Pediatric Hip Fractures: An Intraoperative Masterclass in Reduction and Fixation

Introduction and Epidemiology

Pediatric hip fractures are exceptionally rare orthopedic injuries, comprising less than one percent of all pediatric fractures. Despite their low incidence, they demand a high level of surgical acumen due to the profound risk of devastating complications, including avascular necrosis, coxa vara, premature physeal closure, and nonunion. Appropriate, timely management is essential to avoid proximal femoral deformity and maintain long term hip joint integrity.

The mechanism of injury is predominantly high energy trauma, such as motor vehicle collisions, auto-pedestrian accidents, or falls from significant heights. Consequently, these patients frequently present with concomitant life threatening injuries, including closed head trauma, thoracic injuries, and abdominal visceral damage, which must be managed per Advanced Trauma Life Support protocols prior to definitive orthopedic intervention. Low energy mechanisms resulting in a pediatric hip fracture should immediately raise the clinical suspicion for a pathologic fracture secondary to underlying metabolic bone disease, benign or malignant osseous lesions (such as unicameral bone cysts or fibrous dysplasia), or osteogenesis imperfecta. In patients younger than two years of age, non accidental trauma must be rigorously excluded.

Clinical presentation typically involves a shortened, externally rotated lower extremity. The patient will exhibit profound pain with any attempted range of motion of the hip. In the infant and neonatal population, diagnosis can be particularly challenging due to the lack of ossification of the proximal femur. In this cohort, pseudoparalysis and limb shortening are the hallmark physical examination findings. The differential diagnosis in the very young patient must include septic arthritis, osteomyelitis, and developmental dysplasia of the hip.

Fractures of the pediatric hip are universally classified using the Delbet classification system, which stratifies injuries based on their anatomic location and correlates directly with the risk of avascular necrosis.
* Delbet Type I: Transphyseal fractures (often associated with dislocation of the capital femoral epiphysis).
* Delbet Type II: Transcervical fractures (the most common subtype).
* Delbet Type III: Cervicotrochanteric fractures (occurring at the base of the femoral neck).
* Delbet Type IV: Intertrochanteric fractures.

Surgical Anatomy and Biomechanics

A profound understanding of the developing proximal femoral anatomy and its dynamic vascular supply is the cornerstone of successful pediatric hip fracture management. Pediatric hip fractures can propagate through the physis, but more commonly occur through the femoral neck or intertrochanteric region, rendering them either intraarticular or extraarticular depending on the capsular insertion.

Proximal Femoral Ossification

The proximal femur develops from a single cartilaginous anlage. The capital femoral epiphysis begins to ossify at approximately four months of age in females and six months of age in males. The greater trochanteric apophysis center of ossification appears at four years of age in both sexes. The proximal femoral physis and the trochanteric apophysis eventually fuse at age fourteen for females and age sixteen for males. The lesser trochanter serves as an apophysis in the developing child and functions as the primary insertion site for the iliopsoas tendon.

Vascular Anatomy

The vascular supply to the pediatric proximal femur is age dependent and highly vulnerable to traumatic disruption.
* Birth to Four Years: The metaphyseal blood supply to the femoral head persists, with primary contributions crossing the physis from both the medial and lateral circumflex femoral arteries.
* Four Years to Maturity: The metaphyseal supply diminishes as the physis acts as a barrier. The lateral epiphyseal vessels, derived primarily from the posteroinferior and posterosuperior branches of the medial circumflex femoral artery, become the predominant and critical blood supply to the epiphysis of the developing hip.
* Ligamentum Teres: The artery of the ligamentum teres (a branch of the obturator artery) provides a negligible contribution to the epiphyseal blood supply in the pediatric population, making the retinacular vessels the sole lifeline to the femoral head.

Disruption of these retinacular vessels, either via the initial trauma, intracapsular hematoma tamponade, or iatrogenic injury during reduction and fixation, leads to avascular necrosis.

Indications and Contraindications

The management of pediatric hip fractures leans heavily toward operative intervention to ensure anatomic reduction, stable fixation, and early mobilization, thereby minimizing the risk of coxa vara and avascular necrosis.

Operative Indications

Operative intervention is indicated for virtually all displaced pediatric hip fractures, as well as the majority of nondisplaced fractures due to the high risk of secondary displacement. Urgent surgical intervention (within 24 hours) is highly recommended to decompress the intracapsular hematoma and restore vascularity.

Non Operative Indications

Non operative management is strictly reserved for a very narrow subset of patients. This includes completely nondisplaced Delbet Type IV (intertrochanteric) fractures in very young children, or patients whose medical comorbidities or polytrauma status preclude safe administration of general anesthesia. Non operative management typically requires application of a one and a half spica cast.

