Chapter 22 Pediatric Hip Fractures

 

Ernest L. Sink Benjamin F. Ricciardi

 

DEFINITION

Pediatric hip fractures comprise less than 1% of all pediatric fractures; however, appropriate management of these injuries is essential to avoid proximal femoral deformity and maintain hip joint

integrity.14

 

 

ANATOMY

 

Pediatric hip fractures can occur through the physis, but more commonly, they occur through the femoral neck or intertrochanteric region. Therefore, they may be intraarticular or extra-articular (FIG 1).

 

The femoral head is composed of the capital femoral epiphysis, the subcapital physis, and the most proximal portion of the femoral neck

 

The capital femoral epiphysis begins to ossify at around 6 months in boys and 4 months in girls. The trochanteric apophysis center of ossification appears at 4 years of age in both sexes. The proximal femoral physis and trochanteric apophysis fuse at age 14 years for females and 16 years for males.

 

Vascular anatomy: Metaphyseal blood supply to the femoral head persists until approximately 4 years of age with primary contributions from both medial and lateral circumflex femoral branches. After 4 years of age, the lateral epiphyseal vessels, derived primarily from posteroinferior and posterosuperior branches of the medial

 

circumflex femoral artery, are the predominant blood supply to the epiphysis of the developing hip.12 The lesser trochanter is an apophysis in the child and the insertion for the iliopsoas.

 

 

 

 

FIG 1 • A. Diagram of the hip from the front. There are growth plates beneath the capital femoral epiphysis, the greater trochanteric apophysis, and the lesser trochanteric apophysis. B. Diagram of the hip viewed from the side. The lesser trochanter protrudes posteriorly. C. Femoral regions where hips fracture: intracapsular

neck (green), extracapsular neck (blue), and intertrochanteric-subtrochanteric area (red).

 

 

Much of the greater trochanter is apophyseal and is the insertion for many of the abductors.

 

 

Classification: Pediatric hip fractures are generally classified as described by Delbet5 into type I (transphyseal), type II (transcervical), type III (cervicotrochanteric), and type IV (intertrochanteric) ( FIG 2). Subtrochanteric fractures are not described by this classification system.

 

NATURAL HISTORY

 

 

Pediatric hip fractures are rare injuries in children and account for less than 1% of all pediatric fractures.2 Pediatric hip fractures tend to result from high-energy trauma such as motor vehicle accident or fall from height. High rates of concomitant injury have been reported with these injuries.8

 

Low-energy mechanisms of injury should raise suspicion for pathologic fracture due to underlying metabolic bone disease, benign or malignant lesions, or prior trauma.15

PATIENT HISTORY AND PHYSICAL FINDINGS

 

History should include age, mechanism of injury (rule out child abuse in patients younger than 2 years old), locations of pain to rule out concomitant injury, and relevant medical history or family history especially in low-energy mechanism fractures suspicious for underlying pathology.

 

Physical examination reveals shortening and rotational deformity of the affected extremity with painful range of motion.

 

Infants and newborns can be challenging patients to diagnose with hip fractures due to limited ossification of the proximal

 

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femur, and differential diagnosis may include infection and congenital dislocation of the hip. After excluding infectious etiologies, pseudoparalysis and shortening in this age group should increase suspicion of a fracture.

 

 

 

FIG 2 • Delbet classification of pediatric femoral neck fractures: type I, transphyseal; type II, transcervical; type III, cervicotrochanteric; and type IV, intertrochanteric.

 

 

Concomitant injury should be ruled out because pediatric hip fractures usually represent high-energy injuries in many cases and can be associated with neurologic, visceral, and other musculoskeletal trauma.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

An anteroposterior (AP) radiograph of the pelvis provides a view of the contralateral hip for comparison.

 

A cross-table lateral radiograph of the injured side should be considered to avoid further displacement and unnecessary discomfort from an attempt at a frog-leg lateral view.

 

Any break or offset of the bony trabeculae near Ward triangle is evidence of a nondisplaced or impacted fracture.

