Pediatric orthopedic surgeons believe that pediatric pelvic fractures account for only 1 to 2 percent of all fractures and that these fractures are closely associated with high-energy trauma and life-threatening complications. Anteroposterior radiographs and rapid CT scans are used to diagnose and classify these fractures and identify the presence of comorbid injuries. Treatment often varies depending on the age of the child, fracture classification, stability of the pelvic ring, and severity of comorbid injuries. The vast majority of pediatric pelvic fractures can be treated nonoperatively, i.e., with protected weight bearing and gradual return to normal activity. However, acetabular fractures displaced >2 mm and any intra-articular fracture or Y-shaped cartilage fracture displaced >2 mm must be treated with incision and internal fixation. For pelvic ring displacements >2 cm, external fixation is feasible to prevent unequal lower limb length. Pelvic fractures often interfere with the development of the immature Y-shaped cartilage of the acetabulum, resulting in acetabular dysplasia, hip subluxation and poor hip joint matching. Acetabular fractures combined with hip dislocation increase the risk of femoral head necrosis in the distant future, and some other complications include ossifying myositis, and neurologic defects causing sciatic, femoral, and/or lumbosacral plexus nerve injury.
Pediatric pelvic fractures are often closely associated with high-energy injuries, which are most commonly caused by motor vehicle crashes and motor vehicle-pedestrian accidents, which cause more severe brain, abdominal, and urinary tract injuries than pelvic fractures. Avulsion fractures are a subgroup of pelvic fractures that occur primarily in adolescents who play sports, such as soccer, gymnastics, and track and field, often without life-threatening injury or severe trauma.
In adults, bleeding from pelvic fractures is often a major cause of morbidity and mortality, but this rarely occurs in pediatric patients, probably related to the fact that pediatric patients are more vasoconstrictive than adults and have smaller vascular diameters than adults, so they are able to contract quickly, whereas adult vessels are more prone to atherosclerosis and increased brittleness. Adults and pediatric patients have different mechanisms for pelvic injuries and therefore different types of fractures. In the pediatric population, the injury is often associated with a motor vehicle-pedestrian accident, resulting in a lateral crush injury without sacroiliac joint disruption; in the adult population, it is often the subject of a traffic accident, resulting in an anterior-posterior crush injury, which increases pelvic volume and is associated with sacroiliac joint disruption, resulting in blood loss; lateral crush reduces pelvic volume and is not directly related to the expulsion effect caused by the fracture relationship. Pediatric bone with good elasticity, combined with good flexibility of the sacroiliac joint and pubic symphysis, increases the chance of a single pelvic fracture in the pediatric population, and the occurrence of a single pelvic fracture correlates with a reduced risk of vascularized rupture hemorrhage.
Diagnosis
History and physical examination
When evaluating an injured pediatric patient with suspected pelvic injury, the first thing to look for is airway patency, respiratory and circulatory status, and injuries to the head, chest, abdomen, and spine and pelvis should be carefully evaluated as a potentially life-threatening injury, especially bleeding. If the child has a history of coma or lethargy after the injury, then a systematic and comprehensive neurological examination is necessary. And it is important to understand the child’s medication and treatment and to learn about the cause and course of the injury from family members, EMS personnel, responders at the site of the accident, and, if possible, from the patient.
A pediatric patient with a pelvic fracture should be given adequate attention for life-threatening injuries, and the pelvic fracture itself can be treated once respiratory, abdominal, and central nervous system injuries are well monitored. Visual examination of the pelvis and perineal area can indicate the presence of lacerations, bruising, and edema, and an intact evaluation of the scrotum, vagina, and urethra is necessary to rule out their injury. When urethral injury is suspected, retrograde urethrography should be performed before catheterization. A subsequent rectal examination can help identify rectal rupture, bony fragments, or displaced prostate.
The pediatrician should be carefully examined for contusions and local bruising. Morel Lavellee injury is a shearing injury to the skin and subcutaneous fat beneath the trim, often in overweight children; this injury is rare in young children, but can occur in older children and adolescents. Next, palpation of the anterior superior iliac spine, iliac spine, sacroiliac joint and pubic symphysis should also be performed. Direct compression of the iliac spine can trigger pain on the side of the fracture by vibration on one side, as can compression of the pelvic ring at the iliac spine. Pain, twisting sounds, and fluid wave tremors often indicate potentially severe pelvic injury.