Contraindications to Immediate Surgery

Absolute contraindications include hemodynamic instability requiring massive transfusion protocols or damage control resuscitation. In such cases, the hip fracture is temporarily stabilized (often with gentle traction) until physiologic parameters normalize.

Pre Operative Planning and Patient Positioning

Thorough preoperative planning is critical to execute a precise surgical intervention.

Imaging Protocols

Standard anteroposterior and cross table lateral radiographs of the affected hip, along with an anteroposterior pelvis radiograph, are mandatory. In cases of severe displacement or suspected intraarticular comminution, a fine cut computed tomography scan with three dimensional reconstructions can aid in understanding fracture morphology. For suspected pathologic fractures, magnetic resonance imaging of the entire femur is indicated to evaluate the extent of the lesion.

Patient Positioning and Operating Room Setup

The choice of operating table depends heavily on the patient's age, size, and the planned fixation construct.

• Radiolucent Flat Table: Preferred for infants, toddlers, and young children. The patient is positioned supine with a bump under the ipsilateral hip. This allows for unrestricted manipulation of the limb for closed reduction maneuvers and facilitates the immediate postoperative application of a spica cast without needing to transfer the patient.
• Fracture Table: Utilized for older adolescents approaching skeletal maturity. The fracture table allows for sustained, controlled traction and simplifies intraoperative fluoroscopy. However, care must be taken to avoid excessive traction, which can stretch and spasm the remaining intact retinacular vessels.

Fluoroscopy must be positioned to allow seamless transition between anteroposterior and lateral views without compromising the sterile field.

Detailed Surgical Approach and Technique

The surgical objective is to achieve an anatomic reduction, decompress the hip capsule, and apply stable internal fixation that respects the remaining growth potential of the proximal femur.

Closed Reduction Maneuvers

Initial management involves an attempt at gentle closed reduction. The Leadbetter maneuver is frequently employed: the hip is flexed to ninety degrees with slight adduction to unlock the fracture fragments, followed by gentle longitudinal traction, internal rotation, and subsequent extension and abduction. Forceful or repeated closed reduction attempts are strictly contraindicated, as they directly traumatize the fragile medial circumflex femoral artery anastomosis. If anatomic reduction is not achieved after one or two gentle attempts, the surgeon must proceed immediately to open reduction.

Open Reduction Approaches

For Delbet Type I, II, and III fractures requiring open reduction, the Watson Jones (anterolateral) or Smith Petersen (anterior) approach is utilized.

The Watson Jones approach utilizes the internervous plane between the tensor fasciae latae (superior gluteal nerve) and the gluteus medius (superior gluteal nerve). While not a true internervous plane, it provides excellent access to the femoral neck. The fascia lata is incised, and the interval is developed. The anterior capsule is exposed by retracting the gluteus medius laterally and the rectus femoris medially.

Capsulotomy and Hematoma Evacuation

Regardless of whether closed or open reduction is performed, an anterior capsulotomy is highly recommended for Delbet Type I, II, and III fractures.

The intracapsular hematoma creates a tamponade effect, elevating intracapsular pressure above the perfusion pressure of the epiphyseal vessels. A longitudinal or T shaped capsulotomy parallel to the femoral neck safely evacuates the hematoma and restores perfusion.

Fixation Strategies by Fracture Pattern

Fixation constructs are dictated by the Delbet classification and the age of the patient.

Delbet Type I (Transphyseal)
These fractures are highly unstable. Following reduction, fixation is achieved using smooth Kirschner wires or partially threaded cannulated screws. The fixation must cross the physis to engage the capital femoral epiphysis. In older children nearing skeletal maturity, the risk of premature physeal closure is outweighed by the need for absolute stability, and screws are preferred.

Delbet Type II (Transcervical) and Type III (Cervicotrochanteric)
Anatomic reduction is paramount. Fixation is typically achieved with multiple cannulated screws. In younger children, every effort should be made to stop the screw threads short of the capital femoral physis to preserve growth. However, if the fracture is highly unstable or the proximal fragment is too small to achieve purchase without crossing the physis, the surgeon must cross the physis to prevent displacement and coxa vara. Pediatric sliding hip screws can also be utilized for Type III fractures to provide robust biomechanical stability.

Delbet Type IV (Intertrochanteric)
These fractures are extraarticular. Fixation options include a pediatric sliding hip screw, a proximal femoral locking plate, or flexible intramedullary nails depending on the fracture obliquity and patient size. Capsulotomy is generally not required for Type IV fractures unless there is a concomitant intracapsular injury.

