Hip fractures in children

INTRODUCTION — This topic reviews issues related to hip fractures (proximal femur and femoral neck fractures) in children. Slipped capital femoral epiphysis (SCFE), femoral shaft fractures, and pelvic avulsion fractures in children are discussed separately:

●(See "Evaluation and management of slipped capital femoral epiphysis (SCFE)" and "Femoral shaft fractures in children".)

●(See "Femoral shaft fractures in children".)

●(See "Pelvic trauma: Initial evaluation and management", section on 'Avulsion fractures'.)

EPIDEMIOLOGY — Hip fractures, also known as proximal femoral fractures, are uncommon in children, accounting for <1 percent of all pediatric fractures [1-4]. The vast majority of pediatric hip fractures (85 to 90 percent) occur as a result of high-energy trauma. Hip fractures in infants and young children without a history of major trauma or evidence of a pre-existing lesion or osteopenia should raise concern for child abuse given the large force needed to cause this injury [1,5,6]. (See "Physical child abuse: Recognition", section on 'Fractures'.)

Minor trauma can result in hip fracture if there is a pre-existing pathologic lesion. Stress fractures of the hip are unusual but may occur in adolescents from repetitive trauma, such as long-distance running [1,7,8]. They are rarely seen in younger children. (See 'Mechanism of injury' below.)

CLINICAL ANATOMY — The femur is the largest bone in the body. The femur joins with the acetabulum of the pelvis proximally to form the hip joint and with the patella, tibia, and fibula distally to form the knee joint.

●Anatomic regions – The pediatric femur can be divided anatomically into the following regions (figure 1):

•Hip or proximal femur (made up of the femoral head, femoral neck, and greater and lesser trochanter)

•The femoral shaft

•The distal femur (made up of the medial and lateral epicondyles, the medial and lateral condyles, and the trochlea)

●Development – Pertinent for pediatric patients, the femur can also be divided into its developmental components. At birth, a single proximal physis is present, which then separates into two discrete physes (capital femoral and greater trochanteric), occurring between four and six months and four years of age, respectively. These physes fuse around the age of 14 in girls and around the age of 16 in boys [1]. The persistence of these physes into late adolescence coupled with a weak blood supply make the immature hip vulnerable to growth abnormalities following fractures.

●Blood supply – The high rate of complications associated with hip fractures is directly related to its tenuous blood supply. The two branches off the profunda femoris artery, the medial and lateral circumflex arteries, provide the primary blood supply to the head of the femur until about age four (figure 2). The medial circumflex artery runs posterior to the femoral neck; the lateral circumflex artery runs anterior to the femoral neck. This initial blood supply is replaced by lateral epiphyseal vessels which consist of two branches, the posterosuperior and posteroinferior branches, off the medial circumflex artery. These two branches provide the sole blood supply to the head of the femur into adulthood. Direct damage to either or both of these vessels can lead to avascular necrosis of the femoral head and permanent disability [1,9]. These vessels are also extremely susceptible to tamponade from hemarthrosis secondary to intracapsular fracture.

MECHANISM OF INJURY — There are three mechanisms for hip fractures in children:

●High-force trauma – The pediatric hip is strong and, with the exception of the physis, requires high-energy forces to fracture in most children and adolescents. Examples include [1,10-16]:

•Motor vehicle collisions

•Falls from a height greater than 10 feet (or three times the height in young children)

•Pedestrians struck by automobiles or trucks

Hip fractures in infants and young children without a history of major trauma or evidence of a pre-existing lesion or osteopenia should raise concern for child abuse given the large force needed to cause this injury [1,5,6]. (See "Physical child abuse: Recognition", section on 'Fractures'.)

