## 1 Introduction  
The Anterior Cruciate Ligament (ACL) is a crucial stabilizer of the knee, limiting the forward translation of the tibia in relation to the femur and preventing excessive internal rotation of the knee [1, 2]. It consists of two bundles: the anteromedial bundle, which functions during flexion to restrain anterior tibial translation, and the posterolateral bundle, which provides rotational stability during extension [2, 3]. ACL tears account for approximately 20% to 50% of all knee injuries [3, 4]. These injuries affect both athletes and the general population, and have shown an increasing tendency across the years [5], particularly due to a rise in sports participation [4, 6, 7]. While conservative treatment may be appropriate for cases of partial tears [3], it is typically reserved for less active patients or those with significant comorbidities due to the increased joint instability, greater difficulty with certain activities, such as jumping or descending stairs, lower rates of return to sport, and an increased risk of developing osteoarthritis [8]. Nevertheless, the preferred treatment is surgical reconstruction (ACLR) [7; 8], although there is no gold standard for which is the best graft choice. The two most common techniques involve the use of four-strand hamstring tendon (HT) and bone-patellar tendon-bone (PT), each with its own advantages and disadvantages [7]. PT grafts are associated with faster incorporation, greater stability, better return to pre-injury levels, and decreased incidence of graft failure (1.9% vs. 4.9%). Nonetheless, they are more likely to have an extension deficit greater than 3 degrees and more anterior knee pain when kneeling [1; 7; 9]. Due to the greater stiffness of the PT autograft and the rigid fixation that bone-to-bone healing allows, it was expected that knees reconstructed with this graft would show less valgus, as well as less general laxity, as the ones reconstructed with HT autografts [10]. HT grafts are associated with reduced extensor strength deficits, a lower probability of osteoarthritis development, decreased incidence of a postoperative range of motion complications requiring re-intervention, fewer donor-siteorbidities, and improved cosmetic outcomes. However, it predisposes for a greater valgus knee alignment on initial contact during single-hop landing and greater flexion and internal rotation deficits, especially if both the gracilis and semitendinosus were harvested [1; 6; 7; 11; 12; 13]. The choice of autograft should be shaped to the patient's necessities and expectations, as well as the surgeon's experience and preference, to achieve the best possible outcomes [13; 14]. Even though ACLR restores knee stability, improves functional outcomes, and prevents further articular damage--specifically cartilage injury, meniscus tears, and osteoarthritis [15]--a significant number of patients still fail to regain their pre-lesion levels of movement [5], with only 65% of athletes returning to pre-injury levels of participation [6; 16; 17]. Two factors that may contribute to these unsatisfactory outcomes are the lack of standardized return-to-sport guidelines and inadequate assessments to address physical and psychological impairments [5; 18; 19]. Return-to-sport criteria following ACLR include the time since surgery and subjective measures such as pain and instability, the absence of effusion, range of motion normalization, quadriceps strength, and performance on the side-hop test [5; 18; 20]. The side-hop test is a pivotal test in return-to-sports evaluation because not only is it capable of analyzing muscle strength and endurance but it can also give information on proprioceptive and neuromuscular adjustments that only a dynamic test can provide [17; 19; 21]. Its unique ability to challenge dynamic knee stability in the frontal and transverse planes makes it particularly suited for assessing biomechanical parameters such as knee valgus/varus angles and joint movements.