Anterior cruciate ligament (ACL) injuries are among the most common knee ligament injuries, causing joint instability and impairments. Besides being challenging, this type of injury greatly affects the athlete's passion and wellbeing, and it is associated with several risk factors. Injuries to the ACL are estimated to occur within 80,000 to 250,000 young, active and healthy athletes each year. This cross-sectional observational study aimed at translating, adapting cross-culturally, and investigating the psychometric properties of the Marx Activity Rating Scale (MARS) and the Knee Stability in Sports/Cutting-Pivoting Ability (KSS/CPA) scale in Saudi patients with anterior cruciate ligament injuries. For this study, a convenient sample size of 100 athletes with ACL injuries and healthy participants will be selected from different Saudi hospitals and clubs. Study participants will be informed about the study and a consent form will be obtained before they participate. A number of scales will be used as outcome measures, including the MARS, KSS/CPA scale, Knee Injury, and Osteoarthritis Outcome Score, Lysholm Knee Score, and International Knee Documentation Committee Subjective Knee Form. Internal consistency of both the MARS and KSS/CPA scales will be tested using Cronbach's alpha. A construct's validity will be measured by Spearman's correlation coefficient. Content validity can be determined by examining whether there are floor and ceiling effects. A significance level of 0.05 will be used to determine whether the data is significant. Ultimately, the study will help patients with ACL injuries to make informed decisions about their treatment, empower healthcare professionals to understand patients' concerns, and facilitate research.