Table 1

Operational definitions

Chronic ACL injuryA non-operatively treated ACL injury with persistent complaints of instability more than 6 months after initial injury
Acute ACL reconstructionAn ACL reconstruction taking place within 3 months from injury
Delayed ACL reconstructionAn ACL injury that is planned to be treated with reconstruction and take place after 6 months from injury, or an ACL reconstruction that takes place after non-operative treatment has been tried without a satisfactory outcome
InstabilityA patient’s perception of the knee not feeling stable
LaxityThe passive displacement of the knee joint when an external force or torque is applied
  • ACL, anterior cruciate ligament.