A musculoskeletal injury (MI) refers to any injury to the body’s bones, muscles, joints, or attaching ligaments and tendons. As these are the bodily systems that are responsible for movement, this type of injury is generally caused by activity, though it may also be caused by a trauma, like an accident, or by heredity. Age is also a factor, as activity over time can lead to such conditions as osteoarthritis, a type of musculoskeletal injury involving degeneration of joint structures. Since these injuries affect movable parts of the body, immobilization of the injured area is a common form of treatment, although, depending on the damage, treatment recommendations can range from surgery to icing to stretching.
The human skeletal system is made up of 206 bones, the majority of which are movable. These include the bones of the arms, legs, hands, and feet, as well as those of the pelvis, spine, shoulders, and skull. Bones attach to one another via lengths of collagen-based connective tissue known as ligaments, which surround and cover the joints between them. Muscles move the bones about these joints. They do so by attaching at either end to two bones via rope-like tendons. This type of muscle is referred to as skeletal muscle, whereas the muscle in the heart wall is known as cardiac muscle and the muscle in the walls of the esophagus, intestines, and other bodily vessels is known as smooth muscle.
Damage to any of the above structures can be classified as a musculoskeletal injury. Common musculoskeletal injuries afflicting the bones are fractures, which are bone breaks typically brought on by an abrupt impact, like a blow or a fall. Stress fractures can be brought on over time by a repetitive activity such as running.
Injuries of the ligaments between the bones are sprains and tears, in which the ligament is overstretched or ruptured, either partially or completely. An example is a sprained ankle, which most often occurs when the foot is rolled at the ankle so that the sole of the foot turns inward, resulting in a sprain or overstretching of the talofibular ligaments along the outside of the joint.
A common musculoskeletal injury of the muscles is a strain, in which the muscle tissue is stretched beyond its normal limits much like a ligament during a sprain; similarly, muscle tissue can be torn. This type of injury normally occurs during a strenuous activity, as when a sprinter pulls a hamstring mid-stride. The tendons that attach muscle to bone are more likely to sustain a musculoskeletal injury, however, as they are less flexible and therefore more likely to absorb forces transferred across a joint. Common tendon injuries include strained or torn tendons — also a consequence of activity — and tendinitis, an inflammation of a tendon that results from frequent and repetitive activity, such as a tennis player experiences at the shoulder or elbow.
Joint injury is a final category of musculoskeletal injury. This may range from a dislocation caused by a trauma to a joint disease like arthritis. Arthritis may be classified as an injury as it involves damage to joint structures. Osteoarthritis occurs over time as the cartilaginous disk that acts as a cushion between the adjoining bones gradually wears away, leading to stiffness, pain, and inflammation at the joint; this condition may be exacerbated by injury or excessive loading on the joint over time, as from obesity. Rheumatoid arthritis is often genetic and involves inflammation of the joint’s synovial lining, the membrane that encapsulates the disk, several ligaments, and synovial fluid within the joint.