I want to try recovering from an ACL tear without surgery. Since I’m on a soccer scholarship, the surgeon advised me to come back in four weeks if rehab doesn’t work. If I’m getting better, could I go longer than the four weeks? What’s the magic in that number?

The four week time period may be just a way to follow-up quickly after a trial of rehab. If you have made enough progress to support continued therapy, you’ll know by then. But if it’s a marginal (or no) response, and you need to return-to-sports quickly to keep your scholarship, then surgery may be advised sooner than later.

It’s not that you couldn’t go to rehab for more than four weeks and still have a successful result. It’s more the fact that you are a high-activity athlete who wants to get back to your preinjury level of play as soon as possible. Waiting more than four weeks would mean missing important competitive events — and that would defeat the purpose of trying rehab for a rapid return to high-demand sports activities.

In general, anyone who qualifies for nonoperative care but who experiences any signs of knee instability (pain, swelling, buckling) should return to their physician right away. The risk of reinjury, episodes of instability, and premature knee joint degeneration is great enough to warrant early surgical intervention.