MSK - Developmental dysplasia of the hip

Question 1

Definition

Answer 1

Developmental dysplasia of the hip (DDH) = spectrum of anatomical abnormalities of the hip joint due to abnormal development of the foetal bones:
- Dysplasia: the acetabulum is shallow but the femoral head remains within the joint.
- Subluxation: the femoral head is partially displaced but some contact remains with the acetabulum
- Dislocation

Question 2

Epidemiology

Answer 2

• Sex: females are 4-5 times more likely than males to have DDH
• Family history: first-degree
• Firstborn child
• Breech presentation
• Multiple pregnancy
• Oligohydramnios
• Birth weight > 5kg
• Congenital calcaneovalgus foot deformity

Question 3

Signs

Answer 3

• Positive Ortolani Sign
• Positive Barlow Sign
• Asymmetry of thigh or gluteal folds
• Limited hip abduction

Question 4

Symptoms

Answer 4

• Asymptomatic
• Abnormal gait: unilateral toe-walking or limp
• Leg length discrepancy

Question 5

Screening

Answer 5

The newborn and infant physical examination (NIPE) screens for DDH using two special tests.
Performed within 72 hours of birth + again at 6 to 8 weeks of age:
- Barlow: The examiner grasps the infant’s thigh near the hip and with gentle posterior/lateral pressure, attempts to dislocate the femoral head from the acetabulum.
= Normally, there is no motion in this direction. If the hip is dislocatable, a distinct “clunk” may be felt as the femoral heads pops out of joint.
Ortolani: The hip is abducted and gentle pressure is applied to the proximal thigh from behind. The examiner attempts to relocate an already dislocated femoral head back into the acetabulum.
= If the joint is dislocated, a palpable “clunk” is noticed as the head slides back into place.

The following infants require a routine USS
- first-degree family history of hip problems in early life
- breech presentation at or after 36 weeks gestation, irrespective of presentation at birth or mode of delivery
- multiple pregnancy

Question 6

Diagnosis

Answer 6

FIRST LINE = Hip USS for infants under 6 months.
- Provides detailed view of the cartilaginous acetabulum and femoral head
Plain radiograph hip: typically used in older children, once the femoral head and acetabulum have ossified

If the infant is > 4.5 months then x-ray is the first line investigation

Question 7

Treatment

Answer 7

FIRST LINE: Pavlik harness: used for babies up to 6 months old.
- The harness holds the hip joint in abduction while allowing movement, promoting normal development
SECOND LINE:
- Closed reduction and spica casting: If FL unsuccessful/older infants. The hip is manually realigned under general anaesthesia and immobilised using a cast.
- Surgery (open reduction): recommended if non-surgical methods fail or in children over 18 months. After surgery, the hip is usually immobilised in a spica cast.

Question 8

Complications

Answer 8

Pain
Hip instability
Early-onset hip osteoarthritis
Femoral nerve palsy: this is typically a complication of treatment
Avascular necrosis of the femoral head