Musculoskeletal injury is an associated risk of physical activity participation.1 Injury to the anterior cruciate ligament (ACL) is a serious musculoskeletal health condition that can affect the stability of the knee,2 potentially affecting participation in a desired physical activity and return to preinjury levels of sports participation after injury.3 After an ACL injury, most individuals undergo ACL reconstruction.4 The impetus behind ACL reconstruction is to stabilize the knee, which theoretically allows the patient to return to preinjury levels of sport.5 However, recent literature has suggested that a return to preinjury or competitive levels of sport does not always occur. After ACL reconstruction, only 55% of patients return to competitive levels of sports participation and only 65% of patients return to preinjury levels of sports participation.5 It has been previously reported that individuals after ACL reconstruction have reduced participation in moderate to vigorous physical activity (average: 79.37 ± 23.95 minutes per day),1 daily step counts (average: 8,158 ± 2,780 steps per day),1 and decreased health-related quality of life (HRQL) compared to healthy participants.3
This is concerning because the recommended 150 minutes per week of moderate physical activity, 75 minutes per week of vigorous physical activity by the Centers for Disease Control and Prevention,6 or 10,000 steps per day by the U.S. Department of Health and Human Services7 are not met. Additionally, ACL reconstruction is common in young individuals, so a decrease in HRQL at a young age may indicate decreased health for many years to come. Specifically, individuals after ACL reconstruction are at an increased risk to develop knee osteoarthritis8 and engagement in physical activity can decrease this risk.9 This scenario is perplexing because the individuals are most often young, previously active, and have undergone reconstruction to repair knee stability, but these individuals fail to return to previous levels of sports participation. The biopsychosocial model suggests that contributors to health are not merely biological: health is affected by a combination of biological, psychological, and social impairment.10 It has been proposed that psychological and social impairments, such as increased levels of fear and decreased levels of self-efficacy, can affect outcomes following ACL reconstruction.11–13
Fear is defined as an intense emotional reaction to an identifiable threat that motivates an individual to engage in defensive behaviors.14 Self-efficacy is defined as an individual's belief in his or her ability to execute a task.15 These two biopsychosocial factors can negatively influence return to preinjury levels of sports participation, symptoms, and knee function in patients after ACL reconstruction.3,13 Two theories that could explain the relationship between the biopsychosocial factors and poor outcomes after ACL reconstruction are the fear avoidance model (FAM)16 and the social cognitive theory (SCT).17 These theories can provide a foundation to develop theory-based interventions to improve long-term knee health and physical activity engagement in individuals after ACL reconstruction.
The purpose of this article was to evaluate the literature examining injury-related fear and self-efficacy and discuss applying theory to understand failure to return to prein-jury levels of sports participation and the amount of lifelong physical activity engagement in patients after ACL reconstruction. The literature discussed in this review is not exhaustive, but each presented article highlights the impact of these biopsychosocial impairments and represents the influence that injury-related fear and decreased self-efficacy have on return to preinjury levels of sports participation in individuals immediately after ACL reconstruction until 20 years postoperatively. We follow this theoretical discussion with recommendations for clinical practice. Moreover, this article contributes to a broader call in health care literature to emphasize a theory-based understanding of, and intervention for, health- and injury-related concerns.18,19
The FAM is an individual level cognitive behavioral model that was established to help explain chronic pain development in patients with musculoskeletal injury.16 The model, which is primarily used for patients with chronic low back pain, suggests that following a painful experience, a person can either confront or avoid the experience, such as lifting a heavy object.16 Individuals who have catastrophizing behaviors, most commonly pain catastrophizing in patients with chronic low back pain, will begin a cycle of avoidance, disuse, disability, and/or depression.16 Despite previous use for chronic low back pain, this model can be slightly modified to understand health outcomes in individuals after ACL reconstruction. In this study of individuals after ACL reconstruction, we propose to supplement avoidance of the painful experience with injury-related fear or avoidance of an additional knee injury. After undergoing ACL reconstruction, patients may confront their injury-related fear, which would lead to a normal recovery. However, if patients after ACL reconstruction have increased levels of injury-related fear and engage in catastrophizing behaviors associated with sports participation, then these individuals may begin to avoid engagement in physical activities. The catastrophizing behaviors associated with injury-related fear can lead to avoidance behaviors, including failure to return to sport or failing to engage in physical activities. When avoidance occurs, disuse, disability, and/or depression can transpire, which can transition to further negative experiences and long-term chronic disease.16,20 Thus, the modified FAM further highlights the relationship of injury-related fear and return to preinjury levels of sports participation after ACL reconstruction. However, we propose the FAM in isolation fails to incorporate other pertinent biopsychosocial factors, such as self-efficacy, to help explain why an individual may or may not return to preinjury levels of sports participation after ACL reconstruction. We believe the combination of the FAM and the SCT can serve as a more encompassing theoretical model to better treat these patients.
