Q: I had my ACL repaired two years ago and just reinjured it again. My surgeon wants me to try physiotherapy for a few months. If that doesn't work, I can have surgery again. Can they repair this a second time?

A: Revision surgery for failed anterior cruciate ligament (ACL) rupture is uncommon but sometimes a necessary procedure. The surgeon confirms there is ACL deficiency with clinical testing and (if necessary) arthroscopic examination.

Physiotherapy can be helpful to correct any postural issues related to the knee. The therapist will teach you activity modifications to help prevent further injury or damage.

A program of manual therapy and exercises will help restore kinaesthesia (awareness of movement), proprioception (joint sense of position), and motor control(coordination of brain, nerve, and muscle function). Flexibility, strength, and endurance are three other areas the therapist will address.

Give the conservative (nonoperative) approach plenty of time before considering surgery. It can take two to six months to recover lost strength, incorporate correct alignment, and regain normal motor control.

Compliance on your part with your home program is a key factor in success. If the knee remains unstable despite all rehab efforts, then a second (revision) surgery may be needed. The surgeon will have to evaluate your situation carefully.

A second ACL reconstructive surgery will probably require another graft to replace the failed graft. Graft tissue may be taken from your other knee or from a donor bank. The source of the graft material may depend on where the first graft came from (your injured knee, your other knee, or donor bank).

Studies in the past seem to indicate that the most common reasons for ACL reconstructive graft failure are technical problems. The number one reason may be tunnel malposition (the tunnel is where the graft is threaded through and then attached to the bone).

And, in fact, a recent large combined U.S./Canadian study confirmed that technical considerations are important. But age, type of graft (bone-patellar tendon-bone), and injury to the knee cartilage are also significant factors. The source of the graft (whether taken from the patient or from a donor bank) might be important but this study was unable to prove that one way or the other.

Your surgeon will be able to advise you more directly once you have completed the recommended rehab program. It is entirely possible for you to recover function through a carefully designed rehab program. Stick with it and good luck!

Reference: The MARS Group. Descriptive Epidemiology of the Multicenter ACL Revision Study (MARS) Cohort. In The American Journal of Sports Medicine. October 2010. Vol. 38. No. 10. Pp. 1979-1986.