Joints are anatomical structures formed at the point where two or more bones meet, allowing movement between them while also contributing to stability and the transmission of mechanical loads during daily activities. Depending on the degree of mobility they allow, joints are classified into immovable joints (such as the sutures of the skull), slightly movable joints (such as the intervertebral discs of the spine), and freely movable joints or synovial joints, including the knee, hip, and shoulder, which represent the main focus of orthopedic study.
Synovial joints are typically composed of articular cartilage, which covers the bone surfaces and reduces friction, the joint capsule that surrounds and stabilizes the joint, the synovial membrane that produces synovial fluid for lubrication, and ligaments that provide additional stability.
Normal joint function depends on the coordinated interaction of all these structures, as well as the surrounding muscles and tendons that control movement and maintain dynamic stability.
Pathological conditions such as osteoarthritis, rheumatoid arthritis, traumatic injuries, or inflammatory joint diseases can disrupt the structure or function of joints, leading to pain, stiffness, reduced mobility, and significant impairment of the patient’s quality of life.