Sprains and strains are injuries affecting the muscles and ligaments. A sprain is an injury or tear of one or more ligaments that commonly occurs at the wrist, knee, ankle or thumb. A strain is an injury or tears to the muscle. Strains occur commonly in the back and legs.
The articular surfaces of the body’s joints are lined by hyaline cartilage, a smooth tissue that serves as a shock absorber and allows easy movement of the bones within the joint. Normal wear-and-tear or injury can damage and cause defects in the cartilage, resulting in irregular articular surfaces that interfere with movement, causing pain, swelling and disability.