MSK Flashcards
Epiphysis are initially ______
Cartilaginous, converting to bone with development of secondary ossification center
Primary physis is responsible for
Longitudinal growth of the bone
Secondary physis is responsible for
Spherical growth of epiphysis
What are the characteristics of pediatric bone as compared to adults
Less dense, more porous and have lower mineral content compared with adults
Due to pediatric bones characteristics, it can undergo a greater degree of deformation before breaking. Therefore, what fractures are common in pedia population
Greenstick (unicortical) and torus (buckle) fractures, as well as plastic deformation, complete fractures and physeal injuries
In newborn, bone marrow is entirely
Hematopoietic (red marrow)
Bone marrow transformation to fatty (yellow) marrow begins when
Within the first year of life and occurs in a predictable manner
In the body as a whole, marrow transformation begins where
In the periphery, first occurring in the phalanges of the fingers and toes and progressing centrally
Order of fatty marrow conversion of epiphysis, metaphysis and diaphysis
Epiphyses are first to convert, occurring within 6 months of radiologic appearance of secondary ossification center, continues within diaphysis, followed by metaphysis, with the proximal metaphysis the last to convert
On MR, the physis has a ______ appearance
Trilaminar appearance
The trilaminar appearance of physis in MRI consists of:
Zone of cartilage- active chondrocytes;
Zone of provisional calcification- cartilage matrix become calcified;
Primary spongiosa- where woven bone is formed
Fibrocartilaginous structure that surrounds the physeal cartilage, low signal on all sequences. This is tightly tethered to the physis and acts as a barrier to disease
Perichondrium
A thin low SI structure that parallels bone cortex and is loosely attached to the shaft and tightly attached to the perichondrium. Deep to this structure is a rich vascular network that helps to feed the growing metaphyses
Periosteum
This fracture occurs from longitudinal stress and results in bowing of the bones, with an intact periosteum
Plastic deformation
Plastic deformation are common in
Forearm, tibia, fibula
Fractures that results from axial loading on an extremity, occurring at the metaphysis or metadiaphysis. The cortex is compressed and bulges without extension of the fracture to the cortex
Buckle or torus fracture
Represent 50% of pediatric wrist fractures
Buckle fracture
Incomplete fractures resulting from perpendicular forces that break one cortex, the side opposite the site of stress
Greenstick fractures
Most vulnerable to injury during periods of active growth, such as during early adolescence
Cartilage
Weakest portion of the physeal cartilage
Zone of provisional calcification
Pathophysiology of chronic physeal trauma
Repetitive loading can alter metaphyseal perfusion and interfere with the mineralization of hypertrophied chondrocytes
In high intensity runners, chronic physeal injury are common in _____, while in baseball players its common in the ______ which is called little league shoulder and in the _______ in gymnasts (gymnast wrist)
Knees- runners
Proximal humerus- baseball players
Distal radiu- gymnast
Manifests radiographically as widening of the primary physis, with sclerosis at the margins of adjacent metaphysis
Chronic physeal trauma
A subset of physeal injuries (either sequela of trauma, infection or ischemia) can lead to cellular disruption and ischemia, giving rise to the development of abnormal osseous connection (bone bridge or bar) between epiphysis and metaphysis. These bone bars can result in limb length discrepancy, angular deformity, or altered joint mechanics
Physeal bars
The incidence of physeal bar formation is higher after injuries to the
Distal femur, proximal tibia and distal tibia
These areas contribute to the greatest proportion of limb growth, and therefore, bars in these regions have the biggest impact on limb length discrepancies
Distal femur and proximal tibia
Salter harris type: separation thru the physis, usually thru areas of hypertrophic and degenerating cartilage cell columns
1
Salter harris type: fracture thru a portion of the physis that extends thru the metaphyses
2
Salter harris type: fracture theu a portion of the physis that extends thru the epiphysis
3
Salter harris: fracture across the metaphysis, physis and epiphysis
4
Salter-harris type: crush injury to physis
5
Growth centers that serve as the attachment sites for tendons and have a physis at its bone interface
Apophyses
Apophyseal injuries due to repetitive submaximal stress on an apophysis is called ______ Which causes microavulsions at the chondro-osseous junction with resultant secondary inflammatory changes that attempt to repair the physis leading to overgrowth. Manifests radiographically as widenjng and irregulariy at the physis
Traction apophysitis
Little league elbow location of traction apophysitis, due to chronic valgus stress applied to the medial epicondylar apophysis causing medial elbow pain
Medial epicondyle of elbow
Location of traction apophysitis in Sinding-Larsen-Johansson syndrome, resulting from excessive force exerted by the patellar tendon on the lower pole of the patella. Causes anterior knee pain
