The anatomy of the pediatric musculoskeletal system is unique and reflects the active growth and development that occurs during childhood. Fracture classification, treatment approach, and types of complications are directly related to this unique anatomy. In general, both injury patterns and treatment approaches in children in whom closure of the physes (growth plates) has already occurred is similar to those of the adult. Therefore, the major focus of this chapter is directed at injuries occurring in the prepubescent child with open physes. In addition, diseases specific to children that cause nontraumatic musculoskeletal complaints are covered.
The long bones of children consist of discrete anatomic areas. The physis is an area of growth cartilage and may occur at one (e.g., the phalanges) or both (e.g., the tibia and the femur) ends of a long bone. The area of bone between a physis and the adjacent joint is termed the epiphysis. An apophysis is an outgrowth of bone, usually with its own ossification center in childhood that often serves as a point for muscle or ligament attachment. The midshaft of a long bone is referred to as the diaphysis. The metaphysis of a long bone represents the area between the diaphysis and the physis (Figure 140-1; see chapter 267, "Initial Evaluation and Management of Orthopedic Injuries").
The anatomy of the pediatric long bone as demonstrated by the femur. Longitudinal growth occurs at the physes (growth plates) located at either end. Bony prominences that serve as sites of muscular or ligamentous attachment are known as apophyses (e.g., greater trochanteric apophysis).
The long bones of children are less dense and more porous than the long bones of adults. Pediatric long bones respond to mechanical stress by bowing and buckling rather than fracturing through and through, as in adults. The periosteum of the diaphysis and the metaphysis is thick in children and is continuous from the metaphysis to the epiphysis, surrounding and protecting the mechanically weaker physis. The weakness of the physis is in part related to the reduced oxygen tension found in the hypertrophic zone of the physis. This hypertrophic zone is the location of frequent fractures within the physis. The physis is also sensitive to alterations in the blood supply, and physeal injuries can result in growth disturbance. Compression forces alone may also affect bone growth. This is particularly true when compression forces are applied to the epiphyseal side of the physis. The injury to bone growth caused by compression results from interruption of the epiphyseal circulation to the reproductive cells of the physis.
The growth of the musculoskeletal system and its response to injury are influenced by the growth of muscle and connective tissue. The ligaments of children are stronger and more compliant than in adults, and ligaments tolerate mechanical forces ...