knie

Knie is the joint that connects the thigh to the leg and is one of the largest and most complex joints in the human body. It consists of three bones—the distal femur, proximal tibia, and the patella (kneecap)—and includes two main articulations: the tibiofemoral and the patellofemoral joints. The joint surfaces are covered by articular cartilage, and the menisci cushion contact between bone surfaces and enhance stability.

The knee is surrounded by a capsule and reinforced by four main ligaments: the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), which control front-to-back movement, and the medial collateral ligament (MCL) and lateral collateral ligament (LCL), which provide side-to-side stability. Bursae and muscular support from the quadriceps and hamstrings, via the patellar tendon and other insertions, contribute to function. The blood supply arises from the genicular arteries, and sensory nerves come from surrounding tissues.

Functionally, the knee bears weight, absorbs shock, and enables a range of motion from close to full extension to deep flexion, typically about 0 to 130–135 degrees in healthy adults. Its biomechanics involve rolling and gliding of the femoral condyles on the tibial plateau, with some rotation of the tibia when flexed and patellar tracking within the femoral groove.

Common conditions include osteoarthritis, meniscal tears, ACL injuries, patellofemoral pain syndrome, and patellar dislocation. Fractures around the knee, such as tibial plateau and patellar fractures, also occur, especially after trauma.

Diagnosis and treatment rely on clinical evaluation and imaging (X-ray, MRI). Management ranges from rest, physical therapy, and analgesia to arthroscopic or open surgery, ACL reconstruction, or knee replacement for advanced disease. Prevention emphasizes strengthening, flexibility, and safe movement practices.