This document discusses ACL reconstruction failure and revision surgery. It notes that instability, stiffness, and pain could indicate failure. The main causes of failure discussed are traumatic failure, biologic failure, and technical error, particularly malpositioned tunnels. It provides statistics on ACL reconstruction and failure rates. It highlights potential pitfalls in revision surgery like malpositioned tunnels, widened tunnels, soft tissue grafts, and fixation devices. The conclusion emphasizes that ACL revision is demanding, requires careful preoperative planning, and has lower success rates than primary ACL reconstruction. Experience is important for managing revision cases.