Developmental Dysplasia of the Hip - Orthopedics Flashcards
DDH etiology and pathology?
Aetiology:
1. Familial tendency
2. More commonly seen in
1. female children,
2. firstborn children,
3. frank/single breech position,
4. and pregnancies complicated by oligohydramnios
Pathology:
1. Maternal and fetal laxity, and intrauterine and postnatal malpositioning leads to initial hip instability, that leads to dysplasia
2. The acetabulum is abnormally shallow, and the femoral head slides our posteriorly
3. The joint capsules and ligaments are stretched and lax
4. Abnormal head-acetabulum relationship leads to both sides’ growth retardation and dysplasia
5. In neglected case, the abnormal hip shape leads to early secondary osteoarthritis
DDH clinical features?
A. Mother’s observation
б Before the baby starts walking, the mother may spot
1. asymmetry,
2. a clicking hip,
3. or difficulty in applying the napkins because of joint dislocation and limited abduction
б After walking, apparent liming with asymmetrical hips and thigh folds
B. Examination
б With unilateral dislocation
1. the skin creases lie at different levels on the two sides.
2. T he affected leg is slightly short and rotated externally.
3. Positive Trendelenburg’s test:
» while standing on the disease side,the pelvis drops on the unsupported healthy side because of abductor muscles impairment.
б Bilateral dislocation
1. is more difficult to detect because there is no asymmetry,
2. and the characteristic waddling gait may be mistaken for normal toddling.
3. However,
a. the perineal gap is abnormally wide, b. and abduction may be limited.
б Neonatal tests for instability.
» Ortolani’s and Bralow’s are easy provocative tests in which the physician can feel the “clunk” of hip dislocation and relocation.
DDH investigations and treatment>
Investigations:
A. Ultrasound examination
1. In neonates (< 6 months)
2. visualizes the cartilaginous head position in relation to the acetabulum.
3. Ultrasound screening is advocated for high-risk babies (females, firstborn, breach presentation)
B. X-ray examination
1. is of little value up to 6 months because the head is entirely cartilaginous and not visible radiologically.
2. In a child > 6 months, it shows
a. Shallow acetabulum and underdeveloped,
c. dislocated femoral head ossification center
Treatment:
б Delay in diagnosis and treatment results in a worse prognosis.
б The principles of treatment are to reduce the hip and to maintain reduction for an adequate period.
1. In newborns < 6 months:
» Most hips with a positive instability sign at birth become normal without treatment.
» However, if the ultrasound shows a defective acetabular roof, it is wiser to start splinting using a special abduction splint.
» This is maintained for 3-6 months until scanning shows a good acetabular roof.
2. Between the ages of 6 – 18 months:
» The objectives are to reduce the hip and hold it reduced until acetabular development is satisfactory.
» Closed reduction and fixation in spica cast.
3. Children > 18 months:
» Open reduction is mandatory.
» Addition of pelvic and/or femoral osteotomies may be required to reform the proper head acetabulum relationship