Distal femoral fractures in children

INTRODUCTION — Distal femur fractures in pediatric patients are discussed here. Hip fractures and femoral shaft fractures in children are discussed separately. (See "Hip fractures in children" and "Femoral shaft fractures in children".)

CLASSIFICATION — Distal femur fractures can be classified as metaphyseal fractures or physeal fractures.

Metaphyseal fractures — Transverse distal metaphyseal fractures (also called supracondylar femoral fractures) are the most common type of distal femur fracture in infants and young children (image 1) [1].

Physeal fractures — Distal physeal (growth plate) femur fractures occur more commonly in older children and adolescents. The Salter-Harris classification of physeal fractures is most often used (figure 1).

●Salter-Harris type I – Salter-Harris type I fractures were thought to be an uncommon type of distal pediatric femur fracture in early studies, accounting for only about 7 percent of distal femur physeal fractures [2]. However, more recent studies suggest an incidence of between 21 to 25 percent [3-5]. Salter-Harris Type I fractures occur in vaginally delivered breech newborns, abused infants, and as a sports related injury in adolescents [6,7]. When there is no fracture displacement, initial plain radiographs may be negative which can make these injuries difficult to diagnose. (See 'Imaging' below.)

●Salter-Harris type II – Salter-Harris type II fractures are the most common of the distal femur physeal injuries [2-6,8-11]. These fractures most often result from a sports-related injury in the older child or adolescent and are often displaced when diagnosed (figure 2 and image 2) [2,11,12]. Metaphyseal corner fractures are type II Salter-Harris injuries that occur in infants and toddlers and are highly suggestive of child abuse (image 3 and image 4). (See "Orthopedic aspects of child abuse", section on 'Metaphyseal'.)

●Salter-Harris type III and IV – Salter-Harris type III and IV fractures are less common [2-5,8]. These fractures are often displaced upon presentation and frequently require surgical intervention for stabilization, particularly when they extend into the knee joint (image 5 and image 6) [2,6].

●Salter-Harris type V – Salter-Harris type V distal femur fractures are rare and result from extreme axial compression of the physis. Initial plain radiographs may be negative and these fractures are often diagnosed retrospectively when growth failure occurs [3-6].

A combination of the Salter-Harris classification, mechanism of injury, and degree of initial displacement is most accurate in predicting future limb-length discrepancy, growth arrest and overall outcome after distal femoral fractures rather than relying on the Salter-Harris classification alone [2-4,6,8].

EPIDEMIOLOGY — Distal femur fractures are uncommon, but not rare, injuries, accounting for 12 to 18 percent of all pediatric femur fractures [13,14]. Distal femur physeal fractures account for 7 percent of all lower extremity growth plate injuries, but only 1 percent of all physeal fractures [5,15].

As with other types of femur fractures, boys remain at greater risk than girls [2-4,8,10,12-14,16]. The highest frequency is in older children and young adolescents [2-4,8,12,14,16]. This injury results from high force mechanisms, such as motor vehicle collisions, pedestrians struck by cars, child abuse, falls, and sport-related injuries [17].

Underlying medical disorders place patients at higher risk for sustaining a distal femur fracture either from inherent skeletal fragility (eg, osteogenesis imperfecta) or low bone density from disuse (eg, cerebral palsy, spina bifida, or arthrogryposis) [3,6,14].

CLINICAL ANATOMY — The femur is the largest bone in the body. It articulates with the patella, tibia and fibula distally to form the knee joint (figure 3). The distal femur is made up of the medial and lateral epicondyles, the medial and lateral condyles and the trochlea. It contains the distal femoral metaphysis, physis, and epiphysis.

The distal femoral epiphysis ossifies at 36 weeks gestation in normally developing children, and is present at birth [6,18]. The distal femoral physis is the largest and fastest growing physis in the body contributing 70 percent of femur growth and 40 percent of overall lower extremity growth. It closes between 14 and 16 years of age in girls and 16 to 18 years of age in boys [18].