The SCT, which was developed from the social learning theory, suggests that people develop certain behaviors through the observation of others and self-perception is a significant factor toward engagement in those behaviors.17 Bandura15 defined these self-perceptions as self-efficacy. Self-efficacy is an individual's belief in his or her ability to complete a behavior or succeed in a task and is associated with cognitions, emotions (including fear), and behavioral outcomes.15 Furthermore, a fundamental tenet of the SCT suggests that personal, environmental, and behavioral factors are interconnected.17 For example, an athlete's desire to disengage from participation in soccer could be explained by the SCT. An athlete may not believe in his or her ability to play soccer (ie, self-efficacy as a personal factor), and may also negatively perceive responses from teammates about his or her performance (ie, lack of social support as an environmental factor), which then influences the athlete's decision to no longer play soccer (ie, disengagement from athletics as a behavioral outcome). In this example, personal and environmental factors influenced the behavioral factor to disengage from soccer.
Examination of this dynamic process in individuals after ACL reconstruction can provide further insight on how decreased levels of self-efficacy can affect return to prein-jury levels of sports participation. To further explain this dynamic process, imagine that the soccer athlete described has undergone ACL reconstruction previously. Further imagine this athlete does not believe in his or her own ability to successfully complete the rehabilitation plan to return to sport (ie, self-efficacy as a personal factor). In addition, imagine that teammates and coaches never engage with the athlete to assess his or her rehabilitation progress (ie, lack of social support as an environmental factor), which encourages the athlete to not adhere to rehabilitation and ultimately not return to sport (ie, failure to return to prein-jury levels of sports participation as a behavioral outcome).
Fear and Self-Efficacy After ACL Reconstruction
After patients undergo ACL reconstruction, they often exhibit changes in their psychological schema due to factors such as increased injury-related fear and decreased self-efficacy.11–13 In a systematic review that examined the psychological predictors of return to sport, rehabilitation compliance, knee pain, and knee function after ACL reconstruction, Everhart et al.21 used aspects of the SCT (including self-efficacy and social support) and the FAM to demonstrate possible psychological changes that could occur. Consistent with the SCT, self-confidence, optimism, self-motivation, self-efficacy, and social support were all predictive of return to sport, rehabilitation compliance, knee pain, and knee function after ACL reconstruction. It was demonstrated that patients with higher levels of self-efficacy and self-motivation were more compliant with rehabilitation, more frequently returned to sport, and reported fewer symptoms.21 As explained by the SCT, self-efficacy and self-motivation (ie, personal factors) led to increased compliance in rehabilitation with their therapist (ie, environmental factors), which ultimately allowed for return to sport, decreased levels of knee pain, and increased knee function (ie, behavioral outcomes). Thomeé et al.22 also investigated self-efficacy as a predictive factor of physical activity, knee symptoms, and muscle function. Preoperative levels of self-efficacy were predictive of physical activity levels, symptoms, and muscle function 1 year after reconstruction.22 These results suggest that self-efficacy may be a mediating factor for successful outcomes after ACL reconstruction.
Additional studies evaluated the effects of self-efficacy and injury-related fear on decisions about physical activity engagement in patients with a history of ACL reconstruction postoperatively. For example, researchers have examined the relationship between self-efficacy, health locus of control, fear of reinjury, psychological readiness, and knee function in participants 1 to 7 years after ACL reconstruction.23 Only 40% of participants returned to sport, and these participants had increased levels of positive psychological responses compared to those who did not return to sport.23 Of the 60% who did not return to sport, 24% of participants reported fear of a new knee injury as their reason for not returning.23 Furthermore, 28% of the participants who did not return to sport reported lack of trust in their knee as their reason for no longer engaging in preinjury levels of sports participation.23 In this cohort, the modified FAM and the SCT could help to characterize these results. The modified FAM could help explain why 24% of participants who reported fear of a new knee injury did not return to preinjury levels of sports participation, and the SCT could help explain why a lack of confidence did not allow 28% of participants to return to sport. These results further represent decreased levels of self-efficacy, increased levels of fear, and poor internal locus of control in the ACL reconstruction population.
