KEY POINTS
- 1.
Fractures and musculoskeletal infections in neonates follow a distinct pathophysiology.
- 2.
The clavicle is the most frequently injured long bone in newborns; the injury occurs most often during birth. These fractures heal and remodel well. In some infants, congenital pseudoarthrosis of the clavicle may need to be differentiated from fractures.
- 3.
The humerus is the second most common long bone to be fractured in neonates; most fractures occur during birth or early infancy. These fractures are typically midshaft; some may be seen in proximal and distal epiphyses.
- 4.
Neonatal femur fractures can sometimes occur during birth and have been associated with shoulder dystocia, twin pregnancies, breech presentation, prematurity, small size for gestational age, and congenital osteoporosis.
- 5.
Musculoskeletal infections in the newborn have a unique pathophysiology and may occur in multiple locations simultaneously. The most frequently isolated organisms are Staphylococcus aureus , but sometimes nonstaphylococcal bacteria can also be seen.
Clavicular Fractures
Epidemiology and Risk Factors
The clavicle is the most frequently injured long bone in newborns, composing between 10% and 15% of all fractures. The incidence of clavicle fractures in neonates ranges from 0.5% to 7% of all live births. , The fractured clavicle typically demonstrates excellent healing even with no intervention, and surgery is rarely indicated. The prognosis is almost always highly favorable.
In the neonate, the most common mechanism of clavicular injury is during birth, whereas other traumas such as falling on an outstretched arm are predominantly responsible in older children. Previously identified risk factors for obstetric clavicle fracture include large birth weight (>4500 g), shoulder dystocia, prolonged gestational age, and difficult or complicated deliveries involving mechanical assistance. , Midshaft fractures are the most common pattern of injury in the neonate. Fractures of the medial or lateral clavicle are more likely to involve the physis, although these are difficult to diagnose radiographically because the epiphyses are not yet ossified at this age. The acromioclavicular and sternoclavicular joints are relatively stable due to strong supporting ligaments, making dislocation at these joints fairly uncommon.
Clinical Features and Evaluation
Neonatal clavicle fractures are most commonly detected within the first 3 days of life, although recognition and diagnosis can be challenging. They are often first discovered when parents notice a lack of spontaneous movement in their infant’s upper extremity, often termed “pseudoparalysis.” Visible callus formation within 7 to 10 days of the injury may also be one of the first clinical clues. Common signs and symptoms that aid in diagnosis include point tenderness, swelling or edema, crepitation, asymmetric bone contour, decreased active movement, crying on passive movement, and decreased Moro reflex (also known as startle reflex). , Diagnosis can also be made by palpating a spongy mass over the fracture site. However, the majority of these signs may not persist beyond a few days after birth.
Initial radiographs may be negative or inconclusive, especially for minimally displaced fractures ( Fig. 74.1 ). In such cases, repeat radiographs of the clavicle may be helpful if obtained within 7 to 10 days after callus formation and periosteal reaction have begun. Ultrasonography may occasionally aid in diagnosis of occult neonatal fractures.
The most important differential diagnosis is congenital pseudarthrosis of the clavicle, which is discussed in further detail below. Unlike fractures, pseudarthroses are nontender or minimally tender. Another condition to differentiate is cleidocranial dysplasia. This condition, due to a mutation in CBFA1 , presents with large gaps in the opposing ends of both clavicles, which are also smooth ( Fig. 74.2 ). In some cases, the clavicles are absent entirely. No treatment is needed for the clavicles themselves, although there are other skeletal deformities associated with this condition.
Long-Term Outcomes
Clavicle fractures always heal and remodel well in newborns with no residual deformity. Erb’s palsy (brachial plexus injury) should also be ruled out in neonates with clavicular fracture.
Management
In all cases, management can be conservative. Simple immobilization methods such as a sling, ace wrap, or shirt that holds the affected arm close to the infant’s torso generally provide sufficient comfort and allow for initial stages of healing. Referral to a pediatric orthopedic surgeon can be helpful.
Congenital Pseudarthrosis of the Clavicle
Epidemiology and Risk Factors
Congenital pseudarthrosis of the clavicle (CPC) is a rare condition almost always occurs on the right side, except in patients with situs inversus. Left-sided lesions are therefore strongly associated with dextrocardia and cervical ribs. A few bilateral cases have also been described, although this is exceedingly rare. Some studies suggest a higher predilection for females compared with males. Although the pathophysiology of CPC is poorly understood, reports of familial association suggest a potential genetic component. ,
Clinical Features and Evaluation
Importantly, CPC is commonly misdiagnosed as clavicular fracture or injury due to abuse. The classic physical exam finding is a painless mass or swelling over the middle third of the affected clavicle. This may be due to enlargement of the disjointed pseudoarticular ends. Notably, the mass tends to grow in size with age. Absence of tenderness is a key diagnostic clue that distinguishes CPC from acute fracture, although physical activities producing compression of the lesion may produce pain in some children. Diagnosis is confirmed by the presence of smooth, tapered opposing ends of the bone, in contrast to the sharp edges of a fresh fracture ( Fig. 74.3 ).
The mass is more accentuated when patients raise the upper limb. , Upper-extremity range of motion, strength, and sensation are normal in the vast majority of cases but may be affected depending on severity of fragment misalignment and malunion. Hypermobility of the distal segment and asymmetric drooping of the scapula may be noted in some cases.
Management
The lifetime prognosis is almost always benign with no real complications beyond cosmetic deformity, with very rare occurrences of thoracic outlet obstruction in some patients after reaching adulthood. No treatment is needed in the newborn period, although pseudarthroses that are symptomatic may be successfully fixed as the child ages.