 

Magnetic resonance imaging (MRI) can be useful in suspected minimally displaced fractures, pathologic fractures, or stress fractures due to their improved delineation of soft tissue structures, fluid within the hip joint,

and ability to assess bone marrow edema signal for nondisplaced fractures or avascular necrosis (AVN).

 

Ultrasound can be used to detect epiphyseal separation in infants. Additionally, it can also evaluate for a hip joint effusion in cases of suspected infection and allow concomitant aspiration.

 

In a patient with posttraumatic hip pain without evidence of a fracture, complete blood count, erythrocyte sedimentation rate, C-reactive protein, and temperature are helpful to evaluate for infection.

 

NONOPERATIVE MANAGEMENT

 

For patients younger than 1 year old with nondisplaced or minimally displaced fractures, management can consist of Pavlik harness or abduction brace.

 

For children younger than 5 years old with nondisplaced type II or III fractures, spica casting extended distal to the knee can be considered.

 

Contraindications

 

 

All displaced fractures

 

Type I fractures in children older than 2 years old

 

Type II or III fractures in children older than 5 years old. In children older than 5 years even without fracture displacement, internal fixation will help prevent nonunion and fracture displacement.

 

SURGICAL MANAGEMENT

 

Early operative anatomic reduction with stable internal fixation and selective use of external immobilization (spica casting) is the treatment of choice for pediatric hip fractures in the majority of patients in order to

minimize rates of AVN, nonunion, and coxa vara, which are more likely to occur with nonoperative treatments.1, 3, 6, 7, 10, 14

 

Open reduction with stable internal fixation should be performed for any residual displacement after attempted closed reduction in order to minimize nonunion, malunion, and AVN.1, 3, 4, 6, 7, 11, 13, 14, 15

 

Urgent (<24 hours) reduction and decompressive capsulotomy with successful closed reductions may help reduce rates of AVN.4, 6, 11, 13, 14

Preoperative Planning

 

Operating room (OR) table: radiolucent table to assist with reduction and placement of internal fixation. Traction table may aid reduction in older children and adolescents.

 

Approaches: Closed versus open reduction; anterior (Smith-Petersen) approach, anterolateral (Watson-Jones) approach, and surgical hip dislocation

 

Fluoroscopy: Opposite side from surgeon is usually most helpful. Two C-arm technique may aid in placing internal fixation when possible.

 

Special equipment: Deep retractors may help in older children with open reduction; saw for trochanteric osteotomy for surgical hip dislocation.

 

Approach and Positioning

 

Anterior (Smith-Petersen) approach: supine with support under thoracolumbar spine and posterior superior iliac spine

 

 

Anterolateral (Watson-Jones) approach: partial lateral with support of posterior back and pelvis Surgical hip dislocation: full lateral position with axillary roll

 

Percutaneous fixation: Positioning on a fracture table with one or two C-arms will facilitate treatment of nondisplaced fractures.

 

 

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TECHNIQUES

• Exposure and Open Reduction and Internal Fixation

  Anterior (Smith-Petersen) Approach

  A longitudinal incision distal and lateral to the anterior superior iliac spine or bikini approach can be used, with care taken to protect the lateral femoral cutaneous nerve.

  The fascia over the tensor fascia muscle is split longitudinally.

  Blunt dissection is performed on the medial border of the tensor fascia muscle as far proximal as the iliac crest which will expose the rectus femoris muscle.

  The lateral fascia of the rectus muscle is incised and the rectus is retracted medially.

  The fascia underneath the rectus is incised longitudinally and the lateral iliocapsularis is elevated off the hip capsule in a medial direction. The gluteal muscles can be retracted laterally.

  A longitudinal capsulotomy is made along the anterosuperior femoral neck. Retractors can be placed medially and inferiorly around the femoral neck once the capsule is incised, taking care to avoid damage to the femoral neurovascular bundle and medial femoral circumflex artery, respectively.

  After open reduction, internal fixation must be passed percutaneously or through a small separate lateral incision because the lateral greater trochanter is not exposed through this approach.

  Anterolateral (Watson-Jones) Approach

  An incision is made laterally over the proximal femur just anterior to greater trochanter.

