Alan Stein, nationally known conditioning and basketball coach, shares his insights into ACL (anterior cruciate ligament) injury reduction. He correctly notes that the goal is reducing injury because you cannot completely prevent injury.
The ACL helps stabilize the knee in the anterior-posterior (front-to-back) direction. When you experience an ACL tear, you feel extreme pain and often hear a 'pop' and notice immediate knee swelling (blood). In football, ACL injuries often occur when the planted leg is hit (clipped) from the outside, and frequently accompanied by meniscus (cartilage) injury/tear. In basketball, the plant foot may slip causing the knee to bend in or have overextension stressing the ACL.
Physicians diagnose the injury from symptoms and signs (knee instability on the 'anterior drawer' test). When I had an ACL tear, I could occasionally feel my upper leg bone (femur) slide forward during walking or stopping. Failure to correct that can lead to premature arthritis and early onset need for knee replacement.
"An ounce of prevention is worth a pound of cure." - Benjamin Franklin
ACL repair requires a lengthy recovery that generally requires an entire season for rehabilitation. Athletes also experience psychological 'uncertainty' as they reclaim their strength, mobility, and confidence in cutting on a repaired knee. Some athletes who are ACL deficient can develop enough strength in surrounding muscles to compensate (e.g. former Bills' running back Thurman Thomas). Improvements in surgery and rehab are bringing athletes back sooner (e.g. Blue Jays' pitcher Marcus Stroman).
Watch the videos Coach Stein provides for suggestions on improving hip and ankle mobility, landing, and deceleration footwork.