Pediatrics: Musculoskeletal Flashcards
What should you do if you are unsure whether there is a pediatric fracture or not?
Get a repeat radiograph in 7-10 days (when there should be a periosteal reaction if its fractured)
Physical bar
An “early” bone bridge across a growth plate suggesting premature growth arrest
Note: These can occur secondary to infection or trauma.
Physical bar (suggesting premature growth arrest)
Note: These can occur due to infection or trauma.
Salter-Harris Classification of pediatric bone fractures (SALTR mnemonic)
- Type 1 (S: slipped)
- Type 2 (A: above/away from joint)
- Type 3 (L: lower/epiphyseal; also “3 = E” for epiphyseal)
- Type 4 (T: through the physis)
- Type 5 (R: ruined, compression of the growth plate with poor prognosis)
Type 1 Salter-Harris fracture
“S”ALTR: “S”lipped epiphysis (a complete physical fracture +/- displacement)
Type 2 Salter-Harris fracture
S”A”LTR: “A”bove/away from the joint (involves the metaphysis)
Type 3 Salter-Harris fracture
SA”L”TR: “L”ower/epiphyseal involvement; also “3 = E” (involves the epiphysis)
Type 4 Salter-Harris fracture
SAL”T”R: “T”rough the physis (fracture goes right through the physics, involving both the metaphysis and epiphysis)
Type 5 Salter-Harris fracture
SALT”R”: “R”uined, bad prognosis (compression of the growth plate due to axial loading injury)
What is the most common Salter-Harris fracture
Type 2 (sAltr: Above/Away from the joint, involving the metaphysis)
What type of fracture?
Type 1 Salter-Harris
What type of fracture?
Type 2 Salter-Harris
What type of fracture?
Type 3 Salter-Harris
What type of fracture?
Type 4 Salter-Harris
What type of fracture?
Type 5 Salter-Harris
Which type of Salter-Harris fracture is associated with a bony bridge across the physis?
Type 5 (compression of the growth plate)
Note: These have a bad prognosis with a high rate of growth arrest.
What is a Salter-Harris fracture?
Fractures that extend through the growth plate
2 y/o with an oblique fracture of the tibia involving the midshaft posterior cortex…
Think toddlers fracture (tibial fracture secondary to new stresses after learning to walk)
Classic locations for stress fractures in children
- Posterior tibial midshaft (Toddler’s fracture after learning to walk)
- Calcaneus (often after resuming normal activity following an injury that required a cast)
Pediatric elbow radiograph demonstrates “posterior sail sign”…
Elevated posterior fat pad should make you think occult fracture (most often supracondylar)
Note: You can see a sliver of anterior fat pad normally, but you should never be able to see the posterior fat pad.
What are the most likely occult fractures if you see a posterior fat pad on a pediatric elbow radiograph?
- Supracondylar fracture (60%)
- Lateral condyle fracture (20%)
- Medial epicondyle fracture (10%)
Radiocapitellar line
A line drawn along the center of the radius and through the capitellum
Note: This should pass through the middle third of the capitellum on every view (regardless of position), otherwise think radial dislocation.
Anterior humeral line
On lateral elbow radiograph, a line drawn along the anterior cortex of the humerus and through the caputellum
Note: This should pass through the middle third of the capitellum on the lateral view, otherwise think supracondylar fracture.
What is the order of ossification for the elbow ossification centers?
CRITOE:
- Capitellum
- Radius
- Internal/medial epicondyle
- Trochlea
- Olecranon
- External/lateral epicondyle
What is the age at which the elbow ossification centers ossify?
Odd years starting at 1 (approximation):
- Cap (1)
- Rad (3)
- Int/med epi (5)
- Tro (7)
- Ole (9)
- Ext/lat epi (11)
How can you know whether a lateral humeral condyle fracture is unstable?
If the fracture line passes through the capitello-trochear groove to involve the trochlea-ulna articulation (best seen on an internal rotation oblique view), it is unstable
If you see a lateral humeral condyle fracture, what additional view must you order?