Additional investigations reported similar results in groups years after ACL reconstruction. Filbay et al.3 interviewed individuals with knee symptoms 5 to 20 years after ACL reconstruction and asked them to describe and discuss the factors that affected their HRQL. The four themes extracted from the interviews were physical activity preferences, lifestyle modifications, adaptations and acceptance, and fears of reinjury.3 All participants described some degree of fear of reinjury at some point throughout their ACL reconstruction experience, ranging from their initial injury to the day they completed the interviews. The three common themes associated with fear of reinjury included fear suppression, fear accommodation, and fear avoidance. Participants with elevated levels of fear-avoidance beliefs reported cessation of physical activity and a poorer quality of life.3 Applying the modified FAM and the SCT to the findings can explain why participants engage in avoidance behaviors such as disengagement in sports participation, which ultimately impacted the HRQL.
FAM and SCT for ACL Reconstruction
The FAM and the SCT in concert can explain the sequelae of failure to return to preinjury levels of sports participation and poor HRQL after ACL reconstruction. The impetus behind ACL reconstruction is to return patients to preinjury levels of sports participation.4 After reconstruction and throughout the rehabilitation process, patients will encounter tasks similar to those that may have led to their initial injury (eg, cutting or jumping).12 Due to the frequent exposure of potential fear-eliciting stimuli, patients are at risk of developing injury-related fear, which can lead to catastrophizing and avoidance behaviors as demonstrated by the FAM.24,25 In conjunction with injury-related fear development, an individual may also suffer from decreased levels of self-efficacy when exposed to sport-specific tasks. Injury-related fear in combination with decreased self-efficacy can lead to long-term avoidance behavior. This avoidance behavior could facilitate disuse and cessation of physical activity in these patients, and result in a failure to return to preinjury levels of sports participation.
We believe the combination of the FAM and the SCT may theoretically explain failure to return to preinjury levels of sports participation after ACL reconstruction. Although a relationship between self-efficacy and injury-related fear has not been established in patients after ACL reconstruction, a new model that incorporates self-efficacy into the FAM has been created for patients with chronic low back pain (Figure 1).26 It has been demonstrated that self-efficacy is a mediating factor between pain-related fear and disability and between pain-related fear and pain intensity in patients with chronic low back pain.26 These results suggest that when self-efficacy is low, elevated pain-related fear will likely lead to the development of greater pain and disability.26 Inversely, when self-efficacy is high, elevated pain-related fear may not lead to increased pain and disability.26 These results can be applied to individuals after ACL reconstruction. For example, an individual who was not confident in his or her ability to jump sustains an ACL injury while attempting to rebound a basketball. After ACL reconstruction, the individual may have injury-related fear associated with jumping tasks. This injury-related fear, in combination with the previous decreased self-efficacy levels, could influence whether the individual decides to confront his or her fear of jumping and facilitate a normal recovery or begin the cascade of disuse.
Woby's modified fear avoidance model to include self-efficacy. Reprinted with permission from Woby SR, Urmston M, Watson PJ. Self-efficacy mediates the relation between pain-related fear and outcome in chronic low back pain and disability. Eur J Pain. 2007;11:711–718.
This relationship between the FAM and the SCT highlights the limitations of each theory, when applied to the individuals after ACL reconstruction. One of the main limitations of the use of the FAM in isolation is the exclusion of environmental factors that could affect the development of injury-related fear, such as social support. Social support has been found to influence a patient's return to sport or physical activity.21 However, not all social support is positive. It is possible that the athlete may receive negative reinforcement from others (eg, coaches and/or teammates), which could also lead to avoidance behaviors associated with sports participation.12 The SCT accounts for this limitation by incorporating environmental factors. However, unlike the FAM, there is no direct pathway to extract from the SCT that can accurately describe the decision to return to preinjury levels of sports participation after ACL reconstruction. The lack of a succinct pathway to show causation between factors enhances the difficulty to create an intervention to directly address the problem.
It is also important to understand the limitations of these theories in unison when applied to individuals after ACL reconstruction. Failure to return to preinjury levels of sports participation may not only be due to biopsychosocial impairments after sustaining an ACL injury. It is possible that some individuals who fail to return to preinjury levels of sports participation to engage in competitive levels of sports are no longer present. Therefore, maturation can influence disengagement in sports participation and physical activity after ACL reconstruction. However, aging out of high school or collegiate level athletics should be well understood during the rehabilitation process, and recommendations for future physical activity engagement should be discussed with these patients.