Several important muscles and ligaments of the lower extremities have their proximal insertion sites on the distal femur:

●The heads of both the gastrocnemius and plantaris muscles attach on the posterior distal femoral metaphysis, just proximal to the physis. If there is a fracture proximal to the insertion site, the distal fracture fragment will be pulled into flexion.

●The adductor magnus muscle also attaches to the medial femoral metaphysis, also proximal to the physis. If there is a fracture proximal to its insertion, the distal fracture fragment will be pulled medially (varus position) [6].

●Both medial and lateral collateral ligaments attach distal to the physis at the epiphysis. Excessive varus (force applied medially to move the joint away from midline) or valgus stress (force applied laterally to move the joint toward from midline) is absorbed by the collateral ligaments and transferred to the distal femoral physis. In growing children, the ligaments are stronger than the bones and this force will result in injury to the physis without injury to the collateral ligaments [6,18]. Alternatively, the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) both attach to the distal femoral epiphysis and can be injured with a distal femoral epiphyseal or physeal injury [2,6,8,9,19].

The popliteal fossa is an important anatomic landmark as it contains key neurovascular structures that can be injured with distal femur fractures (picture 1):

●The superficial femoral artery travels through the adductor canal (figure 4) just above the distal femoral metaphysis and then courses posteriorly into the popliteal fossa as the popliteal artery.

●The popliteal artery runs directly posterior to the distal femur and trifurcates below the knee, making it prone to injuries with displaced fractures, most often with hyperextension injuries [4-6]. The knee has poor surrounding collateral circulation, so a popliteal artery injury is important to diagnosis and management since it can result in loss of limb viability [6].

●The tibial nerve lies adjacent to the popliteal artery. The common peroneal nerve travels lateral and superficial to the popliteal artery at the distal femur. Both of these nerves can be injured with distal femur fractures [2,6].

MECHANISM OF INJURY — Fractures of the distal femur are generally thought to result from high-energy mechanisms. The mechanism of injury varies by patient age.

●Neonates – Newborns represent a distinct population of infants who may sustain a distal femur fracture, most often a Salter-Harris Type I fracture, as a direct result of breech delivery. They can be initially undiagnosed until callous formation becomes apparent two to three weeks after delivery [6].

●Infants and toddlers – For infants and toddlers, high-energy falls and child abuse remain the leading causes of distal femur fractures [6,13,20,21]. Femur fractures in children too young to walk independently should heighten awareness for abusive injury, particularly "corner fractures" of the distal femur (image 3 and image 4). "Corner fractures" represent Salter-Harris type II fractures in which the corners of the metaphysis are displaced from the rest of the metaphyseal flare. These fractures are highly suggestive of child abuse. (See "Orthopedic aspects of child abuse", section on 'Metaphyseal'.)

●Older children – In school-age children, distal femur fractures most often result from severe trauma, such as a fall from a significant height or being struck by a car while walking or bicycling [6,12,16].

●Adolescents – In addition to high-energy mechanisms, such as motor-vehicle collisions and being struck by a car, sports injuries are an important cause of distal femur fractures in adolescents [6,9,12,16,19,21,22].

The direction of direct force on the knee determines the type of fracture and associated injuries. For example, when a valgus-type force is applied directly to the lateral side of the distal femur, as with football injuries, it generally results in a Salter-Harris Type II or III fracture (figure 5) [6,19]. Anterior cruciate ligament tears can occur in association with Salter-Harris III fractures [19]. Alternatively, a hyperextension injury of the distal femur can result in the anterior displacement of the epiphyses. In this situation, the proximal fracture fragment can be driven posteriorly into the popliteal fossa where it can damage popliteal vessels and the common peroneal or tibial nerves [4,6].

CLINICAL FEATURES AND EXAMINATION — The presence of a distal femur fracture will usually be suspected based on a history of a high-energy mechanism with physical examination findings of pain and swelling around the distal femur and knee (picture 2). Patients with distal femur fractures will often be in severe pain and unable to bear weight. Associated hamstring muscle spasms will cause the knee to be flexed with resultant obvious knee deformity [6]. The skin may be bruised indicating location of direct force. While distal femur fractures are not commonly open, the physical examination should look for open wounds near the fracture site [2,4,12].