Complications and Management

Pediatric hip fractures are notorious for their high complication rates, which are directly correlated with the initial energy of the injury, the Delbet classification, and the adequacy of surgical management.

Avascular Necrosis

Avascular necrosis is the most devastating complication. The incidence is heavily dependent on the fracture location: Delbet Type I carries a risk of up to 90%, Type II approximately 40-50%, Type III 20-30%, and Type IV less than 10%.

The Ratliff classification is used to describe the pattern of avascular necrosis:
* Type 1: Diffuse involvement of the entire femoral head.
* Type 2: Localized involvement, typically the anterolateral segment.
* Type 3: Involvement restricted to the femoral neck from the fracture line to the physis.

Management of avascular necrosis focuses on containment of the femoral head to prevent collapse and subsequent secondary osteoarthritis. Options include bracing (historical), proximal femoral varus osteotomy, or pelvic osteotomies (Salter or triple innominate osteotomy) to improve acetabular coverage.

Coxa Vara

Coxa vara (neck shaft angle less than 120 degrees) typically results from inadequate initial reduction, loss of fixation, or premature closure of the capital femoral physis.

It leads to abductor weakness, a Trendelenburg gait, and limb length discrepancy. If the neck shaft angle is progressively decreasing or falls below 110 degrees, a valgus producing subtrochanteric osteotomy is indicated to restore normal biomechanics and abductor tension.

Premature Physeal Closure

Iatrogenic injury from hardware crossing the physis or ischemic injury from the initial trauma can lead to premature physeal arrest. This results in limb length discrepancy and potential articular deformity. Management depends on the projected discrepancy at skeletal maturity and may involve contralateral epiphysiodesis or ipsilateral limb lengthening procedures.

Nonunion

Nonunion is a rare complication in the pediatric population, occurring in less than 5% of cases. It is usually the result of inadequate fixation, distraction at the fracture site, or underlying avascular necrosis.

Treatment requires revision internal fixation, autologous bone grafting, and often a valgus producing osteotomy to convert shear forces across the nonunion site into compressive forces.

Post Operative Rehabilitation Protocols

The postoperative rehabilitation protocol must be tailored to the patient's age, compliance level, and the stability of the surgical construct.

Immobilization Strategies

Unlike adults, pediatric patients frequently require supplemental external immobilization to protect the internal fixation, as compliance with weight bearing restrictions is notoriously poor in children. For infants, toddlers, and children up to approximately ten to twelve years of age, a one and a half spica cast is routinely applied in the operating room immediately following fixation. The cast is typically maintained for six to eight weeks.

For older adolescents who can reliably adhere to instructions, spica casting may be omitted in favor of strict non weight bearing precautions using crutches or a walker.

Weight Bearing and Physical Therapy

Following the removal of the spica cast (or at the six to eight week mark for older children), clinical and radiographic evaluation is performed. If bridging callus is evident and the fracture line is obscuring, progressive weight bearing is initiated. Physical therapy focuses on restoring active and passive range of motion, particularly hip abduction and internal rotation, and strengthening the gluteal musculature to prevent a persistent Trendelenburg gait.

Long Term Surveillance

Long term follow up is absolutely critical. Avascular necrosis can present clinically or radiographically up to two years following the initial injury. Patients must be followed with serial radiographs every three to six months for the first two years, and then annually until skeletal maturity to monitor for physeal arrest, progressive coxa vara, and leg length discrepancies.

Summary of Key Literature and Guidelines

The academic consensus regarding pediatric hip fractures emphasizes the urgency of surgical intervention and the critical nature of capsular decompression.

Historical literature, including seminal papers by Ratliff and Delbet, established the foundational understanding of the vascular vulnerability of the pediatric proximal femur. Modern multicenter retrospective reviews have consistently demonstrated that early surgical intervention (within 24 hours of injury) combined with anterior capsulotomy significantly reduces the rate of avascular necrosis, particularly in Delbet Type II and III fractures.

Furthermore, biomechanical studies support the use of robust fixation constructs. While preserving the physis is a secondary goal, the primary objective must always be absolute stability of the fracture site. If anatomic reduction and stability cannot be achieved without crossing the physis with hardware, the surgeon must prioritize stability to prevent the compounding morbidities of coxa vara and nonunion. The literature strongly supports the use of supplemental spica casting in younger cohorts to mitigate the high risk of hardware failure secondary to noncompliance.

Clinical & Radiographic Imaging