FEMORAL HEAD

EPIDEMIOLOGY

Almost all are associated with hip dislocations.

These fractures complicate approximately 10% of posterior hip dislocations.

Most are shear or cleavage type. Although, with the increased use of computed tomography (CT), more indentation-type or crush-type fractures have been recognized.

Impaction fractures are more commonly associated with anterior hip dislocations (25% to 75%).

ANATOMY

Vascular anatomy (see Chapter 27).

Seventy percent of the femoral head articular surface is involved in load transfer and, therefore, damage to this surface may lead to the development of posttraumatic arthritis.

MECHANISM OF INJURY

Same as hip dislocation (see Chapter 27).

CLINICAL EVALUATION

Formal trauma evaluation is necessary because most femoral head fractures are a result of high-energy trauma.

Ninety-five percent of patients have injuries that require inpatient management independent of femoral head fracture.

In addition to hip dislocation, femoral head fractures are also associated with acetabular fractures, knee ligament injuries, patella fractures, and femoral shaft fractures.

A careful neurovascular examination is essential because posterior hip dislocations may result in neurovascular compromise.

RADIOGRAPHIC EVALUATION

Same as hip dislocation (see Chapter 27).

If closed reduction is successful, CT is necessary to evaluate the reduction of the femoral head fracture and to rule out the presence of intra-articular fragments that may prevent hip joint congruity.

Some authors recommend CT evaluation even if the closed reduction is unsuccessful to evaluate for associated acetabular fractures.

Sagittal CT reconstruction may also be helpful in delineating the femoral head fracture.

CLASSIFICATION

Pipkin (Fig. 28.1)

Type I: Hip dislocation with fracture of the femoral head inferior to the fovea capitis femoris Type II: Hip dislocation with fracture of the femoral head superior to the fovea capitis femoris Type III: Type I or II injury associated with fracture of the femoral neck

Type IV: Type I or II injury associated with fracture of the acetabular rim

Orthopaedic Trauma Association Classification of Femoral Head Fractures

See Fracture and Dislocation Classification Compendium at http://www.ota.org/compendium/compendium.html.

TREATMENT

Pipkin Type I

The femoral head fracture is inferior to the fovea. These fractures occur in the non–weight-bearing surface.

If reduction is adequate (<1 mm step-off) and the hip is stable, closed treatment is recommended.

If the reduction is not adequate, open reduction and internal fixation with small subarticular screws using an anterior approach are recommended.

Small fragments may be excised if they do not sacrifice stability.

Pipkin Type II

The femoral head fracture is superior to the fovea. These fractures involve the weight-bearing surface.

The same recommendations apply for the nonoperative treatment of type II fractures as for type I fractures, except that only an anatomic reduction as seen on CT and repeat radiographs can be accepted for nonoperative care.

In general, the treatment of choice is open reduction and internal fixation through an anterior approach (Smith-Peterson).

Mini-fragment implants must be countersunk and/or headless screws utilized. Care must be taken to bury the implants below the articular cartilage.

Pipkin Type III

A femoral head fracture occurs with an associated fracture of the femoral neck.

The prognosis for this fracture is poor and depends on the degree of displacement of the femoral neck fracture.

In younger individuals, emergency open reduction and internal fixation of the femoral neck are performed, followed by internal fixation of the femoral head. This can be done using an anterolateral (Watson-Jones) approach.

In older individuals with a displaced femoral neck fracture, prosthetic replacement is indicated.

Pipkin Type IV

A femoral head fracture occurs with an associated fracture of the acetabulum.

This fracture must be treated in tandem with the associated acetabular fracture.

The acetabular fracture should dictate the surgical approach (although this may not be possible), and the femoral head fracture, even if nondisplaced, should be internally fixed to allow early motion of the hip joint.

Femoral Head Fractures Associated with Anterior Dislocations

These fractures are difficult to manage.

Impaction fractures, typically located on the superior aspect of the femoral head, require no specific treatment, but the fracture size and location have prognostic implications.

Displaced transchondral fractures that result in a nonconcentric reduction require open reduction and either excision or internal fixation, depending on fragment size and location.

COMPLICATIONS

Osteonecrosis

• Patients with posterior hip dislocations with an associated femoral head fracture are at high risk for developing osteonecrosis and posttraumatic degenerative arthritis. The prognosis for these injuries varies. Pipkin types I and II are reported to have the same prognosis as a simple dislocation (1% to 10% if dislocated <6 hours). Pipkin type IV injuries seem to have roughly the same prognosis as acetabular fractures without a femoral head fracture. Pipkin type III injuries have a poor prognosis, with a 50% rate of posttraumatic osteonecrosis.

Posttraumatic osteoarthritis: Risk factors include transchondral fracture, indentation fracture greater than 4 mm in depth, and osteonecrosis.