Internal rotation oblique view (to look for displacement, which needs surgery)
Complications of ulnar nerve injury at the elbow
- Lost sensation in the pinky and 1/2 of ring fingers
- Denervation of flexer carpi ulnaris or flexor digitorum profundus
Which elbow ossification centers often has a fragmented appearance because it can have multiple ossification centers?
Trochlea
Common cause of a lateral condyle fracture
Elbow hyperextension due to fall onto outstretched hand
Fall onto elbow tip or elbow hyperflexion injuries are at high risk for…
Ulnar nerve injury
Which elbow ossification center is the last to fuse?
The External/medial epicondyle ossification center
Note: This doesn’t fuse until ~11 years; don’t mistake a normal ossification center for a medial epicondyle fracture.
Are elbow joint effusions common with a medial epicondyle avulsion fracture?
No, the medial epicondyle is an extra-articular structure
Complications of medial epicondyle avulsion fracture
Dislocation of avulsed bone fragments into the joint (look for loose bodies between the humerus and olecranon)
Note: This can happen even if there is no joint dislocation, but is more common if there is a joint dislocation (always look for avulsion fragments on the post-reduction films).
What should you look for if there is a pediatric elbow dislocation?
The medial epicondyle ossification center (is it in the normal location or dislocated)
You see a trochlear ossification center, but not the medial epicondyle ossification center…
What you think is a trochlear ossification center is probably actually a displaced bone fragment
Note: You should never see the Trochlea before seeing the Internal/medial epicondyle (“the importance of IT in CRITOE”).
Little League Elbow
Medial epicondyle avulsion
Nursemaids elbow
Subluxation of the radial head into the annular ligament
Note: This can happen if the Childs arm is pulled on forcefully.
Next step: you see an ulnar shaft fracture on a forearm radiograph
Get a dedicated elbow radiographs (to look for radial head dislocation)
Note: This would be the Monteggia fracture-dislocation pattern commonly seen in children (rare in adults).
Monteggia fracture-dislocation
Ulnar shaft fracture with dislocation of the radial head
Which avulsion fracture? What muscle attaches?
Iliac crest avulsion fracture (abdominal muscles)
Which avulsion fracture? What muscle attaches?
ASIS (anterior superior iliac spine) avulsion fracture (sartorius muscle)
Which avulsion fracture? What muscle attaches?
AIIS (anterior inferior iliac spine) avulsion fracture (rectus femoris muscle)
Which avulsion fracture? What muscle attaches?
Greater trochanter avulsion fracture (gluteus medius/minimus muscles)
Which avulsion fracture? What muscle attaches?
Lesser trochanter avulsion fracture (iliopsoas muscle)
Which avulsion fracture? What muscle attaches?
Ischial tuberosity avulsion fracture (hamstring muscles)
Which avulsion fracture? What muscle attaches?
Symphysis avulsion fracture (adductor group muscles)
13 y/o boy with sudden onset pain after jumping
Patellar sleeve avulsion fracture
How can you differentiate a patellar sleeve avulsion fracture from Sinding-Larsen-Johansson?
Timing
Patellar sleeve avulsions fractures are an acute injury
Sinding-Larsen-Johansson is a chronic fatigue injury
Sinding-Larsen-Johansson
A chronic traction injury at the insertion site of the patellar tendon on the patella seen in active adolescents
Osgood-Schlatter
Chronic injury to the patellar tendon at its insertion site on the tibial tuberosity
Note: It is bilateral 25% of the time.
Risk factors for Sinding-Larsen-Johansson
Cerebral palsy
“celery stalk” appearance of bone (linear sclerotic streaks at the metaphyses) in a neonate…
Congenital Rubella
Note: Can also be seen in congenital syphilis(though not until 6-8 weeks of life), CMV, and also osteopathia striata.
Congenital syphilis
Note: This is the “wimberger sign” of osseous destruction of the medial portion of the proximal tibial metaphysis.
Caffey disease
A self liminting disorder of soft tissue swelling, periostea reaction, and irritability seen within the first 6 months of life
Classic imaging appearance of Caffey disease
Very hot mandible on bone scan
Note: The clavicle and ulna are other classic sites.
