Developmental dysplasia of the hip (DDH, formerly known as congenital dislocation of the hip) describes any abnormality found in the neonatal hip joint. The degree of abnormality varies considerably. The problem may arise from structural defects in the head of the femur, the acetabulum or surrounding structures. Approximately 1 in 100 births are affected and it is more common in the left hip.
It is not always detectable at birth.
Most cases can be treated conservatively with braces (usually a Pavlik Harness) or in some cases, casting. It is associated with an increased risk of need for hip replacement in adulthood.
Epidemiology and Aetiology
- Affects 1-3% of newborns
- 80% of cases are in females – probably due to hormonal effects on ligament laxity
- 20% of cases are bilateral
- Left hip predominance is thought to be due to the left occiput anterior position in utero, which is more common than the right lie
- Breech position with vaginal delivery increases the risk 17x !
- Breech with caesarian increases the risk 7x
- Swaddling babes tightly, with legs straight (seen in some cultures) increases the risk
- These babies often present later (typically around age 3 months)
- Genetic factors
- Sibling with DDH increases risk by 5%
Screening is part of the newborn examination and the 6-8 week “baby check”.
- Screening consists of examination of the hips, typically with the Barlow and Ortolani tests
- Ultrasound screening is not routinely recommended for all children. However in those with the following risk factors, USS is recommended:
- FHx of DDH, or FHx hip problems in early life
- Breech presentation
Examination of the hips in a newborn
- Inspection: Look for difference in leg length by flexing knees fully and comparing knee height (Galeazzi’s sign). Look for defined skin creases (not very sensitive).
- Ortolani’s test: With knees flexed and in the midline the hip is abducted until flat on the bed. The examiners fingers should be on the greater trochanter.
- Barlow’s test: With hips in the position post-Ortolani’s test hips are adducted back to the midline with pressure applied posteriorly along shaft of femur.
- At >3 months of age, Barlow’s and Ortolani’s tests are unreliable, and ultrasound IS recommended as the investigation of choice in children of this age with suspected DDH
- Signs suggestive of DDH in children this age include:
- Restricted hip abduction
- Leg length discrepancy
- Asymmetrical thigh and gluteal skin folds
- Not a very reliable sign
- Seen in 25% of normal infants
- May not be asymmetrical in bilateral DDH
- Ultrasound is only recommended until 4.5 months old. After this age, X-ray is more sensitive
- CT and MRI are occasionally used, but require sedation
- USS will report:
- Femoral head coverage – this describes the amount of the femoral head that sites in the acetabulum. Normal >50%
- Alpha angle – Normal >60 degrees
- In older children
- Abnormal gait
- Affected hip externally rotated
- Toe-Walking on affected side
- Waddling gait, increased lumbar lordosis may be suggestive of bilateral DDH
- Abnormal gait
- Assess all children during use of a Pavlik harness to ensure adherence to the treatment, and to assess for femoral nerve palsy (loss of knee extension)
- If treatment is started by the age of 3 months, only 6% of children will need any further management
- It is more effective, the earlier it is started
- Pavlik harness is contraindicated in children greater than 4.5 months of age with an irreducible hip
- Defined as femoral head acetabular coverage of 40-50% OR an alpha angle of 50-60 degrees on USS
- Can be safely monitored in general practice without use of a harness
- Advise parents about safe swaddling and wrapping
- Repeat USS at 6 weeks
Moderate and severe DDH
- Obviously dislocating hip on examination, OR
- USS findings of <40% bony coverage or alpha angle of <50 degrees
- Pavlik Harness
- After 6 weeks in Pavlik Harness, repeat USS
- If remains abnormal – Pavlik harness for another 6 weeks, and repeat USS again
- If remains abnormal at 12 weeks, refer to orthopaedics for consideration for surgery
- Surgery typically includes an adductor or poses tenotomy, which reduces hip adduction, followed by 3-4 months of plaster cast – with the legs held in a similar position to Pavlik Harness
- Surgery after the age of 18 months is typically more difficult and less successful
- Surgery after 3 years is generally not recommended, and may have a better outcomes if the hip is left alone. By this age, there may not be sufficient remodelling of the hip after surgery and there is increased risk of osteonecrosis
- DDH - patient.info
- Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
- Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
- Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy