My daughter has anterior cruciate ligament injury. how will this affect her?

Instability?: If the ligament is completely torn and is unstable it may need to be reconstructed if the patient is not very active in sports, rehabilitation may be helpful to decrease pain, increase motion and strength sometimes a stabilization brace is helpful for sports.

Depends: In general it leads to instability of the knee when completely torn and should be repaired or braced to avoid furthervinjury to other structures in her knee. If only the posterior bundle is injured, however, the knee remains stable. The most important factor is her age. If she is past maturity above applies, otherwise she may respond to primary repair.