Neonatal chest radiograph demonstrating sternotomy wires and a periostea reaction in the bilateral humeri…
Think prostaglandin therapy
Note: The sternal wires make you think congenital heart disease and prostaglandin therapy is often used to keep a patent ductus arteriosus open).
What is the major childhood malignancy that occurs in newborns and metastasizes to the bone?
Neuroblastoma
Physiologic periostitis of the infant
Physiologic bone growth can result in a periostea reaction usually around 3 months of age that resolves by 6 months
Where do you most commonly see physiologic periostitis due to bone growth?
First proximally (e.g. femur) and then distally (e.g. tibia), always involving the diaphyses
Note: This occurs in infants around 3 months of age and resolves by age 6 months.
What characteristics make you think that periostitis in an infant is not just physiologic periostitis due to bone growth?
- Periostitis before 1 month of age
- You see it in the tibia before the femur (physiologic periostitis should progress proximally to distally)
- It does not involve the diaphysis
Think Langerhans cell histiocytosis (AKA eosinophilic granulomatosus)
Note: This is the “hole within a hole” or “beveled edge” sign. Neuroblastoma metastases would also be on the differential.
Think Langerhans cell histiocytosis (AKA eosinophilic granulomatosus)
Note: This is vertebra plana (pancaked vertebral body).
What are the characteristic imaging features of Langerhans cell histiocytosis (AKA eosinophilic granulomatosus)
- Lytic skull lesions with a beveled edge
- Lytic rib lesions with expanded appearance
- Vertebra plana (pancaked vertebral body)
What is the typical age group for pediatric osteomyelitis?
Infants (30% of cases occur before age 2)
Pediatric osteomyelitis often seeds the bone by what method of spread?
Hematogenous
Note: In adults, direct spread from a diabetic ulcer is more common.
Where does osteomyelitis usually begin in infants?
In the metaphyses (which has the largest blood supply because its growing the fastest)
Note: It then spreads to the epiphysis via perforating vessels that traverse the physis in infants.
Why does osteomyelitis affect different parts of the bone at different ages?
Only infants have perforating vessels that connect the metaphysis to the epiphysis (allowing osteomyelitis to spread that way)
In older children, these perforating vessels regress and the avascular growth plate prevents osteomyelitis from spreading to the epiphyses (older children tend to have more of a smoldering infection in the long bone metaphyses)
In adults, the growth plates fuse which again allows osteomyelitis to cross over to infect the epiphysis
What is the most common site of osteomyelitis in older children?
Metaphyses of long bones (75%)
Note: Most commonly the femur.
How long does it take bony changes in osteomyelitis to appear on radiographs?
10 days
Brachydactyly
Short fingers
Polydactyly
Too many fingers
Syndactyly
Two or more fused fingers
Camptodactyly
Contractures of fingers
Clinodactyly
Radially angulated fingers (usually the 5th digit)
Arachnodactyly
Long, spider-like finger
Amelia
Limb is absent
Meromelia
Limb is mostly absent
Acromelic
Hands/feet (distal limbs) are short
Note: Think acromegaly (big hands).
Mesomelic
Forearm or lower leg are short (middle limbs)
Note: Meso in the middle.
Rhizomelic
Femur or humerus (proximal limbs) are short
Micromelic
Entire limbs are short
What is the most common type of skeletal dysplasia?
Achondroplasia
Pathophysiology of achondroplasia
Defect in the fibroblast growth factor receptor
What bones are short in achondroplasia
Short femur and short humerus
Note: It is a rhyzomelic dysplasia.
Risk factor for achondroplasia
Advanced paternal age
Narrowing of the interpedicular distance is seen in which skeletal dysplasia?
Achondroplasia
What is the most common lethal form of deawfism?
Thanatophoric dysplasia
Classic features of thanatophoric dysplasia
- Severe rhizomelic shortening (short humerus/femur)
- Platyspondyly (plate-like vertebral bodies)
- Cloverleaf skull
Note: This is usually lethal in the perinatal period.