Inferior patellar pole
Site of traction apophysitis in Osgood-Schlatter disease, pain at the anterior tibial tuberosity due to repetitive traction of the distal patellar tendon on the maturing anterior tibial tubercle
Tibial tuberosity
Location of traction apophysitis in Iselin disease; traction of peroneus brevis tendon on the base of the 5th metatarsal apophysis which presents with lateral foot pain
Base of the 5th metatarsal
Site of traction apophysitis in Sever disease; excessive traction of the Achilles tendon onto the calcaneal apophysis causing heal pain
Calcaneus
Acute apophyseal injuries are common in active adolescents due to
Inherent weakness of apophyseal cartilage
Most common site of pelvic avulsion injuries in adolescents
Ischial tuberosity: hamstrings
Iliac crest muscle/tendon attachment
Abdominal musculature
Muscle/tendon attachment of anterior superior iliac spine
Sartorius, tensor fasciae latae
Muscle/tendon attachment of anterior inferior iliac spine
Rectus femoris muscle
Muscle/tendon attachment of greater trochanter
Hip rotators
Muscle/tendon attachment of lesser trochanter
Iliopsoas muscle
Most common of all pediatric fractures. They may be sen in newborns as a result from birth trauma
Clavicle fractures
Vast majority of clavicle fractures occur in
Middle 1/3 of bone
In children less than 13 years of age, direct impact to shoulder may lead to a physeal fracture of the ______ clavicle, aka periosteal sleeve fracture
Lateral clavicle
Age of the appearance and physeal closure of CRITOE
Capitellum-1 and 14 years
Radial head- 3 and 16 years
Internal (medial) epicondyle- 5 and 15 years
Trochlea- 7 and 14 years
Olecranon- 9 and 14 years
External (lateral) epicondyle- 11 and 16 years
Humerus fractures peaks during adolescence secondary to increased sports participation and are most commonly what type of salter harris fracture
Type 2
In young children, elbow fractures are commonly _______, with a peak incidence if 5-7 years
Supracondylar fractures
Most common mechanism of elbow fractures
FOOSH injury and the hyperextension load
In the normal elbow, the anterior humeral line (line drawn along the anterior cortex of the distal humerus) should bisect the
Middle 3rd of capitellum
In the setting of supracondylar fracture, the capitellum is displaced _____ to the anterior humeral line
Posterior
Have the highest rate of complications among upper extremity fractures
Supracondylar fractures
Complications of supracondylar fractures
Neurovascular compromise, compartment syndrome, Volkmann ischemic contractures and cubitus varus
If the medial epicondyle is displaced greater than ____ mm, fractures require surgical fixation
5 mm
Majority of forearm fractures are located in the
Distal aspect of forearm
Fracture of the ulna and dislocation of the radial head
Monteggia fx
Radial fracture with disruption of the distal radioulnar joint
Galeazzi fx
In older children, the most common carpal bone fx is
Scaphoid fx
Scaphoid fx is important to be recognized due to risk of
Avascular necrosis
Physeal injury of the proximal femur in which the femoral metaphysis displaces anteriorly, superiorly and laterally with respect to the epiphysis
Slipped capital femoral epiphysis
Most sensitive radiographic projection as the slipped epiphysis moves posteriorly and to a lesser extent more medially
Frog leg lateral
Presents as widening and irregularity of the proximal physis, relative loss of height of the epiphysis on the AP projection, loss of anterior concavity of the femoral neck, the metaphyseal blanch sign, and metaphyseal cystic change in chronic cases
Slipped capital femoral epiphysis
It is sign that presents as crescent-shaped area of increased density at the proximal and medial femoral neck as a result of the projection of the posterior portion of the femoral head
Metaphyseal blanch sign
Line drawn along the superior margin of the femoral neck
Kline’s line
In normal hips, the Kline’s line will intersect the _____ aspect of the epiphysis. In SCFE, the epiphysis is displaced ______ and the Kline’s line does not intersect the epiphysis or intersect more ______ compared to the other side
Normal- lateral aspect
SCFE- displaced medially or intersects more laterally compared to the asymptomatic side
Treatment for moderate SCFE
In situ pinning
In more severe SCFE, treatment is
Open reduction with gentle manipulation of the head of the femur back into its normal anatomic location followed by screw fixation
Most common complications following SCFE are
Avascular necrosis and chondrolysis
Occurs when cartilage of the inferior pole of the patella is pulled off from the inferior patellar pole, often with a small avulsed osseous fracture
Patellar sleeve fractures
On radiographs, it may show a small bone fragment inferior to the lower pole of the patella, patella alta and a joint effusion
Patellar sleeve fracture
Seen in children 8-13 y.o and are usually sports-related injuries occuring especially during cycling or skiing
Tibial spine avulsion fractures or tibial eminence fractures
Cause of tibial spine avulsion fracture
Weakness of the incompletely ossified tibial eminence compared to the stronger anterior cruciate ligament
Most common seen in teenage boys and the injury usually involves active extension of the knee with vigorous contraction of the quadriceps muscles, typically in jumping sports
