What’s the difference between an acute and chronic knee injury? I have a torn ACL that is several months old, but still flares up. Is it acute or chronic?

Acute usually refers to how recent the injury occurred and the symptoms present. Redness, warmth, swelling, and pain are signs and symptoms of an acute inflammatory reaction. This can happen months after the original injury when the joint is overused or reinjured in any way.

Chronic describes a condition that has been present past the normal time expected for healing. Most soft tissue and bone injuries heal completely within the first six weeks. The tissue will continue to remodel itself much longer, but strength and movement are restored.

So, it’s possible to have an old injury that’s considered chronic, but with acute flare-ups.