INTRACAPSULAR FRACTURE OF FEMORAL NECK
Femoral neck fractures are very common injuries, especially in older persons. In young persons, these injuries are usually caused by severe trauma. In older patients, especially those with osteoporosis, they are associated with falls, and it is possible that the fracture occurs before the fall.
Garden has classified femoral neck fractures into four categories. In type I fracture, the superior portion of the femoral neck is impacted into the femoral head. Type II is a complete fracture that remains nondisplaced. Type III is a fracture with partial displacement between the femoral head and neck. In a type IV fracture, the femoral head is completely displaced from the femoral neck. The Garden classification is useful because it correlates the incidence of fracture nonunion and avascular necrosis of the femoral head with fracture displacement. The incidence of these complications is very low in type I injury, whereas the type IV fracture has a 33% risk of nonunion and a 30% risk of symptomatic avascular necrosis.
Management of femoral neck fractures involves reducing the fracture in both the anteroposterior and lateral planes and achieving secure internal fixation of the fracture fragments. Most fractures can be reduced with closed means, using a variety of reduction techniques. In the Leadbetter maneuver, reduction occurs with the hip in 90 degrees of flexion. Other techniques involve reduction with the hip in extension or in only slight flexion. Regardless of what method is used, near-anatomic reduction must be achieved in both fracture planes; this is especially important in younger patients. After reduction, the femoral neck fracture is securely fixated to allow for impaction of the fracture fragments.
After surgery, the patient can begin gentle active and passive range-of-motion exercises if the fixation is secure. Active straight-leg raising is best avoided for the first 3 months. Patients who are able to cooperate with a rehabilitation program are allowed gradual weight bearing as healing of soft tissue and bone progresses. Patients who are not able to cooperate are mobilized early from bed to chair, but weight bearing on the injured limb is delayed.
Periodic follow-up is important to monitor fracture healing and to check for development of avascular necrosis of the femoral head. Initially, this tends to occur in the anterolateral segment of the femoral head, where damage to the vascular structures is greatest. If avascular necrosis is detected, intervention may be required to prevent the avascular segment from under-going late segmental collapse, which leads to degenerative changes in the hip joint.