A careful neurovascular exam is imperative because these fractures frequently disrupt blood vessels and nerves that travel through the popliteal fossa [2,4]. Clinicians should also evaluate for associated extremity compartment syndrome and related traumatic injuries.

●Vascular injury – Specific findings suggestive of serious injury to the popliteal blood vessels include:

•Swelling in the popliteal space

•Absent or diminished dorsalis pedis or posterior tibial pulses

•Slow distal capillary refill

•A cold, pale foot

•Ultrasound findings indicating vascular disruption (eg, monophasic continuous wave Doppler, B-mode imaging showing arterial occlusion or disruption, or abnormal flow on duplex imaging) (see "Noninvasive diagnosis of upper and lower extremity arterial disease", section on 'Duplex ultrasound').

Admission for serial examination of vascular integrity with injured extremity index (IEI, resting systolic pressure obtained at the ankle using continuous wave Doppler (picture 3) divided by the systolic brachial pressure) should occur for patients with an injury or physical findings that suggest disruption of the popliteal artery. An IEI of less than 0.90 warrants further investigation by arteriography [23]. (See "Severe lower extremity injury in the adult patient", section on 'Injured extremity index'.)

●Nerve injury – Motor injury with foot drop and sensory deficits on the dorsal or plantar foot can indicate injury to the tibial or peroneal nerves.

●Acute compartment syndrome – Due to the risk of vascular compromise associated with distal femoral fractures, the soft tissues of the lower extremity must also be examined for compartment syndrome at the initial presentation and subsequently. The anterior compartment of the lower leg is the most common site for acute compartment syndrome (ACS). It contains the four extensor muscles of the foot, the anterior tibial artery, and the deep peroneal nerve (figure 6). Signs of ACS affecting the anterior compartment include loss of sensation between the first (ie, great) and second toes and weakness of foot dorsiflexion. ACS rarely develops in the thigh but may do so following major blunt trauma. (See "Acute compartment syndrome of the extremities", section on 'Anatomic compartments and related clinical signs'.)

Symptoms and examination findings of ACS can include the following (see "Acute compartment syndrome of the extremities", section on 'Clinical features'):

•Pain out of proportion to apparent injury (early and common finding)

•Persistent deep ache or burning pain

•Paresthesias (onset within approximately 30 minutes to two hours of ACS; suggests ischemic nerve dysfunction)

•Pain with passive stretch of muscles in the affected compartment (early finding)

•Tense compartment with a firm "wood-like" feeling

•Pallor from vascular insufficiency (uncommon early finding)

•Diminished sensation

•Muscle weakness (onset within approximately two to four hours of ACS)

•Paralysis (late finding)

Direct measurement of compartment pressures is discussed in greater detail separately. (See "Acute compartment syndrome of the extremities", section on 'Measurement of compartment pressures'.)

●Other associated injuries – All patients with distal femoral fractures after major trauma warrant evaluation for other injuries to the cervical spine, head, chest and abdomen according to Advanced Trauma Life Support. (See "Trauma management: Approach to the unstable child", section on 'Initial approach'.)

The remainder of the orthopedic evaluation should look for associated skeletal and ligamentous injuries [2,4,8].

●Other inflicted injuries – Infants and young children who suffer distal femur fractures as a result of child abuse are at high risk for associated injuries including other fractures, retinal hemorrhages, or intraabdominal or intracranial injury. Further evaluation including skeletal survey, dilated eye examination by an ophthalmologist, laboratory studies, and neuroimaging should be pursued. (See "Physical child abuse: Diagnostic evaluation and management" and "Child abuse: Evaluation and diagnosis of abusive head trauma in infants and children".)

IMAGING — Plain radiographs typically establish the diagnosis of a distal femoral fracture. However, physeal injuries and injuries associated with vascular compromise usually require additional studies such as computed tomography and arteriography.

Plain radiographs — Initial evaluation of a suspected distal femur fracture should include standard anterior posterior (AP) and lateral radiographs of the knee and entire femur, including the hip, to determine fracture line, degree of displacement and to rule-out an associated knee dislocation [6,18].

