What this Trial Is About

The goal of this observational study is to explore the significance of subject-reported outcomes and clinical parameters in relation to the occurence of prolonged presence of arthrogenic muscle responses (AMR) in anterior cruciate ligament (ACL) reconstructed patients. The main questions it aims to answer are: 1\. Is there a link between the long-term occurence of AMR in ACL reconstructed patients and the level of kinesiophobia experienced before or after their ACL surgery? We hypothesize that ACL patients with higher levels of kinesiophobia are more likely to exhibit prolonged AMR as an unconscious reaction to protect their affected knee joint. 2\. Is the long-term presence of AMR in ACL reconstructed patients linked to their subjective knee function and stability (at certain time points throughout their recovery)? Our hypothesis is that poorer subjective knee function and stability might be associated with the presence of prolonged arthrogenic muscle responses in ACL reconstructed patients. 3\. Is the prolonged presence of AMR in ACL reconstructed patients linked to their pain levels (at certain time points throughout their recovery)? Our hypothesis is that ACL patients with higher pre- and/or postsurgical pain levels may exhibit a higher degree of long-lasting AMR. 4\. Is the long-term presence of AMR in ACL reconstructed patients linked to clinical parameters such as swelling, isometric quadriceps and hamstrings strength and knee range of motion (at certain time points throughout their recovery)? Our hypothesis is that ACL patients with poorer outcomes in terms of these clinical parameters may be more likely to exhibit prolonged AMR. Participants will: * Fill in the following questionnaires 1 week before surgery and at 1 and 3 months after surgery: * Demopgraphical information * Knee Injury and Osteoarthritis Outcome Score (KOOS) * Lysholm Score (only question 1) * Tegner Activity Scale (current activity level, pre-injury activity level and desired activity level after recovery) * Numeric Rating Score (NRS) for pain levels during the day \& during the night * ACL-Return to Sport after Injury Scale (ACL-RSI) * Complete a testing protocol 5 months after their surgery, which includes bilateral electromyographical measurements of the hamstrings and quadriceps during jumping tasks and a quadriceps inhibition measurement using the interpolated twitch method to evaluate the presence of prolonged AMR.

Exploring Prolonged AMR in ACL Reconstructed Patients