●Low-force trauma – Minor trauma, such as a trip or low energy fall can result in an acute displaced hip fracture if there is pre-existing pathology such as [1,7,8,14]:

•Benign tumors (eg, unicameral (simple) bone cyst (see "Nonmalignant bone lesions in children and adolescents", section on 'Simple bone cyst')

•Malignant tumors (eg, osteosarcoma or Ewing sarcoma) (see "Osteosarcoma: Epidemiology, pathology, clinical presentation, and diagnosis" and "Clinical presentation, staging, and prognostic factors of Ewing sarcoma")

•Fibrous dysplasia (see "Nonmalignant bone lesions in children and adolescents", section on 'Fibrous dysplasia')

•Osteogenesis imperfecta (see "Osteogenesis imperfecta: An overview")

•Secondary osteopenia (eg, immobile patients with myelomeningocele or cerebral palsy)

•Rickets (vitamin D deficiency) (see "Overview of rickets in children")

Skeletally immature children may also have non-displaced fractures through the growth plate (eg, Delbet class IA (figure 3)) after low-force trauma [17].

●Repetitive injury – Adolescents may develop stress fractures of the hip during activities that cause repetitive stress to the hip, such as long-distance running [18,19]. Stress fractures of the hip (image 1) are rare in children younger than 10 years old and may not have an easily identified mechanism but likely represent repetitive injury during play or sport [19-21].

CLINICAL PRESENTATION AND EXAMINATION — The mechanism of injury correlates with the clinical presentation.

High-force trauma or child abuse — Most children with hip fractures present with a history of high-force trauma (eg, high-speed motor vehicle collision [MVC], pedestrian hit by a car, or fall from more than 10 feet) and often have multiple traumatic injuries that require rapid stabilization. Abused infants and children may have no explanation or an implausible history for the injury (table 1). In addition to a hip fracture, abused infants and young children may have bruises or other injuries suggestive of abuse, as shown in the table (table 2). (See 'Stabilization (multiple trauma patients)' below and "Physical child abuse: Recognition".)

Once stabilized, these patients typically have severe pain involving the hip and/or thigh and are non-ambulatory [1]. These fractures are often displaced with the affected leg externally rotated and shortened. The patient typically has marked swelling of the hip and tenderness on palpation.

Low-force trauma — Children with underlying bone pathology can have an isolated displaced hip fracture (pathologic fracture) despite a history of low-force trauma and will be non-ambulatory with physical examination findings, as described above [22,23].

Skeletally immature children can present with a limp and hip, thigh, or referred knee pain after low-force trauma in association with a non-displaced Delbet type IA fracture (figure 3).

Repetitive trauma (stress fracture) — Adolescents with repetitive trauma may have a limp and mild to moderate pain in the hip, thigh, knee, or, with stress fractures of the femoral head, groin [18]. The patient may be generally functional despite the fracture [24]. Physical findings are often subtle and include an antalgic gait, knee and/or hip pain with tenderness on extremes of range of motion of the hip, particularly internal rotation [1,20].

Stress fractures are rare in younger children. These patients may have a different presentation for femoral stress fracture than adolescents that is characterized by chronic limp and pain-free full range of motion or pain only present on terminal hip flexion on physical examination [24,25]. A high index of suspicion and imaging are necessary to identify these fractures.

DIAGNOSIS — The definitive diagnosis of hip fractures in children relies on history, physical examination, and imaging, which vary according to the type of fracture and clinical presentation (see 'Mechanism of injury' above and 'Clinical presentation and examination' above):

Clinical suspicion — Hip fractures in children are suspected based upon the mechanism of injury and clinical findings:

●Displaced fracture – The diagnosis of a displaced hip fracture is made based on the high-force mechanism of injury, significant findings on physical examination and plain radiographs of the hip. If the fracture is displaced, the affected leg will often be externally rotated and shortened. In addition, palpation of the hip typically causes significant pain, and active range of motion is markedly limited or absent. Patients with a pathologic fracture due to osteopenia or a local lesion such as a bone tumor may have a displaced hip fracture after a minor fall or direct blow. In either case, plain radiographs confirm the diagnosis. (See 'Plain radiographs' below.)

