Anterior cruciate ligament (ACL) rupture is a common and incapacitating injury sustained by athletes whilst playing sport. It is an injury which many athletes fear, because it is usually a season-ending injury and typically requires reconstructive surgery in order for an athlete to return to sport. Whilst in the past the primary focus of injury rehabilitation has been directed towards treating the physical problem1 with the aim of getting athletes back to sport as soon as possible, there has been growing interest in the psychological aspects of the return to sport following serious injury (see2 for review). This interest has stemmed from research showing that physical and psychological readiness to return to sport does not always coincide. Indeed, in the case of ACL reconstruction, studies have shown that a considerable number of patients fail to return to their pre-injury level of sport participation despite a seemingly successful rehabilitation and reconstruction surgery.3 4

To date, only a small body of literature has examined the psychological recovery of athletes following ACL reconstruction. Two studies that have assessed athletes’ emotions5 6 using the Emotional Response of Athletes to Injury Questionnaire (ERAIQ) reported that athletes experience an elevated mood disturbance both following their ACL injury and also later in the course of rehabilitation prior to returning to competitive sport. However, neither study determined whether the athletes returned to sport at the end of the rehabilitation period. Recent work has also determined that factors other than post-injury emotion, such as confidence in the reconstructed knee and fear of re-injury, are important to consider in the context of sport resumption following ACL reconstruction surgery.7 8 These findings support the biopsychosocial model of sport injury rehabilitation by Brewer, Andersen and Van Raalte,9 which indicates that a number of psychological factors such as personality, cognition, affect and behaviour are related to sport injury rehabilitation outcomes.

Scales such as the ERAIQ are excellent for documenting athletes’ emotions after injury and have been extensively used in the sport psychology literature. However, more recently developed scales such as the ACL Return to Sport after Injury (ACL-RSI) scale have been designed to include responses that are related to returning to sport, such as confidence and risk of re-injury.8 The Knee Self Efficacy scale10 (which was not available at the time this study commenced) has also been utilised to provide important information regarding athletes’ psychological state during rehabilitation. Perceived self-efficacy has been shown to be low during the first few months of rehabilitation but increases significantly during the first postsurgical year11 and is a predictor of the patient’s returning to physical activity 1 year after surgery.12 Lower levels of self-efficacy have also been documented among women and patients aged 30 years and older.13 It has therefore been suggested that strengthening self-efficacy may result in more patients returning to sport, although this is yet to be investigated.13

Webster, Feller and Lambros8 and Kvist et al4 investigated the psychological differences between athletes who had and had not returned to sport following ACL reconstruction at 12 months and 3 to 4 years respectively. Both studies found that the athletes who had not returned to sport were more fearful of re-injuring their knee by playing sport than the athletes who had returned. Webster et al8 also reported that the athletes who had not returned to sport at 12 months experienced more negative emotions, had lower confidence and thought they were more likely to be re-injured by playing sport than the athletes who had returned. Both studies only examined athletes after they were expected to recommence sport participation and, as such, did not determine whether psychological differences also exist during rehabilitation.

As an important goal of injury rehabilitation is to be able to predict athletes who require psychological counselling or intervention so that psychological recovery from injury can occur in parallel with physical recovery, it is important to know whether the psychological responses athletes experience early on in the rehabilitation period are related to sport resumption. The primary aim of this study was, therefore, to determine whether the psychological responses of athletes who had undergone ACL reconstruction surgery change during the rehabilitation period, and whether these psychological responses are related to returning to competitive sport. A secondary aim of the study was to examine whether any physical differences exist between those athletes who do and those who do not return to competitive sport.

It was hypothesised (1) that athletes’ psychological responses would become more positive during rehabilitation and 2) that athletes with more positive responses would return to competitive sport 12 months following ACL reconstruction. The third hypothesis was that no physical differences would exist between athletes who do and those who do not return to competitive sport at 12 months following ACL reconstruction.

METHOD

Participants

One hundred patients who had undergone uncomplicated primary ACL reconstruction by the same orthopaedic surgeon between mid-March and mid-October 2005 were invited to participate in the study, and 87 (87% response rate) agreed. There were 55 men and 32 women, aged between 18 and 40 years (mean age 27.48 years (SD 5.72)). The mean time from injury to surgery was 18 weeks (range 2–216 weeks). Participants were eligible if they were aged between 18 and 40 years and had been participating in competitive sport (either a level 1 or a level 2 sport on the Cincinnati Sports Activity Scale)14 on a weekly basis prior to their ACL injury and planned to return to sport following their surgery. Participants were excluded if they had associated collateral ligament or posterior cruciate ligament injuries requiring repair or reconstruction, meniscal tears requiring repair, chondral lesions and/or bone injuries requiring surgery or any complications requiring further surgery (e.g. infection) within the first 3 months following the reconstruction.

