DEAR DOCTOR K: I injured my PCL playing football. How long will my recovery take? DEAR READER: Let’s start with some knee anatomy. The posterior cruciate ligament (PCL) and the anterior cruciate ligament (ACL) are two tough bands of fibrous tissue. The ACL is injured more often than the PCL, which is why many people have heard of the ACL but not the PCL. The ACL and PCL connect the thighbone (femur) and the large bone of the lower leg (tibia) at the knee joint. The ACL and PCL form an “X” pattern that stabilizes the knee against front-to-back and back-to-front forces. (I’ve put a detailed illustration of the knee joint on my website, AskDoctorK.com.)

DEAR DOCTOR K: I tend to sprain my ankle fairly often. Are there any exercises that could help me strengthen my ankles and prevent future sprains? DEAR READER: Your ankles are remarkable joints. They must bear the full weight of your body, yet stay nimble and flexible. Every step, every jump, every move puts your ankles through a surprising range of motion. Even when you stand quietly, your ankles are constantly making minute adjustments to help you stay balanced.