●Non-displaced or stress fracture – Non-displaced (Delbet type IA (figure 3)) fractures can occur with low-force injury; stress fractures occur with repetitive trauma (eg, long-distance running). These fractures have more subtle findings including limp, localized bony tenderness, and pain on extremes of internal or external rotation. Some patients may present with knee or thigh pain caused by referred pain from the fracture site. Plain radiographs may be normal in these patients. In this situation, if there is high suspicion for a hip fracture, advanced imaging such as magnetic resonance imaging (MRI) or computed tomography (CT) are necessary to confirm the diagnosis. (See 'Advanced imaging (MRI or CT)' below.)

Imaging — Diagnostic imaging is necessary in all children with suspected hip fractures to confirm the diagnosis and aid the pediatric orthopedist in planning definitive management. Plain radiographs are the most appropriate initial study because they identify most hip fractures. Advanced imaging, either MRI or non-contrast CT, are often necessary to diagnose non-displaced fractures (ie, Delbet class IA (figure 3)) or stress fractures. (See 'Plain radiographs' below and 'Advanced imaging (MRI or CT)' below.)

Plain radiographs — For children with displaced hip fractures caused by high-force trauma or pathologic fractures, plain radiographs confirm the diagnosis.

Radiographic views — Initial imaging for a hip fracture consists of standard anterior-posterior (AP) and lateral radiographs of the affected hip (image 2 and image 3). These radiographs may be adequate to demonstrate the fracture, especially if it is displaced, and also provide key findings including [1]:

●Location and direction of the fracture line

●Amount of displacement

●Degree of angulation

●Location of the femoral epiphyses

●Type of fracture

Non-displaced or stress fractures are often more difficult to see on plain AP and lateral radiographs. Depending on the level of clinical suspicion, more advanced imaging such as a CT or MRI (image 1) may be needed to identify these fractures [1].

Classification — Classification systems for pediatric hip fractures include the Delbet classification (with pediatric modification by Collona) and the Müller-AO system [26,27]. The Delbet classification system is commonly used and divides pediatric hip fractures into four types (figure 3) [4,7,26]:

●Type I: Transepiphyseal – These fractures are Salter-Harris type I fractures through the proximal femoral physis. Subtypes are IA without dislocation) and IB (with dislocation). In neonates, they are equivalent to "proximal femoral epiphysiolysis," which can occur after difficult delivery [1]. These fractures are also associated with femoral head dislocations [8]. In children under two years of age who lack a plausible mechanism, especially non-ambulatory infants, the presence of a transepiphyseal fracture should prompt an evaluation for child abuse. (See "Physical child abuse: Diagnostic evaluation and management".)

These fractures are at the highest risk for the development of avascular necrosis (AVN) of the femoral head (up to 40 percent of transepiphyseal fractures) [12,28].

●Type II: Transcervical ("femoral neck fracture") – This fracture extends through the mid-portion of the femoral neck (image 2 and image 4 and image 5 and image 6).

●Type III: Cervicotrochanteric ("femoral neck fracture") – This fracture occurs through the base of the femoral neck (image 3).

●Type IV: Intertrochanteric – This fracture traverses the greater and lesser trochanters; it has the lowest risk of AVN (approximately 5 percent of all intertrochanteric fractures) (image 7) [28].

The classification, along with other factors, helps to determine management and identifies fractures with an increased risk of complications [12] (see 'Definitive care' below and 'Complications' below):

Advanced imaging (MRI or CT) — In children with non-displaced fractures (ie, Delbet class IA (figure 3)) or stress fractures, MRI or non-contrast CT of the hip may be necessary to establish the diagnosis because plain radiographs are frequently normal [1]. When considering advanced imaging, an orthopedist with pediatric expertise or a pediatric radiologist should direct the choice of study. CT is typically more rapidly available and takes less time. Thus, it is preferred for additional imaging in children with acute hip fractures, especially multiple trauma patients. MRI has the advantage of no radiation exposure but requires sedation or general anesthesia for successful completion in infants and young children. It is especially helpful in evaluating for stress fractures of the hip in children. (See 'Stress fractures' below.)