Additional views of the knee, such as oblique or tunnel views, may be needed to identify minimally displaced or nondisplaced distal femur fractures in patients for whom standard films are equivocal or do not show a fracture despite significant bony tenderness [4,6,18,19]. If the fracture is considered to be potentially unstable, stress views should not be performed as they may exacerbate instability. The unaffected knee can also be imaged and provide a comparison to detect subtle distal femur fractures.

Children under two years of age in whom child abuse is suspected should undergo a skeletal survey to be evaluated for other bony injuries. (See "Orthopedic aspects of child abuse", section on 'Skeletal survey'.)

Other imaging — In most patients, plain radiographs are sufficient to identify and to begin treatment of children with distal femoral fractures. Other imaging may be performed in the following circumstances and as dictated by the orthopedic specialist:

●In unusual cases with a high impact mechanism and marked tenderness directly over the physis in which a physeal fracture is suspected despite plain radiographs showing neither a fracture nor soft tissue swelling at the physis, computed tomography (CT), magnetic resonance imaging (MRI) or ultrasound may be needed to diagnose the fracture or to better evaluate the degree of displacement [6,16,18,19,22]. Of these, CT is typically favored. In one small series of children with Salter-Harris Type III fractures, plain radiographs routinely underestimated the degree of fracture displacement relative to computed tomography with important implications for treatment options [16].

CT scan is often useful in presurgical planning for highly comminuted or intra-articular injuries of the distal femur.

●If there is concern for acute limb ischemia based upon history, physical examination or, if obtained, ultrasound findings, the patient should undergo CT angiography or catheter-based arteriography to assess for vascular injury. CT angiography is preferred in hemodynamically stable patients with multiple trauma. (See "Severe lower extremity injury in the adult patient", section on 'Arteriography'.)

INITIAL TREATMENT — Fractures of the femur represent significant injuries and almost always warrant early, urgent intervention.

Stabilization — Patients with high energy trauma (eg, high speed motor vehicle collision) associated with distal femoral fractures should be rigorously evaluated by standard trauma guidelines, including establishment of an airway with immobilization of the cervical spine, evaluation for pulmonary and circulatory compromise, and placement of appropriate vascular access. (See "Trauma management: Approach to the unstable child", section on 'Initial approach' and "Trauma management: Approach to the unstable child", section on 'Primary survey'.)

Focused vascular evaluation of the affected extremity by careful clinical examination is critical for these fractures as vascular injury may occur. Aside from palpation of pulses, injured extremity indices (IEI, resting systolic pressure obtained at the ankle using continuous wave Doppler (picture 3) divided by the systolic brachial pressure) are helpful in discerning more subtle vascular injury [23]. An IEI of less than 0.90 warrants further investigation by arteriography [23]. (See "Severe lower extremity injury in the adult patient", section on 'Injured extremity index'.)

For children with an isolated femoral shaft fracture and no other serious injury, initial therapy consists of pain management and immobilization.

Analgesia — Femur fractures are incredibly painful injuries. Parenteral opioid analgesia (eg, intravenous morphine 0.1 to 0.15 mg/kg; maximum initial dose: 10 mg) have been the mainstay for initial pain control in children with femur fractures. (See "Pain in children: Approach to pain assessment and overview of management principles", section on 'Opioids'.)

There is increasing evidence that regional nerve blocks such as fascia iliaca compartment blocks [24,25] and ultrasound-guided femoral nerve blocks [26] may safely provide a longer duration of analgesia and lower pain scores when compared with systemic analgesics in pediatric patients with acute femur fractures. (See "Lower extremity nerve blocks: Techniques", section on 'Fascia iliaca (lateral femoral cutaneous) block' and "Femoral nerve block procedure guide".)

Whether systemic analgesia or regional nerve blocks are used, it is important that appropriate pain relief be given as soon as possible.

Immobilization — Once distal neurovascular function has been tested and evaluation for open wounds of the skin is complete, all femur 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. Consequently, splints placed laterally from the iliac crest to the ankle are quite effective. Splints for distal femur fractures work best when extended at least to the proximal thigh. Splints can be further bolstered, or even substituted, by pillows, blankets, or other types of bulky padding.

