Many believe that highly active athletes need surgery more often than less active individuals. Others follow the guideline that anyone with an ACL tear is at risk for reinjury. And reinjury means even more damage to the meniscus and bone.

Often the amount of joint laxity present is used to determine degree of injury and the likelihood of surgery. Laxity in the knee is tested by measuring the amount the tibia (lower leg bone) slides forward under the femur (thigh bone).

But a 10-year study at the University of Delaware has disproved this method of guiding the surgery-verus-rehab decision. They tested many athletes with an ACL tear and found that anterior knee laxity and preinjury activity level are not good predictors of outcome.

They have proposed a new guidance system. It is based on a battery of clinical tests that look at neuromuscular adaptations of the joint. Neuromuscular adaptation refers to the ability of the muscles to contract at the right time and in the right amount to hold the tibia in place even without the ACL.

Several hopping tests are useful in making this determination. Further research is underway to find out if all four of the hop tests are needed (single hop, triple hop, crossover hop, timed hop). It's possible that there is one hop test best suited to this problem. Or it may be that the tests should be done in a specific order for the best results.

Evidently, not everyone has a good joint stiffening strategy to serve them in the absence of a normal ACL. But rapid, coordinated cocontraction of the muscles that cross the knee (hamstrings and quadriceps) can be achieved with the proper training program.

Talk to your surgeon about all the treatment possibilities available in your area. Ask your physical therapist to review this study and see if you qualify for conservative care.