For patients with an isolated pathologic hip fracture and radiographic findings that indicate a tumor at the fracture site, CT scan and possibly MRI with contrast is indicated to further assess tumor characteristics [14]. (See "Bone tumors: Diagnosis and biopsy techniques", section on 'Imaging'.)

INDICATIONS FOR ORTHOPEDIC CONSULT OR REFERRAL — All pediatric hip fractures warrant orthopedic consultation [1]. Displaced pediatric hip fractures are true surgical emergencies that require rapid management by an orthopedist with pediatric or trauma expertise.

INITIAL TREATMENT — Emergency management of hip fractures in children consists of:

●For patients with high-force trauma, trauma evaluation and treatment of associated life-threatening injuries

●Pain management

●Immobilization

●Diagnostic imaging and consultation with an orthopedic surgeon with pediatric expertise

Stabilization (multiple trauma patients) — Hip fractures are a marker of high-energy trauma and are often associated with other musculoskeletal injuries such as hip dislocations, pelvic fractures, and femoral shaft fractures, as well as major trauma to the abdomen, pelvis, and head [1,2,13,29,30].

Thus, a child with a suspected hip fracture in association with high-force trauma requires stabilization according to the principles of Advanced Trauma Life Support including establishment of an airway, evaluation for pulmonary compromise, and rapid treatment of hemorrhagic shock and life-threatening injuries (table 3). (See "Trauma management: Approach to the unstable child".)

Specific interventions for stabilization and definitive care of hip fractures during resuscitation include:

●Primary survey – During the primary survey, the clinician should control external bleeding due to an open hip fracture with direct compression. (See "Trauma management: Approach to the unstable child", section on 'Hemorrhage control'.)

Hip immobilization also helps with fracture-associated bleeding and may be accomplished with prefabricated fiberglass or plaster splints. For older children and adolescents with hip fractures, Buck's traction applied by an orthopedic surgeon temporarily improves bone alignment and can decrease pain. (See 'Immobilization' below.)

Open hip fracture is an indication for emergency orthopedic consultation.

Patients with associated unstable pelvic fractures may require pelvic stabilization with a prefabricated pelvic binder or bedsheet (figure 4).

●Secondary survey – During the secondary survey, the clinician should provide analgesia to stable patients and fully expose and examine the hip. Although rare, distal neurovascular compromise from a hip fracture that does not resolve after splinting also warrants emergency orthopedic consultation for provisional manipulation or reduction.

Patients with suspected hip fractures should undergo immobilization and plain radiographs. (See 'Immobilization' below.)

All proximal femur fractures require urgent consultation with an orthopedic surgeon with pediatric expertise. (See 'Indications for orthopedic consult or referral' above.)

Analgesia — Opioid analgesia (eg, intranasal fentanyl or intravenous morphine or fentanyl) is most appropriate for initial pain control in hemodynamically stable children with hip fractures. (See "Pain in children: Approach to pain assessment and overview of management principles", section on 'Pharmacologic therapy'.)

Immobilization — Once distal neurovascular function has been tested and evaluation for open wounds of the skin is complete, all hip fractures should be immobilized for comfort. Plaster, fiberglass, and various prefabricated splints are commonly used to provisionally stabilize the fracture.

Splints work best when immobilizing both the hip and the knee and is accomplished by placing splints laterally from the iliac crest to the ankle. Splints can be further bolstered, or even substituted, by pillows, blankets, or other types of bulky padding. Distal femoral traction (eg, Buck's traction) placed by an orthopedic surgeon or clinician with similar expertise is another option to temporarily improve bone alignment and decrease pain and may be more appropriate in older children and adolescents when care may be delayed, or treatment requires access to the affected extremity [31].

Prehospital medical providers frequently use traction splints to stabilize suspected femoral fractures in the field. These traction splints should be removed as soon as possible after arrival in the emergency department to prevent pressure ulcers from developing where the splints compress the skin. The traction splint should be replaced by a padded provisional splint or traction as described above.

