When is surgery indicated in anterior knee instability? Considerations on operative and functional treatment.

Rupture of the ACL may result in chronic anterior knee instability. However, in the majority of patients the secondary stabilizers of the joint such as collateral ligaments, menisci, and the capsule will compensate for this instability. We recommend surgical reconstruction of the acute rupture of the ACL only in the young, active athlete. Concomitant ruptures of capsuloligamentuous structures do not indicate surgical treatment: they may be treated by a plaster cast or a splint with good results. Chronic symptomatic anterior knee instability should first be treated by a vigorous muscle-training program. Surgery is performed only for those patients who cannot compensate for their instability after this rehabilitation program.