injury. In the late phase postinjury, there was strong evidence for age, level of pain, self-efficacy, educational level, blue-collar work, and compensation status and moderate evidence for recovery expectations and physical workload as prognostic factors for RTW. Other factors were classified as having limited or inconsistent evidence, and further high-quality studies are needed to understand their impacts. The results from this current update might help in developing effective intervention strategies for RTW and in guiding future research in the field.

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author/s.

HD: involved in conceptualization, data curation, formal analysis, validation, visualization, writing original draft, and writing, reviewing, and editing. AG: prepared conceptualization, data curation, formal analysis, validation, visualization, writing original draft, and writing, reviewing, and editing. RH: contributed in conceptualization, data curation, formal analysis, project administration, supervision, validation, visualization, writing original draft, and writing, reviewing, editing. BL: carried out conceptualization, methodology, project administration, supervision, validation, visualization, writing, reviewing, and editing. FL: carried out conceptualization, methodology, data curation, project administration, supervision, validation, visualization, writing original draft, writing, reviewing, and editing. All authors contributed to the article and approved the submitted version.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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