Asphyxiating thoracic dystrophy (Jeune)
A skeletal dysplasia that results in a bell shaped throax with short ribs that is often fatal in the perinatal period
What is the best way to differentiate thanatophoric dysplasia from asphyxiating thoracic dystrophy (Jeune)
Look at the vertebral bodies:
Severe skeletal dysplasia with flattened vertebral bodies -> Thanatophoric dysplasia
Severe skeletal dysplasia with normal vertebral bodies -> Asphyxiating thoracic dystrophy
Dwarfism and polydactyly…
Think Ellis-Van Crevald syndrome
Note: Polydactyly also occurs in 15% of pts with Asphyxiating thoracic dystrophy (Jeune).
Looks like achalasia but spares the skull and isn’t present at birth (develops later)…
Pseudoachondroplasia
Dwarfism with osteopetrosis, wide-angled jaw, and acro-osteolysis…
Pyknodysostosis
What are the terms for proximal, mid, and distal limb shortening?
- Rhizomelia (proximal limb shortening)
- Mesomelia (mid limb shortening)
- Acromelia (distal limb shortening)
What is the most common type of limb shortening in dwarfs?
Rhizomelia (proximal limb shortening: humerus/femur)
Dwarfism with narrowing of the pedicles…
Think achondroplasia
Note: Can also happen in thantophoric dysplasia, but these pts usually die early on.
What finding is this?
Telephone receiver femur, consistent with thanatophoric dysplasia
Infant with dwarfism passes away shortly after birth and has very short ribs…
Think Jeune (asphyxiating thoracic dystrophy)
What is the most common cause of an anterior wall mass in a child?
Bifid rib
Pt with multiple bifid ribs…
Think Gorlin syndrome
Gorlin syndrome
- Bifid ribs
- Falx calcifications
- Basal cell cancers
- Odontogenic keratocysts (lytic mandible lesions)
Anterior wall mass overlying the 4th rib…
Think bifid rib
Note: If only one bifid rib, think variant. If multiple, think Gorlin syndrome.
Pathophysiology of osteogenesis imperfecta
Defective collagen synthesis resulting in brittle bones
Infant with a totally lucent skull with multiple fractures demonstrating hyperplastic callus formation…
Think osteogenesis imperfecta
Infant with worming bones and leg radiographs demonstrating that the fibula is longer than the tibia…
Think osteogenesis imperfecta
Kid with blue sclera and hearing impairment secondary to otosclerosis…
Think osteogenesis imperfecta
Pathophysiology of osteopetrosis
Defect in osteoclast function, resulting in disorganized bone that is sclerotic and weak
Prognosis for infantile osteopetrosis
Lethal (due to complete replacement of bone marrow leading to anemia/pancytopenia)
Note: Less severe forms result in sclerotic bands parallel to the growth plates.
Osteopetrosis
Note: “Bone-in-bone” appearance (especially at the distal humerus). Also alternating bands of sclerosis parallel to the growth plates (especially at the distal radius).
Infant with diffusely sclerotic skeleton and diffuse loss of the corticomedullary junction in the long tubular bones…
Think osteopetrosis
Picture frame vertebrae, think osteopetrosis
Clinical/imaging findings of pyknodysostosis
- Osteopetrosis
- Worming bones
- Acro-osteolysis
- Wide angled mandible
Congenital fusion of the cervical spine with tall and skinny vertebral bodies…
Think Klippel Feil
Sprengel deformity
High riding scapula
Note: You can see this in Klippel Feil (look for a congenitally fused cervical spine).
What abnormal bone is present?
The omovertebral bone (between the spine and the scapula)
Note: This is often seen with the Sprengel deformity (high riding scapula) in Klippel Feil.
Classic imaging findings of Klippel Feil
- Congenital fusion of the cervical spine
- Sprengel deformity (high riding scapula)
- Omovertebral bone (abnormal bone between the spine and scapula)
Widening of the metacarpal bones which taper proximally, suggestive of a mucopolysaccharisosis (e.g. Hunters, Hurlers, Morquio)
Classic imaging findings of mucopolysaccharidoses
- Widened metacarpal bones with proximal tapering
- Oval shaped vertebral bodies with an anterior beak
- Thickened clavicles and ribs that narrow medially (likened to a canoe paddle)
What are the major mucopolysaccharidoses that have classic imaging findings?