CT is considered one of the most effective methods for evaluating the severity of pelvic injury, and although some believe that CT does not provide good discrimination in the classification and treatment of pediatric pelvic fractures and is considered costly, time-consuming, and radiologically damaging, we are convinced that CT is valid and valuable for preoperative planning if the child has a severe pelvic injury. Three-dimensional reconstructed CT images are capable of depicting complex fracture patterns and are often used in pediatric patients with combined head and abdominal trauma. When spinal fractures, including pelvic fractures, are clinically suspected, CT can provide a more complete and valid assessment of the injury.
MRI with MRI and bone scan is of little significance in the emergency evaluation of severe pelvic injuries, but MRI is useful for later injury analysis of soft tissue and/or cartilage; bone scan is useful in the evaluation of stable fractures without displacement or avulsion fractures.
Classification
There are different fracture subtypes in the pediatric population with unclosed cartilage in the profile. An immature Y-shaped pelvis with unclosed cartilage can usually tolerate fractures of the pubic and iliac wings and rarely requires surgical treatment. This is because the iliac wing is weaker than the elastic pelvic ligaments in an immature pelvis, making it possible for the fracture to precede injury to the pelvic ring. The Y-shaped cartilage of the acetabulum closes at approximately 14 years of age in males and 12 years of age in females, and adolescents can usually survive acetabular fractures, pubic symphysis displacements, and sacroiliac joint separations after the Y-shaped cartilage closes. Once the Y-cartilage closes in adolescence, the pelvis is stronger than the pelvic ligaments. At the same time, injuries are more likely to cause disruption of the pelvic ring. Avulsion fractures of the anterior superior iliac spine, anterior inferior iliac spine, ilium, and sciatic bones are more likely to occur in adolescents and young adults who play sports, and these injuries are low-energy pelvic injuries.
There is no ideal classification standard for pediatric pelvic injuries because fracture staging varies depending on bone maturity. Most pediatric pelvic fractures do not require surgical treatment and healing occurs without complications, thus the classification standard does not serve as a safeguard. When classification criteria are cited, Torode and Zieg’s fracture classification criteria are often cited.
There is also the classification of adult pelvic fractures and the “Tile” classification. However, this classification has limitations in the pediatric population, and the “Salter-Harris” classification of epiphyseal injuries is often used when dealing with acetabular injuries in children with an unclosed Y-shape.
Treatment
The treatment of pediatric pelvic fractures depends on a number of factors. These include the age of the child, the fracture type, the stability of the pelvic ring, and the hemodynamic situation. The age factor is important because as the child grows older, the Y-shaped cartilage gradually closes and the ligaments around the pubic symphysis and sacroiliac joint become less elastic, but most pediatric pelvic fractures occur without complications and heal on their own without surgical intervention. In a patient with multiple injuries, pelvic injuries are often managed as a last level unless there is a risk of bleeding.
(Type I) avulsion fractures, (Type II) iliac pterygofemoral fractures, and (Type III) separated iliac fractures can be treated with 2-4 weeks of protective weight bearing after traction and rehabilitation for symptoms, and the pediatric patient can usually return to normal activities in 6-8 weeks.
(Type III) unicircumferential fracture is a stable pelvic fracture with posterior structural integrity. It consists of a pubic fracture or a separation of the pubic symphysis. It can be treated with pain relief and weight-bearing tolerance for 6 weeks in patients with high compliance, and bed rest or “chair-bed” related activities until pain-free ambulation can be achieved in patients with low compliance or younger age. Since this fracture of the pelvic ring occurs anteriorly, it is necessary to exclude the associated urinary injury as well as the posterior pelvic ring injury. A CT scan is recommended when the pain crosses the sacroiliac joint.
(Type III) fractures also include nondisplaced fractures of the acetabulum, which are usually stable. Treatment is initially non-weight-bearing and then transitions to weight-bearing exercises. In younger children with poor compliance, hip herringbone casts may be used. In children with nondisplaced acetabular fractures that are relatively stable, supracondylar bone traction may be used to treat specific types of fractures to facilitate repositioning of displaced fracture fragments. buck traction may improve the child’s comfort and compliance with gravity-free support in emergency settings, but may be initiated when discomfort subsides.
Hip dislocations can be combined with acetabular fractures and due to constitute an orthopaedic emergency. To reduce the incidence of femoral head necrosis, resetting is usually accomplished within 6-8 h of injury, and post-resetting x-rays and (CT) examinations can be used to compare and assess the degree of hip gap matching. Poor match on the femoral side of the hip suggests intra-articular bone fragmentation and requires arthrotomy to remove small cartilage fragments, with internal fixation often performed for large bone fragments. An intra-articular fracture or Y-shaped cartilage displacement >2 mm also requires an incision and internal fixation to reshape the normal structure of the joint. The pediatric patient should have the hip repositioned when the pain first subsides and should remain nonweight-bearing until the fracture heals, which usually lasts 6-8 weeks.
