Anterior cruciate ligament (ACL) rupture, one of the most common knee injuries in sports, results in anteroposterior laxity, which often leads to an unstable knee. Traditional ACL reconstruction is performed with autograft; disadvantages of this technique are donor site morbidity and a long rehabilitation period. In the 1980s, artificial ligaments became an attractive alternative to biological grafts. The initial enthusiasm surrounding their introduction stemmed from their lack of donor morbidity, their abundant supply and significant strength, immediate loading and reduced postoperative rehabilitation. Synthetic grafts made of different materials such as carbon fibers, polypropylene, Dacron and polyester have been utilised either as a prosthesis or as an augmentation for a biological ACL graft substitute. Nevertheless, every material presented serious drawbacks: cross-infections, immunological responses, breakage, debris dispersion leading to synovitis, chronic effusions, recurrent instability and knee osteoarthritis. Recently, a resurgence of interest in the use of synthetic prostheses has occurred and studies regarding new artificial grafts have been reported. Although many experimental studies have been made and much effort has been put forth, currently no ideal prosthesis mimicking natural human tissue has been found.

The aim of anterior cruciate ligament (ACL) reconstruction is essentially to restore functional stability of the knee and to allow patients to return to their desired work and activities. While in the young and active population, surgery is often the best therapeutic option after an ACL tear, ACL reconstruction in middle-aged people is rather more controversial due to concerns about a higher complication rate. The purpose of our article is to establish, through a systematic review of the literature, useful decision-making criteria for the management of anterior cruciate ligament rupture in patients aged 40 years and older, guiding surgeons to the most appropriate therapeutic approach. Various reports have shown excellent results of ACL reconstruction in patients over the age of 40 in terms of subjective satisfaction, return to previous activity level, and reduced complication and failure rates. Some even document excellent outcomes in subjects of 50 years and older. Although there are limited high-level studies, data reported in the literature suggest that ACL reconstruction can be successful in appropriately selected, motivated older patients with symptomatic knee instability who want to return to participating in highly demanding sport and recreational activities. Deciding factors are based on occupation, sex, activity level of the subject, amount of time spent performing such highly demanding activities, and presence of associated knee lesions. Physiological age and activity level are more important than chronological age as deciding factors when considering ACL reconstruction.