  After identification and division of the fascia lata, the tensor muscle is reflected anteriorly taking care not to injure branches of the superior gluteal nerve 2 to 5 cm above the greater trochanter.

  The plane between the gluteus medius and tensor muscle is developed, and the anterior hip capsule is exposed. The anterior aspect of the gluteus medius is retracted, and a small portion of the tendon may be incised to increase mobilization.

  A longitudinal capsulotomy is made along the anterior femoral neck. This can be extended along the acetabulum or intertrochanteric line for wider exposure.

  After open reduction, internal fixation can be passed perpendicular to the fracture along the femoral neck from the base of the greater trochanter (TECH FIG 1).

  Surgical Hip Dislocation

  An incision is made laterally over proximal femur centered on anterior third of greater trochanter, extending proximally to midpoint between greater trochanter and iliac crest.

  The tensor fascia is incised in the anterior third of the greater trochanter and along the anterior border of the gluteus maximus muscle.

  The femur is positioned in slight extension and internal rotation for visualization, and the piriformis muscle is identified deep to the gluteus medius. Using gentle retraction of the tendon, the inferior fascia of the gluteus minimus is gently lifted in an anterosuperior direction off the hip capsule.

   

  A greater trochanteric osteotomy is performed anterior to the tip of the greater trochanter to the posterior border of the vastus lateralis ridge, obtaining a width of 10 to 15 mm in children.

   

  The gluteus minimus, gluteus medius, osteotomized greater trochanter, vastus lateralis, and vastus intermedius are elevated sharply off the hip capsule in an anterosuperior direction. Flexion and external rotation of the operative hip will facilitate the muscle dissection.

   

  The piriformis tendon remains intact to the nonosteotomized portion of the greater trochanter in order to protect the retinacular branches of the medial circumflex artery.

   

  The hip capsule is opened in a Z-shaped fashion with the longitudinal limb along the axis of the femoral neck in line with the iliofemoral ligament.

   

  The distal limb remains proximal but in line with the intertrochanteric ridge.

   

  The proximal limb of the capsule is opened in the capsular recess of the acetabulum as far posterior as the piriformis tendon.

   

  If hip dislocation is warranted, temporary fixation of the fracture with a threaded K-wire is recommended to avoid damage to retinacular vessels.

   

  The leg is flexed and externally rotated and placed in a sterile leg bag. The hip is subluxated with a bone hook, and curved large scissors are used to transect the ligamentum teres.

   

  After fracture fixation, the hip capsule is loosely approximated. The greater trochanter is reduced and fixation with two or three 3.5-mm screws is performed.

   

   

   

  TECH FIG 1 • Open reduction and internal fixation (ORIF) of intra-articular femoral neck fracture. A. Incision is made for Watson-Jones approach. B. The fascia lata is split longitudinally. (continued)

   

   

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  TECH FIG 1 • (continued) C. The anterior capsule is exposed. D. A T incision is made in the capsule. E.

  The fracture is reduced under direct vision. Pins or screws are placed.

• Type I Fractures

   

  Nondisplaced or minimally displaced fractures in infants younger than 2 years can be treated with spica casting without internal fixation. Limb is immobilized in abduction and neutral rotation.

   

  Displaced fractures in infants younger than 2 years and all fractures in children older than 2 years should be anatomically reduced and stabilized with internal fixation.

   

  A gentle attempted closed reduction is performed. After successful closed reduction, a decompressive capsulotomy can be performed through a limited lateral approach, with access to the hip capsule through the anterior fibers of the gluteus medius muscle.

   

  If anatomic reduction is not achieved, open reduction is indicated. The approach for open reduction is dictated by the position of the displaced fracture fragments and surgeon preference.

   

   

   

  TECH FIG 2 • A,B. AP and lateral radiographs, respectively, of a 10-year-old boy who sustained a type 1 fracture-dislocation playing football. C,D. AP and frog-leg lateral radiographs, respectively, 1 year after open reduction and internal fixation (ORIF). For stability, it is necessary for the screws to cross the physis. More follow-up is required because of the possibility of AVN. (Courtesy of W. Sankar, MD; Children's Hospital of Philadelphia.)

