Porth's Essentials of Pathophysiology, 4e

Disorders of the Skeletal System: Trauma, Infections, Neoplasms, and Childhood Disorders 1079

C h a p t e r 4 3

Sports-Related Injuries Sports and athletic activities are particularly common causes of acute and overuse injuries of the musculoskel- etal system. Acute injuries are caused by sudden trauma and include injuries to soft tissues (contusion, strains, and sprains) and to bone (fractures). Overuse injuries have been described as chronic inju- ries, including tendinopathies, stress fractures, com- partment syndrome, and shin splints, that result from constant high levels of physiologic stress without suf- ficient recovery time. 2–4 They commonly occur in the elbow (“little league elbow” or “tennis elbow”) and in tissue where tendons attach to the bone, such as the heel, knee, hip, and shoulder. Factors that increase the likelihood of sports injuries include intrinsic and extrinsic risk factors. 4 Intrinsic risk factors are those that are unique to the individual that increase the likelihood of sustaining an injury, such as maturation status. Contact sports pose a greater threat for injury to the neck, spine, and growth plates in chil- dren and adolescents, who have not yet reached matu- rity. Extrinsic risk factors are those that, when applied to the athlete, may increase the risk of injury. They may include training methods, or equipment, and environ- ment that may have an effect on the magnitude, stress, or force applied to the body. They include factors such as athletic activity that is repeated so often that areas of the body do not have enough time to heal between efforts. Injuries can often be prevented by proper training, use of safety equipment, and limiting the level of competi- tion according to skill and size rather than chronologic age. Adequate warm-up time, hydration, and proper nutrition are also key factors in injury prevention. SoftTissue Injuries Most skeletal injuries are accompanied by soft tissue (muscle, tendon, or ligament) injuries. These injuries include contusions and hematomas. A contusion is an injury, or bruise, that results from direct trauma and is usually caused by striking a body part against a hard object. 5 Although the resulting dis- ability is usually minor, some contusions can be quite painful. Muscle bruises are common in all athletic events, even the so-called noncontact sports. The thigh and the arm are the most commonly involved. In contu- sions, the skin overlying the injury remains intact while the injured tissue undergoes a well-defined sequence of events including microscopic rupture of blood vessels and damage to muscle cells, swelling, and inflammation. The area often becomes ecchymotic (i.e., black and blue) because of local hemorrhage; later, the discoloration gradually changes to brown and then to yellow as the blood is reabsorbed. A large area of local hemorrhage is called a hema- toma. Hematomas cause pain as blood accumulates and exerts pressure on nerve endings. The pain increases with movement or when pressure is applied to the area. The pain and swelling of a hematoma take longer to subside than those accompanying a contusion.

The treatment for a contusion and a hematoma con- sists of elevating the affected part and applying cold for the first 24 hours to reduce the bleeding into the area. A compression wrapping is sometimes helpful in the early stages. Reinjury is avoided by appropriately protect- ing the area and allowing for complete healing to occur before returning to activities. Joint (Musculotendinous) Injuries Joints, or articulations, are sites where two or more bones meet. Joints (i.e., diarthrodial) are supported by tough bundles of collagenous fibers called ligaments that attach to the joint capsule and hold the articular ends of bones together and by tendons that join muscles to the periosteum of the articulating bones (see Chapter 42). Joint injuries usually involve mechanical overloading or forcible twisting or stretching. Strains and Sprains Strains and sprains are both musculoskeletal injuries, but they differ in terms of the tissue that is affected. 5 Strains involve muscles, or more precisely the muscle– tendon unit. Sprains involve the supporting ligaments of a joint. A strain is a stretching or partial tear in a muscle or a muscle–tendon unit. Strains commonly result from sudden stretch of a muscle that is actively contracting. Although there usually is no external evidence of a spe- cific injury, an inflammatory response develops at the injured site, followed by fibrous tissue replacement of the damaged muscle fibers. Muscle strains are usually characterized by pain, stiffness, swelling, and local ten- derness. Pain is increased with stretching of the muscle group. Strains can occur at any age but are more com- mon in middle-aged and older adults. With aging, the collagen fibers in the muscle–tendon unit change; as a result, muscles have decreased elasticity and are more susceptible to injury. Common sites of muscle strains are the lower back and the cervical region of the spine. The elbow and the shoulder are also supported by muscle– tendon units that are subject to strains. Strains of mus- cle units around the hip, hamstring, and quadriceps are commonly associated with athletic activities. Proper warm-up exercises increase the flexibility of muscle–tendon units and help prevent these types of injuries. A sprain, which involves the joint ligaments or cap- sule surrounding the joint, resembles a strain, but the pain and swelling subside more slowly. It usually is caused by abnormal or excessive movement of a joint. With a sprain, the ligaments may be incompletely torn or, in a severe sprain, completely torn or ruptured (Fig. 43-1). The signs of sprain are pain, rapid swell- ing, discoloration, and limitation of function. Any joint may be sprained, but the ankle joint is most commonly involved, especially in high-risk sports such as basket- ball. Most ankle sprains occur in the lateral ankle when the foot is turned inward under a person, forcing the ankle into inversion beyond its structural limits. Other common sites of sprain are the knee (the collateral