eMedicine Specialties > Emergency Medicine > Trauma & Orthopedics

Fracture, Hip

Author: Moira Davenport, MD, Attending Physician, Departments of Emergency Medicine and Orthopedic Surgery, Allegheny General Hospital
Contributor Information and Disclosures

Updated: Apr 23, 2009

Introduction

Background

Fractures of the hip are relatively common in adults and often lead to devastating consequences. Disability frequently results from persistent pain and limited physical mobility. Hip fractures are associated with substantial morbidity and mortality; approximately 15-20% of patients die within 1 year of fracture. Interestingly, morbidity and mortality in those older than 90 years sustaining a hip fracture were not found to be statistically higher than others in the same age group without such an injury. 

Most hip fractures occur in elderly individuals as a result of minimal trauma, such as a fall from standing height. In young, healthy patients these fractures usually result from high-velocity injuries, such as motor vehicle collisions or falls from significant heights. Despite comparable fracture locations, the differences in low- and high-velocity injuries in older versus younger patients outweigh their similarities. High-velocity injuries are more difficult to treat and are associated with more complications than minor trauma injuries.

A recent study by Egan et al identified several risk factors associated with the risk of a hip fracture patient sustaining a second fall.¹  Increasing age, cognitive impairment, decreasing bone mass, decreasing depth perception, decreased mobility, dizziness, and a poor/fair self-perceived state of health were all linked to increasing likelihood of sustaining a second fall and thus a possible second hip fracture. 

For more information, see Medscape's Fracture Resource Center.

Pathophysiology

Skeletal anatomy

The hip joint is a large multiaxial ball-and-socket synovial joint, enclosed by a thick articular capsule. The hip joint is designed for stability and a wide range of movement. Next to the shoulder, it is the most moveable of all joints. During standing, the entire weight of the upper body is transmitted to the heads and necks of the femurs. The round head of the femur articulates with the cuplike acetabulum. The depth of the acetabulum is increased by the reinforcing fibrocartilaginous labrum, which "grasps" the femoral head, covering more than half of it. Articular cartilage covers the entire head of the femur, except for the pit (fovea) for the ligament of the femoral head.

The strong, loose fibrous capsule permits free movement of the hip joint, attaching proximally to the acetabulum and transverse acetabular ligament. The fibrous capsule attaches distally to the neck of the femur only anteriorly at the intertrochanteric line and root of the greater trochanter. Posteriorly, the fibrous capsule crosses to the neck proximal to the intertrochanteric crest without attaching to it. The fibrous capsule thickens to form 3 ligaments of the hip joint: the Y-shaped iliofemoral ligament (of Bigelow), the pubofemoral ligament, and the ischiofemoral ligament.

The hip joint is further supported by the femur and the muscles that cross the joint; this bone and these muscles are the largest and most powerful in the human body. The anatomy of the femur is shown in Media file 1.

Vascular supply

The vascular supply to the proximal femur is tenuous and provided largely by two sources.

Branches of the medial and lateral circumflex femoral arteries, usually branches of the deep femoral artery, ascend on the posterior aspect of the femoral neck in the retinacula (reflections of the capsule along the neck of the femur toward the head). The branches of the medial and lateral circumflex arteries perforate the bone just distal to the head of the femur where they anastomose with branches from the foveal artery and with medullary branches located within the shaft of the femur.

The ligament of the head of the femur usually contains the artery of the ligament of the head of the femur (foveal artery), a branch of the obturator artery. The foveal artery enters the head of the femur only when the center of the ossification has extended to the pit (fovea) for the ligament of the head, around age 11-13 years. This anastomosis persists even in advanced age but is never established in 20% of the population.

Femoral neck fractures often disrupt the blood supply to the head of the femur. The medial circumflex artery supplies most of the blood to the head and neck of the femur and is often torn in femoral neck fractures. In some cases, the blood supplied by the foveal artery may be the only blood received by the proximal fragment of the femoral head. If the blood vessels are ruptured, the fragment of bone may receive no blood and undergo avascular necrosis (AVN).

Classifying fractures

Hip fractures can be classified based on their relation to the hip capsule (intracapsular and extracapsular), geographic location (head, neck, trochanteric, intertrochanteric, and subtrochanteric), and degree of displacement. Higher-grade displacement implies worse prognosis. Fractures of the femoral head and neck are intracapsular, whereas those of the trochanteric, intertrochanteric, and subtrochanteric regions are extracapsular. The treatment as well as the prognosis for successful union and restoration of normal function varies considerably with fracture type.

