Knee in 6: Anterior cruciate ligament (ACL) 뿯½ Anterior cruciate ligament (

Overuse, ligament sprain, meniscus injury, osteoarthritis 6–12 weeks for most soft-tissue injuries The knee is the largest and one of the most heavily loaded joints in the body, connecting the thigh bone to the shin bone while the kneecap glides in a groove at the front to assist with leg extension. Unlike the hip, the knee's bony surfaces are relatively flat, so stability depends heavily on a set of internal and surrounding ligaments.

Because the knee bears substantial load during walking, running, jumping, and pivoting, it is among the most frequently injured joints in sport and one of the most common sites of age-related osteoarthritis. Conditions range from overuse-related tendon and cartilage irritation to acute ligament and meniscus injuries.

This page reviews the knee's anatomy, common conditions across age groups and activity levels, how clinicians assess it, and general exercise and recovery patterns used in both non-surgical and post-surgical rehabilitation. Patellofemoral pain syndrome describes pain around or behind the kneecap, often related to how the kneecap tracks in its groove during bending movements, and is common among runners and young active individuals.