You are right — studies show that half of all patients who have ACL reconstructive surgery develop knee osteoarthritis later. That’s especially true for the folks who have an injury severe enough to damage the meniscus (cartilage) along with the ACL. Researchers in the area of sports medicine are working hard to figure out why this happens. They hope to find risk factors that predict who will develop arthritis and then perhaps modify those risk factors.
Based on what we know so far, it looks like delays in surgery should be avoided. The sooner surgery can be done following the injury, the better. Reconstructing the ruptured ligament before further damage can be done to the joint surface and joint cartilage may be beneficial. A preoperative program of patient education and strengthening exercises is a good idea. The physical therapist will show you how to avoid dangerous sideways and rotational movements that can add insult to injury.
There is some evidence that the type of graft material used to reconstruct the ruptured ligament can make a difference. Right now, it looks like the hamstring graft is a safer bet when trying to avoid arthritis later. The exact reasons for the difference in results between patellar tendon grafts and hamstring grafts are not clear yet. Surgery should also include repair (not removal) of any damaged cartilage whenever possible.
After surgery, every effort should be made to ensure restoration of joint motion and balanced muscle strength between the hamstring muscles along the back of the leg and the quadriceps muscle along the front of the leg. By participating in a pre- and post-operative physical therapy program, it is possible to improve balance, strength, and stability. At the same time, such efforts may help prevent additional damage to the joint that can ultimately contribute to the development of arthritis later.