Radiology 2B Week 7

What is the most common type of hip dislocation?

Posterior (85%)

What fracture is associated with posterior hip fracture?

Posterior lip of acetabulum (90%)

What is the mechanism of posterior hip dislocation?

Hip flexion and adduction with direct blow to the knee

What direction will the hip be on x-ray from the acetabulum in posterior hip dislocation?

Cephalad and lateral

What % of all dislocations are hip dislocations?

5%

What is the normal mechanism of anterior hip dislocation?

forced abduction and extension

What are the complications of hip dislocations?

Nerve injury (more common in adults)

Sciatic nerve paralysis

myositis ossificans

AVN of femoral head (10%)

post-traumatic degenerative arthritis

What are the AKAs of slipped capital femoral epiphysis?

adolescent coxa vara

epiphyseal coxa vara

epiphysiolisthesis

What type of fracture is SCFE?

Salter Harris Type 1

What deformity is caused by SCFE on the femur head?

Upward displacement, external rotation, and adduction of the neck on the head

What deformity is caused by SCFE on the femur?

Varus deformity, adduction, and external rotation of the femur

What is the peak age of SCFE for males?

13

What is the peak age of SCFE for females?

12

What is the peak age range of SCFE?

10-15

What is the most important factor in the ethology of SCFE?

Elevated body weight

What race is most commonly affected by SCFE?

African American

Which hip is more commonly affected by SCFE?

Left

What gender is Bilateral SCFE more common in?

Female (20-30 of SCFE)

What is the most common disorder of the adolescent hip?

SCFE

What is the classic presentation of SCFE?

Limp with hip pain referred to knee in an obese adolescent

What is the term for the presentation of SCFE?

Frolich body type (adiposogenital dystrophy)

What can cause pain at the thigh or knee with SCFE?

Irritation of the gene branch of the obturator nerve

What test is positive with severe SCFE?

Trendelenburg

What other conditions are associated with SCFE?

renal osteodystrophy

hypothyroidism

rickets

radiotherapy

What views are used to observe SCFE?

AP and frog leg

What are the X-ray findings of SCFE?

Posterior medial slippage of the epiphysis

apparent widening of the growth plate

Reduced epiphyseal height

Medial epiphyseal "beaking"

Widened teardrop space

Medial femoral neck periosteal buttressing

Abnormal klein's line

What are the potential complications of SCFE?

Coxa vara deformity

Femoral neck broadening and shortneing

AVN of femoral head (35%)

Acute cartilage necrosis (chondrolysis)

Osteoarthritis (MC)

What is the most common complication of SCFE?

Osteoarthritis

What is the AKA of tibial plateau fracture

bumper/fender fracture

What causes tibial plateau fracture?

Femoral condyles impacting into tibial plateau

What demographic is most commonly affected by tibial plateau fracture?

>50 yo (especially with osteoporosis)

What side of the tibia is more commonly affected by tibial plateau fracture?

Lateral (80%) - (medial 5-10%, BL 10-15%)

What view is best to visualize tibial plateau fracture?

Internal rotation

External rotation

What ligaments are typically injured along with tibial plateau fracture?

MCL/LCL

ACL/PCL

(10-12%)

What ligament of the knee is the anterior tibial spine the origin of?

Anterior cruciate ligament

What is the MOI of anterior tibial spine fracture?

hyperextension of knee with internal rotation of tibia

What demographic is anterior tibial spine fracture most common in?

Children (from fall off bicycle)

What is the MOI of trampoline fracture?

Impact between the descending child's leg and the upward moving mat

What age group is most affected by trampoline fracture?

2-10 yo

What part of the body is affected with trampoline fracture?

Proximal tibial metaphysics fracture

What demographic is most commonly affected by tibial tuberosity avulsion?

Adolescent boys

What can tibial tuberosity avulsion be predisposed by the presence of?

Osgood schlatter

What motion causes tibial tuberosity avulsion?

Athletic activities with knee flexed and quadriceps tendon contracted (jumping)

What is the term for avulsion of the bony insertion of the TFL (iliotibial band) at the margin of the lateral tibial condyle?

Segond's fracture

What motion causes segond's fracture?

Forced internal rotation with various stress (skiing, basketball, baseball)

What is most commonly associated with segond fracture?