   

   

  In small children, 2-mm smooth Kirschner wires (K-wires) can be used for internal fixation, inserted from a lateral position across the physis (two or three wires total). These should be cut off and bent below the skin for later retrieval.

   

  Spica casting is performed and immobilization continues for 6 weeks.

   

  In larger children, 4.0- to 7.3-mm cannulated screws can be used. The decision to have screw fixation cross the physis depends on the size of the child and the location of the fracture (TECH FIG 2).

   

  In a young child with a lot of growth remaining, the surgeon should stop distal to the physis unless the fracture is more proximal; then, fixation is required to cross the physis to achieve union.

   

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  As mentioned, smooth K-wires may be used in younger children but in older children stable fixation should be a primary goal and this may necessitate crossing the physis.

   

  Guidewires for cannulated screws are inserted across the physis through a small incision over the lateral femur, parallel to the femoral neck on fluoroscopy. The wires are overdrilled to the level of the physis but not across to minimize damage.

   

  If patient compliance or fracture stability is in question, older children can be placed in spica cast for postoperative immobilization for 6 weeks.

• Types II and III Fractures

   

  Nondisplaced fractures in children younger than 5 years of age can be managed with spica casting with close radiographic follow-up for displacement.

   

  All displaced fractures should be treated with an attempted closed reduction. If anatomic reduction is not achieved, then open reduction is indicated. The approach chosen for open reduction typically depends on surgeon preference and experience.

   

  Internal fixation with two or three 4.0- to 4.5-mm cannulated screws is appropriate for small children up to age 8 years (TECH FIG 3). For older children, fixation with 6.5- or 7.3-mm cannulated screws is appropriate with ultimate size dictated by the width of the femoral neck. Similar to type I fractures, internal fixation can be placed over guidewires inserted through the lateral femur in line with the femoral neck.

   

   

   

  TECH FIG 3 • AP radiograph of a 10-year-old boy who sustained a nondisplaced femoral neck fracture from a fall. A capsulotomy was performed at the time of surgery and the implants were able to provide enough stability without crossing the physis.

   

   

  For type II fractures, we attempt to avoid crossing the physis, although this is not always possible with this fracture pattern. Achieving stable fixation is paramount.

   

  For type III fractures, it may be possible to achieve stable fixation without crossing the physis, and this would be our preference when possible to avoid growth disturbance.

   

  We believe that if the physis is not crossed with implants, supplementary spica casting should be performed to prevent malunion or nonunion.

• Type IV Fractures

 

Nondisplaced fractures in children younger than 3 to 4 years can be managed in a spica cast without internal fixation. Close radiographic follow-up is necessary to identify lateral displacement.

 

Displaced fractures should be treated with attempted closed reduction. This is achieved by a combination of longitudinal traction and internal rotation of the affected limb.

 

If anatomic reduction is not achieved, an open reduction is indicated.

 

Internal fixation using a pediatric or juvenile compression hip screw or pediatric locking hip plate is our preference. A guidewire is placed parallel to the femoral neck, stopping distal to the physis to avoid penetration. A derotational wire is necessary before drilling and tapping the neck for the dynamic hip screw to avoid fracture displacement (TECH FIG 4).

 

Spica casting is not typically necessary in older children postoperatively in this fracture pattern with the use of internal fixation.

 

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TECH FIG 4 • Internal fixation of extra-articular hip fracture. A. After fracture reduction, a guidewire is inserted from the lateral femoral cortex up the femoral neck. The angle the wire makes with the lateral cortex should match the angle of the fixation device (usually 135 degrees). B. The length of the intended lag screw is measured from the protruding guidewire. The lag screw should stop short of the physis. C. Reaming is accomplished over the guidewire to accommodate the lag screw and the barrel of the side plate.

D. The channel is tapped because a child's bone is usually quite hard. E. The lag screw is inserted. F. The side plate is placed. G. The plate is secured to the femur with cortical screws, and the compression screw

locks the lag screw in the side plate.

 

 

 

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Nonunion

• Anatomic reduction is critical: if unable to achieve anatomic closed reduction,

  then open reduction is indicated.

• Stable internal fixation

• Supplement with spica cast if younger child (younger than 10 years) or any concerns about fracture stability.

