Extracorporeal shock wave therapy (ESWT) is a safe, effective and non-invasive treatment option that can be used in different pathologies of the musculoskeletal system. It is based on the production of acoustic waves that interact directly with cells through mechanotransduction and activate the metabolic process that leads to tissue remodeling. ESWT can be classified as focused ESWT (fESWT) and radial ESWT (rESWT). While rESWT has a more superficial effect and reaches the maximum energy at the skin surface and distributes it radially to the tissue, fESWT develops the maximum energy at a focus located deeper in the body tissues. Studies have suggested that ESWT can be applied in combination with physiotherapy in patients affected by musculoskeletal disorders . In the literature, its effectiveness has been investigated in different musculoskeletal problems such as lateral epicondylitis, rotator cuff tendinopathy, Achilles tendinopathy, patellar tendinopathy, greater trochanteric pain syndrome, plantar fasciitis, and the best evidence supporting the use of ESWT has been obtained with low to medium energy levels for tendon disorders and high energy levels for tendon calcification and bone pathologies . The usability of ESWT treatment in knee-related pathologies has been discussed in the literature. In the treatment of ligament injuries such as the medial collateral ligament, fESWT has been shown to be a reliable and safe light energy shock wave treatment for the management of injuries without surgical indications . It has been reported that it is useful for inducing neovascularization in knee tendon injuries, improving blood flow in the bone-tendon junction, and supporting tissue repair. It has been thought that it has chondroprotective, anti-inflammatory, neovascularization, antiapoptotic and tissue regeneration effects on tissues, and therefore can be used in osteoarthritis. Another situation where the effect of ESWT on knee pathologies has been investigated is anterior cruciate ligament (ACL) surgeries. ACL reconstruction surgery aims to restore knee functions by providing the tightest possible repair so that the reconstruction of the torn ligament can be an excellent biological replacement. The functional outcome of this surgery depends on the solid healing of the graft-bone union in the bone tunnel. It is known that if the bone and tendon do not heal together, this may lead to knee pathology in the future. Although the studies on the use of ESWT after ACL surgery are quite limited, more focus has been placed on the effect of ESWT on the graft. Wang et al. applied 1 session of fESWT in operating room conditions during anterior cruciate ligament reconstruction surgery and reported that the patients had higher functional levels compared to the control group at 1 and 2 years. Song et al. included 72 patients who underwent anterior cruciate ligament reconstruction and applied ESWT once a week starting from the 2nd postoperative day in addition to the standard physiotherapy protocol for 6 weeks. Significant improvements in 6-week functionality and range of motion values compared to the control group, and no significant difference was found between the groups at the end of 6 months. Moi et al. compared graft healing and knee functional results in groups that received only physiotherapy, physiotherapy + ESWT once a week between weeks 6-8, and ESWT once a week between weeks 7-12. As a result, they reported that 6-session application had positive effects on graft healing; and there was no difference between knee functional scores at the end of 6 months . In another study, Weninger et al. applied ESWT at 1 and 6 weeks and evaluated the patients at 3, 6, 9 and 12 months. They reported that there were greater improvements in knee functionality, daily living and pain scores at all times in the ESWT group compared to the control group in the evaluation parameters. In addition, they reported that graft maturation was better in the ESWT group . Rehabilitation protocols commonly used after surgery aim to restore mobility and regain independence in daily living activities through muscle strengthening, functional exercises and proprioception training. When the studies conducted after anterior cruciate ligament surgery in the literature are examined, the effects of ESWT on outcomes such as muscle strength, proprioception and postural stability, which are targeted to be increased with rehabilitation protocols, have not been examined. No studies have been found in the literature examining the effects of ESWT on muscle strength, range of motion and postural stability, which are affected after surgery and targeted to be improved in the rehabilitation program, other than the effect of ESWT on graft healing after ACL reconstruction surgery. In this context, the aim of this study is to investigate the effects of fESWT applied in addition to the traditional rehabilitation protocol after anterior cruciate ligament surgery on muscle strength, range of motion, postural stability, pain and functionality.