DDH (Developmental Dysplasia of the Hip) Flashcards Preview

Pediatrics > DDH (Developmental Dysplasia of the Hip) > Flashcards

Flashcards in DDH (Developmental Dysplasia of the Hip) Deck (20)
Loading flashcards...
1
Q

What is developmental dysplasia of the hip (DDH)?

A

Disorder of abnormal development resulting in dysplasia and possible subluxation or dislocation of the hip secondary to capsular laxity and mechanical factors
Is a spectrum of disease:
Dysplasia- a shallow or underdeveloped acetabulum
Subluxation
Dislocation
Teratologic hip- dislocated in utero and irreducible on neonatal exam presents with a pseudoacetabulum
Late (adolescent) dysplasia- mechanically stable and reduced but dysplastic

2
Q

What are the risk factors for DDH?

A

1) first born
2) female (6:1 over males)
3) breech
4) family history
5) oligohydramnios

Female left hip is MC location

3
Q

Where is the acetabular deficiency typically in DDH?

A

Anterior or anterolateral

Is cerebral palsy it is posterosuperior

4
Q

What are the 3 physical diagnostic tests of DDH?

A

Barlow- a dislocatable hip will dislocate with adduction and posterior force
Ortolani- a reducible hip will reduce with abduction and traction
Galeazzi- knees bent, dislocated leg appears shorter

Barlow and Ortolani a rarely positive after 3 months of age because of soft-tissue contractures about the hip

5
Q

What is the most sensitive sign of DDH in a child >3 months?

A

Limitation of hip abduction

Children who are of walking age may have Trendelenburg gait

6
Q

What are some radiographic lines a/w a hip dislocation in DDH?

A

1) Hilgenreiner’s line- horizontal line through right and left triradiate cartilage; femoral head ossification should be inferior to this line
2) Perkin’s line- line perpendicular line to Hilgenreiner’s through a point at lateral margin of acetabulum; femoral head ossification should be medial to this line
3) Shenton’s line- arc along inferior border of femoral neck and superior margin of obturator foramen
arc line should be continuous

7
Q

Development of what after a hip reduction of DDH after reduction is thought to be good prognostic sign for hip function?

A

Acetabular teardrop

8
Q

What are radiographic signs in dysplasia of DDH?

A

1) Acetabular index- line drawn from point on the lateral triradiate cartilage to point on lateral margin of acetabulum and Hilgenreiners line; should be less than 25° in patients older than 6 months
2) Center Edge Angle (CEA)- angle formed by a vertical line from the center of the femoral head and a line from the center of the femoral head to the lateral edge of the acetabulum; less than 20° is considered abnormal
(reliable only in patients over the age of 5 years)

9
Q

What imaging modality is used to follow reduction with use of a Pavlik harness for DDH?

A

Ultrasound

US not used for screening exam unless at 4-6 wks have positive exam or risk factors

10
Q

What is the study of choice to view reduction following closed reduction and spica casting of DDH?

A

CT

11
Q

What age groups are various treatment modalities initiated for the treatment of DDH?

A

1) 18 months- open reduction and spica casting (or if closed reduction fails)
4) > 2yrs- open reduction and pelvic osteotomy (more common in kids >4yo)

12
Q

What is the goal position in Pavlik harness application in DDH?

A

90-100° hip flexion, 50° abduction
worn for 23 hours/day for at least 6 weeks or until hip is stable; wean out of harness over 6-8 weeks after hip has stabilized until normal anatomy develops
Follow initially every week with US; if not reduced by 3 weeks then closed v open reduction and spica cast

13
Q

What are some technical points of hip spica casting for DDH?

A

1) 100° hip flexion
2) 45° hip abduction (may require adductor tenotomy)
3) use arthrogram to confirm reduction intra-op
4) CT post-op to confirm reduction
5) casted for 3 months; change at 6 wks

14
Q

What are the pelvic osteotomies for DDH?

A

All used to increase anterior or anterolateral coverage of femoral head
Salter- Single cut above acetabulum through the ilium to sciatic notch (Tr open, younger kids)
Triple (Steele)- Salter with additional cuts through rami (Tr open, older kids)
Pemberton- starts below AIIS and ends at Tr (Tr open, moderate to severe DDH, most versatile)
PAO (Ganz)- multiple osteotomies in the pubis, ilium, and ischium near the acetabulum (Tr closed; posterior column intact)

15
Q

What are the salvage pelvic osteotomies for DDH?

A

Shelf- Add bone to lateral acetabulum (relies on fibrocartialge metaplasia)
Chiari- cut above acetabulum to sciatic notch and shift ileum lateral beyond edge of acetabulum (relies on fibrocartilge metaplasia)

16
Q

What are complications seen in the treatment of DDH?

A

Osteonecrosis- increased rates with forceful abduction, failed closed tx, repeat surgery
Transient femoral nerve palsy- seen with excessive flexion with Pavlik bracing

17
Q

The acetabular teardrop is composed of what structures?

A

Quadrilateral surface and cotyloid fossa

18
Q

When does the ossific nucleus of the proximal femur become visible on radiographs?

A

At 6 months of age

19
Q

What are impediments to reduction of the DDH?

A

1) constriction of the joint capsule of hip: most important type of obstruction in older children;
2) contraction of the psoas tendon over acetabular inlet;
3) hypertrophy of the transverse acetabular ligament;
4) pulvinar
5) ligamentum teres;
6) inverted neolimbus
7) Labrum

20
Q

Using the posterior lower extremity straps of a Pavlik harness to produce abduction is a/w?

A

AVN; posterio straps are used to prevent adduction; anterior straps are used for hip flexion