Child protection — Diagnosis of a hip fracture in a child with an implausible mechanism of injury and no evidence of bone pathology on radiographs should prompt further evaluation for child abuse and, whenever available, involvement of an experienced child protection team lead by a child abuse specialist. (See "Physical child abuse: Diagnostic evaluation and management".)

When abuse is suspected, mandatory reporting to appropriate governmental authorities is also required in many parts of the world (including the United States, United Kingdom, and Australia). (See "Child abuse: Social and medicolegal issues", section on 'Reporting suspected abuse'.)

Intracapsular hemarthrosis — In children, intracapsular hemarthrosis complicates Delbet types I, II, or III fractures and may pose a risk of avascular necrosis (AVN) of the femoral head [8,18,32-38]. These patients require emergency orthopedic consultation. Although evacuation of the hemarthrosis with needle aspiration by an orthopedic surgeon who has pediatric expertise within 24 hours of injury has been advocated in the past, this practice is controversial, and evidence supporting the association between hip hemarthrosis and AVN of the femoral head is limited. (See 'Complications' below.)

Evidence regarding the benefit of needle aspiration of intracapsular hemarthrosis of the hip is limited. For example, in several small case series, AVN of the femoral head occurred in 17 to 43 percent of children who did not undergo emergency decompression prior to surgery [8,18]. By contrast, in a series of 10 children with intracapsular hip hemarthrosis who had decompression within 24 hours, none developed AVN [32]. However, in a separate retrospective study of 44 children with hip fractures, the overall rate of AVN was 20 percent. Development of AVN was associated with an age ≥11 years but was not significantly different for patients who had decompression of an intracapsular hemarthrosis or operative reduction within 12 hours [38].

DEFINITIVE CARE — Definitive operative care for hip fractures in children depends upon the age of the child and the type of injury.

Acute fracture (Delbet fractures) — For displaced fractures, definitive care for hip fractures in children two years of age and older is almost always operative. Typically, rigid internal fixation is applied, often augmented by a cast [17,28,35,39]. For children with displaced fractures, operative repair should occur within 24 hours of injury if the patient's clinical status allows [28,32,39-41].

Operative treatment may consist of closed reduction and percutaneous screw fixation (image 8), or a sliding hip screw or locking plate construct. For Delbet type IV fractures, fixation options may also include a trochanteric entry rigid intramedullary nail or retrograde flexible nails with fixation into the femoral neck and greater trochanter [42,43]. Because the risk of serious complications, including avascular necrosis of the femoral head, increases if the reduction is inadequate, pediatric orthopedic surgeons have a low threshold for open reduction using an anterolateral approach to the hip joint [44].

Infants and toddlers under two years of age often have good outcomes with non-operative treatment of displaced fractures [1,44]. Treatment options include spica cast immobilization (picture 1), splinting, traction, and Pavlik harness [45,46]. Spica casting may also be used in children under four years of age with type IA (non-displaced Delbet fractures (figure 3)) [47].

Stress fractures — The diagnosis of stress fractures of the hip in children requires a high index of suspicion. An orthopedic surgeon with pediatric expertise should determine management; treatment (non-weightbearing or surgical fixation) depends upon the type of fracture (compression versus tension-type) and patient age [24,25]. Management of femoral neck stress fractures in older adolescents is similar to adults and is discussed separately. (See "Femoral stress fractures in adults", section on 'Femoral neck stress fracture treatment'.)

FOLLOW-UP CARE — Physical therapy consultation is helpful in all patients to assess ambulatory safety and provide appropriate equipment such as crutches, a walker, or a wheelchair, as indicated.

Children with proximal femur fractures need to be followed by an orthopedist with pediatric expertise for at least one year after injury. Most cases of osteonecrosis will present within the first 9 to 12 months but may be seen as early as six weeks post-injury [48]. Patients can expect to be strictly non-weight bearing for at least six weeks of recovery and may be restricted for as long as 12 weeks or more.

Regular postoperative radiographs to assess healing and the development of osteonecrosis, malunion, or physeal arrest are mandatory. Typically, patients undergo imaging at six weeks and at three, six, nine, and 12 months after injury.