Type IV pelvic fractures can create a zone of instability, including fractures of the upper and lower extremities of the femur bilaterally (fractures from straddle injuries), where the fracture is located in the pubic symphysis or where the pubic symphysis joins the posterior structures anteriorly, and the fracture often results in instability between the anterior pelvic ring and the acetabulum, which can increase the likelihood of urinary injury and necessitate consultation with a urologist.
In type IV pediatric pelvic fractures, which are closely associated with life-threatening hemorrhage, injury to the iliac vessels is often combined with disruption of the sacroiliac joint and consequent retroperitoneal hemorrhage, and initial treatment is focused on volume expansion and transfusion to stabilize the pediatric vital signs after excluding the possibility of abdominal organ injury. A pelvic band may be used as a temporary treatment to assist with repositioning, to prevent post-fracture bleeding, and to facilitate resuscitation. If bleeding is persistent, external fixation should be performed urgently to reshape the sequence and stability of the pelvis and limit its volume. When these measures are not sufficient, pelvic angiography and embolization are indicated.
For hemodynamically stable type IV pelvic fractures, bed rest and bone traction can be used to reposition the sacroiliac joint depending on the patient’s condition, such as pelvic ring displacement <2 mm and pelvic fractures with sacroiliac joint separation and vertical displacement. For minimally displaced fractures, after bone traction, and in patients with multiple fractures, hip herringbone cast fixation may be used. For pediatric patients, damage to the pelvic ring is acceptable as long as the lower extremity is unequal >2 mm after fracture healing. Pelvic fractures that are displaced >2 mm must be repositioned for internal fixation. External fixation is not ideal for the treatment of vertical shear injuries, but emergency fixation for bleeding control is appropriate. Internal fixation can be performed with anterior pubic symphysis splints and percutaneous sacroiliac screws. Unstable pelvic fractures in older children and adolescents are often treated with internal fixation to improve their prognosis for early return to normal activity.
Complications
The vast majority of pediatric pelvic fractures heal without long-term complications, and the chances of osseous discontinuity and ligament instability are very small, but if they do occur there are no long-term effects. Pediatric pelvic fractures can accept deformity healing due to their high plasticity, and when the vertical displacement of the hemipelvis is >2 cm, this can lead to fracture instability and the resulting lower extremity inequality and associated lower back pain. Most of the long-term complications are associated with acetabular and sacroiliac joint injuries, acetabular fractures caused by hip dislocation can increase the incidence of femoral head necrosis, and displaced acetabular fractures can cause premature degeneration of the hip joint.
When a child has a Y-shaped cartilage injury in the acetabulum before the age of 10, it can lead to premature cartilage closure and affect the normal development of the acetabulum, because the growth potential of the epiphyseal plate decreases with age, so the younger the age at the time of injury, the greater the impact on acetabular development. Premature closure of the epiphyseal plate may also cause acetabular dysplasia, hip subluxation, or hip mismatch, because such fractures are often easily missed on initial radiological examination and may also manifest in adulthood because of fracture-induced sequelae. Thus, early diagnosis, treatment and follow-up of the child into adulthood are very important.
Non-bony complications include: ossifying myositis, persistent lower extremity nerve injury. Lumbosacral plexus and sciatic nerve injuries are closely associated with sacroiliac joint destruction and sacral spine instability fractures. Unfortunately, nerve injuries to the lower extremities are rarely noticed immediately after injury because the primary focus of attention after injury is on resuscitation and stabilization of the child’s vital signs.
Overall, the prognosis for pediatric pelvic fractures is due to adults because they have more resilient bones and more flexible joints than adults. They rarely have severe fractures and usually only have fractures of a single pelvic ring. What’s more, pediatric bone has a strong ability to heal, shape, and resist injury, so there are few long-term complications. Death is rarely closely related to the pediatric fracture itself, but is often associated with other combined injuries due to high capacity mechanical injuries.
History, physical examination, and anteroposterior pelvic x-ray are criteria for diagnostic treatment and may indicate the need for additional tests. Most pelvic traumas do not require surgical treatment, only protective weight-bearing and gradual return to normal activity. Instability of the pelvic ring should always be documented. Treatment options include external fixation, incisional internal fixation, and percutaneous screw fixation. For acetabular and Y-shaped cartilage displacement >2 mm, incisional internal fixation is indicated. The age of the child, fracture classification, stability of the pelvic ring, combined injuries and hemodynamics can guide treatment. Under their guidance, surgeons have managed pelvic fractures in pediatric patients with excellent outcomes, and although a small percentage of children have developed complications, all have been followed up until their adulthood.