Refers to a wide range of pathology- from mild acetabular dysplasia with a stable hip to more severe dysplasia with instability, to established dysplasia with or without subluxation or dislocation. Usually detected in the neonate.
- It affects 1-3% of newborns.
- Early (post-natal) diagnosis and treatment can reduce the risk of progression and the development of complications
- When the femoral head is aligned with the centre of the acetabulum, the dysplastic acetabulum often normalises within the first few months of life. If the hip remains dislocated, soft tissue contractures develop rapidly and surgery may be required
- Left hip is more commonly affected than the right. Up to 20% are bilateral.
- More common in females (4:1)
- Exact cause is unknown but genetic factors and environmental influences may contribute.
- Having an affected sibling increases risk by 5%
- Breech presentation (17-fold; 7-fold if C-section)
- Large for gestational age
- Multiple pregnancy
Screening and Diagnosis
- Screening takes place within 24 hours of birth, before discharge from hospital, 6 weeks, between 6-9 months, and at walking age.
- Barlow and Ortilani tests are used post-natally and at 6 weeks to screen for DDH.
- asymmetry of leg folds
- Late diagnosis
- Limited hip abduction at 90° flexion; differences in knee height- ‘short thigh’- Galleazzi test (when lying supine at 90/90 flexion); leg length discrepency
- Problems with walking (NB not usually delayed walking, but trendelenburg gait), painless limp, walking on toes
- Ultrasound scans are useful in assessing DDH up until the age of 4-5 months whilst the hips are still cartilagenous. After this age, radiography is used to assess DDH.
- There may be a small ossific nucleus of the femoral head (the femoral head densifies in the newborn period- this may not occur in DDH)
- The joint may have subluxed (disruption of Shenton’s line)
- A high acetabular index (the angle of the acetabulum to the horizontal line between two hips)
- For children under 4.5-6 months who are Ortolani positive i.e. have a reducible hip, a Pavlik harness is most commonly used
- Secures the hips in 100° flexion and marked abduction. It allows the soft tissues of the capsule to strengthen and the tight hip adductors to stretch
- Surgery is usually required for children presenting late (>6 months) and in those who have failed harness treatment (e.g. Ortolani negative)
- If under 18 months, usually just reduction surgery
- If >18 months, additional osteotomy may be required