The most important finding of this study is that a large proportion of physicians who manage RTS after ACLR believe that psychological issues are important, but few routinely or objectively attempt to measure or treat these issues. This is despite the fact that a large number of patients fail to return to sport after ACLR despite seemingly good functional outcomes - recent evidence has demonstrated that the discrepancy may be in part due to psychological factors [6, 7]. Emotional disturbance, motivation, self-esteem, locus of control, and self-efficacy are strongly associated with an athlete’s adherence to rehabilitation programs and readiness to RTS . Because of this association, validated psychological tests are available that can identify athletes at risk of maladaptive psychological responses; albeit a minority of clinicians engage in this practice [5, 41]. Because low scores on psychological tests strongly suggest poor prognosis, early identification may indicate the need for referral to qualified practitioners as new evidence suggests timely intervention may improve outcomes [25, 36].
Our findings on the lack of implementation of psychological tests in practice are consistent with a meta-analysis and systematic review by Ardern et al.  which highlighted the lack of biopsychosocial approaches to managing and assessing athletes’ readiness to RTS . Since then, a growing body of literature has both provided evidence for the efficacy of psychological measures as necessary components of RTS criteria and made recommendations to include them in the management of ACLR patients [2, 3, 5, 16, 27, 36]. However, these measures are still infrequently used as observed in a review of 209 studies and as confirmed by our results. Their findings revealed that only 12% of studies used psychologically based measures . In our study only 35% reported use of psychological tests and ranking 8 out of 9 for RTS outcome measures, indicating that the majority of surgeons still focus on objective/functional based RTS measures. At this point it is not known why, in light of the growing evidence, more clinicians are not using psychological scores. One possible factor preventing the inclusion of psychological measures into practice could be physician and clinic time constraints, which may be exacerbated with the introduction of additional questionnaires. Mobile based follow up has been successfully implemented in some orthopaedic populations; both patients and surgeons considered post-operative monitoring via smartphone software in ACLR to be a practicable and an acceptable form of follow up . Furthermore, a mobile patient-based application administered by Higgins et al.  was found to accurately assess recovery enough to have avoided follow up for a number of patients . It could be that incorporation of technology into regular patient assessment could enable regular evaluation of patients’ psychological readiness for RTS.
The results of our study revealed that the most commonly used psychological test was the ACL-RSI (23%, Fig. 3); a questionnaire that is strongly associated with RTS [5, 31]. The ACL-RSI has been well validated and used globally with numerous translations; furthermore, a recent short version of the questionnaire was developed and was observed to be robust in predicting RTS outcomes [10, 21, 35, 40, 41]. One of the main factors that the ACL-RSI evaluates is fear of reinjury, the most common reason for reduction of cessation of sport after ACLR according to Ardern et al.  This is consistent with what clinicians felt was the most common patient-cited reason affecting RTS in our study . Langford et al.  tracked fear of reinjury responses throughout the rehab process to assess progress in parallel with functional measures and found that not only did those whom returned to sport at 12 months score more favourably on the ACL-RSI, but that differences between both groups were seen as early as 6 months . Moreover, there is evidence that positive psychological responses including favourable fear of reinjury assessed through the ACL-RSI before and shortly after ACLR were predictive of successful RTS at 12 months following surgery .
More importantly, psychological indicators of knee function are readily modifiable risk factors [3, 5, 43]; suggesting that those with lower scores could be provided with increased surveillance and counseling to monitor for maladaptive responses and provided early intervention to change or deter these responses. Additionally, pre-operative psychological factors may influence ACLR outcomes as depressive symptomology has been associated with poor self-reported functional scores both before surgery and 1 year following ACLR . Psychological interventions administered for athletes recovering from ACLR include positive self-talk, guided imagery, relaxation and goal setting . Scherzer et al.  demonstrated increased adherence to rehabilitation through goal setting, which yielded a positive relationship with ACLR injury outcome . Furthermore, there is evidence that guided imagery and relaxation sessions for ACLR patients significantly reduces reinjury anxiety . However, most orthopedic surgeons are not trained in psychological interventions, but they may be able to identify athletes who could benefit from these practices, which could prompt collaboration with sport psychologists.
The findings of our study regarding currently used objective measures for determining readiness to RTS are relatively consistent with a 2019 review of 209 studies by Burgi et al.  in which, timing, muscle strength, clinical examination and functional tests were reported as the most frequent measures to determine RTS after ACLR . In our study, respondents ranked functional tests as the most important outcome measure for RTS (Table 4); above timing, muscle strength and clinical signs and clinical tests. The single leg hop test is the most commonly reported functional assessment tool in both the literature and our survey for determining readiness to RTS [11, 26, 42]. Time required before RTS was considered the 2nd most important variable; with 98% of the respondents indicating that a minimum of 6 months is required before RTS. Similar findings were presented by Burgi et al.  in 2019, where time was a RTS criterion in 178 of 209 studies with the majority reporting > 6 months recovery time . However, some argue that unrestricted activity should be delayed further after ACLR as optimal joint function occurs long after the 6-12-month timeline, while others postulate that time as an objective measure is less important than repeated evaluation and follow up to monitor individual progress [29, 34]. Muscle strength ranked 3 out 9 (Table 4) with the overwhelming majority measuring both quadriceps and hamstring muscle strength with the goal to achieve > 85% strength of the contra-lateral limb. However, there is still debate as to which level of symmetry leads to clinically meaningful differences as well as the methods used to assess strength [20, 38, 44].
A limitation of our study was the low response rate of 4%. Therefore, it is difficult to generalize our findings to the entire practicing population of those who manage ACLR patients. Our low numbers may serve as a bias. Furthermore, there are limitations inherent to survey research that may be relevant to our study. Respondent bias may be skewed towards those with a vested interest or background in psychological factors involved in ACLR. Additionally, despite anonymity, survey methodology is susceptible to social desirability bias, questions such as the importance of psychological tests in management – with increasing evidence to support their effectiveness – may be overestimated. We were not able to identify differences between different sports, levels of athletes or type of reconstructive surgery as our survey as not designed to determine such differences; however, it would be of interest to investigate this in future studies.