COMPLICATIONS — Complications of proximal femur fractures occur frequently and often result in significant long-term disability [13].

●Avascular necrosis of the femoral head – Avascular necrosis (AVN or osteonecrosis) of the femoral head is the most debilitating complication of pediatric hip fractures (image 9). AVN may become radiographically evident after injury as early as six weeks or as late as one to two years [48]. The vast majority of cases are evident by 9 to 12 months. Restricted weight bearing and, ultimately, subtrochanteric osteotomy may be required for treatment of AVN [44].

Studies have looked at several risk factors for AVN including [28,32-35,38,44,49]:

•Patient age

•Type of fracture (figure 3)

•Amount of displacement

•Quality of fracture reduction

•Surgical timing

•Hemarthrosis decompression

Of these, the risk of avascular necrosis appears to be most associated with [13,28,33,35,38,39,41,50-52]:

•Type of fracture (ranging from 40 percent [Delbet type I fracture]) to 5 percent [Delbet type IV fracture]) [28,53]

•Older age ≥11 years

•Definitive treatment more than 36 hours after injury

Furthermore, time to reduction (greater than or less than 12 hours) did not affect the risk of osteonecrosis either, but age greater than 11 years was associated with an increased risk of osteonecrosis [38].

AVN of the femoral head may become radiographically evident as early as six weeks post-injury or as late as one to two years [48]. The vast majority of cases are evident by 9 to 12 months. Restricted weight bearing and, ultimately, subtrochanteric osteotomy may be required for treatment of AVN [44].

●Inadequate healing – Malunion or non-union occurs in 10 to 30 percent of patients and causes a varus deformity of the femoral neck (coxa vara) [4,48]. Non-union may lead to further complications such as osteonecrosis or coxa vara, as well as prolonged disability due to pain. Coxa vara results in poor hip mechanics with associated pain and weakness during ambulation. Valgus subtrochanteric osteotomy is often required for treatment of these complications [44].

●Physeal arrest – Physeal arrest occurs most commonly in type I (transepiphyseal) hip fractures (figure 3), and almost always occurs in the presence of AVN of the femoral head. Limb-length inequality may result from complete closure of the physis, and can be quite profound in the presence of AVN. Secondary deformity from physeal arrest is uncommon. Long-term management of limb-length discrepancy is dependent upon the magnitude of the resultant difference and is beyond the scope of this discussion.

●Osteomyelitis or joint infection – Infection is uncommon after hip fracture and is generally manifested as persistent hip pain and fevers. Infection is associated with an even higher risk of AVN [12].

RETURN TO SPORT OR WORK — Typically, full weight bearing without the need for assistive devices does not occur until about 12 weeks after injury. This time course extends significantly with the development of complications. Physical therapy is often helpful early in the postoperative course for gait training with assistive devices.

Minimum criteria for return to play are a radiographically healed fracture that is pain free. Return to sport should not be allowed until near complete muscular control and absence of limp occurs. As such, the earliest return to play is typically about four to six months post-injury, and return to sport, in an uncomplicated course, is generally at least six months.

ADDITIONAL INFORMATION — Several UpToDate topics provide additional information about fractures, including the physiology of fracture healing, how to describe radiographs of fractures to consultants, acute and definitive fracture care (including how to make a cast), and the complications associated with fractures. These topics can be accessed using the links below:

●(See "General principles of fracture management: Bone healing and fracture description".)

●(See "General principles of fracture management: Fracture patterns and description in children".)

●(See "General principles of acute fracture management".)

●(See "General principles of definitive fracture management".)

●(See "General principles of fracture management: Early and late complications".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: General management of pediatric fractures" and "Society guideline links: Lower extremity fractures in children" and "Society guideline links: Acute pain management".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Hip fracture (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Mechanism of injury – The pediatric hip typically requires significant forces to fracture, and the vast majority of pediatric hip fractures occur after high-force trauma unless there is pre-existing pathology (eg, bone tumor, osteogenesis imperfecta, rickets, or secondary osteopenia). Adolescents may develop stress fractures of the hip during activities that cause repetitive stress to the hip, such as long-distance running; stress fractures are rare in younger children. (See 'Mechanism of injury' above.)