- Hunters
- Hurlers
- Morquio
Oval shaped vertebral bodies with anterior beaking in the mid-vertebral body…
Think Morquio mucopolysaccharidosis
Note: Hurlers tends to have anterior beaking along the inferior vertebral bodies.
What is the most common cause of death in Morquio mucopolysaccharidosis?
Cervical myelopathy at C2
Anterior tibial bowing, consistent with NF1
Characteristic imaging finding of NF1
Anterior bowing of the tibia and pseudoarthrosis at the distal fibula
Note: These pts also often have scoliosis.
Hepatosplenomegaly with avascular necrosis of the femoral heads and other bone infarctions…
Think Gauchers
Note: This is the most common lysosomal storage disease.
Bone findings of Gauchers disease
- Avascular necrosis of the femoral heads
- H-shaped vertebrae
- Multiple bone infarctions
- Erlenmeyer flask shaped femurs
Caudal regression syndrome
A spectrum of deformities that includes sacral and/or coccyx agenesis
Note: This is seen with VACTERL and Currarino Triads Syndromes.
Absence or hypoplasia of the radius with an absent thumb and no other abnormalities…
Think radial dysplasia (e.g. VACTERL, Holt-Oram, Fanconi anemia)
Note: Thrombocytopenia absent radius would still have thumb.
Differential for radial dysplasia
- VACTERL
- Holt-Oram
- Fanconi anemia
- Thrombocytopenia absent radius
Absent radius with normal ipsilateral thumb…
Think thrombocytopenia absent radius
Hand or foot pain and swelling in an infant with sickle cell disease…
Hand foot syndrome
Imaging appearance of hand foot syndrome (sickle cell attack involving hands/feet in an infant)
Periostitis (which can last 2 weeks after pain has resolved)
Blounts disease
Varus angulation of the medial aspect of the proximal tibia after the age of 2
Note: Blounts is also called tibia vara.
What age group is Blounts disease seen in?
- 2-3 years (NOT before 2)
- Around age 12
Blounts disease (tibia vara)
Blounts disease (tibia vara)
Foot vocabulary: Talipes
Meaning congenital
Foot vocabulary: Pes
Meaning for or acquired
Foot vocabulary: Equines
Meaning plantar flexed ankle (heel often won’t touch the floor)
Foot vocabulary: Varus
Meaning forefoot inward
Foot vocabulary: Valgus
Meaning forefoot outward
Foot vocabulary: Cavus
Meaning high arch
Foot vocabulary: Planus
Meaning flat foot
Foot vocabulary: Supination
Meaning inward rotation
Note: Think about holding soup with the bottoms of your feet by supinating them.
Foot vocabulary: Pronation
Meaning outward rotation
How can you determine whether there is hindfoot valgus or varus?
Look at the talocalcaneal angle on a lateral radiograph:
In hindfoot valgus, the talocalcaneal angle is increased because the talus is taking a nosedive off the calcaneus.
In hindfoot varus, the talocalcaneal angle is decreased because the talus and calcaneus are nearly parallel to each other.
Normal talocalcaneal angle
25-40 degrees
Note: Less than 25 degrees is hindfoot varus and more than 40 degrees is hindfoot valgus.
Talocalcaneal angle of 50 degrees…
Hindfoot valgus (anything over 40 degrees)
Talocalcaneal angle of 20 degrees…
Hindfoot varus (anything under 25 degrees)
What are the major types of congenital pet planus?
- Flexible (improves with plantarflexion)
- Rigid (does not improve with plantarflexion)
What are the major disorders associated with hindfoot valgus?
Pes planus (flat foot)
Note: This can be flexible or rigid. Rigid pet planus includes tarsal coalition and equinus hindfoot valgus (vertical talus, “rocker bottom feet”).
What are the types of rigid pet planus?
- Tarsal coalition
- Vertical talus
What are the two main types of tarsal coalition?
- Talus to calcaneus
- Calcaneus to navicular
Note: These can be bony or fibrous/cartilaginous.
Tarsal coalition is bilateral in ____% of cases
50%
“Continuous C sign” of talocalcaneal coalition (due to an absent middle facet)
Talar beaking, commonly seen in talocalcaneal coalition
Which facet is missing in talocalcaneal coalition?