Tibial tubercle fractures
Treatment for fractures confined to the tibial tubercle only
Conservative management
Tibial tubercle Fractures that extend into the epiphysis are treated by
Surgical fixation
Can occur due to axial loading injuries sustained by young children jumping on trampolines or in similar environments such as bounce houses, generally with larger child/adult
Fractures of the proximal tibial metaphsis or “trampoline fractures”
Presents as nondisplaced and non angulated linear or buckle fracture of the proximal tibial metaphysis and can be quite subtle
Trampoline fractures
Nondisplaced oblique fracture of the distal tibia that typically presents in childreb between 1 and 4 years of age
Tibial “toddler’s fracture”
Nature of trauma is usually mild, such as twisting injury from tripping while walking or running or fall from a modest height. Most of the time no history of trauma can be elicited
Distal Tibial toddler fracture
Appears as a faint oblique line crossing the distal tibial shaft terminating medially
Distal tibial toddler fracture
Ogden tibial fx classification: fracture of distal aspect of the tibial tubercle near the patellar tendon insertion
1A
Ogden tibial fx classification: fragment is displaced anteriorly and proximally
1b
Ogden tibial fx classification: fracture extends thru the junction of the ossification of the proximal end of the tibia and tubercle
2a
Ogden tibial fx classification: tubercle fragment is comminuted
2B
Ogden tibial fx classification: fracture extends to the joint and is associated with discontinuity of the joint surface
3A
Ogden tibial fx classification: tubercle fragment is comminuted
3B
Second most common physeal injuries in children. Seen only in adolescents, generally between 10 and 16 years of age, when the physis closes in an aymmetric pattern
Distal tibial transitional fractures, triplane and Tillaux fractures
Distal tibial physeal closure pattern
Centrally and then proceeds in an anteromedial direction, then posteromedially and finally laterally, which predicts the specific injury pattern
Salter 4 fx and have sagittal, transverse and coronal components traversing the physis
Triplane fractures
Isolated fracture to the anterolateral portion of the distal tibial epiphysis, a salter 3 injury. Seen in teenagers nearing skeletal maturity, affecting the only remaining portion of the distal tibial physis
Tillaux fractures
AP radiographs demonstrate a vertical fracture line withjn the distal tibial epiphysus extending laterally. Lateral radiograph will show an avulsed fragment displaced anteriorly
Tillaux fx
Length of displacement of triplane and tillaux fx that would need surgical reduction
More than 2mm
Tibial stress fx usually involve what part
Proximal 3rd of the bone and more common posteriorly
More sensitive modality in detecting stress fx
MRI
These fx are uncommon in active young children however can be seen in adolescents with the so-called “female athlete triad”: osteoporosis, amenorrhea and eating disorders
Insufficiency fx
Important cause of foot pain in the young child
Metatarsal and tarsal bones injuries
Impaction injuries of the hindfoot in toddlers can cause
Nondisplaced or buckle type fx of talus or calcaneus
May occur in young children with forced plantar flexion of the foot, with compression of the cuboid and the 4th and 5th metatarsals
Nondisplaced cuboid fx
Bunk bed fracture, sustained when a child falls or jumps from a height (vertical loading with plantar flexion) and there is buckle injury of the proximal aspect of the metatarsal
First metatarsal fx
Caused by acute injury or repetitive microtrauma that leads to thinning of the articular cartilage, fragmentation of the subchondral bone, and occasionally, loose bodies
Osteochondral lesions
Most common locations for osteochondral lesions
Weight bearing regions of the femoral condyle, capitellum of elbow in throwing athlete and gymnasts, and the ankle
“Bone-cartilage conditions” common in young children and comprise a heterogeneous group of injuries to the epiphyses, physis and apophyses
Osteochondroses
Result from a disturbance in endochondral ossification and are typically self-limited. Rapid growth, genetics, anatomic considerations, trauma, diet and a defect in vascular supply are proposed etiologies
Osteochondroses
Osteochondroses follow a unique series of events, which are:
Necrosis of bone, revascularization, reorganization, with granulation tissue formation and invasion, osteoclast resorption of necrotic segments and ultimately osteoid replacement with mature lamellar bone formed
Common location of osteochondral lesions in the knee
Lateral aspect of medial femoral condyle, weight-bearing surface of medial or lateral femoral condyle, patella, trochlea
Common OCL in the elbow
Capitellum, lateral aspect of trochlea
Common location of OCL in ankle/foot
Medial aspect of talus, lateral aspect of talus, central talar dome, distal tibia, subtalar facet, talar head
Osteochondrosis of the femoral head and is common cause of hip pain and limp in preadolescent children
Legg-Calve’-Perthes disease
Peak age and sex predilection of legg-calve-perthes disease
5-6 years, more common in boys
Most cases of legg-calve-perthes are unilateral or bilateral?
