Clinical Geriatrics

This article is the sixth and final article in a series on trauma care and the older adult. The series discusses the growing problem of trauma in the elderly, including its causes and possible ways to prevent it, care in the acute stages, and manifestations and treatment strategies when trauma involves the torso, spine, brain, and hip. Authors include skilled experts in the trauma field representing various specialties at the R Adams Cowley Shock Trauma Center at the University of Maryland Medical Center and the University of Maryland School of Medicine.

Introduction
Traumatic injuries involving falls are a major concern for a rapidly aging population.¹ Hip fracture is the second leading cause of hospitalization for older persons, and each year there are approximately 350,000 hip fractures in the United States, occurring predominantly in older adults (≥ 65 yr) with underlying osteoporosis.^2,3 Hip fractures frequently result from minor trauma or a fall, although they may also occur as the bone becomes so deteriorated or fragile that it can no longer support the weight of the individual. Although some data suggest that the age-adjusted incidence of hip fracture has decreased in the last decade,^4,5 the dramatic growth of the older population will greatly increase the number of hip fractures that occur annually; by the year 2040, it is expected that there will be 500,000 hip fractures annually.⁶ The incidence of hip fractures increases exponentially with age (half of all hip fractures occur in persons over age 80 yr), and approximately 75% of hip fractures occur in women.³ These injuries have significant consequences not only to the person affected, but also to his/her family and to society in general. This article will address: (1) the classification of hip fractures; (2) what is known about the sequelae of hip fractures; and (3) aspects of prevention.

Classification of Hip Fractures
The hip is a ball-and-socket synovial joint that is enclosed by a thick articular capsule. It is able to support one’s entire weight and move freely to allow mobility and motion in an almost 360-degree manner. Ligamental structures and muscles help provide support to the hip joint. The round head of the femur articulates with the cuplike acetabulum. This results in significant shearing forces as the hip joint moves to allow mobility. A fracture results when exerted forces exceed the strength of the bone, and they may occur at any aspect of the proximal femur from its head to the first 4-5 cm of the subtrochanteric area. Fractures involving the greater trochanter are rarely the result of trauma and most frequently result from avulsion-type injuries, as may occur in gymnasts and dancers. Intertrochanteric fractures occur when the bone between the greater and lesser trochanters breaks with or without displacement. Subtrochanteric fractures most commonly occur in persons suffering from trauma.

Hip fractures are classified based on their relation to the hip capsule (eg, intracapsular and extracapsular), specific location (eg, head, neck, trochanteric, intertrochanteric, subtrochanteric), and degree of displacement. Fractures involving the femoral head and neck are classified as being intracapsular; those of the trochanteric, intertrochanteric, and subtrochanteric areas are classified as being extracapsular. Intracapsular hip fractures are more prone to complications, such as nonunion and avascular necrosis due to the thick capsule that surrounds these fractures and separates them from soft tissues and blood supply. This results in an impaired ability to form a callous, and thus to heal appropriately. Fractures may have a single defect or multiple defects (comminuted fracture) associated with it.