All patients had undergone an arthroscopically assisted single-incision ACL reconstruction. 83 patients received a hamstring graft in which the gracilis and semitendinosus tendons were harvested through an oblique 3 to 4 cm incision. Four patients received a patellar tendon graft in which a central third bone–tendon–bone graft was harvested through a 5 to 7 cm longitudinal incision. The femoral tunnel was drilled using a trans-tibial technique and all grafts were statically pretensioned at 20 lb (89 N) for 5 minutes prior to insertion.

Procedure

The study procedures were approved by the Faculty of Health Sciences Ethics Committee at La Trobe University. The study was of a prospective longitudinal design. Assessments were conducted at 3, 6 and 12 months following ACL reconstruction surgery to correspond with important stages during the rehabilitation period. All participants followed the same rehabilitation protocol. At 3 months participants were allowed to run and commence sport-specific drills, then at 6 months resume training and commence competitive sport after they had been training for 1 month without problems. By 12 months participants were expected to have returned to competitive sport. At each time point participants completed a self-report questionnaire prior to being reviewed by the orthopaedic surgeon. The questionnaire included background questions regarding the types of sports and frequency of participation prior to injury as well as details about the injury itself. This was followed by questions regarding their current level of sport participation and two psychological measures, the Emotional Responses of Athletes to Injury Questionnaire (ERAIQ)5 and the ACL Return to Sport after Injury scale (ACL-RSI).8 For current sport status, participants were specifically asked to indicate whether or not they had attempted to resume sport participation and, if so, the level of participation (i.e. training, modified competition, full competition). For the psychological measures, participants were asked to refer to their main sport prior to injury when answering all questions. Physical measurements were also conducted at each time point. Any participants who did not attend a postoperative review were mailed a copy of the questionnaire.

Psychological measures

The ERAIQ specifically examines the emotions athletes experience in response to their injury. This scale has been used extensively in the sports psychology literature and also with athletes following ACL reconstruction.5 6 A list of emotions is given and participants assign a rank score (from 0 to 12) to each emotion with higher scores on the scale reflecting more emotional disturbance. The scale’s 12 emotions have been shown to have good convergent validity with the Incredibly Short Profile of Mood Scale.15 The ACL-RSI scale was designed to examine the psychological impact of returning to sport following ACL reconstruction surgery.8 Items on this scale were created around three psychological responses related to sport resumption: emotions, confidence in performance and risk appraisal. For each item a 0–100 scale is used with 10-point increments. Higher scores reflect a more positive psychological response. The ACL-RSI scale has good internal consistency (Cronbach’s alpha = 0.92), principal components analysis confirmed the presence of one underlying factor which accounted for 67.8% of the total variance, and the scale has been shown to be able to discriminate between athletes who do and athletes who do not return to sport.8

Physical measures

Knee passive range of motion (flexion and extension), presence of effusion and knee stability tests (Lachman and pivot shift) of the operated knee were taken by the same orthopaedic surgeon at each time point. At the 12 month assessment, side-to-side differences in anterior knee laxity were measured using a KT-1000 arthrometer and the single hop for distance and cross-over hop for distance tests were also conducted to assess functional outcome.16 Both hop tests have been shown to have good retest reliability following ACL reconstruction (single hop for distance test: intraclass correlation coefficient (ICC)>0.75,17 cross-over hop for distance test: ICC = 0.90).18 A limb symmetry score was calculated for each test. A score of 85% and above is considered within the normal range.16

Data analysis

Participants were divided into two groups based on whether or not they had returned to full competition at 12 months following surgery. Descriptive statistics were applied to the demographics, psychological and physical measures. A two-factor repeated-measures ANOVA was conducted to determine the effect of time (within-subjects factor with three levels: 3, 6 and 12 month assessments) and group (between-subjects factor: returned, not returned) on each psychological measure. A univariate approach was used as we were interested in the individual effect of each psychological measure rather than the effect of taking all measures together. Statistical significance was determined at the p<0.05 level. Significant F ratios for the repeated factor, time, were explored using polynomial contrasts. Significant F ratios for group were explored using independent samples t tests with Bonferroni correction. Scores on the hop tests were compared between groups using either the independent samples t test or the Mann–Whitney U test based on the normality of the data.

RESULTS

All participants completed the psychological and physical measures at 3 and 6 months. At 12 months all participants completed the psychological measures and 65 (75%) participants completed the physical measures.

