Embargoed until October 2024

Background Psychological and physiological factors could negatively affect patients' recovery and increase re-injury rate after anterior cruciate ligament reconstruction (ACLR). In daily practice surgeons and physiotherapists see athletes struggling to improve muscle strength and complaining of lack of self-confidence during the progress of return to sport. The Tampa Scale for Kinesiophobia is a valid questionnaire to measure a patient's psychological status and isokinetic test is widely used to measure muscle recovery. Hypothesis Patients with kinesiophobia have inferior self reported and functional outcomes after ACLR. Methods 140 patients, 100 (71%) men and 40 (29%) women, mean age 32.5 (±8.3), were included in the study 5.5 (±1.25) years after ACLR. All patients were operated by two senior surgeons. Preoperative and postoperative assessments were performed by two sports specialized physical therapists. Patients completed the Knee injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee score and Tampa Scale of Kinesiophobia (TSK-17). Quadriceps and hamstring muscle isokinetic strength was assessed at 60°/sec and 180°/sec using the HumacNorm dynamometer. Functional performance was tested with the single-leg-hop test for distance and the Y-balance test for anterior reach. Variables of the study were described by means and standard deviations. Shapiro-Wilk test was conducted to test for normality of the variables and unpaired t-tests were used to test for differences between subgroups. After tests were conducted, simple Bonferroni adjustment was applied to account for the number of tests made. Results 68/140 patients (48.6%) reported a Tampa kinesiophobia score equal or higher than 37 points, above which is the cut off score for kinesiophobia. Patients with kinesiophobia had statistically significant lower scores in the KOOS Symptoms (p=0.001) and Quality of Life subscores (p=0.001), Total score (p=0.001) and the Oxford Knee Score (p=0.024). Isokinetic peak torque muscle strength mean deficits at 60°/sec and 180°/sec for knee flexion and extension were between 6% and 7% for patients with kinesiophobia and between 2% to 4% for patients without kinesiophobia compared with the contralateral side, with no significant differences between groups. There was no statistically significant difference in the Single-leg-hop test for distance leg ratio (0.98 (±0.19) and 1.00 (±0.26)) and the Y-balance test for anterior reach leg ratio (0.99 (±0.08) and 1.01 (±0.07)) respectively between the groups. Conclusion At 5 years after ACLR operated leg functional performance is equal to nonoperated leg. However kinesiophobia is present in nearly half of patients. Strength and functional tests alone are not good enough instruments for assessing complete recovery, on the other hand self-reported questionnaires have high correlation to kinesiophobia after ALCR. Further studies are needed to avoid development of kinesiophobia as well how to recognize phobia at early stages of rehabilitation.