Middle facet
Which facet is missing in calcaneonavicular coalition?
Anterior facet
“Anteater nose sign” of calcaneonavicular coalition (due to an elongated anterior process of the calcaneus)
Congenital vertical talus (AKA equinus hindfoot valgus; AKA rocker-bottom feet)
Note: The talus is vertically oriented overlying the calcaneus.
Congenital vertical talus (AKA equinus hindfoot valgus) is associated with…
Myelomeningocele
Talipes equino varus
Club foot:
- Hindfoot varus (decreased talocalcaneal angle)
-Medial deviation and inversion of the forefoot - Elevated plantar arch
Note: Talipes equino varus means “congenital plantar-flexed ankle with varus/forefoot-in angulation” (AKA club feet).
Is talipes equino varus (club feet) more common in males or females?
Males
Talipes equino varus (club foot) is bilateral in ___% of cases
50%
Talipes equino varus (club foot)
What is the most common complication following surgical correction of talipes equino varus (club foot)?
Surgical overcorrection to hindfoot valgus (rocker bottom flat foot deformity)
What are the major disorders associated with hindfoot varus?
Talipes equino varus (club foot)
Risk factors for developmental dysplasia of the hip
- Female sex
- Breech presentation at birth
- Oligohydramnios
Newborn with asymmetric gluteal folds and a leg length discrepancy…
Think developmental dysplasia of the hip
Infant with delayed ambulation and a palpable clunk during physical exam of the hips…
Think developmental dysplasia of the hip
Developmental dysplasia of the hip is bilateral in ___% of cases
33%
Best test for diagnosing developmental dysplasia of the hip
Ultrasound (prior to bone ossification)
Note: If bones are ossified, then you should get radiographs.
Why should you be extra careful performing a hip ultrasound during the first week of life for development dysplasia of the hip?
During the first week of life, soft tissue laxity (due to maternal estrogen) can mess up angle measurements
How is developmental dysplasia of the hip diagnosed?
Hip ultrasound with an alpha angle less than 60 degrees
OR
Hip radiograph with an acetabular angle greater than 30 degrees
How do you draw the alpha angle?
It is the angle between the acetabular roof and the vertical cortex of the ileum
Note: It should be 60 degrees or more.
What is the pathophysiology of developmental dysplasia of the hip?
Acetabulum is too shallow (small alpha angle) and cannot reliably hold the femoral head in place
How do you draw the acetabular angle?
Angle between two lines:
- The Hilgenreiner line ( a line drawn horizontally through the inferior aspect of the bilateral triradiate cartilages: the junction where the ischium, ilium, and pubis meet in skeletally immature pts)
- A line drawn parallel to the acetabular roof
Note: This should be less than 30 degrees.
What is a normal acetabular angle?
Less than 30 degrees
Note: It is usually close to 30 degrees at birth and decreases to 22 degrees by age 1.
How do you know that the femoral epiphysis is in the right location?
It should be:
- Below Hilgenreiner’s line (line through the bilateral triradiate cartilages)
- Medial to Perkin’s line (line perpendicular to Hilgenreiner’s that intersects the lateral most aspect of the acetabular roof)
What line is this?
Perkin’s line (vertical line through the lateral aspect of the acetabular roof)
Note: The femoral epiphysis should be medial to this line.
What line is this?
Hilgenreiner’s line (horizontal line through both triradiate cartilages)
Note: The femoral epiphysis should be inferior to this line. You can also use this line to measure the acetabular angle.
What line is this?
Shenton line (a continuous curved line along the inferior border of the superior pubic ramus and along the inferomedial border of the femoral neck)
Note: If this line is interrupted, think developmental dysplasia of the hip or femoral neck fracture.
Proximal focal femoral deficiency (absent/hypoplastic proximal femur)
Clinical manifestations of proximal focal femoral deficiency
- “weird fucked up looking tiny leg”
- Varus deformity
Pathophysiology of a slipped capital femoral epiphysis
Type 1 Salter-Harris fracture
Note: Unlike most type 1 Salter-Harris fractures this has a bad prognosis unless corrected.
