Occasionally a child will fall from a counter top or the back of a couch and strike the floor in just the right way, sustaining an isolated sub- or inter-trochanteric femur fracture. However, more commonly, hip and pelvis fractures in children are the result of high-energy mechanisms and are associated with other injuries. In these cases the initial exam needs to concentrate on identifying any life-threatening injuries including head, spine, thoracic, abdominal, pelvic, neurologic, and vascular trauma. A coordinated plan to care for each injury must be established. The hip exam itself must be gentle to avoid further disruption of blood supply (especially femoral neck).

Pelvic fractures may be accompanied by genitourinary and/or gastrointestinal injury. It is important to look for blood at the urethral meatus, and check for hematuria; a retrograde urethrogram/cystogram should be obtained if clinically indicated (Fig. 12-2). Abdominal, vaginal, and rectal exams are performed by or together with the general surgery team; blood at the anus suggests injury to the lower GI tract, which can contaminate a pelvic fracture and which can be problematic if missed. The rectal exam can also identify a displaced prostate, indicating transection of the urethra.

Instability of the pelvis can often be felt with a compression test, testing for both lateral and anteroposterior instability. This test should
not be repeated by multiple examiners as there is risk for compounding the damage already done by the fracture. Feel the pulses and test active movements in both legs. Subtle neurologic injuries are easily missed—always test sacral sensation. When the SI joint is dislocated, the lumbosacral trunk, superior gluteal nerve, and obturator nerve are at risk. However, as will be described later, children rarely have true SI joint disruption; typically they fracture through the physis adjacent to the SI joint. Sacral fractures can rupture the sacral roots, or the foramina can be compressed causing compression of the sacral roots.

In the field, prior to arrival at the hospital, hemorrhage from a pelvic fracture can often be partially controlled by binding the pelvis with a sheet wrapped tightly around the patient at the level of the AIIS. This will close down fractures and tamponade the bleeding during transport or until further treatment can be rendered.

Extraperitoneal hemorrhage to some degree is common and in most cases is allowed to tamponade with blood transfusion given as needed. In a few instances, bleeding can be massive and well concealed. An arteriogram may be required to identify the site of bleeding, and coils can be placed by the interventional radiologist.

The pelvis is a very complex three-dimensional structure, and analyzing films can be difficult. Fractures are difficult to see and can occur through growth areas such as the tri-radiate cartilage, which makes x-ray interpretation difficult.

The ischio-pubic synchondrosis is even more puzzling, and may mimic a fracture (Fig. 12-3). This syndesmosis often fuses asymmetrically, making interpretation difficult. Further complexity is added by Ogden’s noting that in very rare instances this syndesmosis can be the site of a stress fracture in a young jogger.

The femoral head can be dislocated either anteriorly or posteriorly, or rarely into the obturator foramen (Table 12-1). A hip is most commonly dislocated posteriorly (Fig. 12-5) causing the limb to be held in a shortened, flexed, adducted, and internally rotated position. Anterior dislocations cause the limb to extend, abduct, and externally rotate. Traumatic obturator dislocations (or intrapelvic dislocations) are very rare in children but have been reported. The hip tends to be held in flexion, abduction and external rotation, but this is more variable.

Although complications are unusual, during a reduction maneuver an unrecognized proximal femoral epiphyseal separation may become apparent. In such a case the neck, not the head, reduces into the acetabulum. Such a circumstance mandates open reduction and pinning.

A trapped intra-articular fragment can easily be missed if a post-reduction CT study is not obtained (Fig. 12-7). A fragment in the joint can be removed arthroscopically or through an arthrotomy where fixation can be performed if the fragment is large. This can be a posterior acetabular rim fragment, the ligamentum teres with an avulsed head fragment, or both.

The overall incidence of AVN in the literature is 10% or less. Delayed reduction and severe injury are the most important causes. Recurrent dislocation of the hip is a rare sequel to traumatic dislocation.

Some teenaged girls complain that they can feel the hip dislocate. The usual cause is a snapping hip, in which the tensor fascia lata jumps across the greater trochanter as the girl rotates her hip. Once learned, some teenagers seem to have a morbid preoccupation with repeating the maneuver. Some very convincingly impress the neophyte examiner as being a dislocation. Treatment is by stretching (physical therapy) and only very, very rarely surgery (incision in tensor fascia). A rare cause is a true voluntary dislocation, a condition described by Broudy and Scott.

The following differentiate hip fractures in children as compared to adults:

Pediatric hip fractures (from the femoral head to the lesser trochanter) have been classified by Delbet (Table 12-2). More distal fractures of the femur will be discussed in Chapter 13.