Recommendations for Practice and Research
There is room for the development and implementation of theory-based research regarding return to sports participation for individuals after ACL reconstruction. Early identification of biopsychosocial factors that may deter return to preinjury levels of sports participation, such as catastrophizing behaviors and decreased self-efficacy, may help mediate injury-related fear and prevent avoidance behaviors. Frequently used patient-reported outcome measures to evaluate injury-related and pain-related fear in the chronic low back pain literature include the Fear Avoidance Belief Questionnaire27 and the Tampa Scale of Kinesiophobia.28 Unfortunately, these methods have not been validated for the ACL reconstruction population, but they could be useful clinical tools for patients after ACL reconstruction. Biopsychosocial outcome measures that have been developed for the ACL reconstruction population include the Knee-Self Efficacy Scale,21 Anterior Cruciate Ligament Return to Sport after Injury,29 and Quality of Life Assessment in Anterior Cruciate Ligament Deficiency Scale.30 Using these outcome measures in clinical practice may allow clinicians to identify potential biopsychosocial factors that could impede rehabilitation and return to preinjury levels of sports participation. Additionally, the clinician can use these measures to evaluate the patient-perceived effectiveness of treatment. These patient-reported outcome measures are relatively easy to use, access, and score. Early assessment of these modifiable biopsychosocial factors in the rehabilitation process can allow the clinician to intervene at an earlier stage, and may facilitate better health outcomes for these patients.
Intervention strategies to abate pain-related fear and fear of movement in patients with chronic low back pain may be useful in the individuals after ACL reconstruction, due to the similar biopsychosocial factors exhibited in these populations. Interventions such as patient education31 and in vivo exposure32 have been used in patients with chronic low back pain. For example, with in vivo exposure, a patient after ACL reconstruction could be asked to rank and rate his or her perceived severity of becoming injured while completing fear-eliciting tasks such as cutting or jumping. Afterward, the patient would be asked to complete the cutting or jumping task. Following the performance of the task, the patient would be asked again to rate his or her perceived severity of injury while completing that task. If the rating has decreased, the clinician would move to the patient's next fear-eliciting task on the list. Gradual exposure to the fearful stimulus can assist with the reduction of injury-related fear.32 Performance-based treatments such as exposure therapy may not only decrease injury-related fear, but can also demonstrate performance accomplishments, which are significant when strengthening self-efficacy.15
Additionally, it is important for clinicians to recognize the importance of integrated care with behavioral health specialists to assist with treating these biopsychosocial issues. Some methods of addressing injury-related fear and self-efficacy fall under the purview of behavioral health. For example, treatment for severe depression and anxiety as a result of injury should be referred to a behavioral health specialist. Although there are psychosocial intervention strategies within the scope of a rehabilitation specialists' skill set, it is important to integrate behavioral health specialists on the sports medicine team to help with early recognition and treatment of factors that may impede return to sport and HRQL.
Other cognitive-behavioral treatment strategies such as positive self-talk, deep muscle relaxation techniques, and visual imagery can assist with decreasing fear and anxiety, and they can be easily implemented by rehabilitation specialists into after ACL reconstruction rehabilitation.33 However, it is important for the clinician and the patient to meet and discuss injury-related fears to determine which psychosocial intervention strategy will be the most effective. The proper identification of biopsychosocial impairments is essential to the implementation of specific psychosocial intervention strategies.
Patients after ACL reconstruction are affected by many biopsychosocial factors, including injury-related fear and decreased self-efficacy. The purpose of this review was to examine how the FAM and the SCT can influence health outcomes, specifically the return to preinjury levels of sports participation after ACL reconstruction. Few studies explore the effects of return to preinjury levels of sports participation factors or interventions to mitigate impairments. However, by reviewing this phenomenon in other musculoskeletal populations, future research can explore the efficacy of interventions in the individuals after ACL reconstruction. Because patient-centered care continues to rise to the forefront of health care in the United States, it is important to evaluate biopsychosocial factors affecting a patient's health outcome. Additional theory-based research is needed to further elucidate the relationship between biopsychosocial factors in the individuals after ACL reconstruction to improve health outcomes. Once this relationship is established, implementation of theory-based interventions to treat biopsychosocial factors can be integrated into rehabilitation programs.
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- Øiestad BE, Engebretsen L, Storheim K, Risberg MA. Knee osteoarthritis after anterior cruciate ligament injury: a systematic review. Am J Sports Med. 2009;37:1434–1443. doi:10.1177/0363546509338827 [CrossRef]
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