Slipped capital femoral epiphysis is bilateral in ___% of cases
33%
Note: Usually one hip presents before the other, which is why they are both usually surgically corrected even if only one seems affected.
Best imaging test to evaluate for slipped capital femoral epiphysis
Frog leg view radiograph
What lines are these?
Line of Klein (straight line drawn along the superior edge of the femoral neck)
Note: If there is asymmetry in how these lines intersect with their ipsilateral femoral epiphysis, consider slipped capital femoral epiphysis. This case has SCFE on the left.
Slipped capital femoral epiphysis on the left
What is the typical age range for slipped capital femoral epiphysis?
Adolescents (boys later than girls)
Girls (8-15)
Boys (10-17)
Which view should Lines of Klein be drawn on to evaluate for slipped capital femoral epiphysis?
Frogs leg view is most sensitive, but frontal views can make the diagnosis also
Idiopathic avascular necrosis of the proximal femoral epiphysis is also known as…
Legg-Calve-Perthes
Note: This is a diagnosis of exclusion after ruling out other diseases that cause epiphysis necrosis (e.g. sickle cell disease, leukemia, Gaucher)
Is Legg-Calve-Perthes more common in males or females?
Males (4:1)
Legg-Calve-Perthes typically occurs in what age group?
5-8 y/o (usually male)
Legg-Calve-Perthes is bilateral in ___% of cases
10%
Classic imaging appearance of Legg-Calve-Perthes
- Subchondral lucency (crescent sign) in the femoral head(s)
- Asymmetric small ossified femoral epiphysis
- Flat collapsed femoral head
7 y/o M with low normal weight
Think avascular necrosis of the femoral hear (e.g. Sickle cell disease, Legg-Calve-Perthes)
Note: There is a subchondral lucency (crescent sign) in the femoral head suggesting avascular necrosis.
What is considered the most urgent cause of a painful hip in a child?
Septic arthritis
How can you identify a hip joint effusion on ultrasound?
Look for a pocket of fluid with a biconvex shapeat the junction between the femoral head and femoral neck
Next step: Pediatric hip pain with radiograph demonstrating widened medial joint space with lateral displacement of the femoral head
Hip ultrasound to look for a joint effusion and arthrocentesis if there is (to exclude septic arthritis)
Note: This is suspicious for a joint effusion.
Transient synovitis
A sterile reactive joint effusion that occurs in the setting of a systemic illness (e.g. viral URI or GI infection)
What should make you suspect a hip joint effusion on radiographs?
Widening of the medial joint space with lateral displacement of the femoral head
Transient synovitis of the hip is more common in what age group?
Growing children (peak age is 5 y/o)
What is the best way to discern between transient synovitis and septic arthritis prior to arthrocentesis in pediatric pts?
The Kocher Criteria:
- Fever
- Inability to bear weight
- Elevated ESR or CRP
- WBC > 12
Note: If 3 are positive, then its a septic hip. If CRP is negative and the kid can bear weight, it’s not septic.
What clinical finding is the strongest independent risk factor for septic arthritis?
Elevated CRP
Why is it so important to identify septic arthritis?
Septic arthritis will destroy a kids joint cartilage if not found (usually the cartilage is destroyed if its missed for more than 4 days)
Most common finding of septic arthritis on hip radiographs
Normal (no findings)
Note: On the exam, they will likely show you medial joint widening with subtle lateral displacement of the femoral head (which should make you think effusion -> septic arthritis).
How long does it take transient synovitis of the hip to resolve?
Usually a few days
Most common cause of hip effusion in a child
Transient synovitis (secondary to systemic illness, such as a URI)
Note: However, this should make you suspicious for a septic joint if there is elevated CRP, fever, or inability to bear weight.
Kocher Criteria
Risk stratification scoring to aid in differentiating between septic arthritis and transient synovitis in the pediatric population:
- Non weight bearing
- Fever
- Elevated CRP or ESR
- WBC > 12
Note: Scores 3-4 are very likely to be septic arthritis (>90%) and should go straight to arthrocentesis. Scores 1-2 are intermediate and an ortho consult is recommended to see if arthrocentesis should still be done.
Pathophysiology of Rickets
Vitamin D deficiency
Note: This is why it’s never seen in newborns, who still have mom’s vitamin D.