Paramedical staff will 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 as described above.

Skeletal traction (traction applied to temporary pins drilled through bone), although commonly used in adults, is less frequently used in pediatric patients. Such traction is typically avoided initially because improper pin placement and excessive traction risk injury to growth plates. If a traction pin is deemed necessary, it should be placed by an experienced pediatric orthopedist in an operating room using sterile technique and radiographic guidance.

Child protection — Diagnosis of a femoral shaft fracture in a child, especially a nonambulatory infant, with a questionable mechanism of injury should prompt involvement of an experienced child protection team (eg, social worker, nurse, physician with more extensive experience in the management of child abuse), if available. In many parts of the world (including the United States, United Kingdom, and Australia), a mandatory report to appropriate governmental authorities is also required for cases of suspected abuse. (See "Child abuse: Social and medicolegal issues", section on 'Reporting suspected abuse'.)

In addition, the medical care team should ensure that children under two years of age with suspected intentional trauma undergo additional evaluation to determine the presence of other injuries once stabilized. The safety of other children in the home must be ensured by local Child Protective Services. (See "Physical child abuse: Diagnostic evaluation and management" and "Child abuse: Evaluation and diagnosis of abusive head trauma in infants and children", section on 'Evaluation'.)

INDICATIONS FOR ORTHOPEDIC CONSULT OR REFERRAL — Patients with distal neurovascular compromise or signs of acute compartment syndrome warrant emergency orthopedic evaluation. An orthopedist with pediatric expertise should be consulted during the initial visit for all other distal femoral metaphyseal and physeal fractures.

DEFINITIVE CARE — Treatment options for distal femur fractures in infants and children include [4,7,8]:

●Bracing

●Splinting

●Casting

●Closed reduction with external frame fixation

●Open internal fixation with plates, screws, wires, or pins

Treatment largely depends upon the location of the fracture, age of the patient, the patient’s premorbid function and their ability to tolerate an operation. Management of life-threatening traumatic injuries takes precedence over orthopedic treatment of stable distal femoral fractures. Fractures with vascular compromise or acute compartment syndrome warrant emergency orthopedic reduction and stabilization.

●Metaphyseal and diaphyseal fractures:

•Infants <6 months old – Infants less than six months of age are easily treated with a splint. In neonates, a soft cotton roll and a tongue depressor make a nice splint of appropriate size and padding [4,7]. Femur fractures in this age group usually heal within a month without long term complications. (See 'Complications' below.)

•Children ≥6 months to <6 years – Older infants, toddlers and young children under six years of age with distal diaphyseal or metaphyseal femur fractures can usually be treated in a high, long leg cast [7,8]. Closed reduction under sedation is required for fractures with more than 10 degrees of angulation in ambulatory children. Pediatric procedural sedation is discussed in greater detail separately. (See "Procedural sedation in children: Approach" and "Procedural sedation in children: Selection of medications", section on 'Moderately or severely painful procedures'.)

•Children ≥6 years old – As children approach six years of age, pins, screws, intramedullary flexible rods, plates, and external fixators can be used successfully [7,27]. Several factors, such as the presence of multiple trauma, vascular injury, or other soft tissue constraints, determine the specific hardware used and timing of the procedure (image 7).

●Physeal fractures – Fractures involving the distal femoral physis should be reduced with adequate sedation or anesthetic to allow gentle reduction and avoid further damage to the growth plate. Fractures in younger children and fractures that seem stable after reduction may be treated in a long leg cast or pinned. In patients with Salter-Harris type II fractures, interposition of periosteum may prevent anatomic reduction and require open reduction prior to pinning (figure 2). Some experts recommend fixation of all physeal fractures due to the increased risk of displacement with casting alone [7,8]. In either case, casted patients are to be kept strictly non-weightbearing for six weeks after reduction.

In patients with Salter-Harris II and IV fractures that contain a large enough metaphyseal/epiphyseal fragment, screws that do not violate the physis may be placed to stabilize the fracture (image 8) [7]. Epiphyseal screws are also appropriate in Salter-Harris III fractures that are large enough to accept screw placement. Smooth Kirschner wires may be used in a cross pin configuration when fixation across or near the physis is required (image 9).