Intracapsular hip fractures, like all other intracapsular fractures, frequently have complicated healing. The thick capsule that surrounds these fractures separates them from adjacent soft tissue and capillaries, leading to impaired callous formation. Thus, nonunion and AVN are added complications of these fractures.

Femoral head fractures

Isolated femoral head fractures are rare and are usually associated with hip dislocations. Superior femoral head fractures normally are associated with anterior dislocations, while inferior femoral head fractures are associated with posterior dislocations. They are usually best appreciated on postreduction radiographs for hip dislocations. Fractures of the femoral head are more common in younger patients as a result of major trauma, which is more likely to cause femoral neck fractures in older patients.

• Type 1 - Single fragment fractures (see Media file 2)
• Type 2 - Comminuted fractures (see Media file 2)

Femoral neck fractures

These are rare among younger patients but are commonly seen in older adults, most often secondary to osteoporosis or osteomalacia. These fractures usually result from minor trauma with falls accounting for 90%, or torsion. From proximal to distal, femoral neck fractures can be further delineated as subcapital, transcervical, and basicervical, all of which are intracapsular and associated with potential disruption of the vascular supply. The incidence of avascular necrosis (AVN) is up to 15% in nondisplaced fractures and increases to nearly 90% with untreated, completely displaced fractures.

• Type 1 - Stress fractures or incomplete fractures (see Media file 3)
• Type 2 - Impacted fractures (see Media file 3)
• Type 3 - Partially displaced fractures (see Media file 4)
• Type 4 - Completely displaced or comminuted fractures (see Media file 5)

Greater trochanteric fractures usually result from avulsion injuries at the insertion of the gluteus medius. Lesser trochanteric fractures may be caused by avulsion injuries of the iliopsoas secondary to forceful contraction. These are most common in children and young athletes (eg, dancers, gymnasts).

• Type 1 - Nondisplaced fractures (see Media file 6)
• Type 2 - Displaced fractures; >1 mm displacement for fractures of the greater trochanter and >2 mm displacement for fractures of the lesser trochanter (see Media file 6)

Intertrochanteric fractures

These extracapsular fractures occur in a line between the greater and lesser trochanters, generally in elderly patients and women secondary to osteoporosis.

• Type 1 - Single fracture line without displacement; stable (see Media file 7)
• Type 2 - Multiple fracture lines (comminution) with displacement; unstable (see Media file 7)

Subtrochanteric fractures

These fractures have a bimodal age distribution and are seen most often in those aged 20-40 years in association with high-energy trauma and in patients older than 60 years secondary to falls on osteoporotic bones.

• Stable: Bony contact of medial and posterior femoral cortices
• Unstable

Frequency

United States

In the United States, hip fracture occurs in approximately 80 per 100,000 persons or approximately 250,000 persons each year. The rate of hip fracture increases with age, doubling each decade after age 50 years. Nearly half of all hip fractures occur in adults older than 80 years. Hip fracture at a young age is rare and is usually the result of a high-velocity injury or, rarely, secondary to bone pathology. 

International

The US frequency of hip fracture, when age and sex are adjusted, ranks the highest in the world. Western Europe and New Zealand also have reported high rates, with the lowest rates occurring in the South African Bantu people and in East Asian countries, where the incidence of osteoporosis is low.

Mortality/Morbidity

• Reported overall mortality rate of hip fractures is 15-20%, yet in older persons this can increase to 36% over the year following hip fracture. Rate of mortality is greatest in the first few months following injury but remains high for up to 1 year. It then returns to the same rate for age- and sex-matched people without hip fracture. Surgical delay independently affects mortality. Patients for whom surgery is delayed for 2 days or more, have a 17% higher mortality rate at 1 month. A subsequent study showed increased mortality but decreased readmission rate in those repaired more than 4 days from the time of injury.²  Also, general anesthesia was associated with higher morbidity than was spinal/epidural anesthesia.²
• Morbidity associated with hip fracture is staggering, especially in older persons. Morbidity from immobilization includes development of deep vein thrombosis, pulmonary embolism, pneumonia, and muscular deconditioning. Morbidity from surgical procedures includes complications of anesthesia, postoperative infection, loss of fixation, malunion or nonunion, as well as the complications associated with immobilization as outlined above.
• Hip fracture resulting from major trauma often is associated with other bone and soft-tissue injuries, intra-abdominal and intrapelvic injuries, major blood loss, head and neck injuries, and other extremity injuries. Morbidity associated with an inability to return to a prefracture level of mobility results in a loss of independence, reduction in quality of life, and depression, particularly in older persons.