Humerus Fractures
Epidemiology and Risk Factors
The humerus is the second most common long bone to be fractured in neonates, just behind the clavicle. The incidence of birth-related fractures is near 0.1 out of every 1000 live births, although this figure varies widely. ,
Factors associated with birth-related humerus fractures include maternal obesity, shoulder dystocia, vacuum-assisted delivery, male sex, multiple births, breech delivery, preterm birth, large size for gestational age, large birth weight (>4000 g), and brachial plexus injury. Of note, humerus and other long-bone fractures can occur with both vaginal deliveries and cesarean section deliveries. , Importantly, breech presentation is the single most influential risk factor for birth-related fracture of the humerus regardless of delivery, and neonates delivered in breech position should be assessed for orthopedic injuries soon after birth.
Additionally, 14% of humerus fractures in early infancy (age <6 months) have been associated with abuse. The high contribution of maltreatment to the incidence of population-level humerus fracture among infants is also supported by other literature. As such, pediatricians and other healthcare providers must be observant for other signs indicating abuse in infants presenting with long-bone fractures, especially outside of the immediate neonatal period. In later infancy, 56% of humerus fractures could be attributed to accidental fall trauma.
Clinical Features and Evaluation
The most common type of humeral fracture is transverse midshaft, followed by proximal and distal epiphyseal fractures. Proximal or distal fractures may mimic dislocations at the shoulder or elbow and are more difficult to diagnose. Radiographic confirmation of epiphyseal separations is particularly challenging in newborns. Furthermore, soft-tissue swelling may impede palpation of distal anatomic landmarks such as the olecranon and epicondyles, making such injuries difficult to ascertain through physical examination alone. Thus, the chances of missed or late diagnosis are increased with physeal fracture-separations in newborns. One study reported an average time to diagnosis of 9 to 30 days after birth for distal epiphysis separations. Nonetheless, some diagnostic signs that raise clinical suspicion for a distal humeral epiphysis fracture-separation include focal tenderness, swelling and edema, pseudoparalysis of the arm, and “muffled crepitus” upon movement, representing friction between preossific cartilaginous structures. ,
Ultrasonography is generally the most useful imaging modality for humeral physeal fracture detection and classification in neonates. Compared with magnetic resonance imaging (MRI) and radiography, ultrasonography is readily available, inexpensive, and nonirradiating, and it can be performed easily at the bedside without the need for sedation. Ultrasonography is also far more sensitive than traditional radiography for detection of physeal fractures in neonatal patients with cartilaginous epiphyses.
Management
Birth-related humerus fractures generally demonstrate good remodeling, with no observable deformity after 6 months. , The primary goals of care are comfort and immobilization, because the young bone has excellent healing potential. We recommend a conservative treatment approach involving immobilization with a splint, cast, or swaddling. No reduction is needed. , , Although traditional slings and shoulder immobilizers are unlikely to fit an infant, a simple yet effective option for management of upper-extremity fractures in these very young patients is to pin the sleeve of the newborn to their shirt.
Femoral Fractures
Epidemiology and Risk Factors
Unlike the clavicle and humerus, the femur is rarely fractured in neonates. The incidence varies from 0.02 to 0.13 per 1000 live births. , , Infants do sustain femoral fractures more frequently after the immediate neonatal period; however, the etiologies in this age group are distinct from birth-related fractures. Like other neonatal fractures, prognosis is generally favorable. At least two studies have reported complete union by 4 weeks, with no evidence of long-term leg length discrepancy or residual deformity after appropriate treatment. ,
Neonatal femur fractures have been associated with shoulder dystocia, twin pregnancies, breech presentation, prematurity, small size for gestational age, and congenital osteoporosis. , The mean gestational age reported in one study was 37.2 weeks. Birth-related femur fractures have been more frequently reported in the setting of cesarean sections compared with vaginal births, especially for breech presentation babies. This is well documented despite the widely accepted paradigm that cesarean section delivery reduces the risk of neonatal trauma. The most common pattern of injury is a diaphyseal spiral fracture of the proximal half of the femur, suggesting that excess torque applied during fetal extraction is likely responsible. , It is important for pediatricians and obstetricians to conduct a thorough assessment for signs of femoral fracture in neonates delivered by difficult cesarean section wherein traction was applied.
In utero fractures that are discovered postnatally may occur secondary to syndromic osteoporosis, such as in patients with myelomeningocele or metabolic bone disease of prematurity in neonates born after less than 28 weeks of gestation. , , Other pathologic etiologies such as osteogenesis imperfecta and osteomyelitis have also been described. In fact, underlying bone fragility is recorded in 5% of infantile femur fractures. Birth-related femur fractures may therefore be a useful clinical indicator for pediatricians to screen for underlying pathologies.
Notably, 20% of femur fractures in early infancy (age <6 months) were associated with abuse. , After the immediate neonatal period, 73% of femur fractures in later infancy were associated with accidental fall trauma. As with humerus fractures, pediatricians must be observant for other signs indicating abuse in infants presenting with long-bone fractures.
Clinical Features and Evaluation
Diagnosis can be challenging due to the nonspecific presentation in newborn children. Typical signs include local swelling, point tenderness, redness, fever, lack of spontaneous movement, and crying with passive movement such as during diaper changes. Nonetheless, because the majority of femoral fractures in the neonate are midshaft injuries, plain radiograph is a reliable diagnostic tool ( Fig. 74.4 ).
