DDH Flashcards
What are risk factors for DDH?
Mat HTN, FGR, oligo, PROM, prolonged gestation, increased birth weight, Potter’s syndrome
How much more likely are breech babies to develop DDH?
four times
How much more likely are females to develop DDH than males?
2.5 times
How often is the left hip affected by DDH? How often is it unilateral?
Both 64% of the time
How does birth order affect DDH?
more common in first born
What ethnicities is DDH more common in?
Caucasians/North American tribes due to swaddling
What causes DDH?
Unknown, possibly increased laxity within joint capsule
What is the hormonal theory of DDH development?
Hormones affect connective tissue, maternal estrogen increase can increase muscle laxity
What is the mechanical theory of DDH development?
Restricted mobility: Swaddling, oligo, breech, primigravid uterus
What is the highest risk fetal position for DDH?
Frank breech
What is the genetic theory of DDH development?
Higher risk with family history
What clinical sign warrants hip US?
clicking sound
What is hip dysplasia?
Acetabulum is too shallow in socket
What age can the hips be evaluated until?
Until femoral head ossifies, up to 6 months, over 6mo xray
What forms the pelvic girdle?
Ilium, ischium, pubis
What is triradiate cartilage?
Connects 3 pelvic bones, made of growth plates that ossify at adulthood
What does the triradiate cartilage become after ossification?
Part of acetabulum
What forms the hip joint?
Femur and acetabulum
What is the labrum?
Fibrocartilage surrounding acetabulum, forms extension of acetabular “roof”
How much of the femoral head should be covered by labrum?
2/3
Where does blood supply travel to the pelvis?
Acetabular notch, nerves & vessels travel through
What is the transverse ligament?
Band of fibrous tissue surrounding nerves & vessels traveling through acetabular notch
Where does the gluteus maximus lie?
Superior to other muscles and posterior to hip
Where is the gluteus minimus located?
Immediate covering to upper hip joint
Where is the gluteus medius located?
Starts superior to minimus, both travel to greater trochanter, covers minimus
What is the Barlow maneuver?
Determines whether hip can be dislocated
- Pt supine, hip flexed 90 deg, adducted
- Press down & out
- Feel femoral head move out of acetabulum
What is Ortolani maneuver?
Determines whether dislocated femur head can be reduced back into place
- Supine pt, hip flexed 90 deg, abducted
What does a click during Ortolani maneuver indicate?
Does not indicate DDH
What does a clunk during Ortolani maneuver suggest?
DDH
What is the probe and patient position for transverse images?
Posterolateral over hip joint, hip flexed
How should the normal transverse hip appear?
Femoral head centered between metaphysis and ischium, triradiate cartilage b/w M & I
How does an abnormal hip appear in transverse?
Stress displaces femoral head, gap b/w fem head & ischium
What does the coronal view determine?
Degree of labrum covering fem head and position of fem head within acetabulum
What is the landmark for coronal flexion view?
gluteus medius
What needs to be visualized in the coronal view?
Ilium: straight and parallel
Labrum: included
Femoral head: sitting in acetabular roof and covered at least half by ilium
What are the appearances of the acetabular roof in coronal?
Sloped, irregular, rounded
How should the femoral head sit in relation to the acetabular roof?
FH shouldn’t be above AR, AR should cover FH by at least half
Where is line 1 drawn?
Baseline, drawn along ilium extending through femur
Where is line 2 drawn?
Drawn from bony edge of acetabulum at triradiate cartilage to lowest part of ilium
Where is line 3 drawn?
From ilium along labrum
What does alpha angle measure?
Acetabular depth, normal >60 degrees, between lines 1 & 3
What is the normal beta angle?
Between 1 & 2, normal <55 degrees
What are the Graf measurements for Type 1 hips? Modified & Graf classification
Modified: alpha >60 deg
Graf: alpha >60 deg, beta <55 deg
What are the modified and Graf classification measurements of a Type II hip?
Modified: alpha >50, <60
Graf: alpha >43, <60
What is a Type IIa hip?
normal from 0-3 mo, may be physiological laxity, f/u
What is type IIb hip?
up to 3 mo, indicates delayed development, f/u
What are the modified and Graf measurements of Type III hips?
Modified: alpha >43, <50, mild dysplasia
Graf: alpha <43, beta >77
What are the modified and Graf measurements of type IV hips
Modified: alpha <43, significant dysplasia
Graf: alpha <43, beta immeasurable
How does the Pavlik harness treat DDH?
Subluxed hip in neutral position will reinsert itself with constant flexion and abduction, harness keeps femur in place