Forty-four participants (51%) had returned to full competition at 12 months following surgery, while 43 participants (49%) had not. No significant differences were found between the two groups in terms of age (t(85) = −1.069, p = 0.288), graft type (p = 0.360, two-tailed Fisher’s Exact Test), time between injury and surgery (U = 732.00, z = −0.092, p = 0.926) or hours of sport participation per week prior to injury (p = 0.088, two-tailed Fisher’s Exact Test). For three participants more than 2 years had elapsed between injury and surgery; however, two of these patients had returned to sport. Only five participants had a prior ACL reconstruction on the contralateral knee, and of these two had returned to competition and three had not (p = 0.676, two-tailed Fisher’s Exact Test).

Psychological measures

ERAIQ scores, presented in table 1, were found to decrease significantly over time (F(2,170) = 5.79, p = 0.005). This was confirmed by a significant linear contrast (F(1,85) = 7.86, p = 0.006). These results indicate that as the participants progressed through rehabilitation they experienced fewer negative emotions regarding their injury. Although ERAIQ scores were higher in the group who had not returned to sport, no significant differences were found between groups (F(1,85) = 3.148, p = 0.08), nor was there a significant interaction between group and time (F(2,170) = 1.95, p = 0.15).

ACL-RSI scale scores, presented in table 2, were found to increase significantly over time (F(2,170) = 16.47, p<0.001). This was also confirmed by a significant linear contrast (F(1,85) = 22.06, p<0.001). These results indicate that the participants felt more positive about returning to sport as rehabilitation progressed. A significant group effect was also detected (F(1,85) = 10.54, p = 0.002). Specifically, significant differences were found between the groups at 6 months (t(85) = 2.90, p = 0.005) and 12 months (t(85) = 3.50, p = 0.001). At both these time points the group who had returned to competition scored significantly higher than the group who had not returned. There was no group by time interaction (F(2,170) = 2.12, p = 0.13).

Physical measures

All participants had no (n = 74) or mild (n = 13) swelling in their operated knee and were assessed to have a stable knee (Lachman 0, n = 77, Lachman 1+, n = 10; all patients firm end point) by the 3 month assessment. All participants had regained neutral (0 degrees) knee extension and 130 degrees or more of flexion of their operated knee by 6 months. At 12 months side-to-side differences in anterior knee laxity were not different between the group that had and the group that had not returned to sport (1.5 mm versus 1.2 mm respectively; t(85) = 0.88, p = 0.38). All participants received medical clearance to return to sport. No participants were identified as having experienced any major difficulties in terms of their physical recovery. As presented in table 3, the mean limb symmetry index scores for both groups on both hop tests were above 85%, which is considered to be within the normal range. Statistical analysis revealed no significant difference between groups for the mean scores on the single hop for distance test (t(59) = 0.902, p = 0.371) or the cross-over hop for distance test (U = 436.5, z = −0.17, p = 0.865). Of the 22 participants who did not complete the physical measures, 11 had returned to competition and 11 had not returned.

DISCUSSION

This study investigated the psychological recovery of athletes following ACL reconstruction to examine whether athletes’ psychological responses change over time, and, further, whether these responses are related to whether or not athletes return to full competition by 12 months following surgery. This study also examined the physical recovery of these athletes over this time period.

The first major finding of the study was that, as participants progressed through rehabilitation, they experienced fewer negative emotions related to their injury, and felt more positive about returning to sport. This finding supports the study’s first hypothesis that psychological responses change over time. It is reasonable to suggest that, as participants physically recovered and were allowed to start sport-specific drills then training, this may have helped alleviate the negative emotions in response to their injury and also help them feel more positive about returning to sport. Interestingly, the current findings are contrary to the findings of Morrey et al,6 who also used the ERAIQ but found athletes experienced an increase in negative emotions 6 months following surgery. While it is not evident why this difference is present, possible explanations are that the current study had a larger sample (87 compared with 27) and that Morrey et al studied both professional and recreational athletes, whereas the current study only examined recreational athletes.

The second hypothesis, that athletes’ psychological responses are related to sport resumption at 12 months following surgery, was partially supported. Interestingly, participants’ emotional responses towards their injury (as measured by the ERAIQ) were not related to competitive sport resumption at 12 months. This is important to note, considering that the main focus of several previous studies has been to investigate the emotional responses of athletes to injury. However, athletes’ feelings about specifically returning to sport (emotions, confidence and risk appraisal regarding sport resumption as measured by the ACL-RSI scale) at 6 and 12 months were found to be related to whether or not athletes resumed full competition by 12 months following surgery.