Avascular

necrosis

• Urgent reduction (<24 hours) may reduce rates of AVN.

• Achieve an anatomic reduction, open if necessary.

• Supplement anatomic closed reduction with capsulotomy.

Physeal

arrest

• Avoid fixation crossing physis if possible (although do not compromise stability).

PEARLS AND PITFALLS

 

 

POSTOPERATIVE CARE

 

Spica casting

 

 

 

All type I fractures except for adolescents with two or three large-diameter cannulated screws into epiphysis Children younger than 10 years old with type II or III fractures

 

All cases in which compliance or fracture stability is in question.

 

For children older than 12 years of age, transphyseal fixation will have less consequences on growth and may avoid the need for spica casting.

 

All fractures are followed closely with serial radiographs to assess for late displacement and union.

 

Patients are non-weight bearing for at least 6 weeks or until evidence of fracture healing is seen on plain radiographs. Progressive weight bearing and physical therapy as necessary can be prescribed at that time.

 

OUTCOMES

Poor outcomes are associated with the development of complications such as AVN, nonunion, and growth abnormalities of the proximal femur, and patients who avoid these complications generally return to full function.1, 3, 6, 7, 9, 10, 14, 16

 

 

COMPLICATIONS

 

 

AVN is the most serious complication of pediatric hip fractures. A meta-analysis by Moon and Mehlman9 found that both fracture classification and patient age were predictive factors for development of AVN.9

The incidence of AVN in type I through type IV fractures was 38%, 28%, 18%, and 5%, respectively.9 Early (under 24 hours) fracture reduction, anatomic reduction, stable fixation, and decompressive capsulotomy may all help reduce the rate of AVN.4, 6, 11, 14

Nonunion results from nonanatomic reduction or loss of stable fixation. Increased use of internal fixation and increased recognition of the value of anatomic reduction has helped reduce the incidence of nonunion in more recent series.1, 4, 6, 14

Coxa vara is the second most common reported complication after pediatric hip fractures next to AVN historically. It can result from malunion due to nonanatomic reduction, loss of reduction, and physeal injury. Severe coxa vara increases the height of the greater trochanter in relation to the femoral head, resulting in abductor inefficiency. Remodeling of an established malunion may occur if the child is younger than 8 years of age or with a neck-shaft angle greater than 110 degrees. The use of internal fixation and improved efforts to achieve anatomic reduction have also reduced its incidence.

Physeal arrest can result from hardware penetration of the physis, AVN, or type I fractures. The contribution of the capital femoral physis is only 13% of total extremity growth; therefore, it only results in significant (>2.5 cm) limb length discrepancies in young children.

 

REFERENCES

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8. Mirdad T. Fractures of the neck of the femur in children: an experience at the Aseer Central Hospital, Abha, Saudi Arabia. Injury 2002;33:823-827.

    

    

9. Moon ES, Mehlman CT. Risk factors for avascular necrosis after femoral neck fractures in children: 25 Cincinnati cases and meta-analysis of 360 cases. J Orthop Trauma 2006;20:323-9.

    

    

10. Morsy HA. Complications of fracture of the neck of the femur in children. A long-term follow-up study. Injury 2001;32:45-51.

     

     

11. Ng GP, 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;27:419-421.

     

     

12. Ogden JA. Changing patterns of proximal femoral vascularity. J Bone Joint Surg Am 1974;56:941-950.

     

     

13. Pförringer W, Rosemeyer B. Fractures of the hip in children and adolescents. Acta Orthop Scand 1980;51:91-108.

     

     

14. Shrader MW, Jacofsky DJ, Stans AA, et al. Femoral neck fractures in pediatric patients: 30 years experience at a level 1 trauma center. Clin Orthop Relat Res 2007;454:169-173.

     

     

15. Swiontkowski MF, Winquist RA. Displaced hip fractures in children and adolescents. J Trauma 1986;26:384-388.

     

     

16. Togrul E, Bayram H, Gulsen M, et al. Fractures of the femoral neck in children: long-term follow-up in 62 hip fractures. Injury 2005;36: 123-130.