FOLLOW-UP CARE — Children with distal femur fractures require frequent evaluation by an orthopedic surgeon with pediatric expertise after reduction or repair. The frequency and timing of follow-up is determined by the treating surgeon based upon several factors including patient age, whether closed reduction alone was performed, and the type of operative repair. Significant healing of distal femur fractures usually occurs by six weeks of treatment [2,7]. As such, treatment by casting, splinting, traction or external fixation rarely exceeds this time frame.

All patients with femur fractures have early limitations to their mobility. Physical therapy is required in patients who are old enough to navigate with crutches or a walker. A wheelchair is provided for all patients to facilitate longer distances. Once ambulatory, physical therapy is rarely necessary. Full weightbearing, with rare exception, is expected by six weeks after initiation of treatment.

Patients with injuries to the growth plate require monitoring for at least one year after surgery for the development of growth arrest. Patients with growth arrest require longer follow-up care. Injuries away from the growth plate are typically resolved by 6 to 12 months after injury.

For children treated with internal or external fixation, early mobilization is facilitated by a physical therapist prior to discharge from the hospital, but typically physical therapy is not required subsequently.

COMPLICATIONS — As a rule, complications in the treatment of pediatric femur fractures are uncommon [27-30]. Many undesired outcomes can be overcome through the resiliency of childhood and growth. Complications from femur fractures can be broken down into two general categories: perioperative and delayed. Perioperative complications are those encountered early and are associated with the significant energy required to result in a femur fracture. Delayed complications are most common with physeal fractures.

●Perioperative – Perioperative complications include neurovascular injury, compartment syndrome and infection. They are often associated with higher energy trauma such as motor vehicle accidents and falls from extreme heights. Nerve injuries are often transient, but if severe enough can result in permanent nerve palsy.

Patients with signs of vascular injury in addition to fracture require vascular imaging and, if confirmed, urgent treatment directed by a vascular surgeon with pediatric expertise [31]. Infection can occur with operative fixation, and typically presents approximately a week postoperatively with erythema, drainage from the operative site, and fever, but can be delayed by several weeks (low grade infections may manifest as nonunion, months after initial treatment) [32].

●Stiffness – Most children have early stiffness of the knee as a result of these injuries, particularly when treated in a cast [7]. This stiffness typically resolves spontaneously over time. Most children recover full range of motion without formal intervention. Physical therapy may be a useful adjunct in recalcitrant cases of stiffness, or in patients where more rapid return to sports is desired.

●Growth arrest and leg-length discrepancy – Growth disturbance and subsequent leg-length discrepancies or angular deformity are common remote complications after distal physeal femoral fractures [33]. In a meta-analysis of 16 series encompassing 564 pediatric distal femur fractures, 50 percent of distal femoral fractures involving the growth plate developed growth disturbance and 22 percent resulted in a leg-length discrepancy >1.5 cm.

Minor discrepancies in length, rotation and angular deformity from malunion are generally well tolerated [34,35]. In younger children, these abnormalities often resolve spontaneously with growth, due to their proximity to the growth plate [36]. In the case of symptomatic angular deformity, corrective osteotomy is an effective treatment [37]. When this is due to partial physeal arrest, bar resection may be required as well.

For predicted leg-length difference at maturity of less than 2 cm, shoe inserts (or nothing) are the recommended treatment of choice. For predicted differences of 2 to 5 cm, contralateral epiphysiodesis (growth plate obliteration) can be performed prior to reaching skeletal maturity, resulting in equalization of leg-lengths [38]. If the child has already reached skeletal maturity, then femoral shortening with intramedullary fixation is the recommended treatment of choice. Patients with a predicted leg-length difference greater than 5 cm are typically treated with femoral lengthening via distraction osteogenesis.