ACL tear (75-100%)

Meniscus tears (70%)

T or F: Isolated fractures of proximal fibula commonly occur with knee injuries

False (they are rare (in general))

What is usually associated with proximal fibula fractures?

Ligamentous injury to the knee

lateral tibial plateau fracture

ankle fracture

What nerve is commonly injured with proximal fibula fracture

common peroneal nerve

What causes lipohemarthrosis?

Intra-articular fracture of the knee

What is the name sign of lipohemarthrosis?

FBI sign (fat-blood interface)

Which floats on top in FBI sign?

Fat

What view is necessary to view lipohemarthrosis?

Cross table lateral

What is the most common patellar fracture?

transverse (60%) or slightly oblique

Which bursa of the knee is affected by lipohemarthrosis?

Suprapatellar bursa

What are the DDxs of patellar fracture?

bipartite or tripartite patella (80% are bilateral)

What is the AKA of stellate patellar fracture?

Comminuted

What % of patellar fractures are stellate?

25%

What % of patellar fractures are vertical?

15%

What is the location of bipartite patella?

Superolateral portion (a rare site for patellar fracture)

What are the potential directions of patellar dislocation?

Lateral, horizontal, or vertical

Which patellar fracture is associated with recurring patellar dislocations?

Flake fracture (osteochondral fragment)

What is the most common direction of patellar dislocation?

Lateral (from trauma or torsional stress with fast change in direction)

What is the name sign of flake fracture on x-ray?

Sliver sign

What views are used to see flake fracture of the patella?

Sunrise view or CT scan

T or F: Patellar dislocation is a predisposing factor for patellar dislocation

True

What causes flake fracture in patellar dislocation?

Spasm of muscles pulling the medial patellar facet into the femur

What are the potential complications of knee fracture or dislocation?

Ligamentous tear

Meniscus injury

Osteochondral fracture

What is the term for fracture through both the tibia and fibula near the mid shaft?

Boot top fracture

What are the routine radiographic projections of the ankle?

AP

lateral

medial oblique

What is the best modality for viewing the ankle articulations?

CT

What is the best modality for viewing soft tissue contrast of the ankle?

MRI

What are the two major classification systems of ankle fracture?

Dennis weber

Lauge-hansen

What is the Dennis-weber classification based on?

Fibular fracture compared to the tibiotalar joint space

What is the lauge-hansen classification based on?

MOI

What motion is primarily restricted with ankle fracture?

Dorsiflexion

What motion will cause a push-off fracture of the distal fibula?

Pronation

What motion will cause a pull-off (avulsion) of the distal tibia?

Supination

What is the typical orientation of medial malleolus fractures?

Transverse or oblique

T or F: Fractures distal to the ceiling of the tibiotalar joint (plafond) are less stable than proximal ones

False (more stable)

What is the most common fracture of the ankle?

Lateral malleolus

What is the normal orientation of lateral malleolus fracture?

Oblique or spiral

What is the MOI of lateral malleolus fracture?

external rotation of the foot

What is the best projection for viewing lateral malleolus fracture?

Medial oblique

What complication often comes with lateral malleolus fracture?

Talar dome osteochondral defect

T or F: Bimalleolar fractures are usually transverse on one side and oblique or spiral on the other

True

What type of force causes the transverse fracture on one side of bimalleolar fracture?

Tensile

What is the term for a fracture of posterior lip (third malleolus) of the tibia?

Cotton fracture

What other deformity often comes with cotton fracture?

Tibiotalar dislocation

What is the MOI of cotton fracture?

External rotation of the foot

What other deformity often comes with trimaleolar fracture?

Tibiotalar dislocation

What is the MOI of trimaleolar fracture?

External rotation of the foot

What is the best projection for fracture of the third malleolus?

Lateral ankle

What direction is the third malleolus displaced when fractured?

Posterior and superior

What is the term for proximal fibular shaft fracture with rupture of the distal tib-fib syndesmosis?

Maisonneuve fracture

What is the MOI of Maisonneuve fracture?

Forceful inversion and external rotation of the ankle

Where is the pain found in Maisonneuve fracture?

Ankle

What is the term for a non displaced spiral fracture of the tibia in children?

Toddler's fracture

What age is toddler's fracture found in?

9 mo to 3 yo

What is the MOI of toddler's fracture?

Fall or child gets a foot caught between the slats of the crib and then rolls over