Knee joint

The knee joint is the largest synovial hinge joint in the human body, formed by the articulation of the femur, tibia, and patella, with the fibula contributing indirectly.[1][2][7][10] It comprises the tibiofemoral and patellofemoral compartments, supported by a joint capsule, medial and lateral menisci for shock absorption and stability, and key ligaments including the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL).[1][3][7][9] These structures enable primary movements of flexion and extension in the sagittal plane, plus limited medial and lateral rotation, facilitating walking, running, and weight-bearing via the screw-home mechanism.[1][2][12] In disease, the knee joint is commonly affected by osteoarthritis due to cartilage wear, rheumatoid arthritis involving synovial inflammation, and traumatic injuries to ligaments or menisci, leading to pain, instability, and reduced mobility.[3][7] While not a molecular therapeutic target like receptors or enzymes, it is a frequent site for surgical interventions such as ligament reconstruction or joint replacement, rather than direct pharmacological modulation.[1][3][7][10]