Given that athletes would not be expected to have already returned to full competition at 6 months, this finding has important implications. It suggests that athletes’ emotions about returning to sport, their level of confidence and the risk they associate with returning to sport at 6 months may be related to whether or not they recommence full competition by 12 months. This finding provides further evidence that psychological hindrances may be a factor influencing athletes’ return to competitive sport4 and supports Morrey et al’s6 contention that the 6 month time point is an important stage following ACL reconstruction.

Furthermore, while it cannot be definitively concluded that the higher score obtained at the 12 month time point on the ACL-RSI scale (more positive) by the group who had returned to competition at 12 months was a direct result of returning to full competition, it can be proposed that the experience of playing competitive sport may have influenced this group’s responses. Playing sport in a competitive situation would have enabled participants to test their operated knee, and therefore probably increased their confidence and reduced any fear they were experiencing.19 Consequently, the returned-to-competition group may have been responding to the questions on this scale based on their actual experience of playing competitive sport compared with the group who had not returned and were yet to have this experience.

Despite all participants receiving medical clearance to return to sport, only 51% of participants resumed full competition 12 months following their surgery. This finding is consistent with several previous studies.3 4 8 Additionally, no significant differences were identified between the participants who had and had not returned to competitive sport in terms of functional outcome as tested by the hop tests conducted at the 12 month assessment. These findings provide evidence to support the hypothesis that no physical differences exist between the athletes who did, and did not, return to competitive sport at 12 months following surgery. But, perhaps more importantly, these findings suggest that factors other than physical recovery may also contribute to whether or not athletes return to competitive sport. These likely include a mix of psychological factors (such as personality cognition and coping style) and biological factors (such as immune function, nutrition and tissue repair) as well as social and contextual factors (such as support networks and the rehabilitation environment) (see9 20 for review). Having an internal locus of control, that is, a strong belief that the outcome of the surgery is directly related to one’s individual behaviour, has also been shown to be an important determinant of an athlete’s perceived self-efficacy during rehabilitation from ACL injury.13

Clinical implications

The study’s findings have implications for clinicians who spend a substantial amount of time with athletes following ACL reconstruction. Even though an athlete may be physically ready to return to competitive sport, he or she may not feel psychologically prepared to do so. Therefore, instead of just focusing on the physical aspect of an injury, clinicians should adopt a holistic approach to management to address all aspects of recovery. In particular, if clinicians can be made more aware that athletes’ feelings about sport resumption at 6 months may influence returning to competitive sport at 12 months, they may be able to identify patients at risk of not returning to competitive sport due to psychological reasons. This could enable clinicians to implement intervention strategies to help facilitate the timely return of athletes to competitive sport.

Strengths and limitations

This study used the largest sample size to date to examine athletes’ psychological responses at multiple time points during rehabilitation following ACL reconstruction (the previous largest sample included 40 ACL patients).5 Therefore, the results obtained in this study are likely to be more representative of this population of athletes. Furthermore, it is the first study to examine whether athletes’ psychological responses during the rehabilitation period are related to whether athletes return to competitive sport following ACL reconstruction, which is important in terms of clinical implications.

As some participants did not attend their post-operative reviews it was not possible to obtain physical measurements from all participants in the study, which was a limitation of the study. While there was only a small number of physical measurements not taken, this may potentially have influenced the physical results. Interestingly, though, of the participants who did not return for physical review, equal numbers had and had not returned to competition.

Future research directions

The study identified a significant difference in psychological responses between the two groups on the ACL-RSI scale at 6 months before athletes would be expected to return to competitive sport; however, the reasons for this difference were not examined. Future research may therefore examine whether differences in psychological responses are associated with different personality types (i.e. some people are generally more anxious) or social support networks (e.g. team mates), for example. Additionally, as it was beyond the scope of the current study to examine the effects of gender, level of previous sport participation (i.e. elite vs. non-elite) or the experience of a previous ACL reconstruction on psychological responses and sport resumption, these are also areas of potential interest for future research.

CONCLUSION

Despite all participants receiving medical clearance to return to sport, only 51% had returned to full competition 12 months following ACL reconstruction. Although no physical differences were found, significant differences in psychological recovery were identified between the participants who did and those who did not return to competitive sport. While all participants’ psychological responses became more positive over time, the participants who failed to return to competitive sport at 12 months scored significantly lower on the ACL-RSI scale (i.e. felt less positive about returning to sport) at both 6 and 12 months following surgery. This finding indicates that athletes’ psychological responses regarding sport resumption during rehabilitation are related to whether or not athletes return to full competition by 12 months. Most importantly, the difference found in psychological responses at 6 months, before athletes were expected to return to competitive sport, has important clinical implications. When treating injured athletes, clinicians should aim to address all aspects of recovery, not just the physical component, in order to help facilitate athletes returning to competitive sport.