Pediatric femoral neck fractures require urgent reduction and decompression

Data comparison shows that current management may reduce avascular necrosis risk.

Issue: September 2006

Although uncommon, pediatric femoral neck fractures carry a high risk of avascular necrosis and potential lifetime disability, which has led pediatric orthopedic surgeons at Children's Hospital of Philadelphia to study the current management of these fractures.

Their new treatment modality employs a consistent approach: "Treat femoral neck fractures as an emergency and decompress in some manner," John M. Flynn, MD, of Children's Hospital of Philadelphia (CHOP), said at the American Association of Hip and Knee Surgeons Specialty Day meeting.

Shown to reduce the risk of avascular necrosis (AVN), urgent reduction and decompression are now the surgeons' main priorities. CHOP's treatment modality routinely involves aspiration or decompression of the intercapsular hematoma, fracture reduction and stable internal fixation, Flynn said.

If the fixation does not extend into the femoral epiphysis — most common in children younger than 10 years old — a spica cast should be used to avoid fixation loss. "If the patient is too young for you to put screws into the epiphysis, then you can protect the kid in a cast usually from 4 to 6 weeks," Flynn said.

Management affects AVN rate

In the past, surgeons managed these fractures with a cast alone for younger children and limited fixation with Steinmann pins in older children. "There was no sense of urgency, and capsulotomy was not commonly discussed," Flynn said.

Research on this management technique has shown high incidences of coxa vara, nonunion and malunion, and most significantly, AVN (up to 42% in some series).

"The factors that may affect avascular necrosis in pediatric hip fractures are the displacement of fractures [and] fracture type, but then we as surgeons, with our treatment, affect that rate," Flynn said.

It is well known that Type 1 (transepiphyseal) fractures have the highest avascular necrosis risk, while Type 4 have the lowest (peritrochanteric). About 80% of pediatric hip fractures fall into the Type 2 (transcervical) and Type 3 (cervicotrochanteric) Delbet classifications, Flynn said.

However, vascular injury during trauma, pressure on the vessel from displacement or hemarthrosis, and fracture instability may be additional AVN causes. "As surgeons, we can't control the first of these, but we may be able to do something about the other three," Flynn said.

Age, fracture specifications

In addition to decompression and reduction, Flynn manages each pediatric femoral neck fracture based on patient age and fracture type.

In children younger than 8 years with Type 1 fractures, he uses smooth pins or modified screws across the physis, as well as a spica cast. He treats children older than 8 years with Type 1 fractures as if they had an unstable epiphysis.

"In Types 2 and 3 we use multiple pins only for the very small kids and then a spica cast," Flynn said.

For children 3 years to 10 years old with Type 2 or Type 3 fractures, Flynn and his colleagues use 4.5-mm and/or 7.3-mm screws, as well as a spica cast.

For those children older than 10 years with Type 2 or Type 3 fractures, they use 7.3-mm screws. "If they're young enough, we can spare the physis and use a cast," Flynn said. "If they're older, we cross the physis just as we would for an adult."

Finally, for Type 4 fractures, Flynn said he uses sliding hip screws for all patients and sometimes uses intramedullary hip screws in adolescent patients.

In favor of decompression

Literature comparisons have shown significantly decreased avascular necrosis rates in more recent series of pediatric femoral neck fracture management. Studies from 1962 to 1980 found 17% to 42% AVN incidence rates, Flynn said.

But, "A big series in Toronto ... found AVN in 22 out of 54 [patients], in which they didn't decompress," Flynn said, "and then AVN in three out of 39 with decompression. That's certainly a big difference."

A 1999 study by Cheng and colleagues in Hong Kong found a 0% AVN rate in displaced fractures, but surgeons performed aspiration and not a true capsulotomy on these patients, Flynn said.

CHOP surgeons found a 5% AVN rate in their 2002 study. They reviewed 20-year results of 18 children who sustained displaced nonpathologic hip fractures at a mean age of 8 years (range, 2 years to 13 years old), according to the presentation abstract.

The patient group included one Type 1 fracture, eight Type 2 fractures, eight Type 3 fractures and one Type 4 fracture.

Surgeons treated the patients with closed or open reduction and internal fixation within a day of their injury. And they immobilized all but two of the patients with a spica cast.

At a mean eight-year follow-up, patients returned for re-evaluation and radiographs. Surgeons found no complications in 15 patients.

They found one Type 3 fracture patient with avascular necrosis and one Type 1 fracture patient with a growth arrest.

"We had one nonunion [in a Type 2 fracture patient] and it was one of the two kids that were not treated in a cast," Flynn said.

For more information:
Cheng JC, Tang N. Decompression and stable internal fixation of femoral neck fractures in children can affect the outcome. J Pediatr Orthop. 1999;19(3):338-343.
Flynn JM, Wong KL, Yeh GL, et al. Management by early operation and immobilization in a hip spica cast. J Bone Joint Surg Br. 2002;84-B(1):108-112.
Flynn JM. The management of femoral neck fractures in children. Presented at the American Association of Hip and Knee Surgeons Specialty Day Meeting. March 25, 2006. Chicago.
Ng GPK, Cole WG. Effect of early hip decompression on the frequency of avascular necrosis in children with fractures of the neck of the femur. Injury. 1996;27(6):419-421.