Which bones are most affected by Rickets?
The most rapidly growing bones (at the knees and wrists)
Risk factors for slipped capital femoral epiphysis
- Obesity (major risk factor)
- Rickets
Classic imaging findings of Rickets
Metaphyseal abnormalities due to reduced minealization, especially around the wrists and knees:
- Fraying (indistinct metaphyseal margins)
- Splaying (widening of the metaphyseal ends)
- Cupping (concavity of the metaphysis)
metaphyseal irregularities at the distal radius/ulna bialterally, suggestive of Rickets
Expansion and flaring of the anterior rib ends at the costochondral junctions, suggestive of Rickets
Note: This is the “Rachitic rosary” appearance. Can also see something similar in scurvy (“scorbutic rosary” appearance).
Newborn with generalized osteoporosis, irregular generalized metaphyseal changes, and bowing of the long bones…
Think hypophosphatasia
Note: This looks similar to Rickets, but in a newborn (Rickets does not occur in newborns due to maternal vitamin D).
Pathophysiology of hypophosphatasia
Genetic defect leading to deficient serum alkaline phosphatase, resulting in defective bone mineralization
Prognosis of hyperphosphatasia
Variable (ranges from perinatal lethality in severe disease to adult presentation in mild disease)
Pathophysiology of scurvy
Vitamin C deficiency resulting in defective collagen cross-linking and weakened skin, bone, joint, and vascular integrity
Scurvy does not occur at what age?
Before 6 months (before maternal stores of vitamin C are depleted)
Clinical manifestations of scurvy
- Lethargy/malaise
- Bone pain
- Bleeding diathesis (e.g. subperiosteal hemorrhage, hemarthrosis, petechiae, bleeding gums)
- Impaired wound healing
Joint effusion in a pt with scurvy…
Consider hemarthrosis
Lead poisoning is most common in what age group?
Kids less than 2 years old (especially if their in an old house eating paint chips)
1 y/o
Wide sclerotic metaphyseal lines that also involve the proximal fibula, suspicious for lead poisoning
Note: These “lead lines” can occur in other disorders as well, but involvement of the proximal fibula is more specific.
Differential for lucent transverse metaphyseal lines in a pediatric pt
LINE:
- Leukemia
- Infection (TORCH)
- Neuroblastoma mets
- Endocrine (rickets, scurvy)
TORCH infections
- Toxoplasmosis
- Other (syphilis, Zika, varcicella-zoster)
- Rubella
- Cytomegalovirus
- Herpes simplex
Note: These infections can be acquired in utero and cause significant morbidity/mortality.
Which fractures are suspicious for non-accidental trauma and should prompt a skeletal survey?
- Metaphyseal corner fractures
- Posterior medial rib fractures
- Skull fractures (other than parietal which tend to be accidental trauma)
- Any fracture that is discordant with the childs developmental status (e.g. Toddler fracture in a nonambulating child)
- Any solid organ/lumen injury
Which type of rib fractures are most suspicious for non-accidental trauma?
Posterior medial rib fractures in a child under age 3 (specific for squeezing injury)
When is a metaphyseal corner fracture specific for non-accidental trauma?
Prior to age 1 with no history of obstetrical trauma
Note: After age 1, this is less specific.
Which type of skull fracture is suspicious for non-accidental trauma?
Any skull fracture other than parietal bone fractures (which tend to be due to accidental trauma)
Duodenal hematoma in an infant…
Think nonaccidental trauma and get a skeletal survey
Note: The infant didn’t get into a bike accident.
How old is a pediatric fracture with a periosteal reaction?
Likely less than 1 week old
How long does it take a pediatric fracture to completely heal?
~12 weeks
Note: Unlike in adults, pediatric fractures that completely heal are usually no longer visible on imaging.
Which pediatric fractures tend to heal without any periosteal reaction?
- Metaphyseal fractures
- Skull fractures
- Costochondral junction fractures
What are the most common diseases that can mimic non-accidental trauma (multiple fractures of different ages)?
- Osteogenesis imperfecta
- Rickets
Note: Look for wormian bones and bone mineral density issues to suggest one of these mimics.
