In this longitudinal prospective cohort study including young people with anterior cruciate ligament (ACL) reconstruction, the investigators will evaluate if poor sensorimotor function at baseline can predict 1) graft rupture 2) the risk of contra-lateral ACL injury and 3) failure to return to sport/previous activity level within 3 years following ACL reconstruction.

In this longitudinal prospective cohort study including young athletic men and women (aged 15-35) with ACL reconstruction (ACLR), it will be investigated if poor sensorimotor function at baseline (1 year post ACLR), such as hop performance, muscle strength and postural orientation can predict 1) graft rupture 2) the risk of contra-lateral ACL injury and 3) failure to return to sport/previous activity level within 3 years following ACLR.

Statistics Separate logistic regression models will be used to elucidate the influence of each muscle sensorimotor function variable on the outcomes (graft rupture, contra-lateral injury, return to sport/activity level failure), adjusted for potential confounders. With the LSI for the single-leg hop test as main outcome, power calculations show that with a re-injury rate of 7%, an estimated odds ratio of 0.95, power=80% and alpha=5 %, at least 174 individuals are needed. Based on this calculation, 200 individuals will be included for the prospective analysis, allowing for an approximate drop-out of 10%.

Inclusion Criteria:

• 8-16 months after ACL reconstruction
• With or without associated injuries to other structures of the knee (e.g., collateral ligament(s), meniscal injury)
• Age 15-35 years.

Exclusion Criteria:

• ACL injury other knee and previous ACL injury index knee
• Diseases or disorders overriding the knee condition (e.g., neurological or rheumatological disease)
• Not understanding the languages of interest (any Scandinavian language or English).

Patients will be recruited from the Department of Orthopedics, Norrland University hospital, Umeå, Sweden and Skåne University Hospital, Lund, Sweden.