2 – Congenital dislocation of the hip
7. DDH (developmental dysplasia of the hip), etiology and pathology of
- DDH is the most common congenital musculoskeletal deformity
- Affects approx. 2 out of 100 000 newborns in Europe
- Left hip is slightly more often affected than the right
- Etiology
- Girls > boys
- Breech position during delivery
- Causes abnormal flexion of the hip
- Firstborn children > later-born children
- Family history
- Oligohydramnios
- Pathology
- The acetabulum is dysplastic and shallow
- Normally the acetabulum contains 2/3 of the femoral head
- In DDH the acetabulum contains less than 2/3
- This increases the pressure on the surface of the hip
- Subluxation / dislocation of the femoral head
- Due to the shallow acetabulum
- Secondary changes
- Occurs in untreated DDH -> secondary changes develop in the femoral head and acetabulum
- These secondary changes make hip reduction more and more difficult
- Bony changes
- Delayed ossification of femoral head
- Increased femoral antetorsion
- = the shaft of the femur has a torsion, causing the femoral neck to rotate anteriorly
- This increases the angle between the femoral neck and the condylar axis
- Increased collodiaphyseal angle
- Coxa valga
- Due to increased collodiaphysal angle
- Soft tissue
- Loose capsule
- Abnormal position of iliopsoas
- The iliopsoas normally runs in front of the head of the femur
- In DDH the tendon of the iliopsoas comes between the cavity of the acetabulum and the head of the femur
- This makes it difficult to reduce the head of the femur through the narrowed opening
38. DDH, clinical and X-ray features of
- Clinical features
- Limited motion of the limb
- Especially abduction (adduction contracture)
- Asymmetric skin folds on the thigh and gluteal region
- Positive Barlow sign
- A click is heard and felt when pressure is applied to dislocate the hip
- This test shows that the hip can be dislocated, but is not currently dislocated
- Positive Ortolani sign
- A click is heard and felt when pressure is applied to reduce the hip
- This test shows that the hip is reduceable and therefore currently dislocated
- Positive Ortolani sign is the only definitive sign of DDH
- Late
- Limb length difference
- Trendelenburg gait
- Diagnosis
- Screening at birth, 3 weeks, 3 months, 6 months
- Only in those with risk factors or if there is clinical suspicion
- US or X-ray
- Ultrasound
- Used for infants < 4 months
- Can detect clinically silent DDH
- X-ray
- Used for infants > 4 months
- In AP and Lauenstein view
- Shows acetabular dysplasia and hip location
- Femoral head is above the Hilgenreiner line
- Femoral head is lateral to the Perkin line
41. Conservative treatment of DDH
- If patient is < 6 months
- Baby must use a so-called Pavlik harness or an abduction splint, which secures the baby’s hips in a stable “frog-leg” position, allowing them to develop normally
- Pavlik harness fixes the femoral head in the correct position
- Over the time acetabulum will be deepened
- Abnormal use of the Pavlik harness can cause osteonecrosis of the femoral head
- Pavlik harness rapidly becomes ineffective after 4 months of age -> abduction splint or plaster cast
- Has high success rate when used correctly
52. Surgical treatment of DDH (developmental dysplasia of the hip)
- If patient is already > 6 months old OR conservative treatment didn’t work
- The specific surgical treatment depends on the exact pathology, but it always involves open reduction of the joint
- Other procedures which may be necessary
- Soft tissue procedures
- Adductor and/or iliopsoas muscles may need operation because they adapt to the dislocated joint, causing contracture
- Femur osteotomy (= varus de-rotational osteotomy)
- Corrects collodiaphyseal angle and antetorsion
- Pelvic osteotomy (= acetabulum-plasty)
- Dega osteotomy
- Done when socket is too wide and too shallow
- Salter osteotomy
- Done when the socket doesn’t sit properly on the femoral head
- Patient must wear spica cast afterwards