Race

The incidence of hip fracture is 2-3 times greater in whites than in nonwhites, primarily because of the increased rate of osteoporosis in whites. This difference is not unique to females; African American and Asian men have been found to have significantly higher bone densities than their Caucasian and Latino counterparts.³

Sex

Rate of hip fracture is 2-3 times greater in women than in men. At least 75% of all hip fractures occur in women. The lifetime risk of hip fracture in white women and men is 15% and 5%, respectively. Femoral neck fractures are more common in women than in men by about 4:1, while intertrochanteric fractures are more common in women than in men by about 5:1.

Clinical

History

• In elderly patients, hip fracture most often results from a simple fall; in a small percentage, it occurs spontaneously, in the absence of any trauma.
• Patient complains of pain and inability to move the hip.
• With stress fractures in young athletes and nondisplaced fractures, patient may complain of pain in hip or knee and may be ambulatory.
• Patient may have a history of other osteoporotic fractures, such as Colles or vertebral compression fractures.

Physical

• Perform a primary survey in trauma patients and stabilize as needed.
• Complete a detailed secondary survey because of the high likelihood of associated injuries. Up to 70% of patients with femoral head fracture-dislocations experienced major associated injuries, including other extremity injuries, intra-abdominal or intrapelvic injuries, neck injuries, and head injuries.
• Pay particular attention to vital signs and secondary manifestations of shock such as changes in skin, mental status, and urine output. Hip fractures are associated with blood volume losses of up to 1500 mL.
• Inspect and palpate for deformity, hematoma formation, laceration, and asymmetry.
• Observe the anatomical position of the extremity because this alone provides useful clues to the type of injury the patient has sustained.
• Femoral head fracture: Posterior dislocation is most common (eg, a dashboard injury), in which case the extremity appears adducted and internally rotated. With anterior dislocation, the extremity is abducted, and externally rotated.
• Femoral neck fracture: With partial or completely displaced fractures (types 3 and 4, respectively), the patient has severe pain and lies with the extremity slightly shortened, abducted, and externally rotated. In the case of a stress fracture or severe impaction fractures (types 1 and 2, respectively), the only physical findings may be minor pain with little or no limitation in range of motion.
• Trochanteric fracture: With a greater trochanteric fracture, the patient presents with pain, especially with abduction and extension. No deformity may be apparent, but pressure through greater trochanters will result is pain. With a lesser trochanteric fracture, pain occurs during flexion and internal rotation.
• Intertrochanteric fracture: The extremity appears shortened and significantly externally rotated, in contrast to the minimal deformities associated with femoral neck fractures. Pain, hip edema and ecchymosis, and pain with any movement may also be noted.
• Subtrochanteric fracture: The proximal femur usually is held in flexion and external rotation.
• In assessing range of motion (ROM), first test external and internal rotation with the extremity held in extension. If a fracture exists, especially one that is displaced, the remainder of ROM examination is extremely painful, of limited diagnostic use, and potentially dangerous. If the patient has pain with the initial ROM examination, obtain radiograph before completing the examination.
• Perform a detailed distal neurovascular examination.
• If the patient is a trauma victim, assess for pelvic fractures by stressing the pelvis anteriorly to posteriorly through iliac crests and symphysis pubis, and laterally to medially through iliac crests.

Causes

• In young persons, hip fractures generally result from trauma associated with significant force. For example, 75% of all femoral head fractures, more common among young patients, occur as a result of motor vehicle collisions.
• In older persons, more than 90% of hip fractures result from trauma or torsion associated with a minor fall or, occasionally, in the absence of any obvious traumatic event.
• Osteoporosis is the leading cause of hip fracture.
• Other risk factors for hip fracture include the following:
  • Neurological impairment
  • Caucasian race
  • Cigarette smoking
  • Institutional living
  • Maternal history of hip fracture
  • Previous hip fracture
  • Physical inactivity
  • Tall stature
  • Alcohol abuse
  • Previous Colles or vertebral fracture attributed to osteoporosis
  • Low body weight
  • Impaired vision
  • Prolonged corticosteroid use
  • Use of medications that decrease bone mass, including furosemide, thyroid hormone, phenobarbital, and phenytoin

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