Hip fractures in children under two years of age without a history of major trauma or pathologic condition should raise concern for child abuse. (See 'Mechanism of injury' above.)

●Clinical presentation – The mechanism of injury correlates with the clinical presentation:

•High-force trauma or children abuse – Clinical features include:

-External rotation and shortening of the affected leg

-Marked swelling of the hip

-Tenderness on gentle palpation

In addition to a hip fracture, abused infants and young children frequently have implausible mechanisms of injury or no explanation (table 1) and may have bruises or other injuries suggestive of abuse (table 2). (See 'High-force trauma or child abuse' above.)

•Low-force trauma — Children with underlying bone pathology can have an isolated displaced hip fracture despite a history of low-force trauma. Skeletally immature children can present with a limp and hip, thigh, or referred knee pain after low-force trauma in association with a non-displaced hip fracture (eg, Delbet class IA (figure 3)). (See 'Low-force trauma' above.)

•Stress fracture – Stress fractures present in adolescents with limp and mild to moderate pain in the hip, thigh, knee, or, with stress fractures of the femoral head, groin. Younger children may have pain-free full range of motion or pain only present on terminal hip flexion. (See 'Repetitive trauma (stress fracture)' above.)

●Diagnosis – The diagnosis of a hip fracture is suspected based upon the mechanism of injury and clinical findings. (See 'Diagnosis' above and 'Clinical suspicion' above.)

Diagnostic imaging confirms the diagnosis and aids the pediatric orthopedist in planning definitive management. Plain radiographs (image 3 and image 4 and image 5 and image 6 and image 7) are the most appropriate initial study because they identify most hip fractures. The Delbet classification is commonly used to classify these fractures (figure 3). (See 'Imaging' above and 'Plain radiographs' above.)

Advanced imaging, either MRI or non-contrast CT, is often necessary to diagnose non-displaced Delbet class IA fractures or stress fractures (image 1). When considering advanced imaging, an orthopedist with pediatric expertise or a pediatric radiologist should direct the choice of study. (See 'Advanced imaging (MRI or CT)' above.)

●Initial treatment:

•Stabilization and analgesia – Children with suspected hip fractures after high-force trauma require a trauma evaluation and management according to the principles of Advanced Trauma Life Support (table 3). (See 'Stabilization (multiple trauma patients)' above.)

After stabilization, as needed, initial therapy consists of analgesia and immobilization. (See 'Analgesia' above and 'Immobilization' above.)

•Specialty consultation – Displaced pediatric hip fractures are true surgical emergencies. They require management by an orthopedist with pediatric expertise. (See 'Indications for orthopedic consult or referral' above.)

•Child protection – Diagnosis of a hip fracture in a child with an implausible mechanism of injury and no evidence of bone pathology on radiographs should prompt further evaluation for child abuse and, whenever available, involvement of an experienced child protection team lead by a child abuse specialist. (See "Physical child abuse: Diagnostic evaluation and management".)

•(See 'Intracapsular hemarthrosis' above.)

●Definitive care – Definitive care depends on the type of fracture and patient age:

•Acute hip fracture – Displaced hip fractures in children two years of age and older require reduction and internal fixation (image 2). The timing of operative repair depends upon the type of hip fracture and the patient's clinical status but should occur within 24 hours whenever possible. (See 'Acute fracture (Delbet fractures)' above.)

Infants and toddlers under two years of age are usually treated non-operatively with immobilization (eg, spica cast, splinting, traction, or Pavlik harness).

•Stress fractures – The diagnosis of stress fractures of the hip in children requires a high index of suspicion. An orthopedic surgeon with pediatric expertise should determine management based upon the type of fracture (compression versus tension-type) and patient age. (See 'Stress fractures' above.)