Multiligament knee injuries are typically caused by high-energy mechanisms and are classified according to the number of ligaments involved using Schenk's classification (Knee Dislocation) into KD 1, KD 2, KD 3, and KD 4. These types of injuries can have devastating consequences on the individual's quality of life, affecting their ability to return to sports and perform daily activities.

In the literature, there is still no consensus on the management of these types of traumas, both due to the wide range of situations that can present to the orthopedic surgeon and the difficulty in their diagnostic and therapeutic framing. The main controversies concern the conservative or surgical management of the injuries and the timing of when to undertake surgical treatment, if at all.

The instability resulting from multiligament knee injuries is poorly tolerated by patients, who find their daily activities limited. It is also well known that this instability can dramatically accelerate the development of osteoarthritis, leading to the need for joint replacement surgery even in young individuals, thus increasing the likelihood of revisions and re-operations over time.

Due to the lack of standardized and satisfactory treatment, the economic cost of the outcomes of multiligament knee injuries is particularly high. A recent study by XXX showed that only XXX% of individuals are able to return to work. The rate of participation in sports is even lower, which has a long-term potential impact by increasing the risk of sedentary lifestyle-related diseases such as obesity, diabetes, and cardiovascular diseases.

The choice of surgical treatment aims to eliminate the patient's subjective feeling of instability and to repair, when possible, or reconstruct the injured ligament structures to reduce the risk of secondary osteoarthritis. Available studies in the literature are often case reports presenting short- and medium-term results of non-standardized surgical techniques with great heterogeneity in rehabilitation protocols, so the real long-term effectiveness of these treatments in terms of joint stability and osteoarthritis prevention is not known.

Inclusion Criteria:

1. Patients aged between 18 and 65 years at the time of surgery
2. Male and female gender
3. Patients undergoing multiligamentous knee reconstruction from January 1, 2000, to December 31, 2019, at the Rizzoli Orthopedic Institute.

Exclusion Criteria:

1. Patients no longer reachable;
2. Patients who do not consent to be included in the study;
3. Pregnant women;
4. Presence of infection or hematologic, rheumatic, or coagulative disorders at the time of evaluation.

Patients will be recruited from all subjects treated surgically with multiligament knee reconstruction techniques from January 1, 2000, to December 31, 2019, at the Rizzoli Orthopedic Institute.