Unilateral
Early in its course of disease, radiographs may demonstrate widening of the medial joint space and asymmetrically smaller femoral epiphysis of the affected side with sclerosis. Physis may become indistinct, lucency may be seen within the femoral metaphysis, overtime the epiphysis may begin to fragment and flatten. Coxa magna of the femoral neck develops
Legg-calve- perthes disease
Prognostic indicators in legg-calve-perthes disease
Extent of osteonecrosis, amount of lateral extrusion, physeal involvement and metaphyseal abnormalities
Radiographic findings indicative of subsequent growth disturbance in legg-calve-perthes disease
Physeal abnormalities and metaphyseal lucencies
True or false: the younger the age of presentation in legg-calve-perthes disease, the more benign the course
True
asymmetrical, circumferential enlargement and deformation of the femoral head and neck.
Coxa magna of femoral neck
Self limiting osteochondrosis of the developing capitellum that affects children younger than 12 years. Most commonly seen in baseball pitches and falls into the spectrum of “little leaguers elbow”
Panner disease
Presumed cause of panner disease
Repetitive chronic impaction injury to the tenuous blood supply of the capitellum
True or false: the entire capitellum is usually involved in panner disease
True
Radiographically, it appears as demineralization of the capitellum with loss of the normally sharp cortical margins, followed by sclerosis and loss of volume and ultimately progressing to frank fragmentation
Panner disease
True or false: the overlying articular cartilage of capitellum is not affected in panner disease
True
Osteochondrosis of the tarsal navicular bone which occurs between 4 and 9 years of age with a higher prevalence in boys
Kohler disease
Sclerosis and narrowing/flattening of the tarsal navicular bone
Kohler disease
Osteochondrosis of the metatarsal head
Freiberg’s infarction
Freiberg’s infarction commonly affects the
Second metatarsal head, followed by the 3rd metatarsal head
On radiographs, it appears as widening of the metatarsophalangeal joint with collapse and sclerosis of the metatarsal head. This may be associated with loose body formation, dorsal spurring and consequent thickening of the metatarsal shaft
Freiberg’s infarction
Non accidental trauma such as skull fractures, rib fractures and displaced metaphyseal injuries predominate at what age
Infancy
Long bone injuries from non accidental trauma predominate at what age
After 1 year of age
Fractures with high specificity for abuse include
Classic metaphyseal lesions, rib fractures (especially posterior), scapular fractures, spinous process fx, and sternal fractures
Aka corner fractures or bucket handle fractures
Classic metaphyseal lesion
Salter-Harris II
Most frequently encountered long bone injury in abused children and are commonly seen in what bones
Distal femora, proximal and distal tibia and proximal humeri
True or false: CMLs may heal without significant callus or subperiosteal new bone formation which makes dating assessment difficult
True
When should follow up skeletal surveys be done in non accidental trauma patients as this will increase the sensitivity of depicting subtle or occult fractures
2 weeks after
3 major pathways of bone infection
Hematogeneous, direct inoculation and via extension from adjacent soft tissue infections
In children, acute osteomyelitis is most commonly acquired _______
Hematogeneously
Most common organisms involved in osteomyelitis in children
Staphylococcus aureus, B-hemolytic streptococcus and streptococcus pneumoniae, E.coli and pseudomonas aeruginosa
Acute hematogeneous osteomyelitis primarily involves the
Metaphyses of long bones or metapgyseal equivalents (osseous regions adjacent to a physis)
Metaphyses of long bones are common site for acute hematogeneous osteomyelitis due to
Presence of slow-flowing venous sinusoids
Complications of acute osteomyelitis
Subperiosteal abscess and ultimately dissecting into the adjacent soft tissues, thrombophlebitis, septic emboli, growth arrest due to bone bar formation, pathologic fx and chronic osteomyelitis
Most cases of epiphyseal osteomyelitis or chondritis occur in children of what age
Younger than 4 years
Epiphyseal osteomyelitis or chondritis are best demonstrated as
Avascular/non enhancing regions of affected cartilage