Self-efficacy of knee function in patients with an Anterior Cruciate Ligament injury

Sammanfattning: Abstract Self-efficacy of knee function in patients with an Anterior Cruciate Ligament injury The overall purpose of this thesis was to investigate the clinical relevance of perceived self-efficacy of knee function among patients with an Anterior Cruciate Ligament (ACL) injury. Study 1: The purpose was to develop an instrument for measuring perceived self-efficacy of knee function in patients with an ACL injury. A total of 210 patients with an ACL injury participated in the study. Items were generated and analysed and the final Knee Self-Efficacy Scale (K-SES) was tested for reliability and validity. A factor analysis revealed two factors that should be treated as separate sub-scales; how the patients perceived their present physical performance/function (K-SESPresent) and how the patients perceived their future physical performance/prognosis of their knee (K-SESFuture). The K-SES was found to be reliable and valid for perceived self-efficacy of knee function in patients with an ACL injury. Study 2: The purpose was to describe perceived self-efficacy of knee function prospectively up to one year after ACL injury/surgery. The purpose was also to describe the influence of symptoms, gender, age and physical activity on the patients? perceived self-efficacy of knee function. Thirty patients with a recent ACL injury and 33 patients with an ACL reconstruction participated. The perceived self-efficacy of knee function changed significantly during the course of rehabilitation. There was also a significant increase between each test occasion up to six months for patients with an ACL injury and up to twelve months for patients who had undergone surgery. The improvement in perceived self-efficacy of knee function could, however, only be partly explained by the improvement in subjective symptoms. Furthermore, a significant difference in self-efficacy of knee function was observed early in the rehabilitation process, between men and women, both young and old, and patients with a low and high pre-injury physical activity level. Study 3: The purpose was to explore physical and psychological measures believed to determine patients? perceived self-efficacy of knee function in the rehabilitation of patients with an ACL injury. One year after ACL injury or reconstructive surgery, 116 patients were tested for their self-efficacy of knee function and for 15 outcome measures. A stepwise linear regression analysis was conducted on the K-SES to detect the strongest model describing self-efficacy of knee function. The Lysholm score, KOOSSports/Recreation, Internal Locus of Control and Locus of Control by Chance explained 40% of the variance in the complete K-SES as well as 41% of the variance for K-SESPresent. The strongest model, explaining 38% of the variance for K-SESFuture, was the Lysholm score, KOOSSports/Recreation, TegnerPresent level, and Internal Locus of Control. Study 4: The purpose was to explore the potential of the K-SES to predict outcome one year after an ACL reconstruction. Thirty-eight patients scheduled for an ACL reconstruction were evaluated pre-operatively using the K-SES. One year after surgery, patients were evaluated using outcome measures for present physical activity, knee symptoms and knee muscle function. K-SESPresent and K-SESFuture were found to be significant predictors pre-operatively of present physical activity, knee symptoms and knee muscle function one year after ACL reconstruction, when adjusted for age, gender and pre-injury physical activity level (TegnerPre-injury). Conclusion: The K-SES was found to be a reliable, valid and responsive instrument to be used for assessing self-efficacy of knee function in patients with an ACL injury. The possible determinants of the K-SES may help both to provide a better understanding of some of the underlying factors characterising self-efficacy of knee function and to improve strategies in the rehabilitation of patients with an ACL injury. Clinicians may consider using the K-SES in order possibly to predict the outcome after ACL surgery and rehabilitation.