Proximal Femoral Fractures

According to the U.S. Census, about 340,000 hip fractures occur annually; about 50% occur in persons >= 85 years. The annual age-specific incidence of hip fracture increases exponentially with age, doubling every 6 years, reaching 4% per year in women > 90. One in three women and one in six men who reach age 90 will fracture a hip during their lifetime.

Etiology and Pathology

Hip fractures may be intracapsular or extracapsular. Subcapital and femoral neck fractures (see Figure 22-1) are intracapsular and frequently disrupt the blood supply to the femoral head (see Figure 22-2). Because the femoral head is intra-articular, its sole blood supply comes from vessels traversing the bone of the femoral neck, the surrounding hip capsule, and the ligamentum teres. A displaced fracture completely disrupts the blood vessels of the femoral neck and can tear those of the hip capsule, increasing the risk of osteonecrosis of the femoral head and nonunion of the fracture.

Intertrochanteric and subtrochanteric fractures are extracapsular; they expose large areas of well-vascularized cancellous bone surfaces, increasing acute blood loss but favoring callus formation. Osteonecrosis and nonunion rarely occur. In simple two-part fractures, the fracture typically slopes obliquely between the greater and lesser trochanters, as seen on the anteroposterior x-ray view (see Figure 22-3). In comminuted fractures, fragments of the greater and lesser trochanters may be present. Subtrochanteric fractures extend below the lesser trochanter.

Acetabular fractures in the elderly occur most frequently as extensions of pubic and ischial rami fractures. Most are minimally displaced and are treated nonoperatively. Central fracture dislocations of the femoral head through the acetabular wall into the pelvis are very rare and are very difficult to treat.

Symptoms, Signs, and Diagnosis

Most patients with displaced fractures of the proximal femur present with obvious diagnostic features: a history of a fall, inability to bear weight, and a fracture easily seen on x-rays. However, occult and insufficiency stress fractures can occur in the elderly without a clearly defined traumatic event. Such patients report persistent pain when weight is placed on the injured leg. A crack, initially undetectable on x-rays, can continue to propagate through the bone with the stresses of walking, resulting in complete displacement. A bone scan or MRI can detect the fracture earlier than plain x-rays.

During physical examination, patients with displaced fractures typically lie with their injured leg shortened and externally rotated because of the pull of the leg muscles and gravity. Any movement of the leg is painful. Often, patients with impacted or occult fractures can flex their injured hip with only mild discomfort. Passive flexion with internal rotation of the hip, which tightens the joint capsule, is a sensitive test for occult fractures.

Prognosis and Treatment

Most patients benefit from the increased mobility and pain relief provided by surgery, but patients unable to tolerate anesthesia (eg, those who have just had an acute myocardial infarction) may need to delay surgery. A few patients (eg, those who were not ambulatory before the event for reasons unrelated to the affected joint) are candidates for nonsurgical management. Rehabilitation is an important aspect of care.

For bedridden patients, nursing care must be diligent and meticulous. Complications of enforced bed rest include joint contractures, deconditioning, pressure sores, deep vein thrombosis, pulmonary embolism, pneumonia, osteoporosis, and psychiatric disturbances.

Subcapital and femoral neck fractures: Occult, impacted, or nondisplaced femoral neck fractures are usually managed by internal fixation with multiple pins (see Figure 22-4), which allows immediate, full weight bearing and prevents later displacement. Because the blood supply to the femoral head is not severely disrupted, these types of fractures usually heal well.

Displaced fractures can be managed with surgical stabilization or prosthetic replacement. Open reduction with internal fixation is usually reserved for active patients who can comply with a postoperative regimen of limited weight bearing using crutches. The procedure preserves the femoral head, and when healing is successful, the hip is nearly normal. However, if osteonecrosis or nonunion occurs, the result is a painful, nonfunctional joint that requires total hip replacement. Because the need for a second operation is minimized, primary prosthetic replacement of the femoral head (hemiarthroplasty) is often preferred for less active elderly patients with displaced fractures. This procedure also enables the patient to bear weight immediately and fully and to return to independent functioning more quickly.

The simplest prosthesis, the Moore prosthesis, consists of a smooth metal sphere attached to a stem that is wedged into the medullary canal of the femur (see Figure 22-5). Disadvantages include a tendency to erode the acetabular articular surface and pain from a loose fit of the stem in the femoral medullary canal. Other prostheses are designed to be stabilized inside the femur and are coated with acrylic cement or with a hydroxyapatite or porous metal, which facilitates direct bone fixation. A bipolar prosthesis with an internal metal-polyethylene bearing can reduce acetabular erosion. Patients who develop acetabular arthritis after hemiarthroplasty may require total hip replacement. Primary total hip replacement is performed for acute femoral neck fractures only when patients have severe preexisting arthritis, because this operation is more extensive and has a higher morbidity rate than does hemiarthroplasty or internal fixation with pins.

Intertrochanteric and many subtrochanteric femoral fractures: Surgical stabilization with a sliding compression screw and side plate (see Figure 22-6) provides rigid stabilization while pressing the fracture fragments together, thus helping to ensure healing. Postoperatively, most patients can bear weight immediately, as tolerated with a walker, but some patients with comminuted unstable fractures cannot bear weight fully for several weeks, when healing is sufficient. Patients with good balance and muscle strength can use a cane in 6 to 12 weeks.