●Non-union – Non-union in children is very uncommon, especially in the metaphyseal bone of the distal femur [37]. It is typically associated with infections or cases in which significant soft tissue injury or bone loss has occurred. Evaluation for infection should always occur in the face of fracture nonunion, including cultures of blood and bone and measurement of inflammatory markers such as white blood cell count, C-reactive protein and erythrocyte sedimentation rate. In most instances, open treatment with curettage of fibrous nonunion and bone grafting with either autograft (gold standard) or demineralized bone matrix are warranted. Rigid fixation with a plate is often required.

RETURN TO SPORT OR WORK — By three months the majority of patients will be able to gradually return to normal activity, with full function typically restored by six months [7]. Involvement of the growth plate results in little deviation from this course, unless further surgical intervention becomes warranted.

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 topics (see "Patient education: How to use crutches (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Classification and mechanism of injury – Distal femoral fractures in children typically result from high force trauma such as motor vehicle collisions, falls, contact sports, and, in infants and young children, child abuse (see 'Classification' above and 'Mechanism of injury' above):

•Transverse distal metaphyseal fractures (also called supracondylar femoral fractures) are the most common type of distal femur fracture in infants and young children (image 1).

•Metaphyseal corner fractures are type II Salter-Harris injuries that occur in infants and toddlers and are highly suggestive of child abuse (image 3 and image 4). (See "Orthopedic aspects of child abuse", section on 'Metaphyseal'.)

•Distal physeal femur fractures occur more commonly in older children and adolescents. These injuries are described using the Salter-Harris classification system (figure 1).

●Clinical features – The presence of a distal femur fracture will usually be suspected based on the history of a high-energy mechanism with physical examination findings of pain and swelling around the distal femur and knee (picture 2). Patients with distal femur fractures will often be in severe pain and unable to bear weight. Associated hamstring muscle spasms will cause the knee to be flexed with obvious deformity. (See 'Clinical features and examination' above.)

A careful neurovascular exam is imperative because these fractures frequently disrupt blood vessels and nerves that travel through the popliteal fossa (picture 1). Focused vascular evaluation of the affected extremity by careful clinical examination is critical for these fractures as vascular injury may occur. Aside from palpation of pulses, injured extremity indices (IEI, resting systolic pressure obtained at the ankle using continuous wave Doppler (picture 3) divided by the systolic brachial pressure) are helpful in discerning more subtle vascular injury. An IEI of less than 0.90 warrants further investigation by arteriography.

●Imaging – Plain radiographs consisting of standard anterior posterior (AP) and lateral radiographs of the knee and entire femur, including the hip, typically establish the diagnosis of a distal femoral fracture. However, some physeal injuries and injuries associated with vascular compromise require additional studies such as computed tomography and arteriography. Children under two years of age in whom child abuse is suspected should undergo a skeletal survey to be evaluated for other bony injuries. (See 'Imaging' above.)

●Initial treatment – Patients with high energy trauma (eg, high speed motor vehicle collision) associated with distal femoral fractures should be rigorously evaluated by standard trauma guidelines, including establishment of an airway with immobilization of the cervical spine, evaluation for pulmonary and circulatory compromise, and placement of appropriate vascular access. For children with isolated distal femoral fractures and no other serious injury, initial therapy consists of pain management and immobilization. (See 'Initial treatment' above.)

●Child protection – Diagnosis of a distal femur fracture in a child, especially a nonambulatory infant, with a questionable mechanism of injury should prompt further evaluation, involvement of a multidisciplinary child protection team (eg, social worker, nurse, child abuse specialist) whenever available, and reporting to governmental Child Protective Services. (See "Physical child abuse: Diagnostic evaluation and management".)

●Specialty consultation – Patients with distal neurovascular compromise or signs of acute compartment syndrome warrant emergency orthopedic evaluation. An orthopedist with pediatric expertise should be consulted during the initial visit for all other distal femoral metaphyseal and physeal fractures.

●Definitive care – Definitive care can vary significantly, from short splint immobilization to open, operative treatment depending upon the patient's age and ability to tolerate operative repair. (See 'Indications for orthopedic consult or referral' above and 'Definitive care' above.)

By three months after injury, most children with distal femoral fractures heal enough to start a gradual return to normal activity, with full function typically restored by six months. Involvement of the growth plate results in little deviation from this course, unless further surgical intervention becomes warranted.